Platelet aggregability in sleep-related stroke.

We examined platelet aggregability during nocturnal sleep and daytime wakefulness in patients with a history of sleep-related stroke onset (SOS) and compared it to that of matched awake-onset stroke (AOS) patients and controls without evidence of vascular disease. Aggregability was evaluated in-vitro at least seven weeks following stroke onset. Platelets were more aggregable to ADP, collagen and arachidonic acid (AA) during both sleep and wakefulness in patients with AOS (p less than 0.01). No significant difference in the mean aggregation thresholds during sleeping or waking periods were found between SOS and control groups. However, platelets were significantly more responsive to AA during sleep than during wakefulness in the SOS patients (p less than 0.01). This difference was confined to the subgroup of SOS patients who had experienced nocturnal as opposed to daytime sleep-related stroke onset, suggesting that the observed difference in platelet responsiveness to AA may be related to a circadian fluctuation in platelet aggregability rather than to a sleep-related fluctuation. Significant sleep-related changes in platelet aggregability were not identified in the other two groups.

The value of noninvasive investigation in the diagnosis of total occlusion of the internal carotid artery.

A battery of simple noninvasive tests consisting of directional Doppler ultrasound and carotid phonoangiography has been used to detect carotid stenosis in 700 patients Forty four carotid occlusions in 42 patients were confirmed on angiography, and this study examines the accuracy of this noninvasive battery in predicting the presence of an occluded internal carotid artery. Although the sensitivity of the battery described has been 70% for occlusion, with a specificity of 98% (only five false positives), this relatively low sensitivity and the uniform requirement for surgery in the false positive group have led us to conclude that this battery should not be used as a substitute for angiography when the diagnosis of internal carotid occlusion requires to be confirmed. Nevertheless, these noninvasive tests do have a role in alerting the physician to the presence of carotid occlusion and contralateral carotid artery stenosis, allowing more specific planning of any subsequent arteriography required.

Internal carotid artery occlusion: clinical and therapeutic implications.

Five hundred patients referred to the Cerebrovascular Clinic of the Johannesburg Hospital were examined by a battery of noninvasive tests and angiography. Thirty four occlusions of the internal carotid artery were found in 32 patients. These patients were prospectively evaluated, including clinical examination, analysis of risk factors and subsequent management. This group of patients was followed up for a mean period of 18 months, and the clinical and laboratory findings and follow up data of this group were compared to an age and sex matched group of patients with matched presenting symptoms, but with patent internal carotid arteries on angiography. Four clinical patterns emerged in the patients with occluded carotid arteries; asymptomatic (3), TIA's (17), initial fixed stroke (7), and TIA with subsequent stroke (5). Follow up of the occluded group revealed 19 patients (59%) with no further symptoms and no indication for surgical intervention. Nine patients required surgery; 4 external carotid endarterectomies (ipsilateral), 4 internal carotid endarterectomies (contralateral), and one extracranial to intracranial bypass. Two were lost to follow up and one died. After 18 months mean follow up 29 patients (91%) were well and asymptomatic. Follow up for a similar period of the non-occluded group revealed three deaths, three late strokes and three myocardial infarctions. None were lost to follow up. After 19 months mean follow up 26 patients (81%) were well with no new neurological symptoms. The prognosis of appropriately treated patients with total occlusion of the internal carotid artery does not appear to be worse than in patients with similar presenting features and patent carotid arteries.(ABSTRACT TRUNCATED AT 250 WORDS)