Deviation of eyes and head in acute cerebral stroke

Background  

It is a well-known phenomenon that some patients with acute left or right hemisphere stroke show a deviation of the eyes (Prévost's sign) and head to one side. Here we investigated whether both right- and left-sided brain lesions may cause this deviation. Moreover, we studied the relationship between this phenomenon and spatial neglect. In contrast to previous studies, we determined not only the discrete presence or absence of eye deviation with the naked eye through clinical inspection, but actually measured the extent of horizontal eye-in-head and head-on-trunk deviation. In further contrast, measurements were performed early after stroke onset (1.5 days on average).     

Middle cerebral artery occlusion in Macaca fascicularis: acute and chronic stroke evolution

BACKGROUND: An intravascular stroke model designed for magnetic resonance imaging was developed in Macaca fascicularis (M. fascicularis) to characterize serial stroke lesion evolution. This model produces a range of stroke lesion sizes which closely mimics human stroke evolution. This paper describes the care of animals undergoing this stroke procedure, the range of outcomes we experienced and the cause of mortality in this model. METHODS: Anesthesia was induced with atropine and ketamine and maintained with isoflurane or propofol. Non-invasive blood pressure, oxygen saturation, heart rate, respiration rate, temperature and end tidal CO2 were monitored continuously. The stroke was created by occluding a distal branch of the middle cerebral artery. During catheter placement animals were heparinized and vasospasm was minimized using verapamil. RESULTS: Anesthetic induction and maintenance were smooth. Animals with small strokes showed very rapid recovery, were able to ambulate and self-feed within 2 hours of recovery. Animals with strokes of >or=4% of the hemispheric volume required lengthy observation during recovery and parenteral nutrition. Large strokes resulted in significant brain edema, herniation and brainstem compression. CONCLUSIONS: Intracerebral hemorrhage and or subarachnoid hemorrhage coupled with a stroke of any size was acutely fatal. In the absence of an effective acute stroke therapy, the spectrum of outcomes seen in our primate model is very similar to that observed in human stroke patients.     

Predicting the outcome of stroke: acute stage after cerebral infarction.

On admission to hospital during the acute phase of a stroke presumed due to ischaemic infarction in one cerebral hemisphere 93 patients were examined to determine the factors associated with a poor prognosis for immediate survival. The patients particularly at risk were those who were overtly unconscious and those with any combination of impaired consciousness, dense hemiplegia, and failure of conjugate ocular gaze towards the side of the limb weakness. Necropsy evidence suggested that these signs usually indicate infarction of the whole of one middle cerebral artery territory which is often secondary to internal carotid artery occlusion and commonly produces fatal cerebral oedema.     

Neuronal co-processing of course deviation and head movements in locusts

Summary Descending deviation detector neurons (DDNs) of Locusta migratoria are characterized physiologically by their responses to light on/off stimuli, simulated course deviation (rotation of an artificial horizon), passive rotation of the head, frontal wind, and flight activity. The investigation emphasises on the co-processing of exteroceptive input signalling course deviation (mainly movement of the retinal image, but also wind), and proprioceptive input signalling head movement and position. Stimuli were presented in combinations as expected during natural behavior. Eight DDNs are described for the first time, and 3 previously described DDNs are characterized further. Responses to horizon rotation and imposed head movements are assigned to one of 4 response types: (1) the horizon-only type codes retinal slip and/or the position of the horizon in the visual field but ignores cervical proprioception; (2) the head-only type ignores visually simulated course deviation but codes for movement or position of the head; (3) in the compensating type, head rolling causes visual input and cervical proprioceptive input of opposite signs, so that head movements themselves are ignored, whereas course deviations are recognized; (4) in the amplifying type, head rolling causes visual input and cervical proprioceptive input of the same sign, i.e. one input amplifies the other. This classification does not take the various responses to wind into account. In several DDNs, responses to phasic and tonic stimuli of the same modality, and/or responses to deviations about different axes could be assigned to different response types. Activity in DDNs has been shown previously to result in steering responses of wings, legs, abdomen and/or the head. It is proposed that different kinds of flight steering (e.g. corrective course control, intentional steering, orientation towards or away from a target) may be controlled by selective enhancement or suppression of responses or motor effects of DDN-subpopulations.Abbreviations AP action potential - DDN descending deviation detector neuron - DNI, DNC, DNM descending deviation detector neurons receiving major input from the ipsilateral, contralateral, and median ocellus respectively - PDDSMD protocerebral, descending direction-selective motion-detecting neuron - PI(2)5 descending deviation detector neuron with the cell body in the pars intercerebralis medialis - TCG tritocerebral commissure giant neuron     

Dysphagia in acute stroke.

