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Biomedical subjects

T Rasmussen

Publications and source records attributed to T Rasmussen.

At least 73 records · Page 4Linked to original sources
PubMed1996

Historical vignette: cerebral cortical stimulation and surgery for epilepsy.

In 1909, in an isolated community hospital, on the northern tip of the Province of Newfoundland and Labrador, Canada, Dr. John Mason Little, Jr. performed electrical stimulation of the cerebral cortex, prior to cortical excision, as treatment of recurrent cerebral seizures in three patients. Extracts from Dr. Little's written records of the clinical features, the neurosurgical procedures and cerebral cortical stimulation are summarised. A brief review of the contemporaneous history of neurosurgical procedures for epilepsy provides a prospective of Dr. Little's remarkable surgical virtuosity.

Canada↗
PubMed1996

The running down phenomenon in temporal lobe epilepsy.

We compared 100 patients with temporal lobe epilepsy, who exhibited the running down phenomenon following temporal resections, with two groups of patients: 100 patients who became seizure-free, and 100 patients who continued to have frequent seizures following temporal resection. We found a significant correlation between prognosis and the size of the epileptogenic area as defined; patients with smaller epileptogenic areas had the best prognosis (seizure-free group). Patients exhibiting the running down phenomenon had intermediate size epileptogenic areas, while those patients who continued to have seizures had the largest epileptogenic areas often involving the lateral temporal and posterior temporal cortex. Other factors predictive of good outcome were: a history of febrile seizures, predominantly unilateral interictal spiking, anterior temporal localization, extent of resection of the mesial temporal structures, surgery under the age of 30 years, and the absence of habitual seizures in the immediate postoperative period. Patients with history of head trauma, encephalitis, posterior temporal localization and bitemporal spiking had a worse outcome. The frequency and types of aurae, and laterality of resection did not correlate with outcome.

Adolescent↗
PubMed1996

Effect of the non-peptide, vasopressin V1a receptor antagonist, SR 49059 and its enantiomer, SR 49770, on isolated human myometrium.

BACKGROUND: Vasopressin seems to be an important etiological factor for the myometrial hyperactivity and reduced blood flow in primary dysmenorrhea. Substances which block the action of vasopressin on the uterus are therefore of interest. METHODS: The effect of an orally active, non-peptide vasopressin V1a receptor antagonist, SR 49059, as well as its enantiomer, SR 49770, which is 50 to 100 fold less potent in binding studies, were tested in vitro on myometrium from 14 subjects. Two doses of the compounds, 2 nmol/L and 10 nmol/L, were used for counteracting the contractile effect of arginine vasopressin in a concentration of 0.7 nmol/L. RESULTS: SR 49059, in the lower concentration, significantly decreased the response to arginine vasopressin, measured as area under the recording curve, to 48 per cent of that to the agonist alone, and in the higher dose to 28 per cent. SR 49770 was much less potent in reducing the response to vasopressin. CONCLUSION: The myometrial action of arginine vasopressin is exerted via V1a receptors. The potent stereospecific inhibitory effect of SR 49059 on arginine vasopressin-induced myometrial activity indicates that the compound acts specifically through V1a receptors and may have a therapeutic potential in primary dysmenorrea.

Arginine Vasopressin↗
PubMed1995

Parietal lobe epilepsy. Clinical manifestations and outcome in 82 patients treated surgically between 1929 and 1988.

We report the clinical manifestations and outcome of 82 patients with nontumoural parietal lobe epilepsy treated surgically at the Montreal Neurological Institute between 1929 and 1988. Patients with extensive resections extending outside the parietal lobe were excluded. Ninety-four percent exhibited aurae: the most common were somatosensory, described by 52 patients; 13 of these also described pain. Other aurae included disturbances of body image, visual illusions, vertiginous sensations and aphasia or dysphasia. A few patients exhibited complex visual or auditory hallucinations and elementary visual hallucinations. Intraoperative cortical stimulation reproduced the habitual aurae in 44 patients. Often the clinical manifestations indicated ictal spread to the frontal, supplementary motor area, or temporo-limbic areas: 28% of patients exhibited tonic posturing of the extremities, 57% unilateral clonic activity, 17% oral or gestural automatisms and 4% complex automatisms. Sixty-one percent of patients with tonic posturing had epileptogenic zones which included the superior parietal lobe, and in 79% of patients with automatisms the epileptogenic zones extended to the inferior parietal lobe, suggesting different spread patterns. Forty-three patients underwent right, and 39 left parietal corticectomies. Postoperative sensory deficits were seen only when the corticectomy extended into the post-central gyrus. Early in the series extensive nondominant inferior parietal resections led to disturbances of body image in a few patients. Follow-up ranging from 2 to 50 years was available for 79 patients. Sixty-five percent had a complete or nearly complete cessation of seizures. Those patients with no post-resection electrocorticographic epileptiform discharges had a more favourable outcome.

