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Biomedical subjects

L R Caplan

Publications and source records attributed to L R Caplan.

At least 127 records · Page 7Linked to original sources
PubMed1991

Changing attentional demands in left hemispatial neglect.

Seven variations of a letter cancellation test were used to examine how varying attentional demands affect hemispatial neglect in patients with right hemisphere lesions. While the 14 targets always remained in the same location, the number of distractors (zero, nine, 28, or 82) as well as their complexity (one letter or nine different letters) were varied. The percentage of targets canceled in the left hemispace was linearly related to the number of distractors. There were no differences between the complexity conditions. In a second study, the same 14 targets were presented but the distractors (zero, 14, or 41) were all placed on the right. Increasing the number of distractors on the right increased neglect on both sides of the space. Taken together, these results suggest that, while the limited attentional resources of the left hemisphere are biased toward the right hemispace, the absence of contralateral attentional demands allows these resources to be directed ipsilaterally.

Aged↗
PubMed1991

Strokes in African-Americans.

Hypertension is the most important risk factor for stroke, especially in African-Americans. Improved control of high blood pressure nationwide is a key factor in the recent dramatic decline in stroke frequency, most notably in African-American women. Hypertension control programs must be adequately funded and expanded. African-Americans have a disproportionately high incidence of risk factors for stroke, including hypertension. There is evidence that the cerebral vessels involved in ischemic stroke in African-Americans may differ from those of Caucasians. There is an urgent need for more research on stroke in general, risk factor relations in particular, and mechanisms in the pathogenesis of stroke in African-Americans.

Black People↗
PubMed1991

Migraine and vertebrobasilar ischemia.

I studied 9 patients with migraine and posterior circulation ischemia. Inclusion criteria were (1) brainstem or cerebellar infarcts or transient ischemic attacks, (2) satisfactory vertebrobasilar angiograms, and (3) migraine. Excluded were patients with only occipital lobe ischemia, known arteriosclerosis, or other nonmigrainous vascular disease. Two women and 7 men, ages 6 to 58 years (mean, 34.7), had transient attacks only (2), single strokes (4), single stroke followed by attacks (1), or multiple strokes (2). Five had antecedent classic, 2 common migraine, and classic migraine began only after the initial ischemic event in the other two. The 7 stroke patients all had CT- or MRI-documented brainstem (4) or cerebellar (6) infarcts. Angiography was normal (3) or demonstrated basilar artery (BA) narrowing (2) or occlusion (4), or branch occlusion (1). In 3 patients the initially occluded BA later reopened. At follow-up (average 4.3 years, range 1 to 9 years), 5 were normal and 4 had important clinical deficits. I conclude that (1) "basilar migraine" is not always benign; it affects both sexes and a wide age range; (2) the pattern of headaches, attacks, and strokes varies; (3) migraine may appear only after ischemia; (4) some patients have BA occlusion or diffuse narrowing; and (5) BA occlusion can be temporary.

Adult↗
PubMed1991

Fatal brainstem stroke following internal jugular vein catheterization.

Neurologic complications of central venous catheterization are uncommon, and there are no reports of cerebrovascular events. We report a case of massive postoperative vertebrobasilar territory stroke following internal jugular vein cannulation due to inadvertent vertebral artery injury. Autopsy revealed thrombosis at the site of puncture wound in the right vertebral artery, with emboli present in the distal basilar artery.

Adult↗
PubMed1991

Cerebrovascular disease in hypertensive blacks.

There is convincing evidence that all grades of persistent diastolic hypertension, especially in blacks, should be treated in order to prevent stroke and other cardiovascular complications. Studies are now in progress to gather additional information concerning isolated systolic hypertension, especially in the aged. Inasmuch as at least one half or more of stroke deaths in blacks develop as the result of hypertension, lowering blood pressure offers the perfect opportunity to reduce considerably the frequency of this devastating illness. The recent dramatic fall in U.S. stroke mortality, greatest in the black female, is a commendable achievement, but the flattening of the declining mortality curve over the past several years should be a cause for alarm and intensive investigation.

Acute Disease↗
PubMed1991

Of birds and nests and brain emboli.

Technological methods for diagnosing brain embolism have improved. Both donor sources and recipient sites are now more readily documented. Embolism is a dynamic process. Thrombi develop and change in their cardiac or arterial 'nests', discharge into the vascular system, lodge in brain or systemic arteries, and often break up and move on. Traditionally, clinicians have sought to distinguish a cardiac from intraarterial source in order to prescribe warfarin for cardiac origin embolism. Most often surgery or aspirin is given for intraarterial embolism. Yet substances that embolize from either site are diverse. Might identification of the embolic material ("birds") be a more rational guide to treatment than simply the locations of the "nests"?

Arteries↗
PubMed1990

Caudate infarcts.

Eighteen patients had caudate nucleus infarcts (10 left-sided; 8 right-sided). Infarcts extended into the anterior limb of the internal capsule in 9 patients, and also the anterior putamen in 5 patients. Thirteen patients had motor signs, most often a slight transient hemiparesis. Dysarthria was common (11 patients). Cognitive and behavioral abnormalities were frequent, and included abulia (10 patients), agitation and hyperactivity (7 patients), contralateral neglect (3 patients, all right caudate), and language abnormalities (2 patients, both left caudate). The majority of patients had risk factors for penetrating artery disease. Branch occlusion of Heubner's artery, or perforators from the proximal anterior or middle cerebral arteries were the posited mechanism of infarction.

