Biomedical subjects

C A Marsan

Publications and source records attributed to C A Marsan.

12 recordsLinked to original sources

PubMed1976

Depth and direct cortical recording in seizure disorders of extratemporal origin.

This study is based on 28 patients with intractable seizures in whom exclusively extratemporal or a combination of temporal and extratemporal electrodes were chronically implanted for the localization of the epileptogenic process and possible surgical treatment. Clinical and electrographic data are briefly summarized, the indications for the use of implanted electrodes are outlined, and the number and position of the electrodes and the findings in each individual case are given. Four illustrative examples are described in greater detail. Mainly on the basis of data derived from this particular technique of investigation, surgical treatment was eventually carried out in 14 patients. It is concluded that the use of implanted electrodes in seizure disorders of probable extratemporal origin can be of real diagnostic benefit in certain specific situations. In most instances, however, this technique simply serves to demonstrate the complexity of an apparently simple case or, of greater clinical consequence, might tend to oversimplify cases that are actually very complex. Indeed, many data in this study raise some doubts about the validity of the classic concepts of "focal" epilepsy.

Adolescent↗

PubMed1975

EEG changes after withdrawal of medication in epileptic patients.

Fifty-five patients with intractable partial seizures whose on-medication EEGs demonstrated either predominantly focal epileptiform lesions or absence of paroxysmal activity, were studied, and the effect of withdrawing all anticonvulsive drugs on their EEGs was observed. Four types of response were encountered: (1) no effect (20%); (2) specific (focal) activation (25%); (3) complex activation (29%) with widespread of the initial on-medication focus or appearance of the additional independent epileptogenic foci; and (4) "non-specific" activation (63%), consisting of bursts of either bilaterally synchronous and frontally dominant spike and waves, triphasic waves, or sharp slow complexes, or smaller amplitude rapid and diffuse spike-and-wave complexes. This latter effect is thought to be secondary to metabolic derangements resulting from the withdrawal of neurotropic agents and not directly related to the specific epileptogenic process. No association was found between type of effect and any of the following parameters: topography of on-medication focus, duration of therapy, type of anticonvulsant used, suspected underlying etiopathology, or median age when medication was withdrawnn. Furthermore no evidence could be found that the development of a "complex" or "non-specific" EEG effect carried with it a bad prognosis for surgical cure following focal cortical excision. Performing off-medication tracings seems to be of greatest value in patients with partial seizures and EEGs revealing either a relative paucity of definite absence of epileptiform discharges. The occurrence of a "non-specific" response in a questionable epileptic during the off-medication period, on the other hand, should be interpreted with caution.

Adult↗

PubMed1975

Cerebral seizures of probable orbitofrontal origin.

Four patients with seizures of presumed temporal lobe origin are presented in whom a definite focal ictal onset in the orbitofrontal cortex was revealed during recording, either by chronically implanted electrodes or ECoG. In three cases automatisms occurred concomitantly with orbitofrontal activation without spread of paroxysmal activity into the temporal structures monitored. With eight additional cases of possible orbitofrontal epilepsy found on reviewing the literature, two subgroups emerge: (1) patients with primarily psychomotor-type fits, and (2) patients with loss of consciousness, head and eye deviation, and generalized convulsions. Scalp EEGs, in patients on whom we have available data, manifested bilaterally synchronous, paroxysmal discharges which were bifrontal, frontopolar, or maximal in one anterior quadrant, with or without evidence of additional temporal lobe involvement. On the basis of anatomic and physiological studies, as well as our own electrographic data, it is felt that a posterior orbitofrontal and temporo-limbic relationship exists, within which autonomous epileptogenic zones may develop, with the ability to discharge directly and independently to subcortical centers, while eliciting similar clinical patterns.

Adolescent↗

PubMed1975

Clinical ictal patterns in epileptic patients with occipital electroencephalographic foci.

Seizure patterns and other clinical features were analyzed in 55 epileptic patients with electrographic evidence of exclusive or predominant occipital involvement. Few statistically significant differences in clinical or ictal patterns were found between subjects with purely focal occipital involvement and those with temporal and temporo-parietal spread or minor additional independent foci. On the other hand, cases with bilateral synchronous occipital spike activity appeared to reflect a different type of epileptic disorder. Clinical pleomorphism was more apparent than is commonly conceived; thus, although the incidence of visual auras was relatively high (47 percent), epigastric, psychic, somatic, and other sensory phenomena were not infrequently encountered. Ictal motor patterns were most commonly (53 percent) nonfocal or absent, but partial or focal motor attacks and psychomotor seizures were amply represented. Ictal features with their localizing and lateralizing reliability were also analyzed and discussed in relation to those found in a comparison study of seizures of fronto-centro-parietal origin.

Adolescent↗

PubMed1975

Temporal-lobe seizures with additional foci treated by resection.

The authors describe the use of temporal lobectomy following careful and repeated electroencephalogram (EEG) evaluation (with implanted electrodes in otherwise unresolvable cases) in the epileptic group characterized by automatisms (psychomotor seizures) with temporal epileptiform activity complicated by EEG foci in the opposite temporal lobe or by extratemporal activity. They found that this can render a significant number of patients (between 25% and 50%) either seizure-free or with significant and useful reduction in their seizure frequency. The cure and improvement rates of cases followed up after temporal resection with or without prior study with implanted electrodes were approximately equal. However, the implanted electrodes permitted surgical treatment of certain cases which would have been rejected on the basis of evidence derived from the scalp recordings alone. Of 28 of these 34 patients with persisting EEG epileptiform activity in the postoperative period, only one had such activity in a different location in a follow-up period of 6 years. No evidence of spreading epileptic activity or appearance of "mirror foci" was seen during a follow-up period averaging 8.2 years. Seizure remission up to 15 years with eventual recurrence of the original seizure type may occur following surgical therapy. Follow-up studies of surgical epileptic treatment of less than 3 to 5 years are of doubtful value.

Adolescent↗

PubMed1970