Dynamic cerebral autoregulation (DCA) capacity along with the degree of internal carotid artery (ICA) stenosis and characteristics of the plaque can also play an important role in selection of appropriate treatment strategy. This study aims to classify the patients with severe ICA stenosis according to preoperative state of DCA and to assess its dynamics after surgery. Thirty-five patients with severe ICA stenosis having different clinical type of disease underwent reconstructive surgery. DCA was assessed with transfer function analysis (TFA) by calculating phase shift (PS) between Mayer waves of blood flow velocity (BFV) and blood pressure (BP) before and after operation. In 18 cases, regardless of clinical type, preoperative PS on ipsilateral side was within the normal range and did not change considerably after surgery. In other 17 cases preoperative PS was reliably lower both in patients with symptomatic and asymptomatic stenosis. Surgical reconstruction led to restoration of impaired DCA evidenced by significant increase of PS in postoperative period. Our data suggest that regardless clinical type of disease various state of DCA may be present in patients with severe ICA stenosis. This finding can contribute to establishing the optimal treatment strategy, and first of all for asymptomatic patients. Patients with compromised DCA should be considered as ones with higher risk of stroke and first candidates for reconstructive surgery.

A significant variability in the cerebrovascular reserve capacity in symptomatic and asymptomatic types of carotid artery stenosis was found. CA can be used in determining the indications for surgical treatment and evaluation of its effectiveness in patients with stenosis of carotid arteries.

No abstract

Purpose. To study the potential of non-invasive assessment of cerebral blood flow autoregulation (CA) using cross-spectral analysis of slow dopplerographic patterns. Materials and methods. The study involved 40 healthy volunteers and 228 patients with different neurosurgical pathology: cerebral aneurysm - 50 cases, arteriovenous malformation - 52, traumatic brain injury - 61, communicating hydrocephalus - 24, parasagittal meningioma - 20, stenosis and thrombosis of the carotid arteries - 21. Blood flow velocity (BFV) in middle cerebral arteries was monitored using Multi Dop X (DWL, Germany), systemic blood pressure (BP) - noninvasively with Finapres (Ohmeda 2100 USA) within 4 minutes. CA was assessed by calculating the phase shift (PSM) between spontaneous slow oscillations of BP and BFV within the range of systemic Mayer waves (80-120 mHz) and amplitude of intracranial B-waves of BFV (AB) within the range from 8 to 50 mHz). Results and discussion. CA demonstrated different patterns in neurosurgical patients and varied from normal autoregulation to its complete absence. This indicates the degree of compensation of cerebral hemodynamics in pathological conditions such as intracranial hypertension, vasospasm, traumatic edema, ischemia, abnormal arteriovenous shunting. On the basis of perioperative evaluation of PSM and AB, the predictors of efficacy and outcome have been identified in patients with cerebral aneurysms in an acute period of hemorrhage, severe brain injury, cerebral arteriovenous malformations and communicating hydrocephalus. Conclusions. Analysis of slow-wave dopplerographic patterns of BFV in intracranial cerebral arteries and BP is informative, adequate, safe non-invasive way to assess CA in normal and pathological conditions. Perioperative assessment of these patterns can be used to predict the effectiveness of treatment in patients with different neurosurgical pathology.

No abstract