Category Archives: Operative Neurosurgery

Update: Cervical arthroplasty

Cervical arthroplasty was developed with the goal of preserving mobility of the cervical segment in patients with cervical degenerative disc disease.

Cervical total disc replacement (TDR) has been shown in a number of prospective clinical studies to be a viable treatment alternative to anterior cervical discectomy and fusion (ACDF) for symptomatic cervical degenerative disc disease. In addition to preserving motion, evidence suggests that cervical TDR may result in a lower incidence of subsequent surgical intervention than treatment with fusion.

One reason for this trend is the observation that in clinical studies, patients with a history of cervical arthrodesis seem to have a higher incidence of adjacent segment degeneration 1) 2) 3).

Furthermore, in biomechanical investigations, most authors have reported an increase in the segmental range of motion (ROM) and the intradiscal pressure (IDP) in the levels proximal and distal to a simulated mono- or bisegmental arthrodesis 4) 5) 6) 7) 8) 9) 10) 11) 12) 13).

While anterior cervical discectomy and fusion (ACDF) has been the standard of care for 2-level disease, a randomized clinical trial (RCT) suggested similar outcomes.

There are also critical debates regarding the long-term effects of heterotopic ossification (HO) and the prevalence of adjacent-level degeneration.

Evidence

Several large-scale clinical trials demonstrate the efficacy of 1- and 2-level cervical disc arthroplasty (CDA) for degenerative disc disease (DDD) in the subaxial cervical spine, while other studies reveal that during physiological neck flexion, the C4-5 and C5-6 discs account for more motion than the C3-4 level, causing more degenerative disc disease (DDD).

The results of a observational study were in accordance with those of the published randomized controlled trials (RCTs), suggesting substantial pain reduction both after anterior cervical interbody fusion (AIF) and Cervical total disc replacement, with slightly greater benefit after arthroplasty. The analysis of atypical patients suggested that, in patients outside the spectrum of clinical trials, both surgical interventions appeared to work to a similar extent to that shown for the cohort in the matched study. Also, in the longer-term perspective, both therapies resulted in similar benefits to the patients 14).

The available evidence showed that most of the pre-selected factors had no effect on outcome after CTDR, and the range of motion (ROM) success rate, incidence of heterotopic ossification (HO) and radiographic adjacent segment degeneration (r-ASD)/adjacent segment disease (ASD), and surgery rate for ASD are acceptable. There is a lack of evidence for some factors 15).

With a significant exception of a Cochrane review, the methodological quality of systematic reviews evaluating the evidence of C-ADR versus ACDF has to be improved. 16).

Outcome

Cervical total disc replacement presented favorable functional outcomes, fewer adverse events, and fewer secondary surgical procedures. The efficacy and safety of cervical total disc replacement are superior to those of fusion. Longer-term, multicenter studies are required for a better evaluation of the long-term efficacy and safety of the two procedures.

Although cervical disc arthroplasty (CDA) at C3-4 was infrequent, the improved clinical outcomes of CDA were similar at C3-4 to that in the other subaxial levels of the cervical spine at the approximately 5-year follow-ups. In this Asian population, who had a propensity to have ossification of the posterior longitudinal ligament, there was more heterotopic ossification (HO) formation in patients who received CDA at the C3-4 level than in other subaxial levels of the cervical spine. While the type of artificial discs could have confounded the issue, future studies with more patients are required to corroborate the phenomenon 17).

Cost-effectiveness

A study is the first to report the comparative cost-effectiveness of cervical total disc replacement (cTDR) vs anterior cervical discectomy and fusion(ACDF) for 2-level degenerative disc disease at 5 years. Ament et al conclude that, because of the negative incremental cost-effective ratio (ICER), cTDR is the dominant modality 18)

Patients who underwent CTDR for single-level degenerative disease had lower readmission rates, lower reoperation rates, and reduced index and total costs than those treated with ACDF. Cervical disc arthroplasty (CDA) was effective in reducing the monthly cost of care compared with ACDF19).

Based on a modeling evaluation, CTDR was found to be more effective and less costly over a 7-year time horizon for patients with single-level symptomatic degenerative disc disease. These results are robust across a range of scenarios and perspectives and are intended to support value-based decision making 20).

The incremental cost-effectiveness ratio of CTDR compared with traditional ACDF is lower than the commonly accepted threshold of $50,000 per QALY. This remains true with varying input parameters in a robust sensitivity analysis, reaffirming the stability of the model and the sustainability of this intervention 21).

At the same time, while generating clinical results comparable to spinal fusion, TDR incurred significantly lower costs. Therefore, both from the medical and from the financial point of view, TDR is a viable choice in the treatment of DDP 22).

Results of the sensitivity analysis indicated that CDR must remain functional for at least 14 years to establish greater cost-effectiveness than ACDF. Since the current literature has yet to demonstrate with certainty the actual durability and long-term functionality of CDR, future long-term studies are required to validate the present analysis 23).


Although cervical total disc replacement (TDR) has shown equivalence or superiority to anterior cervical discectomy and fusion (ACDF), potential problems include nonphysiological motion (hypermobility), accelerated degeneration of the facet joints, particulate wear, and compromise of the mechanical integrity of the endplate during device fixation.

There is no definitive evidence that TDR has better intermediate-term results than anterior cervical discectomy and fusion (ACDF) 24).


3D motion analysis data comparing patients after ACDF and AD replacement in ten patients who underwent C5-6 ACDF and 7 who underwent C5-6 AD replacement were enrolled. Using biplanar fluoroscopy and a model-based track technique (accurate up to 0.6 mm and 0.6°), motion analysis of axial rotation and flexion-extension of the neck was performed. Three nonoperative segments (C3-4, C4-5, and C6-7) were assessed for both intervertebral rotation (coronal, sagittal, and axial planes) and facet shear (anteroposterior and mediolateral). Results There was no difference in total neck motion comparing ACDF and AD replacement for neck extension (43.3° ± 10.2° vs 44.3° ± 12.6°, p = 0.866) and rotation (36.0° ± 6.5° vs 38.2° ± 9.3°, p = 0.576). For extension, when measured as a percentage of total neck motion, there was a greater amount of rotation at the nonoperated segments in the ACDF group than in the AD group (p = 0.003). When comparing specific motion segments, greater normalized rotation was seen in the ACDF group at C3-4 (33.2% ± 4.9% vs 26.8% ± 6.6%, p = 0.036) and C6-7 (28.5% ± 6.7% vs 20.5% ± 5.5%, p = 0.009) but not at C4-5 (33.5% ± 6.4% vs 31.8% ± 4.0%, p = 0.562). For neck rotation, greater rotation was observed at the nonoperative segments in the ACDF group than in the AD group (p = 0.024), but the differences between individual segments did not reach significance (p ≥ 0.146). Increased mediolateral facet shear was seen on neck extension with ACDF versus AD replacement (p = 0.008). Comparing each segment, C3-4 (0.9 ± 0.5 mm vs 0.4 ± 0.1 mm, p = 0.039) and C4-5 (1.0 ± 0.4 mm vs 0.5 ± 0.2 mm, p = 0.022) showed increased shear while C6-7 (1.0 ± 0.4 mm vs 1.0 ± 0.5 mm, p = 0.767) did not.

This study illustrates increased motion at nonoperative segments in patients who have undergone ACDF compared with those who have undergone AD replacement. Further studies will be required to examine whether these changes contribute to adjacent-segment disease 25).

The data from a investigational device exemption (IDE) study through 48 months signify a number of clinically relevant benefits for total disc replacement (TDR) over anterior cervical discectomy and fusion (ACDF). Patients experienced improved clinical outcomes with TDR—including improvement in pain and function outcomes and superiority in overall primary endpoint success. Additionally, incidences of adjacent segment degeneration and subsequent surgeries were reduced with TDR. Perhaps future studies and also longer-term followup of this patient cohort may continue to establish 2-level cervical TDR as a superior surgical option for symptomatic degenerative disc disease 26).


