Optic Nerve Sheath Diameter (ONSD) changes in patients with normal pressure hydocephalus – a useful supplement to the spinal tab test

Normal pressure hydrocephalus (NPH) is defined by the clinical triad of characteristic gait disturbance, incontinence and cognitive decline. The clinical diagnosis is supported by a specific imaging pattern. Therapy of choice is cerebrospinal fluid (CSF) removal, for evaluation of permanent shunting the spinal tab test is one of the established diagnostic tests.

In spite of exact patient selection a certain amount of patients do not respond significantly to CSF-removal. A possible explanation might be a reduced compliance of the cerebral ventricles, which is already discussed as part of the pathopyhsiology of NPH.

Ocular ultrasound with measurements of the Optic Nerve Sheath Diameter (ONSD) is an elgant, non-invasive technique to monitor intracerebral pressure (ICP) changes. Therefore we tried to pursue the hypothesis that changes in the ONSD – as a correlate of the ventricular compliace – prior to spinal tab test might predict the patients' response to the test.

Here we present the data of a prospective study with 91 patients (31 patients with NPH and 60 healthy age matched volunteers).

Ocular ultrasound might be a useful, noninvasive supplement to the spinal tab test for selection of patients suitable for shunt surgery.