Adolescent↗
PubMed1995

Tumoural parietal lobe epilepsy. Clinical manifestations and outcome in 34 patients treated between 1934 and 1988.

Between 1934 and 1988, 34 patients with tumoural parietal lobe epilepsy were treated surgically at the Montreal Neurological Institute (MNI). Fifteen had right-sided and 16 left-sided resections. The remaining three patients had biopsies only. Follow-up ranging from 1 to 40 years (mean 12.3 years) was available for 28 patients. Seventy-five percent (21 out of 28) became seizure free or had rare seizures. Permanent post-operative sensory deficits were described in 12% of patients. An aura was described by 79%. 62% had somatosensory symptoms, contralateral to the epileptogenic region in all but one. Visual illusions (12%), aphasia (9%) and disturbances of body image (6%), were much less common at the beginning of the attacks. Intra-operative cortical stimulation reproduced the habitual aurae in 10 out of 25 (40%) of the patients. The clinical manifestations suggested different spread patterns: 21% had tonic posturing of the extremities, 82% focal clonic activity, 15% head deviation, 9% automatisms and 6% difficulty speaking. Eleven (32%) had Todd's paralysis and 18% postictal dysphasia. Almost half the patients had impaired two-point discrimination in contralateral fingers; two of these also had impaired stereognosis, but only one had astereognosis without coexisting primary cortical sensory deficit. Review of this, now historical, series shows that parietal lobe tumours can be resected with good control of previously intractable seizures. Such an approach is preferable to postponing resection until the lesion is shown to increase in volume.

Adolescent↗
PubMed1993

Functional hemispherectomy in children.

Functional hemispherectomy, indicated for the control of pharmacologically refractory seizures, has been used at the Montreal Neurological Hospital since 1974. We have used this technique in 18 children suffering from intractable seizures secondary to conditions such as infantile hemiplegia, chronic encephalitis, head trauma, cerebrovascular accident, brain dysplasia and Sturge-Weber angiomatosis. None has developed superficial cerebral hemosiderosis often seen following the classical anatomical hemispherectomy. Eighty-two per cent (82%) of patients have been seizure-free since hospital discharge while another 11.5% have had at least 80% reduction in their seizure frequency. Most patients have shown an improvement in their intellectual capacity and sociability.

Adolescent↗
PubMed1992

Occipital lobe epilepsy: electroclinical manifestations, electrocorticography, cortical stimulation and outcome in 42 patients treated between 1930 and 1991. Surgery of occipital lobe epilepsy.

Our study documents the clinical and electrographic findings in 42 patients with medically refractory occipital lobe epilepsy, who underwent surgery at the Montreal Neurological Institute between 1930 and 1991, and the evolving manner in which those patients were studied by successive generations of investigators. In more than two-thirds of the patients the clinical manifestations indicated the occipital onset of the seizures. Seventy-three percent experienced visual aurae, of which elementary hallucinations were the most common and 12 also had ictal blindness. Other occipital manifestations included: contralateral eye deviation, blinking, a sensation of eye movement and nystagmoid eye movements. Intra-operative cortical stimulation elicited a habitual aura in 37% of 29 patients. Lateralizing clinical features were seen in almost two-thirds of patients: contralateral head deviation occurred in half, 59% had visual field defects contralateral to the epileptogenic area and 64% had abnormal imaging studies ipsilateral to the side of surgery. More than one-third of patients exhibited more than one seizure type, suggesting ictal spread to temporal or frontal lobe: 50% had typical temporal lobe automatisms, and 38% exhibited focal motor seizure activity. Surface electroencephalogram (EEG) recordings showed posterior temporal-occipital epileptiform discharges in 46% of patients. Only 18% had electronegative spiking limited to 01 or 02. Large epileptogenic areas were often found on intracranial recording with depth electrodes and on electrocorticography. Pre-excision electrocorticography spiking was restricted to the occipital lobe in only 13 out of 34 patients. More often spiking also involved the posterior temporal and posterior parietal regions. Twenty-three patients underwent only occipital resections; five had only temporal resections, so as to preserve the visual fields, and the remaining 14 patients had extensive resections, which included the posterior temporal or posterior parietal regions. A follow-up period of 1 to 46 yrs (mean 17 yrs) was available for 37 patients. Forty-six percent became seizure free and 21% had a significant reduction in seizure frequency. A better outcome was observed in those patients in whom there was no post-resection electrocorticographic or surface EEG epileptiform discharge, or who exhibited an occipital lobe lesion.

