DOES THE SIZE OF INTRACRANIAL ANEURYSMS CHANGE WITH INTRACRANIAL-PRESSURE - OBSERVATIONS BASED ON COLOR POWER TRANSCRANIAL DOPPLER ULTRASOUND

Object. The authors sought to determine whether the increased pulsatil ity of aneurysms, compared with normal intracranial arteries, on color ''power'' transcranial Doppler (TCD) ultrasound was due to a true cha nge in aneurysm size and whether aneurysm dimensions change with intra cranial pressure (ICP). Methods. The authors studied nine patients who had suffered recent subarachnoid hemorrhages complicated by hydroceph alus requiring intraventricular cerebrospinal fluid drainage, in whom the presence of an aneurysm was confirmed on angiographic examination. Color ''power'' TCD studies of the intracranial arteries and aneurysm were obtained through the temporal bone window before and after inser tion of the ventricular drain and then at different known ICPs. Of the nine patients studied, four were examined both before and after inser tion of a ventricular drain. At high ICPs, aneurysms appeared very ''p ulsatile'' and the maximum cross-sectional area was small, whereas at low ICPs, aneurysms appeared larger and were much less pulsatile. The normal arteries did not change significantly in terms of pulsatility o r maximum cross-sectional area at different levels of ICP. Conclusions . The change in aneurysm size visualized with the aid of color power T CD is likely to be real. Aneurysm dimensions vary with ICP levels; the lesions are larger and less pulsatile at low ICPs and smaller but mon pulsatile at high ICPs.