A prospective study was undertaken to define the incidence, duration, and consequences of dysphagia in an unselected group of 91 consecutive patients who had suffered acute stroke. The site of the present lesion and of any previous stroke was determined clinically and was confirmed by computed tomography of the brain or necropsy in 40 cases. Of 41 patients who had dysphagia on admission, 37 had had a stroke in one cerebral hemisphere. Only seven patients showed evidence of lesions in both hemispheres. Nineteen of 22 patients who survived a stroke in a hemisphere regained their ability to swallow within 14 days. Dysphagia in patients who had had a stroke in a cerebral hemisphere was associated in this study with a higher incidence of chest infections, dehydration, and death.     

Enhanced protection by melatonin and meloxicam combination in a middle cerebral artery occlusion model of acute ischemic stroke in rat

Mixed efficacy of neuroprotective drugs in clinical trials has led to the emergence of the approach of combination therapy in stroke. The present study was carried out to investigate the effect of the combination of melatonin (potent antioxidant) and meloxicam (preferential inhibitor of cyclooxygenase-2 enzyme) against a middle cerebral artery occlusion model of stroke in rats. Male Wistar rats in the weight range of 250-300 g were used. Rats were anesthetized using chloral hydrate (400 mg/kg i.p) and subjected to 2 h of transient middle cerebral artery occlusion. Melatonin was administered at a dose of 20 mg/kg i.p. four times: at the time of middle cerebral artery occlusion, 1.5 h after middle cerebral artery occlusion, at the time of reperfusion, and 1 h after reperfusion. Meloxicam (2.5 mg/kg) was administered 4 h after middle cerebral artery occlusion. Motor performance tests (grip test, foot fault test, rotarod performance test, spontaneous locomotor activity), markers of oxidative stress, and triphenyltetrazolium chloride staining were carried out 24 h after middle cerebral artery occlusion. A vehicle-treated group was run in parallel. It was observed that melatonin treatment improved the motor performance and significantly attenuated the levels of malondialdehyde (MDA) as compared with the middle cerebral artery occluded group. Meloxicam treatment at the dose used neither showed significant improvement on the motor performance nor decreased the levels of MDA significantly as compared with the middle cerebral artery occluded group. However, when the combination of the two drugs was used, better protection was observed as was evident by the significant decrease in the percent foot fault errors, the increase in the time spent on the rotarod, and the increase in the six-point neurological score and grip test score. There was also a significant decrease in the levels of MDA in the combination group. The results of the present study demonstrate that enhanced protection is observed with the use of a combination of melatonin plus meloxicam in the middle cerebral artery occlusion model of acute ischemic stroke in rats.     

Some epidemiologic and clinical problems in ischemic cerebral stroke

The study involved 739 patients with the ischemic cerebral stroke into two groups: with reversible and irreversible ischemic cerebral stroke. General characteristics of patients (incidence, sex, age etc.) was similar to the characteristics of patients from other centres. Morbidity rate for ischemic cerebral strokes was 93.9, including reversible stroke 21.3 and other 72.6; mortality factor 47.2, and mortality rate 29.6%. An increase in morbidity for irreversible stroke in women over 80 years of age is striking. The authors suggest that the classification of cerebral strokes should include reversible strokes whereas progressive stroke should not be considered distinguished entity.     

Alterations in cerebral autoregulation and cerebral blood flow velocity during acute hypoxia: rest and exercise

We examined the relationship between changes in cardiorespiratory and cerebrovascular function in 14 healthy volunteers with and without hypoxia [arterial O(2) saturation (Sa(O(2))) approximately 80%] at rest and during 60-70% maximal oxygen uptake steady-state cycling exercise. During all procedures, ventilation, end-tidal gases, heart rate (HR), arterial blood pressure (BP; Finometer) cardiac output (Modelflow), muscle and cerebral oxygenation (near-infrared spectroscopy), and middle cerebral artery blood flow velocity (MCAV; transcranial Doppler ultrasound) were measured continuously. The effect of hypoxia on dynamic cerebral autoregulation was assessed with transfer function gain and phase shift in mean BP and MCAV. At rest, hypoxia resulted in increases in ventilation, progressive hypocapnia, and general sympathoexcitation (i.e., elevated HR and cardiac output); these responses were more marked during hypoxic exercise (P < 0.05 vs. rest) and were also reflected in elevation of the slopes of the linear regressions of ventilation, HR, and cardiac output with Sa(O(2)) (P < 0.05 vs. rest). MCAV was maintained during hypoxic exercise, despite marked hypocapnia (44.1 +/- 2.9 to 36.3 +/- 4.2 Torr; P < 0.05). Conversely, hypoxia both at rest and during exercise decreased cerebral oxygenation compared with muscle. The low-frequency phase between MCAV and mean BP was lowered during hypoxic exercise, indicating impairment in cerebral autoregulation. These data indicate that increases in cerebral neurogenic activity and/or sympathoexcitation during hypoxic exercise can potentially outbalance the hypocapnia-induced lowering of MCAV. Despite maintaining MCAV, such hypoxic exercise can potentially compromise cerebral autoregulation and oxygenation.