Intracranial hypotension causing reversible frontotemporal dementia and coma.

Spontaneous Intracranial Hypotension (SIH) was first described over 60 years ago by Schaltenbrand and termed “aliquorrhea”1. In 1997, this syndrome was defined by a classical triad of postural headaches, low cerebral spinal fluid (CSF) pressure and imaging abnormalities2. More recent evidence has redefined this concept and our understanding of the pathological mechanism, as well as the variable clinical presentations and alternative treatment approaches in this condition. In many SIH cases, identification of the CSF leak may be a challenge2,3. Cerebral spinal fluid pressures less than 60 mm H20 may not be present; in fact, normal CSF pressures have been reported in 18-46% of cases4-6. Current understanding suggests that the etiology of SIH is CSF volume loss through a dural CSF leak, and that the clinical features, imaging abnormalities and CSF pressures depend on the extent of this CSF volume loss7. As such, alternative names of “CSF hypovolemia syndrome” and “spontaneous spinal CSF leak” have been proposed4-9. However, not all cases are “spontaneous”, and underlying culprit lesions such as subarachnoid (Tarlov) cysts, other anatomical defects3,5,10-13, or dural micro tears from minor trauma, neck manipulation and violent coughing3,14,15 can lead to CSF leaks. Identifying the CSF leak site and interventional or surgical correction of the underlying defect is therefore necessary to permanently abate persisting symptoms. Various symptoms and neurological findings have been reported with this condition. Nausea, vomiting, dizziness and posterior neck pain are all common. Neurological manifestations include visual symptoms such as diplopia, visual blurring, field defects, or photophobia16, hearing abnormalities including tinnitus, distortions and sensory neural hearing loss15,16, various cranial nerve palsies, and even peripheral manifestations of interscapular pain or radicular symptoms2,5,12,14. Unusual clinical manifestations have been described in case reports and include parkinsonism, gait abnormalities, cerebellar ataxia17, bipolar disorder18, encephalopathy, cognitive changes (including one case of frontotemporal dementia [FTD])19, obtundation and coma11,20-23. Only one case of death related to SIH has been published to date24. We describe the first case of frontotemporal dementia syndrome and coma caused by SIH that was successfully reversed with intrathecal saline infusion and an epidural blood patch targeted at a culprit C2 dural tear with consequent CSF leak. An Medline search from 1966 to present was conducted, and a review of the literature with emphasis on related cases is provided. Intracranial Hypotension Causing Reversible Frontotemporal Dementia and Coma