Dynamic interaction between cerebrospinal fluid and sinovenous pressure in idiopathic intracranial hypertension: a case report

Idiopathic intracranial hypertension (IIH) is a common neurosurgical condition, and the exact pathophysiology remains elusive. Cerebral sinovenous stenosis (CSS) and the resultant decreased venous outflow have been labelled as a potential contributors to the pathophysiology of IIH. We describe the effect of cerebrospinal fluid (CSF) drainage on sinovenous pressure in a patient with IIH and a radiographic evidence of CSS.

A patient in their 40s with a diagnoses of IIH and imaging finding of focal stenosis of the distal left transverse sinus. To assess the nature of the stenosis, we performed venous sinus pressure monitoring with concurrent CSF drainage (5 ml at one minute intervals) through a lumbar drain with continuous mean sinovenous pressures recording. We observed a progressive decline in the pressure recording while draining CSF, after draining 40 ml of CSF, the final pressure gradient recording of the TS-SS trans-stenotic was (7 mm Hg from 27 mm Hg), mean SSS pressure (37 mm Hg from 60 mm Hg), and mean TS pressure (35 mm Hg from 56 mm Hg). The mean SS pressure remained relatively unperturbed.

Our findings indicate that the cerebral sinovenous pressure response to CSF removal generally conforms to a monophasic exponential decay model.