Cervical artificial disc replacement (ADR) is indicated for the treatment of severe radiculopathy permitting neural decompression and maintenance of motion.

The clinical and radiographic outcomes in cervical ADR patients using the ProDisc-C device (DePuy Synthes, West Chester, PA, USA) with a 5-9 year follow-up were collected through a prospective registry, with retrospective analysis performed on 24 consecutive patients treated with cervical ADR by a single surgeon. All patients underwent single- or two-level ADR with the ProDisc-C device. Outcome measures included neck and arm pain (visual analogue scale), disability (neck disability index [NDI]), complications and secondary surgery rates. Flexion-extension cervical radiographs were performed to assess range of motion (ROM) of the device and adjacent segment disease (ASD). Average follow-up was 7.7 years. Neck and arm pain improved 60% and 79%, respectively, and NDI had an improvement of 58%. There were no episodes of device migration or subsidence. Mean ROM of the device was 6.4°. Heterotopic ossification was present in seven patients (37%). Radiographic ASD below the device developed in four patients (21%) (one single-level and three two-level ADR). No patient required secondary surgery (repeat operations at the index level or adjacent levels). Fourteen out of 19 patients (74%) were able to return to employment, with a median return to work time of 1.3 months. The ProDisc-C device for cervical ADR is a safe option for patients providing excellent clinical outcomes, satisfactory return to work rates and maintenance of segmental motion despite radiographic evidence of heterotopic ossification and ASD on long-term follow-up 27).

Types

Biomechanical analysis

Scarce references could be found and compared regarding the cervical ADR devices’ biomechanical differences that are consequently related to their different clinical results.

One fusion device (CJ cage system, WINNOVA) and three different cervical artificial discs (Prodisc-C Nova (DePuy Synthes), Discocerv (Scient’x/Alphatec), Baguera C (Spineart)) were inserted at C5-6 disc space inside the FE model and analyzed. Hybrid loading conditions, under bending moments of 1 Nm along flexion, extension, lateral bending and axial rotation with a compressive force of 50 N along the follower loading direction, were used in this study. Biomechanical behaviors such as segmental mobility, facet joint forces, and possible wear debris phenomenon inside the core were investigated.

The segmental motions as well as facet joint forces were exaggerated after ADR regardless of type of the devices. The Baguera C mimicked the intact cervical spine regarding the location of the center of rotation (COR) only during the flexion moment. It also showed a relatively wider distribution of the contact area and significantly lower contact pressure distribution on the core compared to the other two devices. A ‘lift off’ phenomenon was noted for other two devices according to the specific loading condition.

The mobile core artificial disc Baguera C can be considered biomechanically superior to other devices by demonstrating no ‘lift off’ phenomenon, and significantly lower contact pressure distribution on core 28).

Revision surgery and explantation

Between November 2008 and July 2016, 16 patients with prior implantation underwent removal of the Galileo-type disc prosthesis (Signus, Medizintechnik, Germany) due to a call back by industry. In 10 patients C-ADR was replaced with an alternative prosthesis, 6 patients received an ACDF. Duration of surgery, time to revision, surgical procedure, complication rate, neurological status, histological findings and outcome were examined in two institutions.

The C-ADR was successfully revised in all patients. Surgery was performed through the same anterior approach as the initial access. Duration of the procedure varied between 43 and 80min. Access-related complications included irritation of the recurrent nerve in one patient and mal-positioning of the C-ADR in another patient. Follow up revealed two patients with permanent mild/moderate neurologic deficits, NDI (neck disability index) ranged between 10 and 42%.

Anterior exposure of the cervical spine for explantation and revision of C-ADR performed through the initial approach has an overall complication rate of 18.75%. Replacements of the Galileo-type disc prosthesis with an alternative prosthesis or conversion to ACDF are both suitable surgical options without significant difference in outcome 29).

Case series

2017

As part of an FDA IDE trial, a single center collected prospective outcomes data on 47 patients randomized in a 1:1 ratio to ACDF or arthroplasty.

Success of both surgical interventions remained high at the 10-year interval. Both arthrodesis and arthroplasty demonstrated statistically significant improvements in neck disability index, visual analog scale neck and arm pain scores at all intervals including 7- and 10-year periods. Arthroplasty demonstrated an advantage in comparison to arthrodesis as measured by final 10-year NDI score (8 vs. 16, P = 0.0485). Patients requiring reoperation were higher in number in the arthrodesis cohort (32%) in comparison with arthroplasty (9%) (P = 0.055).

At 7 and 10 years, cervical arthroplasty compares favorably with ACDF as defined by standard outcomes scores in a highly selected population with radiculopathy 30).

2016

A total of 200 subjects underwent single-level activC® (Aesculap AG) implantation between C-3 and C-7 for the treatment of symptomatic degenerative disc disease. Clinical and radiographic assessments were performed preoperatively, intraoperatively, at discharge, and again at 6 weeks, 6 months, 1 year, 2 years, and 4 years. Radiographic evaluations were done by an independent core laboratory using a specific software for quantitative motion analysis.

Neck Disability Index (NDI) and visual analog scale (VAS) score for neck and arm pain decreased significantly from baseline to the 4-year follow-up. The mean improvement for NDI was 20, for VAS severity and frequency of neck pain 26.4 and 28, and for VAS severity and frequency of arm pain 30.7 and 35.1, respectively. The neurological situation improved for the majority of patients (86.4%); 76.1% of cases were asymptomatic. Subsequent surgical interventions were reported in 7% of the cases, including device removals in 3%. In 2.5% a subsidence greater than 3 mm was recorded; 1 of these cases also had a migration greater than 3 mm. No device displacement, expulsion, disassembly, loose or fractured device, osteolysis, or facet joint degeneration at the index level was observed. Segmental lordotic alignment changed from -2.4° preoperatively to -6.2° at 4 years, and postoperative height was maintained during the follow-up. Advanced HO (Grade III and IV) was present in 27.1% of the cases; 82.4% showed segmental mobility. A progression of radiographic adjacent-segment degeneration occurred in 28.2%, but only 4.5% required surgical treatment.

The activ C is a safe and effective device for cervical disc replacement confirming the encouraging results after cTDR. Clinical trial registration no.: NCT02492724 ( clinicaltrials.gov ) 31)


A total of 225 patients received the Mobi-C cervical total disc replacement device and 105 patients received ACDF. The Mobi-C and ACDF follow-up rates were 90.7% and 86.7%, respectively (p = 0.39), at 60 months. There was significant improvement in all outcome scores relative to baseline at all time points. The Mobi-C patients had significantly more improvement than ACDF patients in terms of Neck Disability Index score, SF-12 Physical Component Summary, and overall satisfaction with treatment at 60 months. The reoperation rate was significantly lower with Mobi-C (4%) versus ACDF (16%). There were no significant differences in the adverse event rate between groups.

Both cervical total disc replacement and ACDF significantly improved general and disease-specific measures compared with baseline. However, there was significantly greater improvement in general and disease-specific outcome measures and a lower rate of reoperation in the 2-level disc replacement patients versus ACDF control patients. Clinical trial registration no. NCT00389597 ( clinicaltrials.gov ) 32).


Twenty patients (12 females, 8 males; median age 45.6 ± 6.9 years) treated by ACDA (BryanDisc®, Medtronic, Minneapolis, USA) underwent plain functional radiography and kinematic MRI of the cervical spine at 3T before and 6 and 24 months after surgery.

