1/85. Basal forebrain amnesia: does the nucleus accumbens contribute to human memory?OBJECTIVE: To analyse amnesia caused by basal forebrain lesions. methods: A single case study of a patient with amnesia after bleeding into the anterior portion of the left basal ganglia. Neuropsychological examination included tests of attention, executive function, working memory, recall, and recognition of verbal and non-verbal material, and recall from remote semantic and autobiographical memory. The patient's MRI and those of other published cases of basal forebrain amnesia were reviewed to specify which structures within the basal forebrain are crucial for amnesia. RESULTS: attention and executive function were largely intact. There was anterograde amnesia for verbal material which affected free recall and recognition. With both modes of testing the patient produced many false positive responses and intrusions when lists of unrelated words had been memorised. However, he confabulated neither on story recall nor in day to day memory, nor in recall from remote memory. The lesion affected mainly the nucleus accumbens, but encroached on the inferior limb of the capsula interna and the most ventral portion of the nucleus caudatus and globus pallidus, and there was evidence of some atrophy of the head of the caudate nucleus. The lesion spared the nucleus basalis Meynert, the diagnonal band, and the septum, which are the sites of cholinergic cell concentrations. CONCLUSIONS: It seems unlikely that false positive responses were caused by insufficient strategic control of memory retrieval. This speaks against a major role of the capsular lesion which might disconnect the prefrontal cortex from the thalamus. It is proposed that the lesion of the nucleus accumbens caused amnesia.- - - - - - - - - - ranking = 1keywords = nucleus (Clic here for more details about this article) |
2/85. Isolated superior oblique palsies with brainstem lesions.Isolated unilateral superior oblique palsies resulting from brainstem lesions occurred in three patients. MRI documented contralateral tegmental lesions of the trochlear nucleus and adjacent intraaxial trochlear nerve. Lacunar infarct was the cause in two patients and a small hemorrhage in a third.- - - - - - - - - - ranking = 0.11111111111111keywords = nucleus (Clic here for more details about this article) |
3/85. Hypertrophic olivary degeneration following surgical excision of brainstem cavernous hemangioma: a case report.Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration involving the dento-rubo-olivary pathway. It is distinguished from other types of neuronal degeneration in that hypertrophy, rather than atrophy, takes place in the neurons in the inferior olivary nucleus. Prior to the invention of magnetic resonance imaging (MRI), HOD was difficult to be detected, and a firm diagnosis could only be made at autopsy. We present a case of bilateral HOD following surgical excision of a cavernous hemangioma in the brainstem. The literature and imaging findings of this uncommon condition are reviewed.- - - - - - - - - - ranking = 0.11111111111111keywords = nucleus (Clic here for more details about this article) |
4/85. The auditory pathology of anoxia.A case of anoxic encephalopathy is reported, with study on a whole-auditory-pathways basis, and the method of processing tissues is outlined. Pathologic changes are found throughout the central part of the auditory pathway. The importance of including the superior ventral cochlear nucleus (SVCN) with cochlear structures in correlating findings with audiometric data is supported. The previously advanced tonotopic frequency pattern, with zonal vulnerability, of the spheroid cells of SVCN is supported.- - - - - - - - - - ranking = 0.11111111111111keywords = nucleus (Clic here for more details about this article) |
5/85. Neuropathology of Raine syndrome.We present three cases of Raine syndrome occurring in siblings of consanguineous parents. Raine syndrome is characterised by generalised osteosclerosis with craniofacial anomalies and intracranial calcifications. So far, only nine cases have been reported, and no evaluation of the distribution and extent of the cerebral mineralisations, as well as their impact on the surrounding tissue, has been undertaken yet. In our cases, calcifications were unevenly distributed throughout the central nervous system, not associated with neuronal loss or dystrophic events and appeared mostly as single calcospherites within the neuropil with occasional confluent deposits at advanced gestational age. There was intense perifocal microgliosis around single immature calcospherites, as well as mild astrogliosis around and within the confluent lesions, in which occasional macrophages could be found. Rarely, mineralisations occurred in blood-vessel walls, mainly affecting basal ganglia. Preferential sites of calcification were parietal and occipital periventricular white matter and corpus callosum, while frontal lobes were mildly affected. The cortex, temporal lobes as well as internal capsule, brain stem, cerebellum, leptomeninges, pituitary gland and choroid plexus were devoid of mineralisations. The subcortical grey matter was moderately involved in the putamen and pallidum, mildly in the caudate nucleus and subependymal germ cell matrix and not at all in the thalamus, Ammon's horn, amygdala and substantia nigra. The distribution of mineral deposits was thus inversely correlated to regional blood circulation and capillary density, with calcifications being concentrated in more sparsely perfused areas but lacking in highly vascularised tissue. This inverse relationship between mineralisation and regional blood flow was reflected in the varying distribution of calcospherites in grey and white matter as well as in the white matter of different lobes.- - - - - - - - - - ranking = 0.11111111111111keywords = nucleus (Clic here for more details about this article) |
6/85. Geniculate hemianopias: incongruous visual defects from partial involvement of the lateral geniculate nucleus.Quantitative perimetric studies in 4 patients with involvement of a lateral geniculate nucleus revealed strikingly incongruous defects in the corresponding homonymous fields of vision. The patterns of these hemianopias are analysed and correlated anatomically with established retinotopic projections on the six cellular laminae of the geniculate nucleus. Incongruous wedge-shaped field defects appear to be pathognomonic of focal disease in the dorsal crest of the geniculate nucleus. Other patterns typify lesions of the medical or lateral horns of the nucleus. On theoretical grounds monocular hemianopic defects should result from unilaminar geniculate lesions, but this perimetric sign awaits confirmation. In each case of geniculate disease where the retinal nerve fibre layer has been examined specifically for efidence of retrograde homonymous atrophy, typical hemiretinal signs were found to be present.- - - - - - - - - - ranking = 0.88888888888889keywords = nucleus (Clic here for more details about this article) |
