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Biomedical subjects

G W Duncan

Publications and source records attributed to G W Duncan.

At least 19 recordsLinked to original sources
PubMed1979

Mechanisms of acute carotid stroke.

In a three-year study, the clinical course and results of intracranial angiography were compared in patients having an acute stroke in the carotid artery territory combined with angiographic abnormalities indicating severe extracranial carotid stenosis or occlusion. Two major mechanisms of stroke were delineated. In one group, the angiographic intracranial abnormalities strongly suggested the presence of embolism in the cerebral vessels supplied by the stenotic or occluded carotid artery; many of these patients had no obvious transient ischemic attacks prior to their stroke and experienced a moderate to severe clinical deficit. In the other group, evidence of embolism was absent; many showed a widespread delay in cerebral arterial perfusion, experienced a greater frequency of transient ischemic attacks before their stroke, and had a milder stroke than did those with embolism.

Carotid Artery Diseases↗
PubMed1979

Low-level, progestogen-releasing vaginal contraceptive devices.

Silicone rubber vaginal contraceptive devices of four different formulations, which release predetermined, controlled doses of three progestogens at four distinct levels, were designed and fabricated, and tested in 90-day clinical trials. Data obtained with 70 of the devices indicated that in vivo release rates (microgram/day +/- S.D.) for the formulations were: progesterone, 1400 +/- 30; norethindrone (two levels), 49.4 +/- 2.4, 196 +/- 21; d-norgestrel, 21.6 +/- 1.4. Clinical studies with these devices indicate that the women usually ovulate (with the exception of the high-dose norethindrone-releasing devices) while sperm penetration of the cervix was inhibited by all four fromulations, most consistently by the norgestrel-releasing devices.

Contraceptive Devices↗
PubMed1978

Controlled use of cranial computerized tomography.

This study attempts to assess the impact of computerized cranial tomography (CT) on clinical practice in a veterans hospital. A CT scan could be performed only if there existed a reasonable potential for the results to affect the patient's clinical course. We document many instances of how the 163 CT scans obtained during a one-year period aided patients. We quantitated one beneficial aspect by estimating the major neuroradiologic contrast procedures obviated by CT scan. Case-by-case review indicates 70 cerebral arteriograms and 58 pneumoencephalograms would have been performed had CT scanning not been available.

Adolescent↗
PubMed1978

Neurologic complications of bacterial endocarditis.

(1) Neurologic complications remain a significant problem in bacterial endocarditis. Of 218 patients with endocarditis, 84 (39%) had a neurologic complication and 58% of these 84 patients died. In contrast, the mortality rate was only 20% among those endocarditis patients without neurologic complications. (2) Of the neurologic complications, cerebral embolism is the most frequent and important. An embolic stroke occurred in 37 (17%) of our patients, with 30 of these patients dying. Emboli are important not only in terms of the direct morbidity and mortality they cause via cerebral infarction, but also because of their role in the causation of mycotic aneurysms, brain abscesses, and abnormal CSF formulae. (3) Cerebral emboli are particularly common in patients with mitral valve infection, and in patients with infection due to virulent organisms, particularly S. aureus and enteric gram-negative bacilli. (4) Mycotic aneurysms occur more frequently in the course of acute endocarditis rather than late in the course of subacute disease. Management of angiographically demonstrated mycotic aneurysms is dependent upon the presence or absence of hemorrhage, the anatomic location of the aneurysm, and the clinical course of the patient. Healing of mycotic aneurysms can occur during the course of effective antimicrobial therapy, thus obviating the need for neurosurgical intervention in all such patients. (5) Macroscopic brain abscess is a rare complication of bacterial endocarditis. Miliary microscopic abscesses are more common than larger abscesses, particularly in patients with acute disease and miliary infection in other organs of the body. (6) Focal seizures occur most commonly in endocarditis patients with acute embolic disease; generalized seizures are of diverse etiologies, with metabolic factors being most important. Penicillin neurotoxicity should be considered in patients with impaired renal function who are receiving high dose penicillin. (7) With the exception of hemorrhagic complications, lumbar puncture results tend to reflect the nature of the infecting organism rather than the nature of the neurologic complication. Endocarditis due to virulent organisms such as S. aureus is usually associated with a purulent CSF formula while nonvirulent organisms, such as viridans streptococci, susually have aseptic or normal CSF formulae.

Adolescent↗
PubMed1978

Broca aphasia: pathologic and clinical.

The speech disturbance resulting from infarction limited to the Broca area has been delineated; it differs from the speech disorder called Broca aphasia, which results from damage extending far outside the Broca area. Nor does Broca area infarction cause Broca aphasia. The lesions in 20 cases observed since 1972 were documented by autopsy, computerized tomography, or arteriogram; the autopsy records from the Massachusetts General hospital for the past 20 years and the published cases since 1820 were also reviewed. The findings suggest that infarction affecting the Broca area and its immediate environs, even deep into the brain, causes a mutism that is replaced by rapidly improving dyspraxic and effortful articulation, but that no significant distrubance in language function persists. The more complex syndrome traditionally referred to as Broca aphasia, including Broca's original case, is characterized by protracted mutism, verbal stereotypes, and agrammatism. It is associated with a considerably larger infarct which encompasses the operculum, including the Broca area, insula, and adjacent cerebrum, in the territory supplied by the upper division of the left middle cerebral artery.

Adult↗
PubMed1978

The Harvard Cooperative Stroke Registry: a prospective registry.