A sagittal T2-weighted (T2w) 2D turbo spin echo (TSE) sequence and a 3D T2w dataset with secondary axial reconstruction were acquired. Signal intensity of all nonoperated discs was measured in regions of interest (ROI). Disc heights adjacent to the operated segment were measured. Range of motion (ROM) was evaluated and compared to plain functional radiographs. Clinical outcome was evaluated using the visual analog scale (VAS) for head, neck and radicular pain, and the neck disability index (NDI).

Mean ROM of the cervical spine on functional plain radiographs was 21.25 ± 8.19, 22.29 ± 4.82 and 26.0 ± 6.9 degrees preoperatively and at 6-month and 24-month follow-up, respectively. Mean ROM at MRI was 27.1 ± 6.78, 29.45 ± 9.51 and 31.95 ± 9.58 degrees, respectively. There was good correlation between both techniques. Follow-up examinations demonstrated no signs of progressive degenerative disc disease of adjacent levels. All patients had clinical improvement up to 24 months after surgery.

After ACDA, kinematic MRI allows evaluation of the ROM with excellent correlation to plain functional radiographs. Mid-term follow-up after ACDA is without evidence of progressive DDD of adjacent segments 33).


A prospective, multicenter, randomized, unblinded clinical trial. Patients with symptomatic degenerative disc disease were enrolled to receive 1- or 2-level treatment with either TDR as the investigational device or ACDF as the control treatment. There were 260 patients in the 1-level study (179 TDR and 81 ACDF patients) and 339 patients in the 2-level study (234 TDR and 105 ACDF patients). RESULTS At 5 years, the occurrence of subsequent surgical intervention was significantly higher among ACDF patients for 1-level (TDR, 4.5% [8/179]; ACDF, 17.3% [14/81]; p = 0.0012) and 2-level (TDR, 7.3% [17/234]; ACDF, 21.0% [22/105], p = 0.0007) treatment. The TDR group demonstrated significantly fewer index- and adjacent-level subsequent surgeries in both the 1- and 2-level cohorts.

Five-year results showed treatment with cervical TDR to result in a significantly lower rate of subsequent surgical intervention than treatment with ACDF for both 1 and 2 levels of treatment. Clinical trial registration no.: NCT00389597 ( clinicaltrials.gov ) 34).

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Update: Awake surgery

An awake craniotomy is a safe neurosurgical procedure that minimizes the risk of brain injury. During the course of this surgery, the patient is asked to perform motor or cognitive tasks, but some patients exhibit severe sleepiness.

For neurosurgery with an awake craniotomy, the critical issue is to set aside enough time to identify eloquentcortices by electrocortical stimulation (ECS). High gamma activity (HGA) ranging between 80 and 120 Hz on electrocorticogram (ECoG) is assumed to reflect localized cortical processing.

Indications

Gross total removal of glioma is limited by proximity to eloquent brain. Awake surgery allows for intraoperative monitoring to safely identify eloquent regions.


For a long time, the right hemisphere (RH) was considered as “non-dominant”, especially in right-handers. In neurosurgical practice, this dogma resulted in the selection of awake craniotomy with language mapping only for lesions of the left dominant hemisphere. Conversely, surgery under general anesthesia (possibly with motor mapping) was usually proposed for right lesions. However, when objective neuropsychological tests were performed, they frequently revealed cognitive and behavioral deficits following brain surgery, even in the RH. Therefore, to preserve an optimal quality of life, especially in patients with a long survival expectancy (as in low-grade gliomas), awake surgery with cortical and axonal electrostimulation mapping has recently been proposed for right tumors resection. Here, we review new insights gained from intraoperative stimulation into the pivotal role of the RH in movement execution and control, visual processes and spatial cognition, language and non-verbal semantic processing, executive functions (e.g. attention), and social cognition (mentalizing and emotion recognition). Such original findings, that break with the myth of a “non-dominant” RH, may have important implications in cognitive neurosciences, by improving our knowledge of the functional connectivity of the RH, as well as for the clinical management of patients with a right lesion. Indeed, in brain surgery, awake mapping should be considered more systematically in the RH. Moreover, neuropsychological examination must be achieved in a more systematic manner before and after surgery within the RH, to optimize the care by predicting the likelihood of functional recovery and by elaborating specific programs of rehabilitation 1).

Operations in eloquent areas

Awake craniotomy was introduced for surgical treatment of epilepsy, and has subsequently been used in patients with supratentorial tumors, intracranial arteriovenous malformationdeep brain stimulation, and mycotic aneurysms near critical regions of brain.

Patients are selected for awake craniotomy when the planned procedure involves eloquent areas of the brain, necessitating an awake, cooperative patient capable of undergoing neurocognitive testing, especially speech area, (Broca’s areaWernicke’s area) near motor stripthalamus, removal of brainstem tumors, some seizure surgery.

The critical issue is to set aside enough time to identify eloquent cortices by electrocortical stimulation (ECS). High gamma activity (HGA) ranging between 80 and 120 Hz on electrocorticogram (ECoG) is assumed to reflect localized cortical processing. In this report, we used realtime HGA mapping and functional magnetic resonance imaging (fMRI) for rapid and reliable identification of motor and language functions. Three patients with intra-axial tumors in their dominant hemisphere underwent preoperative fMRI and lesion resection with an awake craniotomy. All patients showed significant fMRI activation evoked by motor and language tasks. After the craniotomy, we recorded ECoG activity by placing subdural grids directly on the exposed brain surface. Each patient performed motor and language tasks and demonstrated realtime HGA dynamics in hand motor areas and parts of the inferior frontal gyrus. Sensitivity and specificity of HGA mapping were 100% compared to ECS mapping in the frontal lobe, which suggested HGA mapping precisely indicated eloquent cortices. The investigation times of HGA mapping was significantly shorter than that of ECS mapping. Specificities of the motor and language-fMRI, however, did not reach 85%. The results of HGA mapping was mostly consistent with those of ECS mapping, although fMRI tended to overestimate functional areas. This novel technique enables rapid and accurate functional mapping 2).

Awake craniotomy for glioma

Craniotomies for glioma resection under conscious sedation (CS) have been well-documented in the literature for gliomas that are in or adjacent to eloquent areas 3) 4) 5) 6) 7).

Awake surgery for glioma aims to maximize resection to optimize prognosis while minimizing the risk of postoperative deficits.

The oncological and functional results of awake glioma surgery during the learning curve are comparable to results from established centers. The use and utility of resection probability maps are well demonstrated. The return to work level is high 8).

AC with the input of the speech and language therapist (SLT) and an experienced neuro-physiotherapist (NP) is a key component in ensuring optimal functional outcomes for patients with gliomas in eloquently located areas 9).

5 aminolevulinic acid guidance during awake craniotomy

Corns et al. describe the case of a patient with recurrent left frontal GBM encroaching on Broca’s area (eloquent brain). Gross total resection of the tumour was achieved by combining two techniques, awake resection to prevent damage to eloquent brain and 5-ALA fluorescence guidance to maximise the extent of tumour resection.This technique led to gross total resection of all T1-enhancing tumour with the avoidance of neurological deficit. The authors recommend this technique in patients when awake surgery can be tolerated and gross total resection is the aim of surgery 10)

Contraindications

Uncooperative (very young or too old patient).

Confusion.

Speech deficit

Language barrier

Brain mapping

Electrocortical stimulation (ECS) is the gold standard for functional brain mapping during an awake craniotomy.

Awake craniotomy could be challenging because of unsecured airway with risks of vomitting, epileptic attacks or unstable level of consciousness. It is considered that the patient monitoring becomes more difficult when iMRI is performed because the patient’s face cannot be obsereved directly. We should remember that conscious level as well as respiration pattern may change during operation 11).

Awake craniotomy can be safely performed in a high-field (1.5 T) iMRI suite to maximize tumor resection in eloquent brain areas with an acceptable morbidity profile at 1 month 12).