7/85. Delayed encephalopathy after strangling.An 11-year-old boy who had been the victim of a strangling attempt was asymptomatic for one week whereupon involuntary movements involving the trunk and limbs developed, along with repetitive episodes of opisthotonos and autonomic dysfunction. Meanwhile, he remained alert and appeared to be mentally intact. An electroencephalogram was normal. He died 13 weeks after the onset of the neurological disorder. The neuropathological examination showed cavitating lesions in the caudate nucleus, putamen, and globus pallidus bilaterally, with sparing of the white matter. The delayed onset of a progressively evolving neurological disorder has been noted in various forms of hypoxicischemic insult, including previously reported cases of strangling, but its occurrence cannot be predicted from the preceding clinical state or course. In the cases in which abnormal movements have been predominant, the pathological findings have been similar despite diversity in the preceding circumstances. We suggest the underlying metabolic disorder common to these cases may be lactic acidosis, and that they should be studied for evidence of a biochemical defect.- - - - - - - - - - ranking = 0.11111111111111keywords = nucleus (Clic here for more details about this article) |
8/85. Selective and sequential therapy of oculomotor and palpebral sequelae resulting from biopsy of dorsal midbrain sarcoidosis.BACKGROUND: biopsy of a dorsal mesencephalon lesion often leads to neuro-ophthalmological complications, namely dorsal mesencephalic syndrome, skew deviation, IV (th) palsy, or Horner's syndrome. history AND SIGNS: A 26-year-old man underwent a biopsy of the quadrigeminal plate for a lesion which revealed to be neurosarcoidosis. Post-operative complications included a left homonymous hemianopia, a left III (rd) nucleus palsy, a bilateral IV (th) palsy and a bilateral internuclear ophthalmoplegia. Palpebral fissures were narrowed to 2 mm on both sides. In primary gaze there was 24 degrees of exotropia, 17 degrees of right hypertropia and 30 degrees of exyclorotation. THERAPY AND OUTCOME: After 24 months of stable evolution, three oculomotor surgical procedures were performed including: surgery on both horizontal muscles of the left eye; shortening of both superior oblique muscles; resection of the right lateral rectus muscle, and posterior fixation of an inferior rectus muscle. Bilateral brow suspension on the frontal muscle of both superior eyelids was then performed. Evolution was favorable with a binocular single field of vision measuring 17 degrees horizontally and 20 degrees vertically centered on the primary gaze. Palpebral fissures measured 7 to 8 mm in primary gaze. CONCLUSIONS: The neuro-ophthalmological sequelae which followed the biopsy of a neurosarcoidosis lesion of the quadrigeminal plate were so severe that this patient was completely handicapped. A four-step surgery correcting the horizontal, torsional, vertical components, then the bilateral ptosis allowed the patient to recover both a satisfying function and esthetical aspect.- - - - - - - - - - ranking = 0.11111111111111keywords = nucleus (Clic here for more details about this article) |
9/85. Complex visual hallucinations (Charles Bonnet syndrome) in visual field defects following cerebral surgery. Report of four cases.The development of visual hallucinations after loss of vision is known as the Charles Bonnet syndrome. This phenomenon was first described in 1760 by Charles Bonnet and others during their observations of elderly patients with degeneration of the retina or cornea. To date a clear association between visual hallucinations and neurosurgical procedures has not been reported. Because of their clear demarcation, however, surgical lesions in the cerebrum offer a unique opportunity to determine the pathoanatomical aspects of visual hallucinations. During a 3-year period, 41 consecutive patients who acquired visual field defects after neurosurgery were examined for the occurrence of visual hallucination. Postoperatively, four of these patients experienced visual hallucinations. In two of them an upper quadrantanopia developed after the patients had undergone selective amygdalohippocampectomy. In the other two patients a complete hemianopia developed, in one case after resection of a parietal astrocytoma and in the other after resection of an occipital glioblastoma multiforme. The visual hallucinations were transient and gradually disappeared between 4 days and 6 months postoperatively. The patients were aware of the fact that their hallucinations were fictitious and displayed no psychosis. Electroencephalographic recordings were obtained in only two patients and epileptic discharges were found. Deafferentiation of cortical association areas may lead to the spontaneous generation of complex visual phenomena. In the present series this phenomenon occurred in approximately 10% of patients with postoperative visual field defects. In all four cases the central optic radiation was damaged between the lateral geniculate nucleus and the primary visual cortex. The complex nature of the visual hallucination indicates that they were generated in visual association areas.- - - - - - - - - - ranking = 0.11111111111111keywords = nucleus (Clic here for more details about this article) |
10/85. Midbrain ataxia: an introduction to the mesencephalic locomotor region and the pedunculopontine nucleus.OBJECTIVE: Although gait ataxia is usually associated with cerebellar lesions, we review a less familiar cause. We present three patients with dorsal midbrain lesions and correlate these presentations with recent findings in the functional anatomy of the midbrain. CONCLUSION: We suggest that these lesions involve a well-studied but generally unfamiliar area of the dorsal midbrain known as the mesencephalic locomotor region. More specifically, we hypothesize that involvement of the pedunculopontine nucleus, a major component of the mesencephalic locomotor region, may be at least partially responsible for producing midbrain ataxia.- - - - - - - - - - ranking = 0.55555555555556keywords = nucleus (Clic here for more details about this article) |
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