Adolescent↗
PubMed1992

Concurrent uveoretinitis and pineocytoma in a child suggests a causal relationship.

Uveoretinitis was observed in a 9-year-old girl 6 months prior to the clinical appearance of a pineal tumour. Surgical removal was not successful but biopsy revealed a parenchymal neoplasm with differentiated pinealocytes and absent mitotic activity. Some of the tumour cells contained S-antigen, rhodopsin, and serotonin. Systemic glucocorticoid therapy followed by radiation therapy caused considerable reduction in size of the tumour and a complete normalisation of all eye symptoms. This report demonstrates for the first time that a pineocytoma can occur together with uveoretinitis in humans. The latter resembles the experimentally induced autoimmune uveoretinitis described in animals. It is speculated that the retinitis might reflect an autoimmune response to S-antigen present in some tumour cells of the pineocytoma.

Antigens↗
PubMed1992

Presurgical EEG investigation in frontal lobe epilepsy.

Poor localization of the interictal epileptic abnormality and the rather unreliable EEG localization of ictal onsets in patients with frontal lobe epilepsy may be due to some of the following factors: (1) high risk of EEG sampling error, (2) early seizure spread within and outside the frontal lobe, (3) widespread distribution of the epileptogenic brain tissue responsible for the patient's habitual seizures, and (4) secondary bilateral synchrony and secondary epileptogenesis. The relevance of these factors in the preoperative investigation of patients with frontal lobe epilepsy was studied in: (a) 34 adult patients (mean age: 25 years) who became and persisted seizure free after restrictive surgical removal of the anterofrontal region, the parasagittal region convexity or the fronto-opercular area; (b) 12 patients in whom the pre-operative EEG investigation with extracranial electrodes failed to localize the site of seizure onset, leading to further investigation with depth electrodes.

Adult↗
PubMed1991

Temporal lobectomy: review of 100 cases with major hippocampectomy.

One hundred consecutive patients between 1961 and 1980, with temporal lobectomy including excision of half or more of the hippocampal formation, have been analyzed for degree of reduction of seizures. Thirty-nine percent have become and remained seizure free for follow-up period of 2 to 24 years (median 12 years). Another 24 patients achieved a marked reduction in seizure tendency as defined in the report and 25 showed a lesser degree of improvement. In fifteen patients no change in seizure frequency was recorded. Thus in this series of 100 patients, a complete or marked reduction of the seizure tendency was achieved in 63%.

Epilepsy, Temporal Lobe↗
PubMed1991

Temporal lobectomy with amygdalectomy and minimal hippocampal resection: review of 100 cases.

The evidence for the role of the amygdala in temporal lobe seizures is supported by this follow-up (2-20 years) of 100 patients who were treated surgically by excision of the antero-lateral temporal cortex, most or all of the amygdala and minimal resection of the hippocampus. The findings showed 53 patients seizure-free or with rare or occasional seizures, 10 patients with marked seizure reduction and 37 with moderate or less reduction of seizures. The results are the same as in another 100 patients where, in addition, half or more of the hippocampus was resected.

Amygdala↗
PubMed1991

Tailoring of cortical excisions for frontal lobe epilepsy.

Follow-up data of 2 to 49 years' duration are presented on 257 patients with cortical excisions for non-tumoral frontal lobe epilepsy. Twenty-six percent have become and remained seizure free. Another 30% have had a marked reduction of seizure tendency. Thus a total of 56% have had a long term complete or marked reduction of seizure tendency after the cortical resection. The cortical resections were classified into 5 regional categories. Forty-seven percent of patients with anterior frontal resections were in the seizure free category, as were 35% of patients with excisions limited to the convexity cortex and 32% of patients with maximal or near maximal frontal lobectomy. Only 18% of patients with frontal parasaggital excisions were in the seizure free category, and 10% of the patients who had excision of frontal cortex plus limited excision of adjacent central and/or temporal cortex.

Adolescent↗