Transcranial Doppler-determined pulsatility index in the evaluation of endoscopic third ventriculostomy (preliminary data)

Objective. Endoscopic 3(rd) ventriculostomy has become the method of choice in the management of occlusive hydrocephalus. The treatment is accompanied by significantly less peri-operative complications than the cerebrospinal fluid shunting procedures previously employed. Close surveillance of patien ts, however, is necessary to avoid the consequences of raised intracranial pressure that may develop in case of obstruction of the artificial outlet o f the 3(rd) ventricle. The aim of this study was to confirm the value of transcranial Doppler-dete rmined pulsatility index (PI) in the assessment of the patency of endoscopi c 3(rd) ventriculostomy and to elucidate its usefulness in early postoperat ive recognition of increased intracranial pressure. Methods. In twenty-two patients suffering from occlusive hydro-cephalus, tr anscranial Doppler sonography (TCD) was performed before, immediately after , and five days after endoscopic fenestration of the floor of the 3(rd) ven tricle. PI was defined with fast Fourier transformation. Mean PI values wer e determined in both middle cerebral arteries (MCA), over five cardiac cycl es. Results. In nineteen cases, PI values showed a significant decrease immedia tely as well as five days after the intervention as compared to the pre-ope rative values, and flow-sensitive MRI confirmed the patency of the fenestra tion in all cases. In one patient the operation failed to produce an effect ive diversion of cerebrospinal fluid as shown by Bow-sensitive MRI, and the pulsatility index was unchanged. In two patients, a significant immediate postfenestration drop in PI was followed by a recurrence of PI to pre-opera tive levels without any clinical deterioration. Conclusions. Preliminary results suggest that the transcranial Doppler-dete rmined pulsatility index is a useful non-invasive tool for the evaluation o f the patency of the fenestration in the early follow-up of patients who un derwent endoscopic third ventriculostomy.