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Biomedical subjects

G Assal

Publications and source records attributed to G Assal.

At least 37 records · Page 2Linked to original sources
PubMed1996

Non-verbal auditory recognition in normal subjects and brain-damaged patients: evidence for parallel processing.

Three different aptitudes involved in sound object recognition were tested in 60 normal subjects and 20 brain-damaged patients: (i) capacity to segregate sound objects on different cues (intensity steps, coherent temporal modulations or signal onset synchrony); (ii) asemantic recognition of sounds of real objects by judging whether two different sound samples belonged to the same object; and (iii) semantic identification of sounds of real objects as judged by means of a multiple choice response test. In 12 patients, different aptitudes involved in auditory recognition were disrupted separately and in a way which speaks in favour of parallel rather than hierarchical processing. There was no strong association between deficits in non-verbal auditory recognition and aphasia or the side of lesion.

Adult↗
PubMed1996

Unilateral spatial neglect recovery after sequential strokes.

We describe a patient who had sequential strokes in both hemispheres with a severe unilateral spatial neglect after a first right-sided parietal infarct and abrupt disappearance of the neglect after a second left-sided frontal infarct. The first lesion involve the caudalmost right angular gyrus (area 39), whereas the second lesion involved the left frontal eye field (area 8) and surrounding cortex. Those two cortical areas are assumed to have a pivotal role in modulating both shifts of attention within extrapersonal space and saccadic eye movements through their connections with subcortical structures, in particular, superior colliculi and thalamic nuclei. Our case supports the existence of a distributed anatomic-functional network in subserving directed spatial attention.

Aged↗
PubMed1995

Klüver-Bucy syndrome after left anterior temporal resection.

A 70-year-old right-handed woman developed a complete Klüver-Bucy syndrome including psychic blindness, aberrant sexual behavior, hypermetamorphosis, aphasia and visual agnosia following left anterior temporal lobectomy for an anaplasic oligodendroglioma. MRI showed no argument for a contralateral ischemic infarct, tumoral growth or white matter damage. Thus the possibility that a unilateral anterior temporal lesion can cause the whole picture of Klüver-Bucy syndrome must therefore be considered.

Affect↗
PubMed1995

Complete callosal disconnection after closed head injury.

We report a patient with complete callosal disconnection syndrome after severe closed head injury. MRI showed a complete destruction of the corpus callosum throughout its length. Although traumatic callosal lesions are a frequent finding in autopsy studies, as well as in some recent MRI studies, clinical signs of callosal disconnection are rarely observed after head injuries and a complete disconnection syndrome has not been reported yet. This case study and the review of other reported cases suggest that posttraumatic callosal disconnection is probably often overlooked. Our patient had also a severe memory disorder that might be partly related to the bilateral involvement of the fornix, as this structure is closely adjacent to the posterior corpus callosum, and was also shown by MRI to be very probably damaged.

Adult↗
PubMed1995

Acute hemiconcern: a right anterior parietotemporal syndrome.

Three patients developed a striking visual and motor behaviour in the acute phase of a stroke involving the territory of the right anterior parietal artery (postcentral gyrus, parts or upper and middle temporal gyri, anterior part of inferior parietal gyrus, and supramarginal gyrus). The patients concentrated on the left side of their bodies, looking at it for long periods and relentlessly rubbing, touching, pinching, pressing, lifting, and manipulating parts of the left arm, trunk, and leg with their right hand or foot. They all had severe loss of elementary sensation on the left (touch, pain, temperature, vibration, position). The behaviour was not associated with overinterest in the left hemispace apart from their own bodies. It lasted no more than a few days, disappearing when left sided sensation improved. The findings suggest an association between sensory dysfunction and this "acute hemiconcern". None of 13 patients with a mirror infarct in the left hemisphere and none of 38 patients with acute hemisensory loss due to thalamic capsular or brainstem stroke showed hemiconcern behaviour. This behaviour may result from a feeling of strangeness critically associated with hemisensory loss without hemispatial neglect, due to involvement of the right anterior parietotemporal region.

Aged↗
PubMed1995

[Lesions of the corpus callosum and syndromes of interhemispheric disconnection of traumatic origin].

We review the different kinds of injury to the corpus callosum in closed head trauma, as well as their different mechanisms. Most frequent lesions are either diffuse and at the microscopic level, secondary to disruption of axons at the time of the trauma, or focal and at macroscopic level, also due to torsion or shearing strains on the corpus callosum. They are associated with diffuse axonal injury of hemispheric and brainstem white matter. Focal macroscopic lesions, sometimes extensive, are encountered in 16-40% of autopsies after fatal head injury. Likewise, MRI allows nowadays to show them in 22-49% of nonfatal head injuries. Such lesions can produce an interhemispheric disconnection syndrome. However, clinical observation of an interhemispheric disconnection after head trauma has been only rarely reported in the literature, as it is showed by a brief overview of those cases, which suggests that this pathology is probably often overlooked. Focal damage to the corpus callosum seems to be a marker of severe injury, with often long-lasting coma and sometimes transitory vegetative state or mutism. Extension of posterior callosal lesions towards adjacent midline structures, such as the fornix, could contribute to the important memory impairment which is particularly frequently associated with posttraumatic interhemispheric disconnection syndromes.

Adolescent↗
PubMed1994

Pure amnesia after unilateral left polar thalamic infarct: topographic and sequential neuropsychological and metabolic (PET) correlations.

