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Biomedical subjects

L R Caplan

Publications and source records attributed to L R Caplan.

At least 145 records · Page 8Linked to original sources
PubMed1990

Effects of changes in stimulus contingency on visual extinction.

Left visual field (LVF) extinction during double simultaneous stimulation (DSS) is common in patients with right cerebral lesions. A postulate is that during DSS, the intact left hemisphere's limited attentional capacity is directed to right hemispace, resulting in LVF extinction. External cueing may help direct attention to the LVF and improve performance. In the present study, we varied patterns of unilateral stimulation preceding DSS in an attempt to redirect attention through expectancy. Nine patients (7 stroke, 2 tumor) with right hemisphere lesions each had 40 DSS trials with the distribution of unilateral stimulation trials systematically varied. Mean extinction percentages on DSS trials were 17% following 5 right unilateral trials, 30% following 1 right unilateral trial, 52% following 1 left unilateral trial, and 63% following 5 left unilateral trials. These findings indicate that the probability of extinction decreases following unilateral stimulation to the right visual field and increases following unilateral stimulation to the LVF. These results suggest that expectancy alters the attentional bias which mediates extinction.

Adult↗
PubMed1989

Encephalopathy, deafness and blindness in young women: a distinct retinocochleocerebral arteriolopathy?

Three young women (aged 18 years, 19 years and 19 years) who developed progressive neuropsychic and neurologic disturbances with hearing loss and multifocal retinal artery branch occlusions are reported. This retinocochleocerebral syndrome has been reported previously only in 12 young North American women. Its pathogenesis is unknown, but an atypical viral infection of the vessel walls has been suggested. Abnormalities of T lymphocytes subsets in blood in one of the patients suggested an immunological dysfunction, but all other tests, including immunological reactions on brain and skin biopsies, were negative or non-specific. Steroids and immunosuppressive agents have been advocated on an empirical basis, but the second patient showed a substantial recovery without any therapy and the third gradually deteriorated despite azathioprine, cyclophosphamide, prednisone and plasma exchanges. This retinocochleocerebral syndrome probably corresponds to an arteriolopathy of unknown nature.

Adolescent↗
PubMed1989

The MICROSTROKE expert system for stroke type diagnosis.

MICROSTROKE is a prototype expert system designed to categorize and diagnose stroke types based on clinical information. The knowledge base of MICROSTROKE includes information from large stroke registries. The system first queries the physician-user for details of the patient's history, information about the onset of stroke, accompanying symptoms, and pertinent neurologic findings and then sums the individual data items, factors in the a priori odds, and arrives at the probabilities of different stroke types for a given patient. Specific diagnosis of stroke type includes thrombosis, embolus, lacune, intracerebral hemorrhage, and subarachnoid hemorrhage. Stroke type diagnoses by MICROSTROKE were correct in 72.8% of 250 cases in the Hamburg Stroke Data Bank. MICROSTROKE runs on any MS-DOS microcomputer and is intended as a practical aid for physicians not fully familiar with the diagnosis of stroke types.

Cerebrovascular Disorders↗
PubMed1989

Morning increase in onset of ischemic stroke.

The time of onset of ischemic stroke was determined for 1,167 of 1,273 patients during the collection of data by four academic hospital centers between June 30, 1983, and June 30, 1986. More strokes occurred in awake patients from 10:00 AM to noon than during any other 2-hour interval. The incidence of stroke onset declined steadily during the remainder of the day and early evening. The onset of stroke is least likely to occur in the late evening, before midnight.

Acute Disease↗
PubMed1989

The TOPOSCOUT expert system for stroke localization.

Clinically, strokes are localized by the findings on neurologic examination. TOPOSCOUT is an expert system designed to diagnose the anatomic location and the corresponding vascular territory of strokes based on the clinical signs and symptoms. The inference engine of TOPOSCOUT uses a backtracking algorithm and a rule-based data base that includes associations of neurologic signs with vascular and anatomic areas. TOPOSCOUT is capable of detecting typical stroke patterns, for example, "top-of-the-basilar" or Wallenberg's syndromes. The accuracy of TOPOSCOUT's diagnoses has been tested for conformity with the final diagnoses of 129 patients in the Hamburg Stroke Data Bank, and a high level of agreement was found for hemispheric lesions. The program runs on microcomputers with MS-DOS and is intended as a practical aid for physicians not fully familiar with topologic stroke diagnosis and as an interactive teaching device.

Cerebral Arteries↗
PubMed1989

Stroke in patients with fusiform vertebrobasilar aneurysms.

We studied seven patients with brainstem infarction and large fusiform vertebrobasilar (VB) aneurysms to clarify the clinical, radiologic, and pathologic features. All presented with pontine infarcts; one also had a cerebellar infarct. VB TIAs preceded brainstem infarction in four patients. Angiography and CT documented VB fusiform aneurysmal dilatation. Four had intraluminal thrombi and one had severe basilar artery stenosis. Two distinct clinical pictures emerged: unilateral pontine infarcts with favorable outcome, presumably related to obstruction of a pontine penetrating artery at its origin from the posterior wall of the aneurysmal basilar artery, and major fatal bilateral pontine infarcts from basilar artery occlusion. Two patients came to autopsy. One had thrombus in the dilated basilar artery and a posterior cerebral artery branch embolus with hemorrhagic occipital infarction; the other had basilar artery thrombus with aneurysmal rupture and subarachnoid hemorrhage. Fusiform VB aneurysms caused brainstem stroke by intraluminal thrombus, local embolism, atherostenosis, and obstruction of paramedian penetrating arteries. Subarachnoid hemorrhage is an uncommon complication.

