Subjects

Patients scheduled to undergo an LP for clinical reasons were recruited from the University of Illinois at Chicago ophthalmology and neurology clinics between November 2014 and March 2016 to participate in a study of ophthalmic manifestations of high ICP, other results of which have been reported separately (6, 9, 10). The research adhered to the tenets of the Declaration of Helsinki and was approved by the University of Illinois at Chicago Institutional Review Board. Written informed consent was collected from all participants in this study after they were notified of the nature and potential outcomes and consequences of the study. Reason for LP as well as the positioning for the procedure, age, gender, and disc appearance were acquired from the medical record. Intracranial pressure was quantitatively measured during the LP as the height of the column of spinal fluid above the spinal canal using a manometer prior to removal of cerebrospinal fluid.

A total of 35 patients receiving lumbar puncture for clinical indications agreed to participate in this study. Fifteen subjects were excluded from further analysis in this study either because a successful LP was not performed or ICP was not measured. Ten eyes (2 eyes in 3 subjects and 1 eye in 4 subjects) were excluded from further analysis due to incomplete optic nerve head imaging on 1 or more B-scans. Thirty eyes from 17 participants were included in the analysis for this study. The ICP range was 10–55 cm H₂O with an average of 28.1 cm H₂O. LP was performed for dementia (4 participants), neuro-inflammation/MS (2 participants) and possible IIH (11 participants). Inclusion of patients with neurological disease other than high ICP was necessary to sample a range of ICP values. Low ICP (ICP ≤ 20 cm H₂O) was seen in five participants, borderline ICP (20 ≤ ICP <25 cm H₂O) was seen in three participants, and high ICP (ICP ≥ 25 cm H₂O) was seen in nine participants (11).