Spontaneous Intracranial Hypotension Presenting as Cryptogenic Coma: A Case Report and Literature Review Emphasizing the Role of Advanced Myelography

Spontaneous intracranial hypotension (SIH) is a difficult-to-diagnose condition that most commonly presents with a postural headache. In this case report we detail an instance of SIH whereby a 57-year-old right-hand-dominant male presented with chief complaint of positional headaches and was found to have a spontaneous right-sided subdural hematoma (SDH). Initially, he was neurologically intact; however, after several days he decompensated and became comatose with anisocoria. A computed tomography scan (CT) of the head showed SDH enlargement and midline shift, prompting emergent craniotomy. He initially improved after surgery, but shortly afterwards developed persistent positional neurological changes; an external ventricular drain revealed low intracranial pressure. Magnetic Resonance Imaging (MRI) revealed diffuse pachymeningeal enhancement, consistent with SIH. CT myelography (CTM) suggested a left Thoracic level 7 CSF leak, while digital subtraction myelography (DSM) identified right Thoracic level 7 and right Thoracic level 10 cerebrospinal venous fistulas (CVFs). Surgical ligation of all three fistulas resolved symptoms initially; however, the patient then experienced rebound intracranial hypertension requiring a ventriculoperitoneal shunt (VPS). At his six-month follow-up appointment, the patient had returned to his neurological baseline, and repeat imaging showed radiographic resolution. This case exemplified several nuances of SIH secondary to CVFs. For one, this is the first case that reports such a severe neurological decline, namely coma. Second, this case adds to the limited existing literature that surgical clip ligation offers definitive treatment. Third, rebound intracranial hypertension can occur following treatment, and patients should be closely monitored for this. Finally, and most importantly, CVFs are a tiny occult pathology that is easily missed and challenging to diagnose but should be considered in cases of non-traumatic SDH. Workup should include both CTM and DSM as these different imaging modalities may reveal different areas of spinal CSF shunting as demonstrated by this case, which we believe is a result of differing flow dynamics.