Spinal cord ependymoma

They are usually well circumscribed, expand the cord focally and are solid, with frequently associated cysts (see astrocytoma) and intratumoral haemorrhages. Histologically they show characteristic rosettes or pseudorosettes, and may be cellular or myxopapillary.

The most common location is the conus and filum terminalis but intramedullary cellular ependymomas are also common, mainly in the cervical region.

Clinical presentation may be neck and back pain for intramedullary forms, followed by mild signs of progressive paraparesis; low back pain, leg pain, leg weakness and sphincter disturbance may be found in myxopapillary ependymomas of the conus and cauda. Since these tumours are slow growing neoplasms, diagnostic delays are common; the average duration of symptoms before the correct diagnosis is made is about two and a half years.

Imaging

The diagnostic modality of choice is MR; plain films (and CT) may show a widened canal in about 20% of cases. Myelography is no longer performed since it shows only nonspecific cord widening.

MR shows a widened cord or a mass lesion involving the cauda and conus medullaris. The signal characteristics are mixed, if haemorrhages and cysts are present. On T1-weighted images the tumour is usually iso- or slightly hypointense, while it is hyperintense in T2-weighted images, with focal areas of hypointensity due to haemosiderin if haemorrhage has occurred.

Cranial and caudal intramedullary cyst are easily recognized within the cord; they expand the cord and cranially may extend within the medulla, at the level of the "clava" elevating the inferior portion of the floor of the fourth ventricle. This is a differential diagnostic sign with true syringes of hydrosyringomyelia.

Despite the histological differences, preoperative differential diagnosis from astrocytomas is almost impossible.

GS