The routine use of fMRI was not useful in identifying language sites as performed and, more importantly, practiced tasks failed to prevent neurological deficits following awake craniotomy procedures 13).

Management of anesthesia

The importance of minimizing pain and preparing patients thoroughly to reduce anxiety and maximize cooperation. Awake surgery is an excellent treatment modality for brain tumors with very positive perception by patients 14).

Different anesthetic combinations, including neurolept, propofol with or without opioid infusions, and asleep-awake-asleep techniques, have been reported for awake craniotomy. In all these techniques, respiratory depression has been reported as a complication.

see dexmedetomidine

Different protocols exist for anesthetic care during awake craniotomy based on monitored anesthesia care (MAC) or general anesthesia (asleep-awake-asleep technique). Nevertheless the administration of anesthetics, expectedly, is not without drawbacks, side effects and risks. A new approach for awake craniotomies emphasizes the need of adequate communication with patients 15).

Scalp block

see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4236942/#ref11

Awake surgery with intraoperative brain mapping is highly recommended for patients with diffuse low grade gliomas in language areas, to maximise the extent of resection while preserving the integrity of functional networks and thus quality of life.

The picture naming test DO 80 is the gold standard for language assessment before, during, and after surgery.

Cognitive functioning is correlated with quality of life, itself linked with return to work.

The objective was to evaluate the significance of measuring naming speed, and its correlation with the return to professional activities. Two complementary studies are reported. In the first retrospective study, eleven patients were examined post-operatively. Five patients were selected because they were not able to resume their professional activities (“no return group 1”). They were compared with a control group of six patients who are working normally after surgery (“return group 1”). The eleven patients performed a global language and neuropsychological assessment, with a post-operative median follow-up of 35 months. In a subsequent prospective study, twelve patients were examined pre-operatively and post-operatively. Six patients who were not able to return to work (“no return group 2”) were compared with a control group of six patients who were working normally after the surgery (“return group 2”). The twelve patients performed a pre and post-operative language assessment, with a median follow-up of 9 months. Our results show, for the first time, that naming speed is significantly correlated with a major criterion of quality of life: the return to professional activities. There were no differences between the two groups regarding other measures of cognition. Assessing naming times, and not only naming accuracy, is essential in the management of low-grade glioma patients, before, during, and after surgery, to preserve their quality of life by resuming their previous professional activity. Our results have fundamental implications concerning the comprehension of language processing and its relationship with cognitive functioning 16).

Cost effectiveness

Retrospective analysis of a cohort of 17 patients with perirolandic gliomas who underwent an AC with DCS were case-control matched with 23 patients with perirolandic gliomas who underwent surgery under GA with neuromonitoring (ie, motor-evoked potentials, somatosensory-evoked potentials, phase reversal). Inpatient costs, quality-adjusted life years (QALY), extent of resection, and neurological outcome were compared between the groups.

Total inpatient expense per patient was ${\$}$ 34 804 in the AC group and ${\$}$ 46 798 in the GA group ( P = .046). QALY score for the AC group was 0.97 and 0.47 for the GA group ( P = .041). The incremental cost per QALY for the AC group was ${\$}$ 82 720 less than the GA group. Postoperative Karnofsky performance status was 91.8 in the AC group and 81.3 in the GA group (P = .047). Length of hospitalization was 4.12 days in the AC group and 7.61 days in the GA group ( P = .049).

The total inpatient costs for awake craniotomies were lower than surgery under GA. This study suggests better cost effectiveness and neurological outcome with awake craniotomies for perirolandic gliomas 17).

Case series

2017

Motomura et al. retrospectively reviewed the records of 33 consecutive patients with glial tumors in the eloquent brain areas who underwent awake surgery using iMRI. Volumetric analysis of MRI studies was performed. The pre-, intra-, and postoperative tumor volumes were measured in all cases using MRI studies obtained before, during, and after tumor resection. RESULTS Intraoperative MRI was performed to check for the presence of residual tumor during awake surgery in a total of 25 patients. Initial iMRI confirmed no further tumor resection in 9 patients (36%) because all observable tumors had already been removed. In contrast, intraoperative confirmation of residual tumor during awake surgery led to further tumor resection in 16 cases (64%) and eventually an EOR of more than 90% in 8 of 16 cases (50%). Furthermore, EOR benefiting from iMRI by more than 15% was found in 7 of 16 cases (43.8%). Interestingly, the increase in EOR as a result of iMRI for tumors associated mainly with the insular lobe was significantly greater, at 15.1%, than it was for the other tumors, which was 8.0% (p = 0.001).

This study revealed that combining awake surgery with iMRI was associated with a favorable surgical outcome for intrinsic brain tumors associated with eloquent areas. In particular, these benefits were noted for patients with tumors with complex anatomy, such as those associated with the insular lobe 18).

2016

Four illustrative cases demonstrate the efficacy of using a tablet computer platform for advanced language mapping testing with sophisticated language paradigms, and the spatial agreement between intraoperative mapping and preoperative fMRI results. The testing platform substantially improved the ability of the surgeon to detect and characterize language deficits. Use of a written word generation task to assess language production helped confirm areas of speech apraxia and speech arrest that were inadequately characterized or missed with the use of traditional paradigms, respectively. Preoperative fMRI of the analogous writing task was also assistive, displaying excellent spatial agreement with intraoperative mapping in all 4 cases. Sole use of traditional testing paradigms can be limiting during awake craniotomy procedures. Comprehensive assessment of language function will require additional use of more sophisticated and ecologically valid testing paradigms. The platform presented here provides a means to do so 19).

2015

Thirty-seven patients with brain tumor who underwent awake craniotomy were included in this study. Prior to craniotomy, the patient evaluated cognitive status, and during the surgery, each patient’s performance and attitude toward cognitive tasks were recorded by neuropsychologists.

The present findings showed that the construction and calculation abilities of the patients were moderately correlated with their sleepiness.

These results indicate that the preoperative cognitive functioning of patients was related to their sleepiness during the awake craniotomy procedure and that the patients who exhibited sleepiness during an awake craniotomy had previously experienced reduced functioning in the parietal lobe 20).

2009

From 1998 to 2007, 79 consecutive fully awake craniotomy (FAC)s for resection primary supratentorial brain tumors (PSBT) near or in eloquent brain areas (EBA), performed by a single surgeon, were prospectively followed. Two groups were defined based on time period and surgical team: group A operated on from March 1998 to July 2004 without a multidisciplinary team and group B operated on from August 2004 to October 2007 in a multidisciplinary setting. For both time periods, two groups were defined: group I had no previous history of craniotomy, while group II had undergone a previous craniotomy for a PSBT. Forty-six patients were operated on in group A, 46 in group B, 49 in group I and 30 in group II. Psychological assessment and selection were obligatory. The preferred anesthetic procedure was an intravenous high-dose opioid infusion (Fentanil 50 microg, bolus infusion until a minimum dose of 10 microg/kg). Generous scalp and periosteous infiltrations were performed. Functional cortical mapping was performed in every case. Continuous somato-sensory evoked potentials (SSEPs) and phase reversal localization were available in 48 cases. Standard microsurgical techniques were performed and monitored by continuous clinical evaluation.

Clinical data showed differences in time since clinical onset (p < 0.001), slowness of thought (p = 0.02) and memory deficits (p < 0.001) between study periods and also time since recent seizure onset for groups I and II (p = 0.001). Mean tumor volume was 51.2 +/- 48.7 cm3 and was not different among the four groups. The mean extent of tumor reduction was 90.0 +/- 12.7% and was similar for the whole series. A trend toward a larger incidence of glioblastoma multiforme occurred in group B (p = 0.05) and I (p = 0.04). Recovery of previous motor deficits was observed in 75.0% of patients, while motor worsening in 8.9% of cases. Recovery of semantic language deficits, control of refractory seizures and motor worsening were statistically more frequent in group B (p = 0.01). Satisfaction with the procedure was reported by 89.9% of patients, which was similar for all groups. Clinical complications were minimal, and surgical mortality was 1.3%.

