Brain: MR images
Musculoskeletal systemCase Type
Michailidis G.(1), Katsiva V., Kailidou E., Rizos K.(2), Seretis A.(2)Patient
52 years, male
MRI study of the brain revealed an empty sella and somewhat prominent subarachnoid spaces, considering the patient's age. MRI study of the orbits disclosed, on the left, vertical tortuosity of the optic nerves and an enlarged perioptic subarachnoid space. On STIR images the right optic nerve demonstrated high signal. No abnormal contrast enhancement or other pathology was noted.
A diagnosis of benign intracranial hypertension was suggested, although the typical symptoms were lacking. Therefore, a lumbar puncture was performed. An elevated CSF opening pressure of 65mmH2O and a high protein level of 3g/dl were found, thus confirming the presence of intracranial hypertension and directing the investigation towards the spinal canal. A lumbar MRI study showed an intradural lobulated mass, filling and expanding the canal, extending from the lower level of L3 to the lower level of S1. The mass was isointense with spinal cord on all pulse sequences and enhanced markedly after administration of contrast material. Prominent, intradural vessels superiorly and an entrapment cyst inferior to the mass were also observed.
The patient was operated on. A highly vascular, friable mass was found and a partial resection was performed because the mass was adherent to the nerve roots. Pathological examination confirmed the diagnosis of paraganglioma.
Most of the time the MRI features of paragangliomas lack specificity regarding the differential diagnosis from ependymoma. The characteristic salt and pepper appearance of paraganglioma that has been described on T2-weighted images, in other locations, is encountered rarely in the cauda equina. The mass is usually isointense or hyperintense to spinal cord, on T2-weighted images, homogeneous or inhomogeneous, and may show cystic components or a hypointense rim and invariably shows marked enhancement. The presence of serpiginous vessels around the lesion favours the diagnosis of paraganglioma, haemangioblastoma or vascular neurinoma. The association of spinal cord tumours with increased intracranial pressure (ICP) is well known but occurs uncommonly, with ependymoma being the cause in more than half of the cases. Several possible explanations exist, most of which are related to elevated CSF protein, made by the tumour. Accordingly, it is proposed that CSF absorption is mechanically blocked primarily at arachnoid villi or that stimulated basal arachnoiditis interferes with CSF flow. Aside from increased CSF protein levels, recurrent subarachnoid haemorrhages and loss of the elastic reservoirs in the lumbar region of the spinal canal have been implicated as possible causes of increased ICP in these cases.
Papilloedema is the hallmark of increased ICP, although it can be caused by intrinsic disease (e.g. optic neuritis) as well. The meningeal covering of the brain normally continues into the orbit to surround the optic nerve. Direct transmission of increased ICP results in protrusion of the optic papilla into the globe. When the pressure exerted on the optic papilla is sufficiently chronic or severe, it causes permanent degeneration of the optic nerve, as was the case in this patient. Several MR imaging characteristics of the brain and optic nerves indicating increased ICP have been described. In this patient the constellation of findings (vertical tortuosity of the optic nerves, enlarged perioptic subarachnoid space, empty sella and prominent intracranial subarachnoid spaces) suggested the diagnosis of intracranial hypertension, despite the absence of headache which almost invariably accompanies this condition.
This unusual case of a giant cauda equina paraganglioma manifesting with isolated papilloedema and visual disturbances, emphasises the need to exclude thoracolumbar intradural pathology in any case of unexplained increased intracranial pressure.
 Brodsky CM, Vaphiades M. Magnetic resonance imaging in pseudotumor cerebri. Ophthalmology 1998;105(9):1686-93. (PMID: 9754178)
 Levy AR. Paraganglioma of the filum terminale: MR findings. AJR 1993;160(4):851-2. (PMID: 8456679)
 Sundgren P, Annertz M, Englund E, Stroemblad LG, Holtas S. Paragangliomas of the spinal canal. Neuroradiology. 1999;41(10):788-94. (PMID: 10552032)
 Aghakani N, George B, Parker F. Paraganglioma of the cauda equina region report of two cases and review of the literature. Acta Neorochir 1999;141:81-7. (PMID: 10071690)
 Hardten DR, Wen DY, Wirtschafter JD, Sung HJ, Erickson DL. Papilledema and intraspinal lumbar paraganglioma. J Clin Neuroophthalmol. 1992;12(3):158-62. (PMID: 1401159)