Insights into the natural history of spontaneous intracranial hypotension from infusion testing

Objective To assess the pathophysiologic changes in patients with spontaneous intracranial hypotension (SIH) based on measures of CSF dynamics, and on the duration of symptoms, in a retrospective case-controlled study.

Methods We included consecutive patients investigated for SIH at our department from January 2012 to February 2018. CSF leak was considered confirmed if extrathecal contrast spillage was seen on imaging (CT or MRI) after intrathecal contrast application, or dural breach was detected by direct intraoperative visualization. We divided patients with a confirmed CSF leak into 3 groups depending on the symptom duration, as follows: ≤10, 11–52, and >52 weeks. Clinical characteristics and measures of CSF fluid dynamics obtained by computerized lumbar infusion testing were analyzed over time and compared with a reference population.

Results Among the 137 patients included, 69 had a confirmed CSF leak. Whereas 93.1% with <10 weeks of symptoms displayed typical orthostatic headache, only 62.5% with >10 weeks of symptoms did (p = 0.004). Analysis of infusion tests revealed differences between groups with different symptom duration for CSF outflow resistance (p < 0.001), lumbar baseline pressure (p = 0.013), lumbar plateau pressure (p < 0.001), baseline pressure amplitude (p = 0.021), plateau pressure amplitude (p = 0.001), pressure–volume index (p = 0.001), elastance (p < 0.001), and CSF production rate (p = 0.001). Compared to the reference population, only patients with acute symptoms showed a significantly altered CSF dynamics profile.

Conclusion A CSF leak dramatically alters CSF dynamics acutely, but the pattern changes over time. There is an association between the clinical presentation and changes in CSF dynamics.