Dimitrios Georgiadis

Hemicraniectomy and Moderate Hypothermia in Patients With Severe Ischemic Stroke

Background and Purpose— We compared the clinical course of 36 consecutive patients with severe acute ischemic stroke (more than two thirds of the middle cerebral artery territory) treated with hemicraniectomy (CE; n=17) or moderate hypothermia (MH; n=19) in terms of intracranial pressure control, mortality, and specific treatment parameters. Methods— Over a period of 18 months, patients with severe ischemic stroke were treated with CE when the nondominant hemisphere was affected and with MH when the dominant hemisphere was affected. MH (33°C) was induced with either cold blankets and fans (n=11) or endovascular cooling (n=8). Intracranial pressure was monitored invasively in all cases. Results— Age, sex, cranial CT findings, level of consciousness, and time to treatment were similar between the 2 groups; significant differences were noted in National Institute of Health Stroke Scale (NIHSS) score (20 [range, 18 to 22] and 17 [range, 16 to 18] for MH and CE, respectively) but were not present when NIHSS score was corrected for aphasia (17 [range, 15 to 19] and 17 [range, 16 to 18] for MH and CE, respectively). Mortality was 12% for CE and 47% for MH; 1 patient treated with MH died as a result of treatment complications (sepsis) and 3 of intracranial pressure crises that occurred during rewarming. Duration of mechanical ventilation and of neurological intensive care unit stay did not significantly differ, but duration of catecholamine application and maximal catecholamine dosage were significantly higher in the MH group. Conclusions— In patients with severe ischemic stroke, CE results in lower mortality and lower complication rates compared with MH. Both treatment modalities, however, are associated with intensive medical treatment and a prolonged stay in the neurological intensive care unit.

Neuroprotective Effect of Delayed Moderate Hypothermia After Focal Cerebral Ischemia An MRI Study

Background and Purpose— In contrast to early hypothermia, the effects of delayed hypothermia in focal cerebral ischemia have not been widely addressed. We examined the influence of delayed hypothermia on secondary ischemic injury, MRI lesion size, and neurological outcome after transient focal cerebral ischemia in a rat model. Methods— Rats (n=30) were subjected to transient middle cerebral artery occlusion (MCAO, 120 minutes) by use of the intraluminal filament model. Animals of the treatment group (n=12) were exposed to whole-body hypothermia of 33°C for 5 hours starting 3 hours after MCAO, whereas the control group (n=18) was kept at 37°C throughout the whole experiment. The normothermia- and hypothermia-treated animals were investigated daily by using the Menzies neurological score. Serial MRI was performed 1, 3, and 6 hours after MCAO and on days 1, 2, 3, and 5. After the final MRI scan, the rats were euthanized, and brain slices were stained by 2,3,5-triphenyltetrazolium chloride. Results— Delayed hypothermia resulted in a significant increase of survival rate and a significant improvement of the Menzies score. Moreover, a significant decrease in the extent of hyperintense volumes in T2-weighted scans and a reduction of cerebral edema as calculated from T2-weighted scans throughout the examination period were obvious. The extent of cerebral infarct volume and cerebral brain edema examined by MRI was consistent with 2,3,5-triphenyltetrazolium chloride staining. Conclusions— Our results suggest that even delayed postischemic hypothermia can reduce the extent of infarct volume and brain edema after transient focal cerebral ischemia.

