Long-term Response of Cerebrospinal Fluid Pressure in Patients with Idiopathic Intracranial Hypertension – A Prospective Observational Study

BACKGROUND: Idiopathic intracranial hypertension (IIH) is increased intracranial pressure (ICP) with normal cerebrospinal fluid (CSF) contents, in the absence of an intracranial mass, hydrocephalus, or other identifiable causes. The current knowledge of the treatment outcome of IIH is limited, and the data on the natural history of this entity are scant. OBJECTIVE: The objective of the study is to study the treatment response of IIH by serially measuring the CSF opening pressure and to delineate the factors influencing the same. MATERIALS AND METHODS: A prospective observational study in a cohort of fifty patients with IIH in whom CSF opening pressure was serially measured at pre-specified intervals. RESULTS: The mean CSF opening pressure at baseline was 302.4 ± 51.69 mm of H(2)O (range: 220–410). Even though a higher body mass index (BMI) showed a trend toward a higher CSF opening pressure, the association was not significant (P = 0.168). However, the age of the patient had a significant negative correlation with the CSF pressure (P = 0.006). The maximum reduction in CSF pressure occurred in the first 3 months of treatment, and thereafter it plateaued. Remission was attained in 12 (24%) patients. BMI had the strongest association with remission (P = 0.001). CONCLUSIONS: In patients with IIH, treatment response is strongly related to BMI. However, patients with normal BMI are also shown to relapse and hence should have continuous, long-term follow-up. The reduction in CSF pressure attained in the first 3 months could reflect the long-term response to treatment.