Objective: To highlight an infrequent, treatable cause of ataxia and myelopathy.

Background: Spontaneous intracranial hypotension (SIH) typically presents with postural headache. Occasionally, MRI may show some superficial siderosis (SS). SS results from repeated subarachnoid hemorrhage, which leads to hemosiderin deposition in the subpial layers of the brain and spinal cord. Since hemosiderin is neurotoxic, prolonged exposure leads to irreversible neurodegeneration. Infratentorial SS is most frequently due to a spinal dural defect.

Method: Description of a case of ataxia and myelopathy due to spontaneous intracranial hypotension with superficial siderosis.

Results: Our patient was a 63-year-old male with hypertension, diabetes, dyslipidemia, and ischemic heart disease. He had no history of trauma. He presented with a one-year history of progressive disequilibrium, gait disturbance, and frequent falls. He also reported vertigo, diplopia, and dysphagia. On neurological examination, he had hypermetric saccades, a positive head impulse test bilaterally, and slight dysarthria; quadriparesis with overall muscle wasting and bilateral extensor plantar reflexes; dysdiadochokinesia, dysmetria, intention tremor, and ataxic gait. Brain MRI revealed thin bilateral subdural collections, cerebellar atrophy and extensive supra and infratentorial SS. Spinal MRI showed SS of the entire spinal cord and an anterior, longitudinal, extradural CSF collection from C2 to D8. Spinal CT revealed a calcified disc herniation at D1-2, and CT myelography showed passage of contrast into the extradural collection, suggesting a dural defect. The patient was considered for surgical repair but was deemed too frail to undergo the procedure.

Conclusion: Our patient presented with an atypical clinical picture for spontaneous intracranial hypotension, with progressive cerebellar ataxia and myelopathy owing to extensive SS. A dural defect was probably caused by impingement of a herniated, calcified disk onto the dura, resulting in CSF leak and intracranial hypotension. Chronic, low volume bleeding from bridging veins under traction and bleeding from friable vessels in the dural defect must have caused SS. Timely diagnosis of SIH and surgical repair of an underlying dural defect can prevent progression of SS, even though symptom recovery is often not seen.

References: [1] Webb AJ, Flossmann E, Armstrong RJ. Superficial siderosis following spontaneous intracranial hypotension. Pract Neurol. 2015;15(5):382-384. doi:10.1136/practneurol-2015-001169
[2] Farb RI, Nicholson PJ, Peng PW, et al. Spontaneous Intracranial Hypotension: A Systematic Imaging Approach for CSF Leak Localization and Management Based on MRI and Digital Subtraction Myelography. AJNR Am J Neuroradiol. 2019;40(4):745-753. doi:10.3174/ajnr.A6016

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MDS Abstracts - https://www.mdsabstracts.org/abstract/spontaneous-intracranial-hypotension-presenting-with-progressive-cerebellar-ataxia-and-myelopathy/