Effects of Induced Hypertension on Intracranial Pressure and Flow Velocities of the Middle Cerebral Arteries in Patients With Large Hemispheric Stroke

Background and Purpose— Our aim was to prospectively evaluate the effects of induced arterial hypertension in patients with large ischemic stroke. Methods— A total of 47 monitoring sessions in 19 patients with acute, complete, or subtotal middle cerebral artery (MCA) territory stroke were performed. Intracranial pressure (ICP) was monitored using a parenchymal catheter. Mean arterial blood pressure (MAP), ICP, and peak mean flow velocity of the middle cerebral arteries (VmMCA) were continuously recorded. Patients with acute ICP crises were excluded. After obtaining baseline values, MAP was raised by an infusion of norepinephrine to reach an MAP increase of at least 10 mm Hg. After MAP had reached a peak plateau level, the norepinephrine infusion was stopped. Results— Baseline MAP was 83.6±1.6 mm Hg and rose to 108.9±2.0 mm Hg after infusion of norepinephrine. ICP slightly increased from 11.6±0.9 mm Hg to 11.8±0.9 mm Hg (P <0.05). Cerebral perfusion pressure rose from baseline 72.2±2 mm Hg to 97±1 mm Hg (P <0.0001). VmMCA was already higher on the affected side during baseline measurements. At maximum MAP levels, VmMCA rose by 25.5±5.5 cm/s on the affected side and by 8.6±1.6cm/s on the contralateral side. Conclusions— In patients with large hemispheric stroke without an acute ICP crisis, induced hypertension enhances cerebral perfusion pressure and augments the VmMCA(s), more so on the affected side. The ICP slightly increases; however, this is probably not clinically significant.

Activated protein C resistance and acute ischaemic stroke: Relation to stroke causation and age

Objectives Resistance to activated protein C (APC) is the most frequent cause of thrombophilia and a well known risk factor for deep and cerebral vein thrombosis. Its causative role in ischaemic stroke is still a matter of debate. We undertook this study to determine the prevalence of APC-resistance in a cohort of consecutive patients with acute ischaemic stroke, especially with respect to patients age and the underlying stroke causation. Materials and methods 489 patients with proven ischaemic stroke were included in this study. Subtypes of stroke were classified according to the TOAST criteria, i. e. large artery artherosclerosis (LAA), small vessel occlusion (SVO), cardioembolism (CE), stroke of other etiology (SOE), and stroke of undetermined etiology (SUE). APC-resistance was determined with a functional method with high sensitivity and specificity for the factor V Leiden mutation. The results were compared with the prevalence of APC-resistance in healthy volunteers, all born in the same area. Results APC-resistance was found in 24 of 489 patients (4.9 %) and in 6 of the 112 (5.4 %) control subjects. In the stroke patients, APC-resistance was distributed as follows: LAA 6.5 % (9/138), SVO 3,9 % (4/104), CE 6.7 % (7/104), SOE 3.6 % (1/28), SUE 2.6 % (3/115). Prevalence of APC-resistance was not significantly different between young stroke patients (6–45 years) and older patients (7.7 % [5/65] versus 4.5 % [19/424]). Conclusions Prevalence of APC-resistance is not increased in patients with ischaemic stroke. Additionally, no significant differences in the prevalence of APC-resistance are evident within the various stroke subtypes.

Energy expenditure in ischemic stroke patients treated with moderate hypothermia

ObjectiveTo determine total energy expenditure (TEE) in patients with acute ischemic stroke in the territory of the middle cerebral artery (MCA), treated with moderate hypothermia (33°C).Design and settingProspective study in a neurological ICU.PatientsTen consecutive patients with severe MCA infarction undergoing moderate hypothermia.Measurements and resultsIndirect calorimetry was performed continuously over the first 6xa0days after admission. Mean daily TEE decreased significantly from 1549 before initiation of hypothermia to 1099, 1129, and 1157 on the first, second, and third days of hypothermia, respectively and returned to baseline values after hypothermia was terminated. The ratio of TEE to predicted basal energy expenditure declined from 1.01 before induction of hypothermia to an average of 0.74 during steady state of hypothermia and increased to 1.16 after rewarming.ConclusionsWe found a significant fall in TEE in sedated, curarized, and ventilated ischemic stroke patients during moderate hypothermia. Indirect calorimetry appears to be a useful tool for measuring energy expenditure in these patients, as predicted basal energy expenditure overestimates the caloric requirements during hypothermia.

