Non-Invasive Intracranial Pressure Waveform Assessment as a Screening Test for Abnormal Lumbar Puncture Results

Lumbar puncture (LP) is essential for detecting intracranial hypertension (IH) but is often non-diagnostic and not without complications. A skull extensometer-based non-invasive intracranial pressure waveform assessment (NIWA) has shown promise in detecting IH in neurocritical settings. This study investigated its feasibility and accuracy among outpatient neurological individuals.

This cross-sectional study enrolled adults referred to routine outpatient LP at a tertiary-care hospital. Subjects underwent baseline supine NIWA, then were sequentially divided (2:1:1 ratio) to: LP then follow-up supine NIWA; follow-up NIWA while sitting then LP; or follow-up NIWA during Valsalva maneuver then LP. Several waveform parameters and their variation between baseline and follow-up assessments were compared with LP results. IH was defined as LP opening pressure > 25cmH₂O.

The study included 130 subjects, and 28 (21.5%) presented with IH. Dicrotic peak slope < 0.143 predicted IH with 89.5% sensitivity and 29.7% specificity (AUROC = 0.680, 95% CI 0.541-0.819). Equations derived from multivariate logistic regression models including mostly latency-related parameters of the entire waveform and its percussion and dicrotic peaks predicted cerebrospinal fluid (CSF) chemocytology changes with AUROC = 0.661 (95% CI 0.542-0.780) and overall abnormal LP results (IH and/or altered CSF chemocytology) with 96.2% sensitivity and 24.1% specificity (AUROC = 0.696, 95% CI 0.572-0.820). Parameter changes after LP, during Valsalva maneuver, and sitting position did not improve diagnostic accuracy.

NIWA was feasible and detected IH and CSF changes with high sensitivity among real-world neurological outpatients. While LP remains pivotal to many cases, pre-LP screening with NIWA may enhance diagnostic yield and mitigate complications and healthcare-related costs.