Adult↗
PubMed1989

Cerebrovascular complications of mucinous cancers.

Six patients with mucinous cancer (2 colonic, 2 pancreatic, and 2 pulmonary origin) had necropsy evidence of thrombosis of large and small systemic, extracranial, and intracranial arteries and veins, and multiple cerebral infarcts and small hemorrhages. On microscopic examination, we found small infarcts and hemorrhages within the brain and mucin within vessels, macrophages, and in areas of infarction. The clinical picture included strokes and encephalopathy. Mucin-producing cancers can be associated with a coagulopathy that causes extensive occlusive vascular disease.

Adenocarcinoma, Mucinous↗
PubMed1988

Lateral thalamic infarcts.

A patient with occlusion of the proximal posterior cerebral artery (PCA), a lateral thalamic infarct, and hemisensory loss later developed hemianopia and hemiparesis and had extensive PCA territory infarction in the midbrain, the lateral portion of the thalamus, and the occipital lobe noted at necropsy. Two other patients had lateral thalamic infarcts on computed tomography, normal angiographic findings, and presumed thalamogeniculate artery branch occlusion. There are three clinical syndromes associated with lateral thalamic infarction: (1) hemisensory loss, hemiataxia, and involuntary movements; (2) pure sensory stroke; and (3) sensory-motor stroke. Ataxia, adventitious movements, and sensory loss are due to infarction of the lateral, posterolateral, and posteromedial ventral nuclei caused by occlusion of the PCA proximal to the thalamogeniculate artery branches or by occlusion of large thalamogeniculate arteries. Pure sensory and sensory-motor strokes are due to smaller infarcts in the posterolateral-posteromedial ventral complex and adjacent internal capsule caused by occlusion of penetrating artery branches of the thalamogeniculate arteries.

Aged↗
PubMed1988

Carotid endarterectomy: what is its current status?

The plethora of recent articles regarding carotid endarterectomy has tended to confuse rather than clarify its indications, efficacy, and acceptability. The National Institutes of Health has recently funded two large multicenter controlled clinical trials, one including asymptomatic persons with carotid stenoses, and the other, patients having transient ischemic episodes or minor strokes. Eight academic professors of neurology (four), neurosurgery (two), and vascular surgery (two) with a long and abiding interest in cerebrovascular disease prepared a statement delineating acceptable levels of mortality and morbidity from this procedure. These might serve as guidelines until the large trials have been completed.

Arteriosclerosis↗
PubMed1988

Local embolism from vertebral artery occlusion.

Basilar artery territory stroke may result from embolism arising from the site of vertebral artery occlusion. This stroke mechanism (local embolism) has been well documented in the middle cerebral artery territory from extracranial internal carotid artery disease but not fully appreciated in the vertebral basilar circulation. We report two patients whose clinical presentation indicated major basilar artery territory infarction documented by angiography to be the result of vertebral artery occlusion and artery-to-artery embolism. Vertebral artery occlusion has often been associated with a benign course, but under certain circumstances embolism to the basilar artery may complicate the outcome.

Adult↗
PubMed1988

Benign disappearance of ventricular thrombus after embolic stroke. A case report.

The source for a patient's middle cerebral artery territory embolic stroke was found by echocardiography to be a left ventricular cardiac thrombus. The apical mass was large, pedunculated, and moved with systole into the ventricular cavity. The absence of ventricular dyskinesia was thought to favor a tumor, and surgery was considered before repeat echocardiography showed disappearance of the mass, making thrombus the likely diagnosis. No further embolic events occurred during or since the disappearance of the thrombus while on anticoagulation therapy. Serial echocardiography for change in or disappearance of a ventricular mass may be critical in distinguishing thrombus from tumor.

Aged↗
PubMed1988

Pentoxifylline in acute nonhemorrhagic stroke. A randomized, placebo-controlled double-blind trial.

The efficacy and safety of pentoxifylline were assessed in 297 adult patients with ischemic stroke in a multicenter, double-blind, randomized and placebo-controlled trial. Treatment was started within 12 hours after the stroke onset. Study medication was administered intravenously continuously (16 mg/kg/day, maximum 1,200 mg/day) for 3 days and per os (400 mg t.i.d.) for the remainder of 28 days. Demographic data were comparable, and functional impairment and mortality (pentoxifylline 12%, placebo 10%) were not different between the two groups. Neurologic deficit scores improved from baseline admission scores during the 4-week study in both groups but did not differ between groups at admission or throughout the study except during the first few days when the consciousness level (Days 1 and 2), motor function (Days 1 and 2), cranial nerve function (Days 1-4), and total neurologic deficit scores (Days 1 and 2) were better in the pentoxifylline group than in the placebo group, especially in a subset of patients with severe deficits at admission. Laboratory values and side effects were also comparable between groups. Our study indicates that pentoxifylline can be given safely in patients with acute ischemic stroke. Although pharmacologic effects were present during the first few days, the clinical benefits were small and not sustained.

Acute Disease↗