Influence of inspiration:expiration ratio on intracranial and cerebral perfusion pressure in acute stroke patients

AbstractAbstractn Objective. We undertook this study to evaluate the influence of the inspiration:expiration (I:E) ratio on intracranial pressure and cerebral perfusion in patients with acute stroke.n Design. Ventilated patients with acute stroke were examined under a protocol involving variations of I:E ratio from 1:2 to 1:1 to 1:2 under positive end-expiratory pressure (PEEP) of 5.3 and – subsequently – 10.6xa0cmH2O. Intracranial pressure was monitored with parenchymal or ventricular catheters. Mean arterial blood pressure, intracranial pressure (ICP), heart rate and peak mean flow velocity of the middle cerebral arteries were continuously recorded.n Setting. Neurological intensive care unit.n Patients. A total of 45 monitoring sessions were performed in 16 patients (subarachnoid haemorrhage 3, ischemic stroke 13).n Results. No significant changes in any of the parameters monitored were evident in association with the I:E ratio variations under either of the PEEP levels applied. It must be noted, though, that ICP exceeded 15xa0mmHg in only 5/45 monitoring sessions, and never exceeded 20xa0mmHg.n Conclusions. Our preliminary results suggest that variations of the I:E ratio cause no significant changes in intracranial or cerebral perfusion pressure and, thus, can be safely used in patients with acute stroke without intracranial hypertension. The influence of I:E ratio variations on stroke patients with intracranial hypertension remains to be evaluated.

Klinische Relevanz der Detektion mikroembolischer Signale mittels transkranieller Dopplersonographie

ZusammenfassungDie Detektion mikroembolischer Signale (MES) wurde bei verschiedenen Patientengruppen beschrieben. Die einzigen Anwendungen dieser Methode, die eine eindeutig belegte klinische Relevanz für individuelle Patienten besitzen, sind (1) das Monitoring in den ersten Stunden nach Karotisendarteriektomie, wodurch Patienten mit drohendem ACI-Verschluss identifiziert werden können und (2) das Monitoring von Patienten mit asymptomatischer Karotisstenose oder verschiedenene Autoimmunkrankheiten, um das embolische Risiko bzw. die Aktivität der Erkrankung abzuschätzen. Intraoperatives Monitoring kann zur Optimierung des operativen Verfahrens beitragen, erlaubt aber keine prognostische Informationen über einzelne Patienten. Bei Patienten mit künstlichen Herzklappen besitzen MES keine Bedeutung als Marker eines erhöhten Schlaganfallrisikos; ihre prognostische Bedeutung für ein neuropsychologisches Defizit bleibt unklar. Nach neuen Studienergebnissen könnte die MES-Detektion zur Evaluierung der Wirksamkeit von Thrombozytenaggregationshemmern verwendet werden. Die fehlenden Möglichkeiten zur automatisierten MES-Detektion verringern die Anwendbarkeit dieser Methode. Insgesamt lässt sich festhalten, dass die MES-Detektion mit Ausnahme der oben erwähnten Indikationen eher pathophysiologische Informationen als klinische relevante Ergebnisse liefert.SummaryDetection of microembolic signals (MES) has been described in several patient groups. A potential clinical relevance of this technique has been established (1) during the first hours following carotid endarterectomy and (2) for patients with asymptomatic ICA stenosis or various autoimmune disorders. Intraoperative monitoring in patients undergoing cardiac or carotid surgery can be used to improve the surgical technique but provides no prognostic information for individual patients. Microembolic signals in patients with prosthetic heart valves cannot be used as markers for stroke risk; their potential significance as markers for neuropsychological deficits remains unclear. Recent reports suggest that MES can be used as surrogate markers for assessing the efficacy of antiplatelet agents. The fact that automated MES detection is not feasible greatly reduces the techniques applicability. On the whole, MES detection – with the exception of the patient groups listed above – provides pathophysiological rather than clinically relevant information.

