Neuropharmacology and linguistic neuroplasticity.
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Aphasia↗
Biomedical subjects
D H Jacobs
Publications and source records attributed to D H Jacobs.
Herpes simplex virus encephalitis following corticosteroids and cranial irradiation.
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Adrenal Cortex Hormones↗
Apraxia differs in corticobasal degeneration and left-parietal stroke: A case study.
Corticobasal degeneration (CBD) is a progressive disorder characterized by both cortical and basal ganglia dysfunction such as asymmetrical apraxia, and akinetic rigidity, involuntary movements, and cortical sensory loss. Although apraxia is a key finding for the differential diagnosis of CBD, it has not been determined whether the features of apraxia seen in subjects with CBD are similar to those features exhibited by subjects with left-hemisphere damage from stroke. Therefore, for both clinical purposes and in order to better understand the brain mechanisms that lead to apraxia in CBD, we studied praxis in a patient with CBD and compared him to patients who are apraxic from left-parietal strokes. We used three-dimensional movement analyses to compare the features of apraxic movement. This subject with CBD was a dentist whose initial complaint had been that he "forgot" how to use his tools in the mouths of his patients. Analyses were performed on the trajectories made when using a knife to actually slice bread, and when repetitively gesturing slicing made to verbal command. Movements of the left hand, wrist, elbow, and shoulder were digitized in 3-D space. Although the CBD subject was clearly apraxic, the features of his apraxia differed markedly from those of the subjects with lesions in the left parietal lobe. For movements to command, the CBD subject showed joint coordination deficits, but his wrist trajectories were produced in the appropriate spatial plane, were correctly restricted to a single plane, and, like control subjects, were linear in path shape. However, when he was actually manipulating the tool and object, all of these aspects of his trajectories became impaired. In contrast, the deficits of the apraxic subjects with left-parietal damage were most pronounced to verbal command with their movements improving slightly although remaining impaired during actual tool and object manipulation. Unlike patients with parietal strokes, patients with CBD have degeneration in several systems and perhaps deficits in these other areas may account for the differences in praxic behavior.
Aged↗
Apraxia in corticobasal degeneration.
Corticobasal degeneration (CBD) is a degenerative disease that often presents with an asymmetric progressive ideomotor limb apraxia. Some apraxic subjects may fail to perform skilled purposive movements on command because they have lost the memories or representations that specify how these movements should be performed (representational deficit). In contrast, other apraxic subjects may have the movement representations but are unable to utilize the information contained in them to execute skilled purposive movements (production-execution deficit). To learn if the apraxic deficit in CBD is induced by a representational or a production-execution deficit, we tested three nondemented subjects with CBD on tasks requiring production of meaningful or meaningless gestures to command, gesture imitation, gesture discrimination, and novel gesture learning. A fourth subject with incomplete data also is presented. The results suggest that the apraxia associated with CBD is initially induced by a production-execution defect with relative sparing of the movement representations.
Aged↗
Apraxia and motor-skill acquisition in Alzheimer's disease are dissociable.
Many patients with Alzheimer's disease (AD) are apraxic and the apraxia has been posited to be related to a loss of movement representations. Whereas patients with Alzheimer's disease have been reported to demonstrate normal motor learning on a rotor pursuit skill acquisition task, it is unknown whether AD subjects who are apraxic demonstrate normal skill-learning. We tested subjects with probable AD and normal controls on a rotor pursuit task. We also tested the AD subjects for ideomotor apraxia. Subjects with AD who were apraxic had normal motor learning. In addition, praxis score did not correlate with performance on the skill-acquisition task. The results suggest that ideomotor praxis and motor learning are at least partly dissociable.
Aged↗
Recovery following lateral medullary infarction.
Lateral medullary infarction (LMI) has a well-defined clinical syndrome and vascular pathology. The functional outcome and degree of disability of patients with LMI, however, have not been as well investigated. We followed 18 consecutive patients with LMI during inpatient stroke rehabilitation. Thirteen patients were followed after discharge from the hospital over a mean time of 1 year. The degree of disability on admission and discharge from the hospital, and at follow-up was assessed using the motor component of the Functional Independence Measurement (FIM-motor). All patients were discharged home. During inpatient rehabilitation, the functional performance of all patients improved substantially from FIM-motor 50.9 +/- 13.0 (mean +/- SD) on admission to 76.9 +/- 10.5 at discharge. Patients with lower FIM-motor scores on admission had more functional improvement from admission to discharge than those with higher FIM-motor scores on admission. Patients with disease of the posterior inferior cerebellar artery showed significantly less functional improvement than patients with disease of the vertebral artery or no identified vascular pathology in the posterior circulation. In the follow-up group, the FIM-motor scores further improved to 84.6 +/- 8.4, indicating nearly full functional independence. Eighty-five percent were totally independent with ambulation. Five of seven previously working patients returned to work. Patients with LMI have few functional deficits after completion of inpatient rehabilitation, continue to improve functionally after discharge, and often resume their previous activities.
