Cases reported "Brain Damage, Chronic"

Filter by keywords:



Filtering documents. Please wait...

1/155. Impairment of social and moral behavior related to early damage in human prefrontal cortex.

    The long-term consequences of early prefrontal cortex lesions occurring before 16 months were investigated in two adults. As is the case when such damage occurs in adulthood, the two early-onset patients had severely impaired social behavior despite normal basic cognitive abilities, and showed insensitivity to future consequences of decisions, defective autonomic responses to punishment contingencies and failure to respond to behavioral interventions. Unlike adult-onset patients, however, the two patients had defective social and moral reasoning, suggesting that the acquisition of complex social conventions and moral rules had been impaired. Thus early-onset prefrontal damage resulted in a syndrome resembling psychopathy.
- - - - - - - - - -
ranking = 1
keywords = cortex
(Clic here for more details about this article)

2/155. A paradoxical improvement of misreaching in optic ataxia: new evidence for two separate neural systems for visual localization.

    We tested a patient (A. T.) with bilateral brain damage to the parietal lobes, whose resulting 'optic ataxia' causes her to make large pointing errors when asked to locate single light emitting diodes presented in her visual field. We report here that, unlike normal individuals, A. T.'s pointing accuracy improved when she was required to wait for 5 s before responding. This counter-intuitive result is interpreted as reflecting the very brief time-scale on which visuomotor control systems in the superior parietal lobe operate. When an immediate response was required, A. T.'s damaged visuomotor system caused her to make large errors; but when a delay was required, a different, more flexible, visuospatial coding system--presumably relatively intact in her brain--came into play, resulting in much more accurate responses. The data are consistent with a dual processing theory whereby motor responses made directly to visual stimuli are guided by a dedicated system in the superior parietal and premotor cortices, while responses to remembered stimuli depend on perceptual processing and may thus crucially involve processing within the temporal neocortex.
- - - - - - - - - -
ranking = 0.53191520949167
keywords = cortex, visual
(Clic here for more details about this article)

3/155. Unconscious activation of visual cortex in the damaged right hemisphere of a parietal patient with extinction.

    Visual extinction is a sign classically associated with right parietal damage. The patient can see a single stimulus presented in the ipsilesional or contralesional visual field, but is characteristically unaware of the same contralesional stimulus during simultaneous stimulation of both fields. The ipsilesional stimulus is said to 'extinguish' the contralesional stimulus from awareness during bilateral stimulation, perhaps due to a pathological bias in attention towards the ipsilesional side. Recent psychophysical evidence suggests that, although extinguished stimuli are not consciously seen, they may undergo residual processing and exert implicit effects on performance. However, the neural structures mediating such residual processing for extinguished stimuli remain unknown. Here we studied the neural activity evoked by an extinguished visual stimulus, using event-related functional MRI (fMRI), in a patient with circumscribed right inferior parietal damage and profound left-sided extinction. Monochrome objects (faces or houses) were presented in the left or right field, either unilaterally or bilaterally on each trial, with the patient indicating by button press whether he saw an object on the left, the right or on both sides. He usually saw only the right object on bilateral trials, yet the fMRI data showed activation of visual cortex contralateral to the extinguished left stimulus on these trials (compared with right-only stimulation), in both striate and early extrastriate areas of the right hemisphere. This activity had a similar location and time-course to that resulting from a single stimulus in the left versus right visual field. Cortical pathways involved in the normal processing of a single seen stimulus can thus still be activated by an unseen, extinguished stimulus after right parietal damage. Comparison of fMRI responses for faces versus houses revealed some category-specific activation for extinguished stimuli in right fusiform regions, but only at low statistical threshold. These results are discussed in terms of theoretical accounts for parietal extinction and, more generally, for the neural substrates of visual awareness.
- - - - - - - - - -
ranking = 15.875953161915
keywords = visual cortex, cortex, visual
(Clic here for more details about this article)

4/155. Visually misguided reaching in Balint's syndrome.