Aktuelle Konzepte der Intensivtherapie des raumfordernden Mediainfarkts

ZusammenfassungIn der Arbeit werden aktuelle Konzepte der Therapie des raumfordernden Mediainfarkts diskutiert. Erhöhte Blutdruckwerte sollen nicht gesenkt werden, solange der Blutdruck nicht extreme Werte annimmt. Für eine allgemeine aktive Blutdrucksteigerung gibt es keine wissenschaftliche Basis. Eine generelle Oberkörperhochlagerung kann nicht empfohlen werden. Falls das Therapieziel ein möglichst hoher CPP ist, sollten die Patienten flach gelagert werden. Die operative Dekompression führt zu einer deutlichen Reduktion der Mortalität. Das funktionelle Outcome ist nicht schlechter als bei den Patienten, die die Erkrankung unter konservativer Therapie überleben. Bei der akuten Hirndruckkrise sind kurzfristige Effekte von Mannit (0,5 g/kg), Hyperhaes® (100 ml) sowie hypertoner Kochsalzlösung (75 ml 10%ige Lösung) auf den ICP gut belegt. Der Nutzen einer längerfristigen Anwendung ist fraglich. Für eine Basistherapie des sich entwickelnden Hirnödems mit Osmotherapeutika liegt keine ausreichende Evidenz vor. Eine PEEP-Beatmung bis zu 12 cm H2O kann problemlos eingesetzt werden, wenn ein begleitender Blutdruckabfall kontrolliert und behandelt wird. Eine Änderung des I/E-Verhältnisses ist gefahrlos möglich. Kortikoide und Hämodilution sind beim postischämischen Hirnödem wahrscheinlich nicht wirksam.SummaryThe aim of this paper is to review new developments in the intensive care of patients with space-occupying middle cerebral artery infarctions. Elevated blood pressure should not be treated; however, there is no scientific basis to induce arterial hypertension in these patients. It is not recommended generally to nurse the patients in a position with the head elevated. If therapy is targeted for an optimum cerebral perfusion pressure, the patients should be nursed in a flat position. Decompressive surgery is associated with a marked reduction in an otherwise high mortality. The functional outcome after surgery is similar to the outcome of the survivors after conventional treatment alone. Treatment options for an acutely raised intracranial pressure are mannitol or hypertonic saline solutions, although the long-term effects have not been ascertained yet. There is not enough evidence supporting a prophylactic standard therapy with hypertonic solutions. Patients who require artificial ventilation can be safely ventilated using PEEP or an inverse inspiration/expiration ratio, if the blood pressure is monitored and a possible drop of the arterial blood pressure is treated. Corticoids and hemodilution are obsolete therapies in these patients.

Noninvasive monitoring of hypertensive breakthrough of cerebral autoregulation in a patient with acute ischemic stroke.

Background and Purpose: We describe the first documentation of hypertensive breakthrough of cerebral autoregulation in a patient with acute stroke with transcranial Doppler sonography. Case Description: A 55-year-old patient with acute left hemispheric stroke was treated with moderate hypothermia. He died of transtentorial herniation 4 days after admission. Static cerebral autoregulation (sCA) of the unaffected hemisphere was evaluated 6 times during this period and always found to be intact. A bolus application of epinephrine resulted in a hypertensive episode (mean arterial pressure (MAP) 135 mm Hg); hypertensive breakthrough of cerebral autoregulation was evident when MAP exceeded approximately 110 mm Hg. Interestingly, no such breakthrough was evident during testing of sCA, even when MAP reached 120 mm Hg. Conclusions: Our observation suggests that (1) the pace of the MAP increase is crucial for the occurrence of a hypertensive breakthrough of the cerebral autoregulation and (2) the disturbance of cerebral autoregulation is potentially longer as previously assumed.