Teaching Case

A 41 year female patient complained of recent onset of urgency and difficulty passing urine, with a background history of lower back discomfort for three years.

A 41 year female patient complained of recent onset of urgency and difficulty passing urine, with a background history of lower back discomfort for three years. Further questioning revealed 1 year history of slowly progressive numbness over the dorsum of the left foot and left medial thigh without motor weakness. Recently she reported urgency and occasional difficulty passing urine. Examination was unremarkable except for subjective sensory changes in her left foot and thigh.

MRI of the lumbar spine (Fig. 1-4) demonstrates a well defined 5.7 x 1.7 x 1.7 cm ovoid intra-dural extra-medullary mass arising anterior to and causing some posterior displacement of the conus (Fig. 1, 2). The lesion is of intermediate T2 signal intensity with a 15 mm cystic area superiorly (Fig.2), with avid enhancement of the solid component following gadolinium administration (Fig. 1). Axial images demonstrate peripheral displacement of cauda equina nerve roots by the tumour (Fig. 3). A fluid-fluid level in the distal aspect of the spinal canal is consistent with recent haemorrhage (Fig. 3, 4). A radiological differential diagnosis of paraganglioma and myxopapillary ependymoma was given.

At surgery, T12 and L1 laminectomies were performed. The tumour was intradural, unattatched to the conus or nerve roots (Fig. 5). Complete resection of a lobulated, well-defined, encapsulated tumour weighing 9.8 g was performed.

Diagnosis of paraganglioma was confirmed histopathologically (Fig. 6, 7)

Paragangliomas are benign neuroendocrine neoplasms which arise from the neuroectoderm derived paraganglionic cells of the sympathetic and parasympathetic nervous system. They are typically located within the adrenal gland with the majority of extra-adrenal paragangliomas located in the carotid body and jugular bulb. Spinal paragangliomas are rare, and are usually intra-dural extra-medullary tumours in the region of the filum terminale. They usually present with symptoms of cauda equina compression [2]. The first reported case in the literature was in 1970, with a number of case reports in the neurological, neurosurgical and histopathological literature since then.

Paragangliomas are encapsulated highly vascular tumours, and therefore have the potential to bleed into the subarachnoid space, attributable to hamorrhage from the tumour or from the feeding vessels.

To our knowledge, there has only been one previously reported case in the literature of subarachnoid haemorrhage as a complication of spinal paraganglioma [1]. The onset of symptoms is usually insidious- in this case, the recent change in symptomatology is considered likely to be attributable to haemorrhage from the lesion into the subarachnoid space as demonstrated on MRI.

These tumours are typically homogenously isointense to the spinal cord on T1 and heterogenously iso or hyperintense on T2 sequences, the latter signal often relating to necrotic foci, cyst formation or intratumoral haemorrhage. Serpiginous flow voids and avid enhancement following Gadolinium relate to the vascular nature of this tumour. Intratumoral haemorrhage is commonly depicted as a low signal rim on T2 images.

The main differential diagnosis of a tumour in the region of the cauda equina is ependymoma, usually of the myxopapillary subtype and distiction from this entity cannot always be made radiologically. Other differentials include metastases, meningioma, neurofibroma and haemangioblastoma.

Spinal paragangliomas can be locally agressive causing bone erosion although distant metastases are rare.

Surgical resection is the treatment of choice for paraganglioma of the cauda equina with radiotherapy considered if complete resection is not possible. Patients should undergo close MR follow up due to the possibly of tumour recurrence, which is more likely with non-encapsulated tumours.