Abstract text (incl. figure legends and references)

Objective

The impact of straining and exercise on intracranial pressure (ICP) regulation and headache is poorly understood in idiopathic intracranial hypertension (IIH). We sought to investigate whether straining and exercise change ICP and cerebrovascular dynamics in IIH.

Methods

Patients with IIH were enrolled in a prospective exploratory trial (IIH Pressure Trial: ISRCTN12678718). After insertion of an intraparenchymal ICP monitor (Raumedic™ Neurovent p-Tel, Hembrechts, Germany) three participants underwent continuous real-time ICP monitoring coupled with cerebrovascular assessments (heart rate, blood pressure, beat-by-beat middle cerebral artery (MCA) blood flow velocity and prefrontal cerebral haemodynamics (near infrared spectroscopy)). During these assessments participants undertook valsalva maneuvers (VMs) and moderate exercise.

Results

The age of the three participants was mean(SD) 40.7(14.4) years, BMI of 38.3(2.1)kg/m2, a supine ICP 15.3(8.7)mmHg and a sitting (upright) ICP of 2.8 (8.0)mmHg. A substantial increase in mean(SD) ICP was noted during VMs of 28.5(14.9)mmHg with an accompanied reduction of -9.1(3.3)mmHg at the end of the VM before returning to baseline. There was an initial reduction of MCA blood flow -20.0(7.4)cm/s followed by an increase of 14.8(5.6)cm/s before returning to baseline. Similar trends were noted in the cerebral pre-frontal cortex perfusion dynamics. The ICP was the fastest to reach its peak during the VMs and within 19(5.6) seconds it returned to baseline. There were no substantial differences in the ICP measures during exercise compared to baseline.

Discussion

These initial observations of ICP changes during VMs and rapid return to baseline are of relevance in a population of patients in whom valsalva is a function of daily activities as well as repeated VMs occurring during labour. The observations during exercise are important in a disease that is driven by obesity that can be modified by increased energy expenditure.