These data suggest that FAC is safe and effective for the resection of PSBT in EBA as the main technique, and in a multidisciplinary context is associated with greater clinical and physiological monitoring. The previous history of craniotomy for PSBT did not seem to influence the outcome21).

1)

Vilasboas T, Herbet G, Duffau H. Challenging the myth of right “non-dominant” hemisphere: Lessons from cortico-subcortical stimulation mapping in awake surgery and surgical implications. World Neurosurg. 2017 Apr 15. pii: S1878-8750(17)30516-8. doi: 10.1016/j.wneu.2017.04.021. [Epub ahead of print] Review. PubMed PMID: 28419879.

2)

Kamada K, Ogawa H, Kapeller C, Prueckl R, Guger C. Rapid and low-invasive functional brain mapping by realtime visualization of high gamma activity for awake craniotomy. Conf Proc IEEE Eng Med Biol Soc. 2014 Aug;2014:6802-6805. PubMed PMID: 25571558.

3)

Bejjani GK, Nora PC, Vera PL, Broemling L, Sekhar LN. The predictive value of intraoperative somatosensory evoked potential monitoring: Review of 244 procedures. Neurosurgery 1998;43:491-8.

4)

De Benedictis A, Mortiz-Gasser S, Duffau H. Awake mapping optimizes the extent of resection for low-grade gliomas in eloquent areas. Neurosurgery 2010;66:1074-84.

5)

Peruzzi P, Bergese SD, Viloria A, Puente EG, Abdel-Rasoul M, Chiocca EA. A retrospective cohort-matched comparison of conscious sedation versus general anesthesia for supratentorial glioma resection. Clinical article. J Neurosurg 2011;114:633-9.

6)

Taylor MD, Bernstein M. Awake craniotomy with brain mapping as the routine surgical approach to treating patients with supratentorial intraaxial tumors: A prospective trial of 200 cases. J Neurosurg 1999;90:35-41.

7)

Wiedemayer H, Sandalcioglu IE, Armbruster W, Regel J, Schaefer H, Stolke D. False negative findings in intraoperative SEP monitoring: Analysis of 658 consecutive neurosurgical cases and review of published reports. J Neurol Neurosurg Psychiatry 2004;75:280-6.

8)

Mandonnet E, De Witt Hamer P, Poisson I, Whittle I, Bernat AL, Bresson D, Madadaki C, Bouazza S, Ursu R, Carpentier AF, George B, Froelich S. Initial experience using awake surgery for glioma: oncological, functional, and employment outcomes in a consecutive series of 25 cases. Neurosurgery. 2015 Apr;76(4):382-9. doi: 10.1227/NEU.0000000000000644. PubMed PMID: 25621981.

9)

Trimble G, McStravick C, Farling P, Megaw K, McKinstry S, Smyth G, Law G, Courtney H, Quigley G, Flannery T. Awake craniotomy for glioma resection: Technical aspects and initial results in a single institution. Br J Neurosurg. 2015 Jul 13:1-7. [Epub ahead of print] PubMed PMID: 26168299.

10)

Corns R, Mukherjee S, Johansen A, Sivakumar G. 5-aminolevulinic acid guidance during awake craniotomy to maximise extent of safe resection of glioblastoma multiforme. BMJ Case Rep. 2015 Jul 15;2015. pii: bcr2014208575. doi: 10.1136/bcr-2014-208575. PubMed PMID: 26177997.

11)

Kamata K, Wada K, Kinoshita M, Nomura M, Ozaki M. [A case of respiratory arrest during intraoperative magnetic resonance imaging (iMRI) for awake craniotomy]. Masui. 2014 Aug;63(8):907-10. Japanese. PubMed PMID: 25199330.

12)

Maldaun MV, Khawja SN, Levine NB, Rao G, Lang FF, Weinberg JS, Tummala S, Cowles CE, Ferson D, Nguyen AT, Sawaya R, Suki D, Prabhu SS. Awake craniotomy for gliomas in a high-field intraoperative magnetic resonance imaging suite: analysis of 42 cases. J Neurosurg. 2014 Oct;121(4):810-7. doi: 10.3171/2014.6.JNS132285.Epub 2014 Aug 8. PubMed PMID: 25105702.

13)

Trinh VT, Fahim DK, Maldaun MV, Shah K, McCutcheon IE, Rao G, Lang F, Weinberg J, Sawaya R, Suki D, Prabhu SS. Impact of Preoperative Functional Magnetic Resonance Imaging during Awake Craniotomy Procedures for Intraoperative Guidance and Complication Avoidance. Stereotact Funct Neurosurg. 2014 Sep 18;92(5):315-322. [Epub ahead of print] PubMed PMID: 25247627.

14)

Beez T, Boge K, Wager M, Whittle I, Fontaine D, Spena G, Braun S, Szelényi A, Bello L, Duffau H, Sabel M; European Low Grade Glioma Network. Tolerance of awake surgery for glioma: a prospective European Low Grade Glioma Network multicenter study. Acta Neurochir (Wien). 2013 Jul;155(7):1301-8. doi: 10.1007/s00701-013-1759-0. Epub 2013 May 21. PubMed PMID: 23689968.

15)

Hansen E, Seemann M, Zech N, Doenitz C, Luerding R, Brawanski A. Awake craniotomies without any sedation: The awake-awake-awake technique. Acta Neurochir (Wien) 2013;155:1417–24.

16)

Moritz-Gasser S, Herbet G, Maldonado IL, Duffau H. Lexical access speed is significantly correlated with the return to professional activities after awake surgery for low-grade gliomas. J Neurooncol. 2012 May;107(3):633-41. doi: 10.1007/s11060-011-0789-9. Epub 2012 Jan 24. PubMed PMID: 22270847.

17)

Eseonu CI, Rincon-Torroella J, ReFaey K, Quiñones-Hinojosa A. The Cost of Brain Surgery: Awake vs Asleep Craniotomy for Perirolandic Region Tumors. Neurosurgery. 2017 Mar 15. doi: 10.1093/neuros/nyx022. [Epub ahead of print] PubMed PMID: 28327904.

18)

Motomura K, Natsume A, Iijima K, Kuramitsu S, Fujii M, Yamamoto T, Maesawa S, Sugiura J, Wakabayashi T. Surgical benefits of combined awake craniotomy and intraoperative magnetic resonance imaging for gliomas associated with eloquent areas. J Neurosurg. 2017 Jan 6:1-8. doi: 10.3171/2016.9.JNS16152. [Epub ahead of print] PubMed PMID: 28059650.

19)

Morrison MA, Tam F, Garavaglia MM, Golestanirad L, Hare GM, Cusimano MD, Schweizer TA, Das S, Graham SJ. A novel tablet computer platform for advanced language mapping during awake craniotomy procedures. J Neurosurg. 2016 Apr;124(4):938-44. doi: 10.3171/2015.4.JNS15312. Epub 2015 Oct 16. PubMed PMID: 26473779.

20)

Itoi C, Hiromitsu K, Saito S, Yamada R, Shinoura N, Midorikawa A. Predicting sleepiness during an awake craniotomy. Clin Neurol Neurosurg. 2015 Oct 31;139:307-310. doi: 10.1016/j.clineuro.2015.10.033. [Epub ahead of print] PubMed PMID: 26571456.