    A patient with bilateral parietal damage leading to Balint's syndrome was tested on his ability to reach to, and to describe the locations of visual targets. RM was better at reaching to targets than he was at describing the locations of the same targets. Moreover, he was better at reaching to targets when he could not see them, compared to when he was reaching with visual guidance. In a final experiment, we found that RM showed strong inhibition of responses to non-target items, even though he had a poor representation of their location in depth. As a result of intact inhibition and impaired depth representation, he ignored both target and non-target items in a given direction. These results suggest that in RM a disturbed visual representation of space disrupts an otherwise relatively intact reaching control system.
- - - - - - - - - -
ranking = 0.16595760474583
keywords = visual
(Clic here for more details about this article)

5/155. Conflict of intentions due to callosal disconnection.

    OBJECTIVES: Three patients with callosal syndrome manifested a peculiar symptom in that they were unable to perform intended whole body actions because another intention emerged in competition with the original one. Attempts were made to clarify the symptomatology of this manifestation and its possible mechanism is discussed. methods: The three patients are described and previous reports on patients with callosal damage were reviewed. Four additional patients with similar symptoms were found and the clinical features common to all seven patients were examined. RESULTS: This symptom could not be attributed to unilateral movement disorders such as unilateral apraxia, intermanual conflict, or compulsive manipulation of tools. The manifestations included marked hesitation in initiating actions, interruption of actions, repetitive actions, and performance of unintended actions with difficulty in correcting them. All patients, except one, had a lesion in the posterior half of the body of the corpus callosum, and there was no significant involvement of the cerebral cortex. The symptom became manifest later than 4 weeks after callosal damage. It occurred during spontaneous actions, but not during well automated actions nor when following instructions. CONCLUSION: This symptom, tentatively named "conflict of intentions", can be regarded as a fragment of diagonistic dyspraxia originally described by Akelaitis, although it can occur independently of intermanual conflict. Normally, the right and left cerebral hemispheres may be complementarily modifying automated whole body actions in order to adapt behaviour to changes of the environment as well as to the intention. Partial callosal disconnection without significant cortical involvement would exaggerate the disparity between the role of each hemisphere through the reorganisation of neural systems after callosal damage. Such double, often contrary, behavioural tendencies may sometimes simultaneously enter the patient's awareness.
- - - - - - - - - -
ranking = 0.2
keywords = cortex
(Clic here for more details about this article)

6/155. Long-term results of functional hemispherectomy for intractable seizures.

    OBJECTIVE: From May 1989 to April 1997, functional hemispherectomy was performed in 8 cases of intractable seizures. We retrospectively analyzed our experience to evaluate the seizure control and complications of this surgical technique. methods: Following Dr. Rasmussen's model of functional hemispherectomy or performing a modification of this operation, we removed the sensorimotor cortex and temporal lobe associated with disconnection of the remaining portions of the frontal lobe and parieto-occipital lobe. RESULTS: All the patients were followed up for 3-11 years (mean 6.7 years). Satisfactory seizure control was obtained in all the cases. life quality improved and patients worked or studied well after the operations. No cases of superficial cerebral hemosiderosis were found. CONCLUSION: Modified functional hemispherectomy may allow the patients to lead more independent lives by leading to a cessation or reduced frequency of seizures.
- - - - - - - - - -
ranking = 0.2
keywords = cortex
(Clic here for more details about this article)

7/155. Verbal encoding deficits in a patient with a left retrosplenial lesion.

