Informativity of pulsatility index and cerebral autoregulation in hydrocephalus

Abstract

A high correlation between transcranial Doppler pulsatility index (PI) increase and intracranial hypertension has been recently demonstrated in most neurosurgical patients. But in patients with hydrocephalus PI is sometimes controversial. This may be due to a different degree of cerebral autoregulation (CA) under condition of cerebral perfusion pressure decrease. To compare the results of PI and CA assessment in patients with hydrocephalus. Twenty-six patients (aged 16–52; male – 9, female – 17) with various types of hydrocephalus were studied. We monitored blood flow velocity in middle cerebral arteries with Multi Dop X and systemic blood pressure with Finapres-2300. CA was assessed with cuff test (evaluation of ARI) and cross-spectral analysis of spontaneous oscillations of cerebral and systemic hemodynamics within the range of Mayer's waves (evaluation of phase shift in radians – PS). Depending on presence of intracranial hypertension (ICH), all patients have been divided in two groups. Mean values of PI did not differ significantly in both groups. At the same time ARI and PS were considerably ( p < 0.01) higher in patients without signs of ICH. In group of patients with ICH postoperative clinical improvement was accompanied with considerable ( p < 0.05) increase of PS. In group of patients without ICH we did not observe any positive changes in neurological state postoperatively. Preoperative CA assessment being more informative than PI evaluation can increase transcranial Doppler valuability in noninvasive diagnostics of cerebral spinal fluid dynamics and may be helpful in clarifying indications for operation in patients with hydrocephalus.