Update Cerebellopontine angle epidermoid cyst

The cerebellopontine angle epidermoid cyst is a posterior fossa epidermoid cyst.

It account for 3-6% of cerebellopontine angle tumors. Comparatively, vestibular schwannomas, the most common CPA angle tumor, account for 85%.

Men and women are equally affected and the symptoms usually arise between the mid-20’s and early 50’s 1) with a mean age of 38.8 years at presentation 2).

Pathophysiology

Although several mechanisms for cranial nerve dysfunction due to these tumors have been proposed.

Hasegawa et al. report the first direct evidence of etiology of cranial nerve dysfunction caused by cerebellopontine angle epidermoid tumors. Young age and rapidly progressive neurological deficit might be the characteristics for strangulation of the affected nerves by the cyst capsule 3).

Clinical features

CPA epidermoid cysts can compress the surrounding cranial nerves, brainstem, and cerebellum. Ataxia and cranial nerve palsies often result 4).Thirty cases of cerebellopontine angle epidermoid cysts treated over a period of 20 years werw reviewed with regard to their clinical features, the pathophysiology of their symptoms and their management. The predominating symptoms were related to the 7th and 8th cranial nerves and headaches. The signs and symptoms were present for an average period of 4 months. It was not always possible to determine if the signs and symptoms were due to local involvement by the epidermoid, increased intracranial pressure, or both 5).

Diagnosis

Diagnostic procedures evolved from angiography and ventriculography to non-invasive computed tomography and MRI 6).


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Treatment

The posterior cranial fossa approach was used in 27 cases in the case series of deSouza et al. Total excision of the epidermoid was the aim and was carried out in five (18%) patients but concern regarding the preservation of nearby important neurovascular structures forced partial removal in 22 patients. To minimise reformation, the residual epidermoid was carefully coagulated with the aid of the operating microscope and bipolar cautery without damaging surrounding neurovascular structures 7).


The characteristics of epidermoid cysts make them amenable to whole course neuroendoscopic resection. Use of physiologic/pathologic interspaces and neuroendoscopic angulations decreases traction on the brain, improves complete resection rates, and decreases postoperative complications 8).

Case series

2016

Twenty-two cases with epidermoid cysts of CPA micro-neurosurgically treated since 2005 were reviewed. Clinical status of the patients before the surgery and post-operative functional outcome were recorded. Available data from the English literature were summarized for comparison. Mass reduction of cyst contents in most cases was usually associated with prompt and marked improvement of the symptoms suggesting neuroapraxia caused by compression of the tumor content and/or mild ischemia. Among them, two cases showed strangulation of the affected nerves by the tumor capsule whose preoperative dysfunction did not improve after surgery in spite of meticulous microsurgical removal of the lesion. Involved facial and abducent nerves in these two cases showed distortion of nerve axis and nerve atrophy distal to the strangulation site.

Hasegawa et al. report the first direct evidence of etiology of cranial nerve dysfunction caused by cerebellopontine angle epidermoid tumors. Young age and rapidly progressive neurological deficit might be the characteristics for strangulation of the affected nerves by the cyst capsule. Even though the number of cases might be limited, immediate decompression and release of the strangulating band might be urged in such patients to prevent irreversible deficits 9).


17 patients, including 7 with tumor limited to the cerebellopontine angle, 7 with cerebellopontine angle tumor penetrating supratentorially, and 3 with cerebellopontine angle tumor extending along skull base to contralateral cerebellopontine angle. All patients were followed-up for the mean duration of 126 months.

On admission cranial nerve symptoms predominated. Total tumor removal was achieved in 5 patients, and incomplete removal (with small tumor remnants left on vessels, nerves, or brainstem) in 12 patients. Postoperatively, preoperative deficits worsened in 2 and new postoperative deficits occurred in 10 patients. The extent of tumor expansion had no effect on postoperative morbidity and risk of recurrence. During long-term follow-up, improvement or resolution of preoperative deficits was seen in 11 of 17 patients, and new postoperative deficits in 8 of 10 patients. Symptomatic recurrences after an average of more than 9 years were noted in 5 patients, 3 of whom were reoperated. Recurrences occurred in some younger patients and always in area of primary tumor. No effect of extent of tumor removal on risk of recurrence was found.

The extent of tumor removal had no effect on the risk of recurrence, and thus it may be acceptable to leave tumor capsule fragments adhering closely to nerves, vessels, or brainstem. During long-term follow-up, resolution or improvement of present preoperatively and new postoperative neurological deficits may be expected in most patients 10).

