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L D DeWitt

Publications and source records attributed to L D DeWitt.

At least 19 recordsLinked to original sources
PubMed1994

Neurologic complications of infectious mononucleosis.

A review of the neurologic complications of Epstein-Barr viral (EBV) infections is presented. EBV has been associated with a wide range of acute neurologic diseases in children. Encephalitis, meningitis, cranial nerve palsies, mononeuropathies, and many other neurologic ailments have been described since the confirmation of EBV as the etiology of infectious mononucleosis. It is important to recognize that EBV can cause a myriad of neurologic illnesses with or without the stigmata of infectious mononucleosis.

Child↗
PubMed1994

Longitudinal monitoring of intracranial arterial stenoses with transcranial Doppler ultrasonography.

The natural history of intracranial arterial stenoses remains relatively unknown. To monitor the progression of these lesions over time, the authors reviewed transcranial Doppler (TCD) laboratory reports at five hospitals for patients with angiographically documented intracranial arterial stenoses along the internal carotid artery distribution, and at least two TCD studies conducted more than 2 months apart. Twenty-two patients (19 men and 3 women; mean age, 64 years) with 29 stenoses were identified. The findings were compared to reproducibility data obtained from 11 age-matched control subjects with repeat TCD studies. During a mean follow-up period of 21 months, peak systolic flow velocities corresponding to the areas of stenosis increased in 9 arteries with lesions, and new collateral flow patterns, indicating further hemodynamic compromise distal to the lesions, developed in 2; one of the latter also had increased corresponding velocities. Thus, 10 (35%) arteries with lesions had TCD evidence of progression. Flow velocities remained the same in 13 (45%) stenotic vessels and dropped in 2 (7%). Findings were considered inconclusive for 4 lesions (14%). These findings suggest that intracranial arterial stenoses are dynamic lesions, and that they can evolve and cause further reductions of the arterial diameters after relatively short periods of time. TCD can noninvasively detect their hemodynamic effects.

Adult↗
PubMed1992

Embolism from vertebral artery origin occlusive disease.

We report 10 patients with severe occlusive disease of the vertebral artery (VA) origin in the neck with intra-arterial embolism to the posterior circulation. The VA lesions in seven patients were complete occlusions, and three patients had severe atherostenosis. All patients had strokes in the vertebrobasilar territory. The most frequent recipient sites of intra-arterial embolism were the intracranial VA-posterior inferior cerebellar artery region (8), and the distal basilar artery (BA) and its superior cerebellar and posterior cerebral artery branches (7). Two patients had pontine infarction due to BA embolism. The most common clinical signs were due to cerebellar infarction. Atherosclerotic disease of the VA origin has features in common with disease of the internal carotid artery origin. Both have similar risk factors and demography, and each can cause strokes by intracranial intra-arterial embolism.

Aged↗
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↗
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↗
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

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

Transcranial Doppler.

TCD recording of flow velocities in intracranial vessels was first described by Aaslid in 1982. The utility of this instrument becomes more apparent as it is used in different clinical settings and compared with angiographic findings (Figures 1 and 2). Its importance in early detection of vasospasm in subarachnoid hemorrhage is now clearly known; increased flow velocity can be documented prior to neurologic deterioration and thus allow early institution of therapy. In patients with stroke or transient ischemic attack of unclear etiology, especially in blacks, Orientals, or females, who have a higher incidence of intracranial arterial disease, TCD can be a very important noninvasive means for detecting stenosis of intracranial vessels. Its value for assessing collateral circulation, intraoperative monitoring, and measuring CBF is quite promising. Hopefully, through further work with TCD, we will be able to clarify the spectrum of its usages as well as its limitations, though the preliminary data indicate that it should be an important addition to present noninvasive evaluations.

Arterial Occlusive Diseases↗
PubMed1988

Dissection of the intracranial vertebral artery.

We describe four patients and review prior reports to clarify the clinical, radiographic, and pathologic findings of intracranial vertebral artery (VA) dissection. A 43-year-old man and a 33-year-old woman had chronic bilateral VA dissecting aneurysms. The man had multiple episodes of subarachnoid hemorrhage (SAH) and necropsy showed multiple dissections and defects in the internal elastica. The woman had many brainstem TIAs and strokes during 3 years. Two other patients had SAH and unilateral dissections. Intracranial VA dissection causes four overlapping syndromes: (1) brainstem infarcts are usually due to subintimal dissection extending into the basilar artery, affect younger patients, and often are single fatal events; (2) SAH is due to subadventitial or transmural dissection; (3) aneurysms cause mass effect on the brainstem and lower cranial nerves; and (4) chronic dissections due to connective tissue defects cause extensive bilateral aneurysms and repeated TIAs, small strokes, and SAH.

Adult↗
PubMed1987

Posterior cerebral artery stenosis.

We analyzed the clinical features of symptomatic posterior cerebral artery (PCA) stenosis in 6 patients selected from 15 patients with angiographically documented PCA atherostenosis occurring during a 7-year period. Transient ischemic attacks (TIAs) were the major presentation in 5 patients. A homonymous visual field defect was present in 2 patients. TIA symptoms were predominantly visual or sensory, or both. The most common visual symptom was difficulty seeing to one side. One patient saw flashing lights. Sensory spells were always paresthetic, usually involving the arm and hand and occasionally the face and leg. Three patients had visual and sensory spells together. Two patients with a visual field defect had calcarine infarcts found by computed tomography. All patients were treated with warfarin. During follow-up (4 months to 4 years), no patient had a new stroke in the PCA territory, and only one continued to have TIAs. PCA atherostenosis is rarer then PCA embolic occlusion. In contrast to those with PCA embolism, our patients with PCA atherostenosis had more TIAs and fewer infarcts. The clinical features of PCA stenosis--preponderance of visual and sensory TIAs--distinguish this vascular lesion from stenosis of the middle cerebral artery.

