Intracranial Hypotension

Spontaneous Intracranial Hypotension (SIH) is a debilitating neurological disorder caused by a cerebrospinal fluid leak (CSF), with an estimated incidence of 5 per 100,000 persons per year, of which mostly women between the ages of 35 years and 55 years. The typical presentation is moderate-to-severe orthostatic headache and several other possible neurological symptoms, that significantly impact patients' quality of life.
Treatment of SIH usually starts with conservative measures, consisting of strict supine bed rest, hydration, caffeine, and simple analgesics. The vast majority of patients will require invasive treatments for their CSF leak, such as epidural blood patches, fibrin glue patches, endovascular coiling, and/or surgical repair. These specialized treatments are only offered in tertiary care centers and require specialized personnel and resources, which implicates a certain waiting time for the patients before permanent treatment is offered. In the meantime, due to the lack of an effective and accessible alternative, patients continue to suffer.
The greater occipital nerve block (GONB) has been reported as a simple, safe, and effective treatment to provide short-to-intermediate term relief of migraine, cervicogenic headache, cluster headache, occipital neuralgia, and more recently, post-dural puncture headaches (PDPH). As the pathophysiology of intracranial hypotension caused by SIH or PDPH is very similar, it is stipulated that the effect of GONB will be similar for SIH patients. However, to date, no studies exploring the efficacy of GONB for SIH have been performed.
The investigators propose to do a prospective observational study to explore the outcome of GONB for SIH. GONB can serve as a bridge therapy to control the debilitating headache of SIH while patients are awaiting permanent SIH treatment. Moreover, GONB can be performed by physicians of different specialties including neurology, which makes it an accessible treatment for all patients. Lastly, by offering better symptom control, this intervention could potentially restore patients' ability to work and reduce healthcare costs.

Intracranial hypotension results from leakage and/or hypotension of cerebrospinal fluid. It can be spontaneous or secondary to a dural puncture complicating perimedullary anesthesia or a lumbar puncture. The incidence remains low with less than 1% post spinal puncture (25 gauge needle), but is observed more frequently following a lumbar puncture, up to 36% with a 20 or 22 gauge needle. Accidental puncture of the dura mater with a 17 gauge needle used for epidural anesthesia is associated with postpuncture headaches in 75-80% of cases. Classically, symptoms appear 24 to 48 hours after the puncture and consist of very intense, postural, fronto-occipital headaches which may be associated with cranial nerve symptoms such as visual or hearing disturbances or vertigo. Among the risk factors are the size and type of the needle, age under 60 and female gender. About 90% of PDPH are self-limiting within 7-10 days.