2015

In a case series, pathophysiology of cranial nerve dysfunction in CPA epidermoid cysts was evaluated with special attention to a new mechanism of capsule strangulation caused by stratified tumor capsule. Twenty-two cases since 2005 were reviewed. Clinical status of the patients before the surgery and post-operative functional outcome were recorded. Available data from the English literature were summarized for comparison. Mass reduction of cyst contents in most cases was usually associated with prompt and marked improvement of the symptoms suggesting neurapraxia caused by compression of the tumor content and/or mild ischemia. Among them, two cases showed strangulation of the affected nerves by the tumor capsule whose preoperative dysfunction did not improve after surgery in spite of meticulous microsurgical removal of the lesion. Involved facial and abducent nerves in these two cases showed distortion of nerve axis and nerve atrophy distal to the strangulation site. Hasegawa et al. report the first direct evidence of etiology of cranial nerve dysfunction caused by cerebellopontine angle epidermoid tumors. Young age and rapidly progressive neurological deficit might be the characteristics for strangulation of the affected nerves by the cyst capsule. Even though the number of cases might be limited, immediate decompression and release of the strangulating band might be urged in such patients to prevent irreversible deficits 11)


Hu et al. performed a retrospective analysis of clinical data of 13 male and 17 female patients (mean age: 42.4 ± 11.4 years) who presented with a CPA epidermoid cyst and underwent whole course neuroendoscopy. Complications and tumor recurrence were assessed at follow-up. Results Clinical manifestations included an initial symptom of headache (n = 21), gait instability (n = 6), intracranial hypertension (n = 13), posterior cranial nerve symptoms (n = 6), ataxia (n = 5), and hydrocephalus (n = 1). All patients tolerated tumor resection with subsequent symptomatic improvement, and the results of the postoperative magnetic resonance imaging scan did not show any remnants of tumor. Mean duration of surgery was 2.61 ± 0.47 hours, mean loss of blood was 96.8 ± 35.4 mL, and the mean duration of hospitalization was 7.5 ± 2.25 days. Postoperative complications (8 of 30 [26.7%]) included fever (n = 5), communicating hydrocephalus (n = 1), facial nerve paralysis (n = 1), and abducens nerve palsy (n = 1). Tumor recurrence was observed in two patients (6.7%). No deaths or intracranial hemorrhage was reported.

The characteristics of epidermoid cysts make them amenable to whole course neuroendoscopic resection. Use of physiologic/pathologic interspaces and neuroendoscopic angulations decreases traction on the brain, improves complete resection rates, and decreases postoperative complications 12).

2010

Between 1996 and 2004, 10 patients with typical symptoms of trigeminal neuralgia were found to have cerebellopontine angle epidermoids and treated surgically.

Total resection was done in 6 patients (60%). Surgical removal of tumor and microvascular decompression of the trigeminal nerve were performed simultaneously in one case. One patient died due to postoperative aseptic meningitis. The others showed total relief from pain. During follow-up, no patients experienced recurrence of their trigeminal neuralgia (TN).

The clinical features of TN from CPA epidermoids are characterized by symptom onset at a younger age compared to TN from vascular causes. In addition to removal of the tumor, the possibility of vascular compression at the root entry zone of the trigeminal nerve should be kept in mind. If it exists, a microvascular decompression (MVD) should be performed. Recurrence of tumor is rare in both total and subtotal removal cases, but long-term follow-up is required 13).

1989

Thirty cases of cerebellopontine angle epidermoid cysts treated over a period of 20 years are reviewed with regard to their clinical features, the pathophysiology of their symptoms and their management. The predominating symptoms were related to the 7th and 8th cranial nerves and headaches. The signs and symptoms were present for an average period of 4 months. It was not always possible to determine if the signs and symptoms were due to local involvement by the epidermoid, increased intracranial pressure, or both. Diagnostic procedures evolved from angiography and ventriculography to non-invasive computed tomography and MRI. The posterior cranial fossa approach was used in 27 cases. Total excision of the epidermoid was the aim and was carried out in five (18%) patients but concern regarding the preservation of nearby important neurovascular structures forced partial removal in 22 patients. To minimise reformation, the residual epidermoid was carefully coagulated with the aid of the operating microscope and bipolar cautery without damaging surrounding neurovascular structures 14).