Adult↗
The influence of center of mass effect on the distribution of spatial attention in the vertical and horizontal dimensions.
Normal subjects attend toward the middle of grouped items (center of mass effect). In order to learn if mass effect could influence performance on line bisection tasks and if the spatial orientation of the line (vertical vs. horizontal) could influence center of mass effect, we administered bisection tasks to 16 normal subjects using either lines composed of two unequal segments (one thick and one thin) or unsegmented lines. When the longer segment was to the right, left, up, or down, subjects erred by deviating their bisection toward the longer segment (center of mass effect). Our results demonstrate that the center of mass effect can be seen with bisection tasks and is greater in the vertical than in the horizontal dimension.
Adult↗
Adynamic aphasia: a transcortical motor aphasia with defective semantic strategy formation.
Adynamic aphasia is a form of transcortical motor aphasia characterized by sparse but otherwise normal spontaneous speech that may improve when concepts are introduced by external stimuli. Akinesia, impaired concept formation, inertia of concept generation, a defective semantic network, damage or impaired access to the verbal output lexicon, and defective semantic strategy formation have been proposed to account for this disorder. We studied a patient with adynamic aphasia and frontal lobe systems dysfunction due to bilateral striatocapsular infarctions. The patient was not akinetic but did demonstrate inertia of concept generation that could be overcome with prompting. However, prompting did not improve the number of concepts generated. He demonstrated a generally intact verbal lexicon and semantic network and normal lexical priming. However, his ability to sort closely related items into different classes without prior cuing regarding the nature of the classes was defective. Although his verbal memory was normal, he appeared to use a serial rather than a semantic strategy to recall items. Finally, despite normal lexical priming, he was impaired on a letter fluency task. These results most clearly demonstrate a defect in semantic strategy formation but indicate an additional and possibly related deficit in concept formation and a partial deficit in lexical strategy formation. All of these deficits appear to reflect impairment in the hierarchical organization of knowledge specific to the task at hand. This appears to be a key component of executive functions supported by frontal lobe systems.
Aphasia↗
Diencephalic temporal order amnesia.
OBJECTIVE: Amnesia for temporal relations may occur without amnesia for content memories. The aim was to determine whether a patient with mild memory loss due to a thalamic lesion had amnesia for temporal relations, and whether the amnesia was specific for particular material. METHODS: A male patient had an isolated right dorsomedial thalamic infarct and resolving amnesia. He was tested on tasks relating to content (what) and temporal (when) memories for both verbal and non-verbal material, three and seven months after his infarct. RESULTS: Three months after his infarct, the man had amnesia for temporal, but not content memories using non-verbal stimuli, and normal performance using verbal stimuli. Seven months after his infarct, he had a normal performance using verbal and non-verbal stimuli. CONCLUSIONS: Patients with thalamic lesions may have a material specific amnesia for temporal relations in the absence of amnesia for content.
Adult↗
Intracranial angioplasty: experience and complications.
PURPOSE: To review our experience with intracranial angioplasty, including the complications we encountered. METHODS: During a 3-year period, from 1993 to 1996, 10 patients had intracranial percutaneous transluminal angioplasty (PTA). The stenosed vessels included three internal carotid arteries, one middle cerebral artery, one basilar artery, and five vertebral arteries. Stenosis in all patients was 75%, or greater. PTA was technically successful in eight patients; in two patients it could not be performed owing to inability to traverse the stenosed area. RESULTS: Two patients had successful and uneventful PTA. Five patients had vasospasm, which resolved with local vasodilators in two and with repeat PTA in one. Vasospasm led to stroke in two patients. Compromise of perforating vessels and arterial dissection were associated with stroke in two patients. CONCLUSION: Intracranial PTA is technically feasible but associated with risks related to vasospasm, arterial trauma, and compromise of perforating vessels.
Adult↗
Right-left confusion in Gerstmann's syndrome: a model of body centered spatial orientation.
