The effect of cranioplasty on cerebral hemodynamics: evaluation with transcranial Doppler sonography.

BACKGROUND: The purpose of cranioplasty is not only cosmetic repair but also neurological improvement. The effect of cranioplasty on the cerebral hemodynamics flow has not been investigated by ultrasonographic techniques. AIMS: To investigate changes of cerebral hemodynamics after cranioplasty in patients with cranial defect using transcranial Doppler sonography (TCDS). SETTING: The Departments of Neurosurgery and Radiology of a university hospital. DESIGN: A prospective clinical study. MATERIAL AND METHODS: We prospectively examined the cerebral hemodynamics with TCDS pre- and postoperatively in 18 patients with cranial defect who underwent cranioplasty. All postoperative studies were done between the 7th and 15th day after cranioplasty. The anterior cerebral artery was examined through the transtemporal and transorbital windows, the middle cerebral artery through the transtemporal window, and the posterior cerebral artery through the transforaminal window. Bilaterally, the peak systolic, end diastolic and mean blood flow velocities of these arteries were measured. STATISTICAL ANALYSIS: Wilcoxon matched-pairs signed-ranks test. RESULTS: Before cranioplasty all the velocities ipsilateral to the cranial defect were significantly low, while in the contralateral side they were near normal. Ipsilateral low cerebral blood flows increased and reached normal levels (P<0.05) after cranioplasty. During the follow-up, neurological improvement was observed. CONCLUSION: Cranioplasty is carried out not only for preserving normal appearances and physical barrier but also for neurological improvement. This should be explained by the normalization of cerebral hemodynamics.