A 54-year-old patient who had an isolated small polar thalamic infarct and acute global amnesia with slight frontal type dysfunction but without other neurological dysfunction was studied. Memory improved partially within 8 months. At all stages the impairment was more severe for verbal than non-verbal memory. Autobiographic recollections and newly acquired information tended to be disorganised with respect to temporal order. Procedural memory was unaffected. Both emotional involvement and pleasure in reading were lost. On MRI, the infarct was limited to the left anterior thalamic nuclei and the adjacent mamillothalamic tract. The regional cerebral metabolic rate of glucose (measured with PET) was decreased on the left in the thalamus, amygdala, and posterior cingulate cortex 2 weeks after the infarct, and in the thalamus and posterior cingulate cortex 9 months later. These findings stress the specific role of the left anterior thalamic region in memory and confirm that longlasting amnesia from a thalamic lesion can occur without significant structural damage to the dorsomedial nucleus. Furthermore, they suggest that the anterior thalamic nuclei and possibly their connections with the posterior cingulate cortex play a role in emotional involvement linked to ipsilateral hemispheric functions.

Amnesia↗
PubMed1993

[Subcortical cerebrovascular accidents: correlation between clinical aspects, topography and flow measurements using single photon emission tomography].

35 patients with subcortical ischemic or hemorrhagic stroke included in the Lausanne Stroke Registry underwent cerebral blood flow measurement using I-123-IMP and 99mTc-HMPAO single photon emission tomography (SPECT). Our findings suggest that neuropsychological disturbances are not systematically correlated to cortical hypoperfusion secondary to the deep lesion (diaschisis). The role of cortical diaschisis was especially prominent in patients with aphasia and left subcortical lesion.

Adolescent↗
PubMed1993

From theory to practice: the unconventional contribution of Gottlieb Burckhardt to psychosurgery.

Gottlieb Burckhardt, a Swiss psychiatrist who practiced in the late 19th century, was the founder of modern psychosurgery. In 1891 he reported the results of cortical extirpations on six patients who evidently suffered from intractable psychiatric disease; two of these cases are discussed here to illustrate how Burckhardt employed contemporary brain models of language and cognition as the basis for removing specific areas of the cerebral cortex with the intention of ameliorating his patients' disturbed behavior.

History, 19th Century↗
PubMed1993

Left hemisphere strategies in visual recognition, topographical orientation and time planning.

Right hemisphere lesions are known to impair, in many cases, visual recognition and visuospatial orientation. We report here on the compensatory strategies used by a patient whose posterior part of the right hemisphere was either destroyed or visually deafferented. She presented a slight appreceptive agnosia, memory disorders, and severe topographical disorientation. Her strategy relied on detail-by-detail analysis of buildings for recognition and on identification of landmarks and memorization of their sequences for finding routes. Time planning was impaired; the patient was unable to use a bi-dimensional timetable, but relied on a (linear) list of assignments. The linear, speech-related strategy she used was sustained uniquely by left hemisphere networks, since no processing of visual information occurred in the right hemisphere.

Adolescent↗
PubMed1993

[A clinicopathological case of progressive aphasia].

We report the case of a 59-year old right-handed woman presenting with progressive aphasia without any other neurological deficit and characterized by anomia, agramatism and auditory comprehension difficulties. CT scan showed no abnormalities. Four years later, aphasia was complete but neurological examination was normal. CT scan disclosed a mild cortico-subcortical cerebral atrophy with slight widening of both sylvian fissures. The results obtained with the Wisconsin Card Sorting Test and the Raven's Matrices showed only minor deficits. The IQ (WAIS) was 90. During the following 6 years the patient remained fully self-sufficient and carried out her homework normally. At that time MRI showed progression of cerebral atrophy more pronounced on the left side. Besides a rapid deterioration, twelve months later she developed severe dementia and died 13 years after the onset of the illness. Brain examination disclosed a severe atrophy (brain weight: 880 g) prominent in both frontal lobes and in the anterior perisylvian structures, more pronounced on the left side. There were no vascular lesions. Microscopy revealed widespread neuronal loss and astrocytic fibrillary gliosis confined to cortical areas and vacuolation in the superficial layers. Neurofibrillary tangles and neuritic plaques were found in the most atrophic areas but not in sufficient number to fulfill the histological criteria for Alzheimer's disease. There were no neuropathological changes of Pick's disease or subcortical degeneration. Previous microscopical studies of primary progressive aphasia showed non specific, mostly lobar atrophy similar to that observed in our case, although Alzheimer, Pick and Creutzfeldt-Jakob diseases have been reported. This neuropathological heterogeneity confirms that progressive aphasia is a non-specific language disorder mostly observed in lobar forms of brain degeneration.

Aphasia↗
PubMed1993

[Post-traumatic psychological disorders].

Mental disorders after closed-head injury are reviewed. Post-concussive syndrome and post-contusional disability are described with particular emphasis on consciousness disorders, amnesia, frontal disturbance and long-term outcome.

Brain Concussion↗
PubMed1992

[Religious delusion 13 years after brain injury].

We report here with a case of religious delusion in a 39 years old woman. She had suffered a head injury with right temporal concussion 13 years before but had no earlier history of psychiatric disorder. In view of the fact that this acute psychiatric state lasted for a short duration of time and that personality and affects were preserved, this incident is compared to the schizophreniform disorder of the type DSM-III-R. The hypothesis of an acquired predisposition due to head injury has been put forward as an explanation.

Adult↗