Wilhelm Sorteberg

Assessment of cerebral autoregulation dynamics from simultaneous arterial and venous transcranial Doppler recordings in humans.

We investigated the validity of transcranial Doppler recordings for the analysis of dynamic responses of cerebral autoregulation. We found no significant differences in percentage changes among maximal (centerline) blood flow velocity, cross-sectional mean blood flow velocity, and signal power-estimated blood flow during 24-mm Hg stepwise changes in arterial blood pressure. We investigated blood flow propagation delays in the cerebral circulation with simultaneous Doppler recordings from the middle cerebral artery and the straight sinus. The time for a stepwise decrease in blood flow to propagate through the cerebral circulation was only 200 msec. Brief (1.37-second) carotid artery compression tests also demonstrated that the volume compliance effects of the cerebral vascular bed were small, only about 2.2% of normal blood flow in 1 second. Furthermore, transients associated with inertial and volume compliance died out after 108 msec. We also investigated the hypothesis that autoregulatory responses are influenced by hyperventilation using the same brief carotid artery compressions. One second after release, the flow index increased by 17% during normocapnia and 36% during hypocapnia. After 5 seconds, the flow index demonstrated a clear oscillatory response during hypocapnia that was not seen during normocapnia. These results suggest that the intact human cerebral circulation in the absence of pharmacological influences does not function as predicted from pial vessel observations in animals.

Cerebral Vasospasm After Subarachnoid Haemorrhage Investigated by Means of Transcranial Doppler Ultrasound

Measurements of flow velocity in defined segments of the basal cerebral arteries can be obtained through the intact adult skull using 2 MHz pulsed Doppler ultrasound. We compared flow velocity in these vessels with findings from 56 cerebral angiographies obtained in 51 patients at from day 1 to day 21 after subarachnoid haemorrhage (SAH). The diameter of the proximal segment of the middle cerebral, anterior cerebral, and posterior cerebral arteries (MCA, ACA, and PCA, respectively) were measured from anteroposterior films produced in one angiographic laboratory. In patients investigated on day 1-2, the median MCA diameter was 2.8 mm with range 2.3-3.4 mm. The median flow velocity was 56 cm/s, range 36-88 cm/s (within normal limits). There was a clear inverse relationship between the MCA diameter and MCA flow velocity. Eleven of the 13 MCAs having diameter 1.5 mm or less showed flow velocity in excess of 140 cm/s. This seems a useful limit to diagnose pronounced MCA spasm (50% diameter reduction) with this method. Further clues to the severity of MCA spasm were obtained from the ratio calculated dividing the MCA flow velocity by the flow velocity in the ipsilateral, extracranial internal carotid artery (ICA), since spasm probably does not involve the neck vessels. This ratio was from 1.1 to 2.3, median 1.7 at day 1-2, but rose to over 10 in patients with the most severe MCA lumen narrowing. The PCA flow velocity was inversely related to the PCA diameter. Assessment of ACA spasm requires considering findings from both hemispheres combined, since the two proximal ACAs usually anastomose through the anterior communicating artery.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of transcranial Doppler and cerebral blood flow studies to assess cerebral vasoreactivity.

Background and Purpose The aim of this study was to determine the ability of transcranial Doppler ultrasonography when used to assess cerebral vasoreactivity. The results of this method were compared with regional cerebral blood flow measurements. Methods Forty-three patients with symptoms suggesting cerebrovascular disease took part Transcranial Doppler findings in the middle cerebral arteries were compared with regional cerebral blood flow in the corresponding perfusion territories before and after acetazolamide administration. Results There was a significant positive correlation between the absolute increase in cerebral blood flow in milliliters per 100 g per minute and the percent increase in velocity (r=0.63). The right-left, side-to-side difference of the acetazolamide response obtained by the two methods also showed a positive correlation (r=0.80). Control limits obtained from healthy subjects were used for both the blood flow increase (absolute values and asymmetry in absolute values) and the velocity increase (percent increase and asymmetry in percent increase). The two methods then agreed in their evaluation of vasoreactivity in 74 (86%) of the 86 middle cerebral artery perfusion territories; 20 (23%) were assessed by both methods as having a reduced vasodilatory reserve. Eleven hemispheres with a slightly reduced regional cerebral blood flow response to acetazolamide were not detected by transcranial Doppler, whereas all territories with a marked reduction were identified by Doppler. Only one hemisphere with a normal cerebral blood flow increase after acetazolamide administration was assessed by Doppler as having reduced vasoreactivity. Conclusions Transcranial Doppler and the acetazolamide test may be used in clinical situations to assess cerebral vasoreactivity.

