Noninvasive Intracranial Pressure Assessment in Patients with Suspected Idiopathic Intracranial Hypertension

Introduction: Idiopathic intracranial hypertension (IIH) usually occurs in obese women of childbearing age. Typical symptoms are headache and sight disorders. Besides ophthalmoscopy, lumbar puncture is used for both diagnosis and therapy of IIH. In this study, noninvasively-assessed intracranial pressure (nICP) was compared to lumbar pressure (LP) to clarify its suitability for diagnosis of IIH. Methods: nICP was calculated using continuous signals of arterial blood pressure and cerebral blood flow velocity, a method previously introduced by the authors. In thirteen patients (f = 11, m = 2; age: 36 ± 10 years), nICP was assessed 1 h prior to LP. If LP was >20 cmH₂O (~15 mmHg), lumbar drainage was performed, LP was measured again, and nICP was reassessed. Results: In six patients, LP and nICP were compared after lumbar drainage. In three patients, assessment of nICP versus LP was repeated. In total, LP and nICP correlated with R = 0.82 (p < 0.001; N = 22). Mean difference of ICP-nICP was 0.8 ± 3.7 mmHg. Presuming 15 mmHg as critical threshold for indication of lumbar drainage in 20 of 22 cases, the clinical implications would have been the same in both methods. Conclusion: TCD-based ICP assessment seems to be a promising method for pre-diagnosis of increased LP and might prevent the need for lumbar puncture if nICP is low.