Aged↗
PubMed1985

MRI and the study of aphasia.

Three-dimensional magnetic resonance imaging (MRI) was used to study various aphasia and neurobehavioral syndromes due to embolic or thrombotic cerebral infarction. Two patients are presented to illustrate how MRI may complement, and sometimes improve on, CT for the in vivo demonstration of anatomic changes underlying said syndromes. MRI images were reconstructed at planes selected to match CT, and at coronal planes through the entire anteroposterior extent of the lesions. Both CT and MRI detected lesions; however, MRI provided better differentiation of gray and white matter. Coronal reconstructions aid in optimally visualizing the relationship of lesions to the opercular and perisylvian gyri. CT may be inadequate to define actual extent of lesions, whereas MRI may more clearly show that apparently subcortical lesions can, in fact, involve the cortex as well.

Adult↗
PubMed1985

Anticoagulant-related intracerebral hemorrhage.

Twenty-four patients had intracerebral hemorrhage while they were being treated with anticoagulants. Hypertension was present in 67% of the cases, head trauma was an uncommon preceding event, and simultaneous bleeding in other organs occurred in only one instance. Neurologic abnormalities progressed for several hours in 58%. Seizures occurred at onset in 12.5%. The location of the hemorrhage was as follows: cerebellum (nine cases), lobar white matter (six), basal ganglia (five), thalamus (two), and hemisphere, unspecified (two). In 61%, the hemorrhages occurred within 6 months of therapy. In 75%, the prothrombin time was beyond 1 1/2 times the control value. Mortality was 62.5%. Survivors had smaller hematomas than did patients with fatal hemorrhage.

Adult↗
PubMed1984

Nuclear magnetic resonance imaging in evaluation of clinical stroke syndromes.

Proton nuclear magnetic resonance (NMR) imaging was performed on normal volunteers and patients with various types of clinical strokes. True three-dimensional volumetric data were obtained for subsequent reconstruction of images at various orientations, including transverse, coronal, and sagittal, and for specific matching to x-ray computed tomographic planes. A variety of radiofrequency pulse sequences was used to generate images weighted by the NMR parameters spin density (p) and spin-lattice (T1) and spin-spin (T2) relaxation times. Quantitative T1 data and qualitative T2 information were obtained from appropriate sequences. Proton NMR images embodying T1 information provided adequate delineation of normal intracranial anatomical structure and a high level of gray matter-white matter contrast; high lesion detection sensitivity in various clinical forms of stroke was seen in images providing both T1 and T2 information. T1 and T2 relaxation times were prolonged in embolic, thrombotic, and watershed infarctions as well as in lacunae; shortening of T1 and T2 was found in hematomas. Serpiginous vessels in an arteriovenous malformation were seen that had particular pulse sequences.

Cerebellar Diseases↗
PubMed1984

Central pontine myelinolysis: demonstration by nuclear magnetic resonance.

An alcoholic, hyponatremic woman developed central pontine myelinolysis (CPM) and improved from a decerebrate, comatose state to alertness and full ambulation. NMR, using inversion-recovery and spin-echo pulse sequences, was performed sequentially from 4 weeks to 8 months after onset of symptoms and revealed a well-defined lesion with prolonged relaxation times. The lesion was anatomically consistent with CPM and was initially also visualized by CT. NMR showed no definite temporal change in the qualitative appearance of the lesion until the 8-month scan; however, quantitatively, a reduction of relaxation times was noted with each serial study.

Adult↗
PubMed1983

Nuclear magnetic resonance imaging in central nervous system disease.

From the preliminary work of many investigators, it appears that proton nuclear magnetic resonance (NMR) imaging will have wide application in the diagnostic assessment (and potential management) of patients with vascular, neoplastic, and demyelinating diseases of the central nervous system (CNS). Findings in isolated cases and small series suggest that NMR imaging may play a role in the evaluation of patients with other CNS conditions including hydrocephalus, malformations, infections, developmental and metabolic disorders, and degenerative processes. Because of the dynamic nature of disease processes involving the CNS, the precise meaning of NMR image parameters (rho, T1, and T2) remains unclear. A comprehensive study correlating NMR images in neurologic disease with precise neuropathologic examination is required. In the future, with accurate quantitative measurements of these NMR parameters, in vivo imaging may provide insight into the dynamic nature of neurologic disease.

Central Nervous System Diseases↗
PubMed1983

Periodic nonalternating ocular skew deviation accompanied by head tilt and pathologic lid retraction.

A 60-year-old black male with a 13-year history of adult onset diabetes mellitus and hypertension with a previous lacunar stroke suddenly developed a periodic head and eye movement disorder characterized by nonalternating skew deviation, rotatory nystagmus, head tilt, and lid retraction. On CT scan, the patient had a lacunar infarct in the right midbrain in the region of the interstitial nucleus of Cajal, an anatomical area involved with head tilt, torsional eye movement, and skew deviation.

Cerebral Infarction↗