Postoperative changes in SPECT-rCBF in hydrocephalus.

OBJECTIVES We investigated the effect of shunt surgery in patients with Normal Pressure Hydrocephalus (NPH) using Single Photon Emission Computerised Tomography (SPECT). MATERIALS & METHODS Thirteen patients diagnosed with NPH were assessed clinically and using (99m Tc)-SPECT and MRI both pre- and post-operatively. Regions of interest were placed manually on T2 MRI and transferred to co-registered SPECT. Differences between pre- and post-operative cerebellum-normalised regional cerebral blood flow (rCBF) were calculated and analysed in relation to clinical findings represented by a new disability scale. RESULTS The patients presented initially with 50 +/- 30% disability score and improved following the surgery by 6 +/- 10% (p = 0.1). We did not observe any significant rCBF changes in the whole group of patients (overall rCBF difference = -0.3%, p = 0.4). Some improvement was in basal frontal lateral cortex, basal ganglia and thalamus (+5%, p = 0.08 to 0.2). Patients with <30% disability score initially (N = 4) had a reversed pattern of changes compared to those with more symptoms (p < 0.05). CONCLUSIONS The small patient sample failed to show significant changes in rCBF due to NPH or surgery. There is indication that in patients with good initial clinical presentation there is little space for relevant clinical improvement and increase in rCBF.