Gerstmann's syndrome encompasses the tetrad of finger agnosia, agraphia, acalculia and right-left confusion and is associated with lesions of the dominant angular gyrus. The localizing value of this syndrome has been questioned because multiple mechanisms can account for each of the components of the syndrome. We present the case of a man who developed Gerstmann's syndrome following a focal infarct of the left angular gyrus. The patient's right-left confusion could not be accounted for by either an aphasia or a degraded body schema. A series of experiments that investigated the patient's spatial mapping system by progressively restricting the degrees of freedom for spatial rotation revealed an isolated defect in deriving the relative position of an object along the horizontal axis. Defective horizontal mapping can account for the other components of Gerstmann's syndrome because they all share a common dependency on relative horizontal positioning.
Aged↗
Neglect of radial and vertical space: importance of the retinotopic reference frame.
Neglect from bilateral brain injury can disrupt responses along space defined by the vertical and radial axes. The spatial reference frames for vertical and radial neglect remain largely undefined, however. The viewer centred system, for example, consists of retinocentric and cephalocentric/corporacentric frames. In the present study, different viewer centred reference frames were dissociated in a patient with combined far radial superior vertical neglect through performance of radial line bisections above and below eye level. To separate reference frames for vertical space, bisections were performed while the patient was lying sideways. Results suggest that this patient's neglect respected a retinotopic viewer centred reference frame.
Adult↗
Impaired perception of facial identity and facial affect in Huntington's disease.
We tested five patients with Huntington's disease on tasks of facial discrimination and facial affect discrimination and matching. Four patients were impaired on a task or tasks of face discrimination, and all patients were impaired on at least one task of facial affect discrimination. We suggest that these findings reflect the role of the basal ganglia or its connections in visual processing.
Adolescent↗
Emotional facial imagery, perception, and expression in Parkinson's disease.
Patients with Parkinson's disease (PD) may be impaired at expressing emotional faces and perceiving emotional facial affect. We tested the hypothesis that patients with PD may be impaired at imaging emotional faces. We first compared 12 patients with PD and 30 control subjects on perceptual and imagery tasks. Patients were significantly impaired on a task of emotional facial imagery but not on a control task of object imagery. Patients were also impaired on a task of perceiving emotional faces. Subsequently, we found that PD patients were impaired relative to controls on making emotional faces. Performance on both the perceptual and motor tasks of facial expression significantly correlated with performance on the emotional facial imagery task. We suggest that the basal ganglia, together with the right hemisphere, are part of a neural network subserving emotional facial tasks.
Aged↗
Visual grasp in corticobasal degeneration.
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Aged↗
Anosognosia for hemiplegia: an electrophysiologic investigation of the feed-forward hypothesis.
The cause of anosognosia for hemiplegia (AHP) remains unclear. Weakness is detected when there is a mismatch between the expectancy of movement and the sensory perception of movement. The feed-forward hypothesis of AHP posits that there is a failure of detection because there is a loss of motor intention and expectancy of movement. We tested motor intention by measuring the activation of proximal muscles (pectoralis majoris) while subjects squeezed a dynamometer with each hand. We tested a group of normal controls, a group of patients with hemiparesis, a patient with neglect, a patient with resolved AHP, and a patient with persistent AHP. The patient with AHP did not contract either of his pectoralis muscles when asked to squeeze with his contralesional, paretic hand, yet he contracted both of them when squeezing the dynamometer with his ipsilesional hand. Normal controls, hemiparetic controls, and the patient with hemispatial neglect contracted both pectorales when asked to squeeze with each hand. The pattern of activation seen in the patients with persistent AHP and resolved AHP demonstrates a loss of motor intention and lends support to the feed-forward hypothesis of AHP.
Agnosia↗
Lambert-Eaton myasthenic syndrome associated with an ameloblastoma of the tibia.
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Adult↗
Meningiomas are not significantly associated with breast cancer.
We studied 283 meningiomas seen at the University of Kansas, Kansas City, from 1948 through 1984, identifying all additional nonmeningeal malignancies and primary brain tumors in these patients and calculating the expected number of additional tumors by the use of a person-year method from age and sex-matched cancer incidence data. We determined expected numbers of total neoplasms in our meningioma population as well as the expected numbers in each major organ system for the sexes independently and together. We then calculated standard morbidity ratios and 95% confidence intervals for each tumor type. The number of breast cancers did not reach statistical significance. We found a significantly increased number of second primary brain tumors in women (standard morbidity ratio, 8.0; 95% confidence interval, 2.2 to 20.4) and an increased number of thyroid cancers in both sexes (standard morbidity ratio, 7.5; 95% confidence interval, 1.5 to 21.9).
Adult↗