Adult↗
PubMed1990

Isopropyl alcohol intoxication.

Three patients had neurologic signs due to isopropyl alcohol (IPA) intoxication. Over a several-week period, a known alcoholic developed apathy, confusion, ataxia, and hyperreflexia. During this period, there was no ethanol available to him, and he denied use of other intoxicants. He was found stuporous in the hospital after drinking IPA and admitted to IPA abuse during the preceding weeks. Two other men were admitted in a stupor after large ingestions of IPA. Intoxication with IPA has two different presentations: stupor in a known alcoholic and encephalopathy of unknown cause in individuals who hide their addiction. Ethanol, methanol, IPA, and ethylene glycol intoxications are associated with different clinical and laboratory findings.

1-Propanol↗
PubMed1990

The accuracy of bedside neurological diagnoses.

The accuracy of bedside diagnoses was prospectively studied in 100 consecutive patients admitted to the neurology service at New England Medical Center, Boston. Each patient was evaluated independently by a junior resident, a senior resident, and a staff neurologist, who were required to make an anatomical and etiological diagnosis based solely on the history and physical examination. Fourteen patients were excluded because their diagnoses were known before admission. Of the remaining 86 patients, it was possible to confirm anatomical and etiological diagnoses in 40 by matching the clinical syndromes with highly specific laboratory findings. In the other 46 patients, the diagnoses could not be confirmed because the laboratory studies (including magnetic resonance imaging) were negative or nondiagnostic. In the 40 patients with laboratory confirmed final diagnoses, the clinical diagnoses of the junior residents, senior residents, and staff neurologists were correct in 26 (65%), 30 (75%), and 31 (77%), respectively. There was a trend for error rates to be higher among junior residents than staff (p = 0.06). The errors by the junior residents, [senior residents], (staff) were attributed to incomplete history and examination in 4 [1] (0), inadequate fund of knowledge in 4 [3] (3), and poor diagnostic reasoning in 6 [6] (6). These results indicate that technology is not a panacea for our diagnostic difficulties and that there is room for improvement in our clinical skills, especially diagnostic reasoning.

Adult↗
PubMed1990

Syringomyelia and arachnoiditis.

Five patients with chronic arachnoiditis and syringomyelia were studied. Three patients had early life meningitis and developed symptoms of syringomyelia eight, 21, and 23 years after the acute infection. One patient had a spinal dural thoracic AVM and developed a thoracic syrinx 11 years after spinal subarachnoid haemorrhage and five years after surgery on the AVM. A fifth patient had tuberculous meningitis with transient spinal cord dysfunction followed by development of a lumbar syrinx seven years later. Arachnoiditis can cause syrinx formation by obliterating the spinal vasculature causing ischaemia. Small cystic regions of myelomalacia coalesce to form cavities. In other patients, central cord ischaemia mimics syringomyelia but no cavitation is present. Scar formation with spinal block leads to altered dynamics of cerebrospinal fluid (CSF) flow and contributes to the formation of spinal cord cystic cavities.

Adult↗
PubMed1990

Chinese-white differences in the distribution of occlusive cerebrovascular disease.

The distribution of cerebrovascular lesions is affected by race. Blacks and Japanese have more intracranial occlusive cerebrovascular disease, while whites have more extracranial disease. Despite a high incidence of stroke in China, there are few formal studies of the distribution of vascular occlusive disease in Chinese populations. We compared clinical and angiographic features of 24 white and 24 Chinese patients with symptomatic occlusive cerebrovascular disease. In symptomatic vascular territories, whites had more severe (greater than or equal to 50% stenosis) extracranial lesions, while Chinese had more severe intracranial lesions. When we counted mild and severe lesions in a symptomatic territory, whites had more extracranial lesions while Chinese had more intracranial lesions. When we combined symptomatic and asymptomatic territories, whites had more extracranial lesions, while Chinese had more intracranial lesions. White patients reported more transient ischemic attacks. The distribution of lesions, however, was not explained by differences in incidence of transient ischemia, hypertension, diabetes, hypercholesterolemia, or ischemic heart disease between the groups. The preponderance of intracranial vascular lesions in Chinese patients is similar to that seen in blacks and Japanese. Racial differences in the occurrence of extracranial and intracranial lesions raise the possibility of a different underlying pathophysiology for the 2 locations.

Aged↗
PubMed1990

Prognostic significance of ventricular blood in supratentorial hemorrhage: a volumetric study.

We reviewed CTs from 47 patients with 48 spontaneous, supratentorial brain hemorrhages to determine the effect of ventricular blood on outcome. We correlated volumetric analysis of the parenchymal (P) and ventricular (V) blood, as well as other clinical and CT features, with clinical outcome in a statistical analysis. Hemorrhages were located in putamen 20/48 (42%), thalamus 13/48 (27%), lobar 9/48 (19%), caudate 3/48 (6%), and miscellaneous locations 3/48 (6%). Outcome in putaminal hemorrhages was highly correlated with the total (P + V) and P blood volumes, whereas the V blood was less important. For thalamic hemorrhages, outcome correlated more highly with the V and P + V volumes than with the P portion. Outcome for all hemorrhages was significantly correlated, in descending order of importance, with the severity of the initial neurologic deficit, P + V blood, hydrocephalus, the number of ventricles containing blood, P, V, and blood in the 4th ventricle. In general patients with more than 20 cc of V blood did poorly. Although hydrocephalus was associated with poor outcome, ventricular drainage did not benefit 8 of 9 patients.

Aged↗