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 patients, however, is necessary to avoid the consequences of raised intracranial pressure that may develop in case of obstruction of the artificial outlet of the 3^rd ventricle.

 The aim of this study was to confirm the value of transcranial Doppler-determined pulsatility index (pI) in the assessment of the patency of endoscopic 3^rd ventriculostomy and to elucidate its usefulness in early postoperative recognition of increased intracranial pressure.

 Methods. In twenty-two patients suffering from occlusive hydrocephalus, transcranial Doppler sonography (TCD) was performed before, immediately after, and five days after endoscopic fenestration of the floor of the 3^rd ventricle. PI was defined with fast Fourier transformation. Mean PI values were determined in both middle cerebral arteries (MCA), over five cardiac cycles.

 Results. In nineteen cases, PI values showed a significant decrease immediately as well as five days after the intervention as compared to the pre-operative values, and flow-sensitive MRI confirmed the patency of the fenestration in all cases. In one patient the operation failed to produce an effective diversion of cerebrospinal fluid as shown by flow-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-operative levels without any clinical deterioration.

 Conclusions. Preliminary results suggest that the transcranial Doppler-determined pulsatility index is a useful non-invasive tool for the evaluation of the patency of the fenestration in the early follow-up of patients who underwent endoscopic third ventriculostomy.