Diamox (R) challenge test to decide indications for cerebrospinal fluid shunting in normal pressure hydrocephalus

Objective. The indications for cerebrospinal fluid (CSF) shunting in patien ts with normal pressure hydrocephalus (NPH) have not been established. Esta blishment of clear-cut indications for this procedure is essential to ensur e cost-effective, and safe treatment. We report the usefulness of the Diamo x(R) challenge test in evaluating indications for CSF shunting in patients with NPH. Methods. Pre- and post-operative responses in cerebral blood flow (CBF) and intracranial pressure (ICP) to intravenous administration of Diamox(R) 100 0 mg (Diamox(R) administration) were analysed in 41 patients with NPH who w ere treated by ventriculoperitoneal (VP) shunt with a programmable valve an d an on-off Valve. Results. The preoperative response of ICP to Diamox(R) administration was m ore than 10 mmHg in most patients in whom the shunt was effective (shunt ef fective group), however, it was less than 10 mmHg in most patients in whom the shunt was ineffective (shunt non-effective group). Furthermore, the pos toperative response of ICP to Diamox(R) administration decreased to less th an 10 mmHg in most patients in the shunt effective group. The increases in CBF in response to Diamox(R) administration were similar in the two groups both before and after placement of the VP shunt. Conclusion. Patients in whom ICP increased by more than 10 mmHg in response to Diamox(R) administration were regarded to have poor CSF circulation and to thus be candidates for CSF shunting. The Diamox(R) challenge test is a simple, safe procedure, useful in evaluating the response to treatment.