Diagnostic intracranial pressure monitoring and surgical management in idiopathic normal pressure hydrocephalus: a 6-year review of 214 patients.

OBJECTIVETo review our experience of managing idiopathic normal pressure hydrocephalus (iNPH) during the 6-year period from 2002 to 2007, when intracranial pressure (ICP) monitoring was part of the diagnostic workup. METHODSThe review includes all iNPH patients undergoing diagnostic ICP monitoring during the years 2002 to 2007. Clinical grading was done prospectively using a normal pressure hydrocephalus (NPH) grading scale (scores from 3 to 15). The selection of patients for surgery was based on clinical symptoms, enlarged cerebral ventricles, and findings on ICP monitoring. The median follow-up time was 2 years (range, 0.3–6 years). Both static ICP and pulsatile ICP were analyzed. RESULTSA total of 214 patients underwent the diagnostic workup, of whom 131 went on to surgery. Although 1 patient died shortly after treatment, 103 of the 130 patients (79%) improved clinically. This improvement lasted throughout the observation period. The static ICP observed during ICP monitoring was a poor predictor of the response to surgery. In contrast, among 109 of 130 patients with increased ICP pulsatility (ie, ICP wave amplitude >4 mm Hg on average and >5 mm Hg in >10% of recording time), 101 (93%) were responders (ie, increase in the NPH score of >2). Correspondingly, only 2 of 21 (10%) without increased ICP pulsatility were responders. Superficial wound infection was the only complication of ICP monitoring and occurred in 4 (2%) patients. CONCLUSIONSurgical results in iNPH were good with almost 80% of patients improving after treatment. The data indicate that improvement after surgery can be anticipated in 9 of 10 iNPH patients with abnormal ICP pulsatility, but in only 1 of 10 with normal ICP pulsatility. Diagnostic ICP monitoring had a low complication rate.

Blood blister–like aneurysms of the internal carotid artery trunk causing subarachnoid hemorrhage: treatment and outcome

OBJECT The object of this study was to evaluate cases of subarachnoid hemorrhage (SAH) from ruptured blood blister-like aneurysms (BBAs) of the internal carotid artery (ICA) trunk. METHODS The authors performed a single-center, retrospective study. Data analyzed were patient age, sex, Hunt and Hess grade, Fisher grade, time from SAH to hospitalization, aneurysm size and location, collateral capacity of the circle of Willis, time from hospitalization to aneurysm repair, type of aneurysm repair, complications, and Glasgow Outcome Scale (GOS) score at follow-up. RESULTS A total of 211 patients suffered SAH from ICA aneurysms. Of these, 14 patients (6.6%) had ICA trunk BBAs; 6 men and 8 women. The median age was 47.8 years (range 29.9-67.7 years). The Hunt and Hess grade was IV or V in 7 cases, and SAH was Fisher Grade 3 + 4 in 6. All aneurysms were small (< 1 cm), without relation to vessel bifurcations, and usually located anteromedially on the ICA trunk. Three patients were treated with coil placement and 11 with clip placement. Of the 7 patients in whom the ICA was preserved, only 1 had poor outcome (GOS Score 2). In contrast, cerebral infarcts developed in all patients treated with ICA sacrifice, directly postoperatively in 2 and after delay in 5. Six patients died, 1 survived in poor condition (GOS Score 3; p < 0.001). CONCLUSIONS Internal carotid BBAs are rare, small, and difficult to treat endovascularly, with only 2 of 14 patients successfully treated with coil placement. The BBAs rupture easily during surgery (ruptured in 6 of 11 surgical cases). Intraoperative aneurysm rupture invariably led to ICA trap ligation. Sacrifice of the ICA within 48 hours of an SAH led to very poor outcome, even in patients with adequate collateral capacity on preoperative angiograms, probably because of vasospasm-induced compromise of the cerebral collaterals.