    Over the past decade, memory impairments associated with retrosplenial damage have received increased attention among neuroscientists, although the exact role of the retrosplenial region in memory has not been clearly defined. Evidence from lesion studies and functional neuroimaging has implicated the retrosplenial region in verbal episodic memory, temporal ordering of information, and topographical memory. In addition, recent positron emission tomography studies have shown increased activation of the retrosplenial cortex during tasks involving both the encoding and retrieval of episodic information. The objective of this study was to define more clearly the nature of memory impairments observed in retrosplenial amnesia. A 47-year-old amnesic male with a left retrosplenial arteriovenous malformation was examined on neurocognitive tasks of automatic and directed encoding, temporal ordering of information, and remote memory. Despite normal performance on frontal cognitive tasks, intact memory for remote information, and a superior IQ, this individual exhibited a profound deficit in the encoding of information, evidenced by poor release from proactive interference, poor category clustering on word list recall, poor semantic encoding on a levels of processing task, and mild impairments in temporal ordering. These results imply that the retrosplenial region plays a role in the verbal encoding of information, which contributes to the profound verbal memory impairment reported in previous case studies of patients with retrosplenial damage.
- - - - - - - - - -
ranking = 0.2
keywords = cortex
(Clic here for more details about this article)

8/155. A neuropsychological outcome study of a child's left pericallosal arteriovenous malformation with occult fornix lesion.

    Pericallosal arteriovenous malformations are rarely reported, particularly in children. Moreover, few arteriovenous malformation studies report thorough neuropsychological outcome data for assessing post-surgical functioning. This case report provides a longitudinal study of a boy who initially presented for neuropsychological testing at the age of 8 years and 1 month, following polyvinyl alcohol embolization, two craniotomies and resections and stereotactic radiosurgery for a pericallosal arteriovenous malformation involving nearly all of the corpus callosum. Follow-up magnetic resonance imaging also indicated absence of the left fornix. Functioning has been assessed over 7 years. Neuropsychological measures identified a consistent pattern of verbally mediated cognitive and memory deficits, with relatively spared visual perceptual and visual motor functioning. No evidence of a split-brain syndrome was found. The findings are consistent with insult to dominant hemisphere language and memory systems, provide an interesting example of neurodevelopmental compensation for significant early brain insult, and may provide insight into functions subserved by the fornix.
- - - - - - - - - -
ranking = 0.11063840316389
keywords = visual
(Clic here for more details about this article)

9/155. The use of visual feedback in establishing normal vocal intensity in two mildly retarded adults.

    A voice-activated relay was used to provide visual feedback of vocal amplitude for two subjects who habitually used very soft voices. The relay system caused a light to go on when vocal intensity was 65 dB SPL or greater. Both subjects demonstrated significant increases in their use of normal vocal intensity. One subject was able to transfer this progress to spontaneous conversational settings. Though some difficulties in generalization and automatization were evident, this system is recommended for use with persons exhibiting functional intensity deficiences.
- - - - - - - - - -
ranking = 0.27659600790972
keywords = visual
(Clic here for more details about this article)

10/155. Intra-operative monitoring of brain tissue O2 (PtiO2) during aneurysm surgery.

    BACKGROUND: Regional cerebral blood flow may be compromised during aneurysm surgery. This may occur during vessel occlusion by temporary cliping or result from the malposition of an aneurysm clip. In this report we monitored intra-operatively the brain tissue oxygen concentration (PtiO2) to visualize regional ischaemic events. METHOD: During surgery of 10 intracranial aneurysms, monitoring of PtiO2 was performed using a polarographic microcatheter (Licox, GMS-Kiel-germany), which was placed in the vascular territory of the artery harboring the aneurysm. FINDINGS: No complications were observed after implantation of Licox electrodes. In 6 patients PtiO2 decreased during transient clipping. In two patients PtiO2 decreased below 2 mmHg without morphological or clinical signs cerebral ischemia. In four patients, without incidence during surgery, only minor oscillations were observed. CONCLUSION: Intra-operative monitoring of PtiO2 is a complimentary procedure to monitor cerebral perfusion and detect episodes of ischaemia. Given the rapid detection of these events, therapeutic intervention may be initiated before irreversible neuronal damage occurs.
- - - - - - - - - -
ranking = 0.055319201581945
keywords = visual
(Clic here for more details about this article)
| Next ->


Leave a message about 'Brain Damage, Chronic'


We do not evaluate or guarantee the accuracy of any content in this site. Click here for the full disclaimer.