Update: Radiography in Spinal epidural metastases

Most of the spinal epidural metastases are osteolytic, but at least 50 % of the bone must be eroded before plain x ray abnormality 1).

Not very specific.

see Winking owl sign

Plain x-rays are quite good at evaluating bony metastases, but not good at evaluating the spinal cord and surrounding soft tissues. Metastatic epidural spinal cord compression most commonly occurs at the site of vertebral involvement on plain x-ray, especially where there is evidence of vertebral collapse. Most common findings on x-rays include pedicle erosion, paravertebral soft shadow, vertebral collapse, and pathologic fracture or dislocation 2).

In the past, if there was back pain or a localizing sign and spinal x-ray was abnormal, the probability of epidural disease was 0.9, but if the x-ray was normal, the probability was only 0.1 3) 4).

In 1990, x-rays were found to have a 10% to 17% false negative rate 5).

The rate of missed metastatic epidural spinal cord compression is unacceptable.

1) Gabriel K, Schiff D. Metastatic spinal cord compression by solid tumors. Semin Neurol. 2004 Dec;24(4):375-83. Review. PubMed PMID: 15637649.
2) Perrin RG. Metastatic tumors of the axial spine. Curr Opin Oncol 1992;4(3):525-32.
3) Rodichok LD, Harper GR, Ruckdeschel JC, et al. Early diagnosis of spinal epidural metastases. Am J Med 1981;70(6):1181-8.
4) Portenoy RK, Galer BS, Salamon O, et al. Identification of epidural neoplasms. Radiography and bone scintigraphy in the symptomatic and asymptomatic spine. Cancer 1989;64(11):2207-13.
5) Bach F, Larsen BH, Rohde K, Børgesen SE, Gjerris F, Bøge-Rasmussen T, Agerlin N, Rasmusson B, Stjernholm P, Sørensen PS. Metastatic spinal cord compression. Occurrence, symptoms, clinical presentations and prognosis in 398 patients with spinal cord compression. Acta Neurochir (Wien). 1990;107(1-2):37-43. PubMed PMID: 2096606.

Update: Spinal arachnoid cyst

Spinal arachnoid cyst


Almost always dorsal, most common in the thoracic spine.

Most are extradural and these are sometimes referred to as arachnoid diverticula – these may be associated with kyphoscoliosis in juveniles or with spinal dysraphism.


Intradural arachnoid cysts may be congenital or may follow infection or trauma.

Clinical features

Usually asymptomatic, even if large.

Differential diagnosis

Vith a ventral cyst, consider a neurenteric cyst.


When indicated, treatment options include:

1. percutaneous procedures: may be done under MRI 1). or CT guidance. CT guidance usually requires use of intrathecal contrast to delineate the cyst

A. needle aspiration.

B. needle fenestration.

2. open surgical resection or fenestration

Case report

Takahashi et al. describe the case of a high cervical, intradural extramedullary cyst located anterior to the spinal cord in a 13-year-old boy. The lesion was fenestrated percutaneously by using real-time magnetic resonance (MR) imaging guidance and a local anesthetic agent. The patient’s symptom, severe exercise-induced headache, immediately resolved after treatment. Nine months later, complete disappearance of the cyst was confirmed on MR imaging and computerized tomography myelography. Magnetic resonance imageing-guided fenestration can be considered a minimally invasive option for intradural cystic lesions 2).

1) , 2) Takahashi S, Morikawa S, Egawa M, Saruhashi Y, Matsusue Y. Magnetic resonance imaging-guided percutaneous fenestration of a cervical intradural cyst. Case report. J Neurosurg. 2003 Oct;99(3 Suppl):313-5. PubMed PMID: 14563151.