Effect of acetazolamide on cerebral artery blood velocity and regional cerebral blood flow in normal subjects.

SummaryThe effect of intravenous acetazolamide L g on cerebral artery blood velocity and regional blood flow (rCBF) was investigated in eight normal subjects. Blood velocity was measured with 2 MHz pulsed Doppler in the proximal segments of the middle, anterior and posterior cerebral artery (MCA, ACA, and PCA) and in the distal extracranial internal carotid artery (ICA). The rCBF in the regions of interest tentatively corresponding to the perfusion territories of these vessels was estimated using133Xe inhalation and a rapidly rotating single photon emission computer tomograph.Both blood velocity and rCBF increased after acetazolamide. There was no significant difference between the percentage ICA blood velocity increase (22 ± 12%) and the percentage rCBF increase in the ICA region of interest (25 ± 9%). In the MCA, ACA, and PCA, however, blood velocity increased more (mean increase 36–42%) than the rCBF in the corresponding regions of interest (mean increase 24–26%). These differences were highly significant suggesting a direct and site specific effect of acetazolamide in narrowing the lumen of the proximal MCA, ACA, and PCA, but not of the extracranial ICA. We also propose that the effect of acetazolamide induces reciprocal changes in the extent of adjacent perfusion territories in individual brain hemispheres.Data compiled from all subjects investigated at two very different perfusion levels (before and after acetazolamide) revealed a significant positive correlation between blood velocity and rCBF.

Blood velocity and regional blood flow in defined cerebral artery systems

SummaryCerebral artery blood velocity and regional blood flow (rCBF) were investigated in 17 normal subjects. Blood velocity was measured with 2 MHz pulsed Doppler ultrasound in the proximal segments of the middle, anterior and posterior cerebral artery (MCA, ACA, and PCA) and in the distal extracranial internal carotid artery (ICA). The rCBF in the regions of interest tentatively corresponding to the perfusion territories of these vessels was estimated using133Xe inhalation and a rapidly rotating single photon emission computer tomograph.Concomitant capnograph recordings showed that the end-expiratory pCO2 was higher during the rCBF than during the blood velocity examinations. This difference was highly significant. While there was no significant correlation between blood velocity and rCBF when these clear differences in pCO2 were disregarded, we did find significant positive correlations when the data were normalized to a standard pCO2 (5.3 kPa) using accepted formulas. The best correlation was found for the MCA (r=0.630, p<0.001) and the PCA (r=0.73, p < 0.001), with a lower correlation in the ACA (r=0.49, p<0.01) and the ICA (r=0.41, p<0.05). The estimated blood velocity (V) given rCBF=0 was not significantly different from 0.The results support the validity of expressing the relationship between blood velocity (V) and rCBF in defined cerebral artery systems as: V=1/60(rCBF) T (A)−1, where A represents the area of the lumen of the vessel segment where the velocity is being measured, and T denotes the size of the brain region being perfused from this artery.

Cognitive outcome after aneurysmal subarachnoid hemorrhage : Time course of recovery and relationship to clinical, radiological, and management parameters

