1311. Intracranial Pressure Monitoring Allows Categorization Of Idiopathic Intracranial Hypertension, CSF Leak, And Mixed CSF Disorders.

Authors: Alexander Perdomo-Pantoja, MD; Riccardo Serra, MD; Rajiv Iyer, MD; Lacie Manthripragada, PA; Aruna Rao; Abhay Moghekar; Mark Luciano, MD, PhD (Baltimore, MD)

Introduction: Assessment of patients with suspected idiopathic intracranial hypertension (IIH) and with CSF leak by lumbar puncture (LP) displays weaknesses in both technique and diagnostic accuracy, particularly in those with borderline pressures and mixed disorders. ICP monitoring (ICPM), though more invasive, may contribute more accuracy in such cases, with its capacity for continuous measures and positional testing. Methods: A retrospective chart review of patients with suspected pressure abnormalities who underwent continuous ICPM at our institution between 2015-2018 was performed. ICPM and LP pressures, and clinical outcomes were collected.Patients were grouped as clinically suspected IIH, CSF leak or mixed disorders, and subcategorized based on ICPM positional testing as high, normal or low pressures. Differences between LP, lying and positional ICPM were examined. Results: 119 patients underwent ICPM procedures, with a median follow-up of 18 (range 6-30) months. Overall mean pressure was 16.01 mmHg with LP and 10.09 mmHg with lying ICPM ( p =<.0001). In the suspected IIH subgroup, a statistical difference was found between LP and ICPM lying pressures ( p =.0004). In this group, high pressures were demonstrated in 82% of LP’s but only 12% with lying ICPM’s. In the low-pressure CSF leak subgroup, LP and lying ICPM pressures were statistically different to standing ICPM ( p =<.0001, .003). In groups suspected of CSF leaks, the addition of positional testing increased detection of low pressures from 1 to 8/33 (24%) of patients. ICPM helped ruled out pressure abnormalities in 36/41 (88%) and 18/23 (78%) of IIH and CSF leak suspected cases, respectively. ICPM sub-categorization was correlated with the outcome in most cases. Conclusion: Information obtained by LP often diverges significantly from ICPM measurements, especially with the addition of positional testing. ICPM provided sub-categorization of IIH and CSF leak, validating high and low pressures in some and ruling out CSF abnormalities in many (54/64, 84%).