21)

Pereira LC, Oliveira KM, L’Abbate GL, Sugai R, Ferreira JA, da Motta LA. Outcome of fully awake craniotomy for lesions near the eloquent cortex: analysis of a prospective surgical series of 79 supratentorial primary brain tumors with long follow-up. Acta Neurochir (Wien). 2009 Oct;151(10):1215-30. doi: 10.1007/s00701-009-0363-9. PubMed PMID: 19730779.

Update: Midline suboccipital subtonsillar approach

Marcos Tatagiba et al. described the surgical anatomy of the midline suboccipital subtonsillar approach to the hypoglossal canal. This approach includes a midline suboccipital craniotomy, dorsal opening of the foramen magnum and elevation of ipsilateral cerebellar tonsil to expose the hypoglossal nerve and its canal. The midline subtonsillar approach permits a straight primary intradural view to the hypoglossal canal. There is no necessity of condylar resections 1) 2).

It offers excellent access with a panoramic view of the cerebellomedullary cistern and its structures and therefore can be useful for a number of different pathologies in the lower petroclival region 3).


A study was performed on three alcohol (ETOH)-fixed specimens (6 sides), and the technique of the approach was highlighted. The tonsillar retraction needed to view the important structures was measured. Additionally, the records of 31 patients who underwent the STA procedure were evaluated and provide three clinical cases as examples.

Tonsillar retraction of 0.3cm (SD±0.1cm) exposed the PICA with its telo-velo-tonsillar and cortical branches. Retraction of 0.4cm (SD±0.2cm) exposed the spinal root of CN XI. Retraction of 0.9cm (SD±0.01cm) exposed the hypoglossal canal. Retraction of 1.3cm (SD±0.2cm) exposed the root exit zone of the glossopharyngeal nerve. Retraction of 1.6cm (SD±0.3cm) exposed the jugular foramen (JF), and retraction of 2.4cm (SD±0.2cm) exposed the inner auditory canal (IAC). In all of the selected cases, the pathology could be reached and exposed using the STA.

They recommend STA as a straightforward, easy-to-learn and therefore time-saving and safe procedure compared with other standard approaches to the cerebellomedullary cistern and its pathologies 4).

Indications

Glossopharyngeal neuralgia5).

Anterior, anterolateral, and posterior Foramen magnum meningioma6).

There was no significant postoperative complication in the remainder of the patientes, and their conditions improved after surgery 7).

Hypoglossal canal meningioma.

Case reports

2015

Two patients with exophytic or focal lesions in the inferior half of the medulla, who underwent surgery by suboccipital midline subtonsillar approach. This approach was not specifically described to reach MO before, and they found that the lesions produced a mild elevation of the tonsils providing a wide surgical view from the medulla to the foramen of Luchska laterally, and up to the middle cerebellar peduncle, offering a wide and safe access 8).

2010

A 36-year-old woman presented with increased intracranial pressure and cerebellar signs without hypoglossal nerve palsy. Magnetic resonance imaging showed a predominantly cystic mass with a fluid-fluid level in the foramen magnum region extending into the hypoglossal canal. The intracranial tumor was largely removed via a midline suboccipital subtonsillar approach, leaving only a tiny residue in the hypoglossal canal. Histology confirmed a schwannoma with relative hypervascularity. Twenty months later, the tumor recurred and presented as a multicystic dumbbell-shaped lesion, extending intra- and extracranially through the enlarged hypoglossal canal. A complete resection of the intracranial and intracanalicular parts of the tumor was achieved with a small extracranial remnant treated by radiosurgery. Histology revealed a focal increased K(i)67 proliferative index. In this report, we discuss the possible reasons for the absence of hypoglossal nerve palsy and the potential mechanism of the formation of the fluid-fluid level, and we consider the treatment of this lesion 9).

1)

Tatagiba M, Koerbel A, Roser F. The midline suboccipital subtonsillar approach to the hypoglossal canal: surgical anatomy and clinical application. Acta Neurochir (Wien). 2006 Sep;148(9):965-9. Epub 2006 Jul 5. Review. PubMed PMID: 16817032.
2)

Herlan S, Roser F, Ebner FH, Tatagiba M. The midline suboccipital subtonsillar approach to the cerebellomedullary cistern: how I do it. Acta Neurochir (Wien). 2017 Jul 22. doi: 10.1007/s00701-017-3270-5. [Epub ahead of print] PubMed PMID: 28735380.
3) , 4)

Herlan S, Ebner FH, Nitz A, Hirt B, Tatagiba M, Roser F. The midline suboccipital subtonsillar approach to the cerebellomedullary cistern and its structures: anatomical considerations, surgical technique and clinical application. Clin Neurol Neurosurg. 2014 Oct;125:98-105. doi: 10.1016/j.clineuro.2014.07.029. Epub 2014 Jul 27. PubMed PMID: 25113380.
5)

Roser F, Ebner FH, Schuhmann MU, Tatagiba M. Glossopharyngeal neuralgia treated with an endoscopic assisted midline suboccipital subtonsillar approach: technical note. J Neurol Surg A Cent Eur Neurosurg. 2013 Sep;74(5):318-20. doi: 10.1055/s-0032-1327447. Epub 2012 Oct 5. PubMed PMID: 23042141.
6)

Dogan M, Dogan DG. Foramen magnum meningioma: The midline suboccipital subtonsillar approach. Clin Neurol Neurosurg. 2016 Aug;147:116. doi: 10.1016/j.clineuro.2016.05.025. Epub 2016 Jun 6. PubMed PMID: 27321572.
7)

Dobrowolski S, Ebner F, Lepski G, Tatagiba M. Foramen magnum meningioma: The midline suboccipital subtonsillar approach. Clin Neurol Neurosurg. 2016 Jun;145:28-34. doi: 10.1016/j.clineuro.2016.02.027. Epub 2016 Apr 2. PubMed PMID: 27064859.
8)

Rabadán AT, Campero A, Hernández D. Surgical Application of the Suboccipital Subtonsillar Approach to Reach the Inferior Half of Medulla Oblongata Tumors in Adult Patients. Front Surg. 2016 Jan 13;2:72. doi: 10.3389/fsurg.2015.00072. eCollection 2015. PubMed PMID: 26793713; PubMed Central PMCID: PMC4710703.
9)

Li WC, Hong XY, Wang LP, Ge PF, Fu SL, Luo YN. Large cystic hypoglossal schwannoma with fluid-fluid level: a case report. Skull Base. 2010 May;20(3):193-7. doi: 10.1055/s-0029-1246219. PubMed PMID: 21318038; PubMed Central PMCID: PMC3037104.

11TH Hands-on Course on Neurosurgical Approaches

VALENCIA 2017
OCTOBER, 24th-27th
Inscripción on-line:
www.neurosurgeryvalencia.com

DIRECTOR DEL CURSO
José M. González Darder

GUEST FACULTY
Radim Lipina

FACULTY
José Hinojosa Mena-Bernal
Tomáš Hrbáč
Vicent Quilis-Quesada
Luis Real Peña
Javier Sendra Tello
Fernando Talamantes

Esteban Vega Torres

DESCARGAR PROGRAMA

Curso auspiciado por la Sociedad Española de Neurocirugía (SENEC)

Solicitado reconocimiento como “Actividad de Interés Sanitario” por la Consellería de Sanitat Universal y Salut Pública

ORGANIZA

Departamento de Neurocirugía
Hospital Clínico de Valencia

SEDE

PATROCINA

Update: Subtemporal approach

It is one of the surgical routes used to reach the interpeduncular fossa, offers a good access to the medial temporal region.

The subtemporal approach avoids neocortical transgression and injury to the optic radiations. 1) 2)

Indications

The subtemporal approach is historically known as the standard approach for the treatment of tumoral, vascular and inflammatory lesions of the middle cranial fossa, the tentorium, the anterior and middle tentorial incisura, the upper-third of the clivus and the petroclival region. This approach had been recognized universally for many years as the best way to treat basilar artery (BA) apex, P1 and P2 posterior cerebral artery (PCA) and superior cerebellar artery aneurysms until the introduction of the pterional approach in 1976 by Yasargil et al. 3).