Data from 694 patients hospitalized with stroke were entered in a prospective, computer-based registry. Three hundred and sixty-four patients (53 percent) were diagnosed as having thrombosis, 215 (31 percent)as having cerebral embolism 70 (10 percent) as having intracerebral hematoma, and 45 (6 percent) as having subarachnoid hemorrhage from aneurysm or arteriovenous malformations. The 364 patients diagnosed as having thrombosis were divided into 233 (34 percent of all 694 patients) whose thrombosis was thought to involve a large artery and 131 (19 percent) with lacunar infarction. Many of the findings in this study were comparable to those in previous registries based on postmortem data. New observations include the high incidence of lacunes and cerebral emboli, the absence of an identifiable cardiac origin in 37 percent of all emboli, a nonsudden onset in 21 percent of emboli, and the occurrence of vomiting at onset in 51 percent and the absence of headache at onset in 67 percent of hematomas.

Cerebral Hemorrhage↗
PubMed1977

Clinical and angiographic features of carotid transient ischemic attacks.

To determine the prevalence of radiologically evident carotid stenosis in patients with transient cerebral ischemic attacks, we analyzed 95 consecutive hospitalized patients who during a two-year period had appropriate symptoms and also underwent angiography. Pure transient hemisphere symptoms affected 52 patients, pure monocular blindness occurred in 33, and 10 experienced each type of attack separately. Tight stenosis (less than or equal to 2 mm) or occlusion was present in 49 patients (52 per cent). Thirteen patients showed intracranial-branch occlusion, nine of whom had no notable stenosis. Only two clinical transient ischemic attack features correlated with angiographic findings: in transient hemisphere attacks lasting for one hour or longer, the carotid arteries revealed no notable stenosis (0.05 less than P less than 0.1); and separate hemisphere and ocular attacks in the same patient correlated with tight carotid stenosis. On the basis of the angiographic findings, the study indicates there are several distinct groups of patients with carotid transient ischemic attacks.

Arterial Occlusive Diseases↗
PubMed1977

The human thalamocortical sensory path in the internal capsule: evidence from a small capsular hemorrhage causing a pure sensory stroke.

A patient is presented who suffered a strokelike event during life that resulted in a hemisensory dificit for some modalities. On pathological examination of the brain, the lesion responsible for the deficit was found to be a small slit hemorrhage located in the posterior limb of the internal capsule adjacent to and minimally involving the thalamus. Clinicopathological correlation suggests that the sensory thalamocortical radiations must lie farther posterior in the posterior limb of the internal capsule than the corticospinal motor fibers, and that they probably lie adjacent to the thalamus. The case emphasizes that small slit hemorrhages deep in the brain, although rare, must be considered in the differential diagnosis of sudden hemisensory deficits.

Aged↗
PubMed1976

An evaluation of baclofen treatment for certain symptoms in patients with spinal cord lesions. A double-blind, cross-over study.

Baclofen (a gamma aminobutylic acid derivative) and a placebo were compared for their efficacy in relieving certain symptoms in patients with long-standing spinal cord lesions and "spinal spasticity." In a double-blind, cross-over clinical investigation, 22 patients with chronic spinal cord disease were studied. Baclofen regularly alleviated involuntary flexor or extensor spasms and increased resistance to passive movement of the legs but did not alter strength, gait, stretch reflexes, or clonus. Side effects were mild and transient. This study demonstrates that (1) baclofen is useful for the treatment of flexor spasms and (2) in evaluating a new mode of therapy, one must consider selectively the response of individual components of such global syndromes as "spasticity."

Adult↗
PubMed1975

Evaluation of carotid stenosis by phonoangiography.

Quantitative spectral (frequency) analyses were performed on 60 carotid bruits in 48 patients with suspected carotid stenosis. The technic was totally noninvasive. Bruits were recorded at the skin surface, analyzed by a minicomputer, and the degree of arterial stenosis estimated using a recently derived theory of sound production by turbulent blood flow. This method has been named phonoangiography. Fifty of the 60 bruits (83 per cent) had spectrums characteristic of turbulent blood flow, and a residual lumen diameter could be calculated. Results from the noninvasvie technic compared well with data obtained from radiographic carotid arteriograms in the 50 bruits with internal carotid artery stenosis. The residual lumen diameter estimated from phonoangiography differed from the radiographic value by less than 1 mm in 83 per cent and less than 1.5 mm in 92 per cent of the studies. Phonoangiography appears to be a useful method for assessment of carotid artery stenosis.

Arteriosclerosis↗
PubMed1975

Acute cerebellar infarction in the PICA territory.

Although old or recent infarcts of a cerebellar hemisphere in the territories of the posterior inferior (PICA), superior, or anterior inferior cerebellar arteries are commonplace autopsy findings, in no case have corresponding clinical symptoms been clearly identified. We have studied three cases, two clinocaopthologically and one clinicosurgically, in which an acute infarct involving only the cerebellum lay in the PICA territory distal to the branches to the medulla oblongata. The clinical manifestations consisted of rotatory dizziness intensified by motion, nausea, vomiting, imbalance, and nystagmus. In two cases, the clinical diagnosis had been a benign labyrinthine disorder. Recognition of a syndrome corresponding to cerebellar infarction in the PICA territory is important insofar as it assists in the differential diagnosis of dizziness. It becomes of crucial importance when cerebellar infarction is the prelude to cerebellar swelling and brain stem conpression leading to coma and death unless surgically relieved.

Acute Disease↗