Low cerebrospinal fluid protein in prepubertal children with idiopathic intracranial hypertension

Purpose To evaluate a clinical observation that prepubertal children with idiopathic intracranial hypertension (IIH) have low cerebrospinal fluid (CSF) protein levels compared to healthy children and pubertal patients with IIH. Methods The medical records of prepubertal and pubertal IIH patients and controls seen in the pediatric neuro-ophthalmology clinic at Duke between 2003 and 2013 were retrospectively reviewed. The control group consisted of children who had normal intracranial pressure on lumbar puncture performed to evaluate for headaches or anomalous-looking optic nerves. The records were analyzed with attention to demographic characteristics, clinical presentation, course, and lumbar puncture results. Results A total of 23 prepubertal children with IIH (age range, 0.75-13 years), 16 pubertal patients with IIH (age range, 13-21 years), and 12 controls (age range 3-14 years) were included. CSF analysis revealed that prepubertal children with IIH had significantly lower CSF protein levels (17.3 ± 5.7 mg/dL) compared to pubertal subjects with IIH (23.4 ± 8.4 mg/dL; P = 0.019) or healthy controls (23.5 ± 6.4 mg/dL; P = 0.011). Furthermore, 9 of 23 prepubertal IIH patients (39%) had abnormally low CSF protein level ( P = 0.005) and zero controls ( P = 0.015). Acetazolamide increased CSF protein level in 100% of patients who underwent repeat lumbar puncture after starting the medication (average increase, 10.3 ± 6.6 mg/dL). Conclusions Low CSF protein level may have diagnostic utility as a biomarker for prepubertal IIH. Furthermore, this finding suggests that some cases of prepubertal IIH may be caused by CSF overproduction rather than decreased CSF resorption.