Case reports

2016

Malignant transformation of a residual cerebellopontine angle epidermoid cyst 15).

2015

Guan et al. the case of a 13-year-old female with a newly diagnosed cerebellopontine angle EC who presented with worsening headaches, photophobia, and emesis. Magnetic resonance imaging demonstrated significant pericystic brainstem edema and mass effect with effacement of the fourth ventricle. Refractory symptoms prompted repeat imaging, revealing cyst enlargement and dense rim enhancement. Resection of the EC resolved both her symptoms and the brainstem edema. This case documents the radiographic evolution of EC rupture and subsequent clinical course 16).


A case of an unusual epidermoid cyst of the cerebellopontine angle extending into the upper cervical canal that appeared hyper-dense on computed tomography scanning, hyper-intense on T1-weighted magnetic resonance (MR) images, and hypo-intense on T2-weighted MR images 17).

1)

Fleming JF, Botterell EH. Cranial dermoid and epidermoid tumors. Surg Gynecol Obstet. 1959;109:403–411.
2)

Fawcitt RA, Isherwood I. Radiodiagnosis of intracranial pearly tumours with particular reference to the value of computer tomography. Neuroradiology. 1976;11:235–242.
3) , 11)

Hasegawa M, Nouri M, Nagahisa S, Yoshida K, Adachi K, Inamasu J, Hirose Y, Fujisawa H. Cerebellopontine angle epidermoid cysts: clinical presentations and surgical outcome. Neurosurg Rev. 2015 Nov 14. [Epub ahead of print] PubMed PMID: 26566990.
4)

Berger M, Wilson C. Epidermoid cysts of the posterior fossa. J Neurosurg. 1985;62:214–219.
5) , 6) , 7) , 14)

deSouza CE, deSouza R, da Costa S, Sperling N, Yoon TH, Abdelhamid MM, Sharma RR, Goel A. Cerebellopontine angle epidermoid cysts: a report on 30 cases. J Neurol Neurosurg Psychiatry. 1989 Aug;52(8):986-90. PubMed PMID: 2795068; PubMed Central PMCID: PMC1031839.
8) , 12)

Hu Z, Guan F, Kang T, Huang H, Dai B, Zhu G, Mao B, Kang Z. Whole Course Neuroendoscopic Resection of Cerebellopontine Angle Epidermoid Cysts. J Neurol Surg A Cent Eur Neurosurg. 2015 Aug 24. [Epub ahead of print] PubMed PMID: 26302403.
9)

Hasegawa M, Nouri M, Nagahisa S, Yoshida K, Adachi K, Inamasu J, Hirose Y, Fujisawa H. Cerebellopontine angle epidermoid cysts: clinical presentations and surgical outcome. Neurosurg Rev. 2016 Apr;39(2):259-66; discussion 266-7. doi: 10.1007/s10143-015-0684-5. PubMed PMID: 26566990.
10)

Czernicki T, Kunert P, Nowak A, Wojciechowski J, Marchel A. Epidermoid cysts of the cerebellopontine angle: Clinical features and treatment outcomes. Neurol Neurochir Pol. 2016;50(2):75-82. doi: 10.1016/j.pjnns.2015.11.008. PubMed PMID: 26969562.
13)

Son DW, Choi CH, Cha SH. Epidermoid tumors in the cerebellopontine angle presenting with trigeminal neuralgia. J Korean Neurosurg Soc. 2010 Apr;47(4):271-7. doi: 10.3340/jkns.2010.47.4.271. PubMed PMID: 20461167; PubMed Central PMCID: PMC2864819.
15)

Pikis S, Margolin E. Malignant transformation of a residual cerebellopontine angle epidermoid cyst. J Clin Neurosci. 2016 Nov;33:59-62. doi: 10.1016/j.jocn.2016.04.008. Review. PubMed PMID: 27519146.
16)

Guan Z, Hollon T, Bentley JN, Garton HJ. Ruptured pediatric cerebellopontine angle epidermoid cyst: a case report detailing radiographic evolution and clinical course. J Neurosurg Pediatr. 2015 Aug 21:1-5. [Epub ahead of print] PubMed PMID: 26295366.
17)

Lim J, Cho K. Epidermoid cyst with unusual magnetic resonance characteristics and spinal extension. World J Surg Oncol. 2015 Aug 7;13:240. doi: 10.1186/s12957-015-0651-1. PubMed PMID: 26245481; PubMed Central PMCID: PMC4527251.

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