Drawbacks

Access to the posteromedial temporal region needs the retraction of the temporal lobe 4) , with a risk of vein of Labbé sacrifice.

Because of the inclination of the tentorium, temporal lobe retraction increases with a more posterior location of the lesion 5).

A more posterior-oriented supratentorial-infra- occipital variation of the subtemporal approach has been described, which is performed to effectively approach and resect epileptogenic lesions in PMT regions 6) 7).

Keyhole subtemporal approaches and zygomatic arch osteotomy have been proposed in an effort to decrease the amount of temporal lobe retraction.

A keyhole and a classic subtemporal craniotomy were executed in 4 fresh-frozen silicone-injected cadaver heads. The target was defined as the area bordered by the superior cerebellar artery, the anterior clinoid process, supraclinoid internal carotid artery, and the posterior cerebral artery. Once the target was fully visualized, Ercan et al. evaluated the amount of temporal lobe retraction by measuring the distance between the base of the middle fossa and the temporal lobe. In addition, the volume of the surgical and anatomical corridors was assessed as well as the surgical maneuverability using navigation and 3D moldings. The same evaluation was conducted after a zygomatic osteotomy was added to the two approaches.

Temporal lobe retraction was the same in the two approaches evaluated while the surgical corridor and the maneuverability were all greater in the classic subtemporal approach.

The zygomatic arch osteotomy facilitates the maneuverability and the surgical volume in both approaches, but the temporal lobe retraction benefit is confined to the lateral part of the middle fossa skull base and does not result in the retraction necessary to expose the selected target 8).


With the help of an endoscope, Sun et al exposed the internal auditory canal and cerebellopontine through a translabyrinthine approach and the inferior colliculus through a keyhole subtemporal approach. This double approach can be combined to expose the internal auditory canal and cerebellopontine angle and inferior colliculus satisfactorily in the same surgical setting. This combined approach can avoid retraction of the cerebellum and reduce serious adverse events and complications 9).

As a minimally invasive approach, this can be considered an effective method for removal of vestibular schwannoma and auditory midbrain implantation in the same surgical setting, while avoiding retraction of the cerebellum and serious adverse events and complications.

see Subtemporal medial transpetrous approach.

see Subtemporal transtentorial approach.

Subtemporal Approach for AICA Aneurysm Clipping

The subtemporal approach represents a feasible approach for retrochiasmatic craniopharyngiomas when gross total resection is not mandatory. It provides rapid access to the tumor and a caudal-to-cranial visualization that promotes minimal manipulation of critical neurovascular structures, particularly the optic apparatus 10).

Subtemporal approach for distal basilar occlusion for giant aneurysm

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Tubbs RS, Oakes WJ: Relationships of the cisternal segment of the trochlear nerve. J Neurosurg 89:1015–1019, 1998
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Yasargil MG, Antic J, Laciga R, Jain KK, Hodosh RM, Smith RD. Microsurgical pterional approach to aneurysms of the basilar bifurcation. Surg Neurol. 1976 Aug;6(2):83-91. PubMed PMID: 951657.
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Olivier A: Temporal resections in the surgical treatment of epilepsy. Epilepsy Res Suppl 5:175–188, 1992
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Campero A, Tróccoli G, Martins C, Fernandez-Miranda JC, Yasuda A, Rhoton AL Jr: Microsurgical approaches to the medial temporal region: an anatomical study. Neurosurgery 59 (4 Suppl 2):ONS279–ONS308, 2006
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Russell SM, Kelly PJ: Volumetric stereotaxy and the supra- tentorial occipitosubtemporal approach in the resection of posterior hippocampus and parahippocampal gyrus lesions. Neurosurgery 50:978–988, 2002
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Ercan S, Scerrati A, Wu P, Zhang J, Ammirati M. Is less always better? Keyhole and standard subtemporal approaches: evaluation of temporal lobe retraction and surgical volume with and without zygomatic osteotomy in a cadaveric model. J Neurosurg. 2017 Jul;127(1):157-164. doi: 10.3171/2016.6.JNS16663. Epub 2016 Sep 16. PubMed PMID: 27636184.
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Sun JQ, Han DM, Li YX, Gong SS, Zan HR, Wang T. Combined endoscope-assisted translabyrinthine subtemporal keyhole approach for vestibular Schwannoma and auditory midbrain implantation: Cadaveric study. Acta Otolaryngol. 2010 Oct;130(10):1125-9. doi: 10.3109/00016481003699674. PubMed PMID: 20367538.
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Wong RH, De Los Reyes K, Alikhani P, Sivaknathan S, van Gompel J, van Loveren H, Agazzi S. The Subtemporal Approach to Retroinfundibular Craniopharyngiomas: A New Look at an Old Approach. Neurosurgery. 2015 Aug 18. [Epub ahead of print] PubMed PMID: 26287553.

Update: NeuroVR

CAE Healthcare NeuroVR Surgical Simulator from CAE Healthcare on Vimeo.

https://caehealthcare.com/surgical-simulation/neurovr


Simulation technology identifies neurosurgical residency applicants with differing levels of technical ability. These results provide information for studies being developed for longitudinal studies on the acquisition, development, and maintenance of psychomotor skills. Technical abilities customized training programs that maximize individual resident bimanual psychomotor training dependant on continuously updated and validated metrics from virtual reality simulation studies should be explored 1).


“Experts” display significantly more automaticity when operating on identical simulated tumors separated by a series of different tumors using the NeuroVR platform. These results support the Fitts and Posner model of motor learning and are consistent with the concept that automaticity improves after completing residency training. The potential educational application of the findings is outlined related to neurosurgical resident training 2).


Ultrasonic aspirator force application was continually assessed during resection of simulated brain tumors by neurosurgeons, residents, and medical students. The participants performed simulated resections of 18 simulated brain tumors with different visual and haptic characteristics. The raw data, namely, coordinates of the instrument tip as well as contact force values, were collected by the simulator. To provide a visual and qualitative spatial analysis of forces, the authors created a graph, called a force pyramid, representing force sum along the z-coordinate for different xy coordinates of the tool tip.

Sixteen neurosurgeons, 15 residents, and 84 medical students participated in the study. Neurosurgeon, resident and medical student groups displayed easily distinguishable 3D “force pyramid fingerprints.” Neurosurgeons had the lowest force pyramids, indicating application of the lowest forces, followed by resident and medical student groups. Handedness, ergonomics, and visual and haptic tumor characteristics resulted in distinct well-defined 3D force pyramid patterns.

Force pyramid fingerprints provide 3D spatial assessment displays of instrument force application during simulated tumor resection. Neurosurgeon force utilization and ergonomic data form a basis for understanding and modulating resident force application and improving patient safety during tumor resection 3).