OBJECTIVEAlthough many patients show a satisfactory physical outcome after aneurysmal subarachnoid hemorrhage (SAH), disabling cognitive dysfunction may still be present. This study focuses on the time course of cognitive recovery during the first year after aneurysmal SAH, and relates the neuropsychological test results to clinical, radiological, and management parameters. METHODSThirty-two patients were followed prospectively with neuropsychological examinations at 3, 6, and 12 months after SAH. Test results were compared with clinical entry variables, management variables, and pre- and postoperative radiological findings. RESULTSThe time course of cognitive recovery after aneurysmal SAH is heterogeneous, with motor and psychomotor functions recovering within the first 6 months, whereas verbal memory did not improve significantly until at least 6 months after the ictus. Clinical and radiological parameters reflecting the impact of the bleed were related to memory function, intelligence, and aphasia. The site of aneurysm and mode of treatment could not be linked to neuropsychological outcome. The time length of volume-controlled mechanical ventilation as a reflector of the aggregated consequences of being subjected to an aneurysm rupture correlated with both motor and psychomotor functioning and memory performance, predominantly 6 to 12 months after SAH, but was not linked to intelligence or aphasia. CONCLUSIONThe various cognitive functions have different time courses of recovery, with verbal memory requiring the longest time. Parameters reflecting the impact of the bleed and patient management can be linked to neuropsychological outcome.

ANGIOGRAPHIC BALLOON TEST OCCLUSION AND THERAPEUTIC SACRIFICE OF MAJOR ARTERIES TO THE BRAIN. Commentary

OBJECTIVETreatment of certain cerebral aneurysms, caroticocavernous fistulae, and tumors of the neck or cranial base may involve therapeutic arterial sacrifice, which requires preoperative knowledge of the feasibility of permanent occlusion of the internal carotid artery (ICA) or vertebral artery or arteries. METHODSRetrospective study of transcranial Doppler ultrasonography-monitored angiographic balloon test occlusion and therapeutic sacrifice of the ICA or vertebral artery. RESULTSWe performed transcranial Doppler-guided balloon test occlusion in 136 patients at a procedural risk equivalent to that of conventional neuroangiography, and with correct prediction of the hemodynamic result of therapeutic arterial sacrifice in all instances. Patients with an immediate drop in ipsilateral middle cerebral artery (MCA) velocity to 65% or more of baseline values upon ICA balloon occlusion tolerated ICA sacrifice well, whereas hemodynamic infarction is likely in those with a corresponding drop in MCA velocity to 54% or less. When ICA balloon occlusion caused a drop in MCA velocity to between 55 and 64% of baseline, the pulsatility of the MCA signal had to be analyzed. Patients who tolerated bilateral vertebral artery closure had reversal of flow and an increase in velocity in the P1 section of the posterior cerebral artery. In 212 patient-years of observation after therapeutic arterial sacrifice, no de novo aneurysms formed. CONCLUSIONAngiographic balloon test occlusion with transcranial Doppler monitoring can be performed ultra-swiftly at a risk equal to conventional neuroangiography and with correct prediction of the hemodynamic outcome of arterial sacrifice. Elective therapeutic arterial occlusion is a safe and efficient treatment of large cerebral aneurysms and caroticocavernous fistulae.

Cognitive functioning and health-related quality of life 1 year after aneurysmal subarachnoid hemorrhage in preoperative comatose patients (Hunt and Hess Grade V patients).

OBJECTIVEThe objective of this study was to determine cognitive functioning and health-related quality of life 1 year after aneurysmal subarachnoid hemorrhage in preoperative comatose patients (Hunt and Hess Grade V patients). METHODSPatients who were comatose at hospital arrival and thereafter were investigated for 1 year using a comprehensive neuropsychological test battery and 2 HRQOL questionnaires. RESULTSThirty-five of 70 patients survived the bleed, and 26 underwent neuropsychological testing. Two distinct patient groups emerged, one (n = 14) with good cognitive function, having mild deficits only, and the other (n = 12) with poor cognitive and poor motor function. Patients performing poorly were older (P = .04), had fewer years of education (P = .005) and larger preoperative ventricular scores, and were more often shunted (P = .02). There were also differences between the 2 groups in the Glasgow Outcome Scale (P = .001), the modified Rankin Scale (P = .001), and employment status. HRQOL was more reduced in patients with poor cognitive function. CONCLUSIONA high fraction of survivors among preoperative comatose aneurysmal SAH patients (Hunt and Hess grade V) recover to good physical and cognitive function, enabling them to live a normal life.