1)

Winkler-Schwartz A, Bajunaid K, Mullah MA, Marwa I, Alotaibi FE, Fares J, Baggiani M, Azarnoush H, Zharni GA, Christie S, Sabbagh AJ, Werthner P, Del Maestro RF. Bimanual Psychomotor Performance in Neurosurgical Resident Applicants Assessed Using NeuroTouch, a Virtual Reality Simulator. J Surg Educ. 2016 Nov – Dec;73(6):942-953. doi: 10.1016/j.jsurg.2016.04.013. Epub 2016 Jul 7. PubMed PMID: 27395397.
2)

Bugdadi A, Sawaya R, Olwi D, Al-Zhrani G, Azarnoush H, Sabbagh AJ, Alsideiri G, Bajunaid K, Alotaibi FE, Winkler-Schwartz A, Del Maestro R. Automaticity of Force Application During Simulated Brain Tumor Resection: Testing the Fitts and Posner Model. J Surg Educ. 2017 Jul 3. pii: S1931-7204(17)30114-9. doi: 10.1016/j.jsurg.2017.06.018. [Epub ahead of print] PubMed PMID: 28684100.
3)

Azarnoush H, Siar S, Sawaya R, Zhrani GA, Winkler-Schwartz A, Alotaibi FE, Bugdadi A, Bajunaid K, Marwa I, Sabbagh AJ, Del Maestro RF. The force pyramid: a spatial analysis of force application during virtual reality brain tumor resection. J Neurosurg. 2017 Jul;127(1):171-181. doi: 10.3171/2016.7.JNS16322. Epub 2016 Sep 30. PubMed PMID: 27689458.

Update: Navigated transcranial magnetic stimulation for language mapping

In respect to language mapping with repetitive nTMS, literature reports have yielded variable results, and it is currently not routinely performed for presurgical language localization.

The expert panel recommends nTMS motor mapping in routine neurosurgical practice, as it has a sufficient level of evidence supporting its reliability. The panel recommends that nTMS language mapping be used in the framework of clinical studies to continue refinement of its protocol and increase reliability 1).

Although language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) gains importance in neuropsychological research and clinical utility, neuroscientists still use different mapping protocols including different stimulation frequencies.

The stimulation frequency has to be adapted to the aim of the rTMS language investigation 2).

2015

Ille et al. performed multimodal language mapping in 35 patients with left-sided perisylvian lesions by using rTMS, fMRI, and DCS. The rTMS mappings were conducted with a picture-to-trigger interval (PTI, time between stimulus presentation and stimulation onset) of either 0 or 300 msec. The error rates (ERs; that is, the number of errors per number of stimulations) were calculated for each region of the cortical parcellation system (CPS). Subsequently, the rTMS mappings were analyzed through different error rate thresholds (ERT; that is, the ER at which a CPS region was defined as language positive in terms of rTMS), and the 2-out-of-3 rule (a stimulation site was defined as language positive in terms of rTMS if at least 2 out of 3 stimulations caused an error). As a second step, the authors combined the results of fMRI and rTMS in a predefined protocol of combined noninvasive mapping. To validate this noninvasive protocol, they correlated its results to DCS during awake surgery.

The analysis by different rTMS ERTs obtained the highest correlation regarding sensitivity and a low rate of false positives for the ERTs of 15%, 20%, 25%, and the 2-out-of-3 rule. However, when comparing the combined fMRI and rTMS results with DCS, the authors observed an overall specificity of 83%, a positive predictive value of 51%, a sensitivity of 98%, and a negative predictive value of 95%.

In comparison with fMRI, rTMS is a more sensitive but less specific tool for preoperative language mapping than DCS. Moreover, rTMS is most reliable when using ERTs of 15%, 20%, 25%, or the 2-out-of-3 rule and a PTI of 0 msec. Furthermore, the combination of fMRI and rTMS leads to a higher correlation to DCS than both techniques alone, and the presented protocols for combined noninvasive language mapping might play a supportive role in the language-mapping assessment prior to the gold-standard intraoperative DCS 3).

2013

nTMS and MEGI were performed on 12 subjects. nTMS yielded 21 positive language disruption sites (11 speech arrest, 5 anomia, and 5 other) while DCS yielded 10 positive sites (2 speech arrest, 5 anomia, and 3 other). MEGI isolated 32 sites of peak activation with language tasks. Positive language sites were most commonly found in the pars opercularis for all three modalities. In 9 instances the positive DCS site corresponded to a positive nTMS site, while in 1 instance it did not. In 4 instances, a positive nTMS site corresponded to a negative DCS site, while 169 instances of negative nTMS and DCS were recorded. The sensitivity of nTMS was therefore 90%, specificity was 98%, the positive predictive value was 69% and the negative predictive value was 99% as compared with intraoperative DCS. MEGI language sites for verb generation and object naming correlated with nTMS sites in 5 subjects, and with DCS sites in 2 subjects. CONCLUSION: Maps of language function generated with nTMS correlate well with those generated by DCS. Negative nTMS mapping also correlates with negative DCS mapping. In our study, MEGI lacks the same level of correlation with intraoperative mapping; nevertheless it provides useful adjunct information in some cases. nTMS may offer a lesion-based method for noninvasively interrogating language pathways and be valuable in managing patients with peri-eloquent lesions 4).


Twenty patients with tumors in or close to left-sided language eloquent regions were examined by repetitive nTMS before surgery. During awake surgery, language-eloquent cortex was identified by DCS. nTMS results were compared for accuracy and reliability with regard to DCS by projecting both results into the cortical parcellation system.

Presurgical nTMS maps showed an overall sensitivity of 90.2%, specificity of 23.8%, positive predictive value of 35.6%, and negative predictive value of 83.9% compared with DCS. For the anatomic Broca’s area, the corresponding values were a sensitivity of 100%, specificity of 13.0%, positive predictive value of 56.5%, and negative predictive value of 100%, respectively.

Good overall correlation between repetitive nTMS and DCS was observed, particularly with regard to negatively mapped regions. Noninvasive inhibition mapping with nTMS is evolving as a valuable tool for preoperative mapping of language areas. Yet its low specificity in posterior language areas in the current study necessitates further research to refine the methodology 5).

1)

Krieg SM, Lioumis P, Mäkelä JP, Wilenius J, Karhu J, Hannula H, Savolainen P, Lucas CW, Seidel K, Laakso A, Islam M, Vaalto S, Lehtinen H, Vitikainen AM, Tarapore PE, Picht T. Protocol for motor and language mapping by navigated TMS in patients and healthy volunteers; workshop report. Acta Neurochir (Wien). 2017 Jul;159(7):1187-1195. doi: 10.1007/s00701-017-3187-z. Epub 2017 Apr 29. Review. PubMed PMID: 28456870.
2)

Hauck T, Tanigawa N, Probst M, Wohlschlaeger A, Ille S, Sollmann N, Maurer S, Zimmer C, Ringel F, Meyer B, Krieg SM. Stimulation frequency determines the distribution of language positive cortical regions during navigated transcranial magnetic brain stimulation. BMC Neurosci. 2015 Feb 18;16(1):5. PubMed PMID: 25880838.
3)

Ille S, Sollmann N, Hauck T, Maurer S, Tanigawa N, Obermueller T, Negwer C, Droese D, Zimmer C, Meyer B, Ringel F, Krieg SM. Combined noninvasive language mapping by navigated transcranial magnetic stimulation and functional MRI and its comparison with direct cortical stimulation. J Neurosurg. 2015 Jul;123(1):212-25. doi: 10.3171/2014.9.JNS14929. Epub 2015 Mar 6. PubMed PMID: 25748306.
4)

Tarapore PE, Findlay AM, Honma SM, Mizuiri D, Houde JF, Berger MS, Nagarajan SS. Language mapping with navigated repetitive TMS: proof of technique and validation. Neuroimage. 2013 Nov 15;82:260-72. doi: 10.1016/j.neuroimage.2013.05.018. Epub 2013 May 20. PubMed PMID: 23702420; PubMed Central PMCID: PMC3759608.
5)

Picht T, Krieg SM, Sollmann N, Rösler J, Niraula B, Neuvonen T, Savolainen P, Lioumis P, Mäkelä JP, Deletis V, Meyer B, Vajkoczy P, Ringel F. A comparison of language mapping by preoperative navigated transcranial magnetic stimulation and direct cortical stimulation during awake surgery. Neurosurgery. 2013 May;72(5):808-19. doi: 10.1227/NEU.0b013e3182889e01. PubMed PMID: 23385773.