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Biomedical subjects

R P Lesser

Publications and source records attributed to R P Lesser.

At least 109 records · Page 6Linked to original sources
PubMed1986

Basal temporal language area demonstrated by electrical stimulation.

We report on a 38-year-old patient with intractable complex partial seizures originating in the dominant left medial temporal region. In the work-up for seizure surgery, arrays of subdural electrodes were placed, and electrical stimulation revealed marked language interference in a 2 X 2-cm area in the left basal temporal fusiform gyrus (3.5 to 5.5 cm posterior to the temporal tip). Complete receptive and expressive aphasia, inability to repeat, agraphia, and alexia were elicited, but visual memory was preserved, and no constructional apraxia was noted. Stimulation of the basal temporal gyrus at lower stimulus intensities produced a relatively selective and severe anomia.

Adult↗
PubMed1986

The lateralizing significance of versive head and eye movements during epileptic seizures.

We studied 37 patients who had head and eye turning during 74 spontaneous epileptic seizures. Videotapes and EEGs were analyzed independently. Turning movements were classified without knowledge of EEG or clinical data as either versive (unquestionably forced and involuntary, resulting in sustained unnatural positioning) or nonversive (mild, unsustained, wandering, or seemingly voluntary). Videotape observations were then correlated with the EEG location of seizure onset. Contralateral versive head and eye movements occurred during 61 seizures in 27 patients, but ipsilateral versive movements did not occur. Nonversive lateral head and eye movements occurred ipsilaterally and contralaterally with equal frequency and were nonlocalizing, but versive movement was a reliable lateralizing sign.

Adolescent↗
PubMed1986

Electrical stimulation of Wernicke's area interferes with comprehension.

Arrays of subdural electrodes were placed over the lateral convexity of the dominant hemisphere for propositional language in four patients with epilepsy as part of an evaluation prior to cortical resections. Stimulation was performed over several days. When we stimulated the posterior temporal language area, reading and comprehension of complex verbal information were impaired, but comprehension of nonverbal and simple verbal data was not affected. Impairment produced by stimulation seemed to be due to language comprehension difficulties, rather than impaired praxis or initial word storage.

Adolescent↗
PubMed1986

Memory for objects presented soon after intracarotid amobarbital sodium injections in patients with medically intractable complex partial seizures.

We evaluated the abilities of 36 patients with intractable temporal lobe epilepsy and left hemisphere dominance for language to later recognize objects presented in the confusional phase after left intracarotid amobarbital injection. Eighteen of 24 patients with left, but only 4/12 with right, temporal lobe epilepsy recognized at least two-thirds of objects during a post-test. These results demonstrate that the initial muteness and apparent confusion after amobarbital injection do not prohibit the formation of new memories; this gives further support to the idea that consciousness can be retained despite transient disruption of function of the language-dominant hemisphere.

Adolescent↗
PubMed1986

Ipsilateral forced head and eye turning at the end of the generalized tonic-clonic phase of versive seizures.

We studied 61 spontaneous seizures in 27 epileptic patients with simultaneous EEG and video recording. Each seizure had an initial forced turning (versive) head and eye movement contralateral to the EEG location of seizure onset. Twelve of the 27 secondarily generalized versive seizures also had ipsilateral head and eye version at the end of the generalized convulsion. Initial contraversion and late ipsiversion both appeared to result from ictal activation of frontal contraversive areas in the hemisphere that, at the time, was predominantly involved in the seizure discharge. During initial contraversion, ictal activation was predominant in the hemisphere of seizure onset; during late ipsiversion, in the hemisphere involved by secondary generalization. Late version, unlike initial version, is frequently ipsilateral and cannot be assumed to indicate seizure onset in the contralateral hemisphere.

Adolescent↗
PubMed1986

Intraoperative spinal somatosensory evoked potential monitoring.

The relationship of intraoperative monitoring of spinal cord somatosensory evoked potentials and postoperative deficit in 220 cases (121 with scoliosis, 41 with neoplasms, and 58 others) is reported. Bilateral posterior tibial nerve stimulation was used in 181 cases and unilateral median nerve stimulation in 39. Spinal cord (interspinous ligament needles), subcortical (neck surface), and cortical (scalp surface) SEP's were monitored. Seven patients had worsening of neurological function after surgery, three of whom demonstrated significant changes in SEP's monitored. In an additional four cases, there was more than a 50% decrease in amplitude of subcortical/cortical SEP's during monitoring, but no change in neurological status postoperatively. Combined monitoring of spinal cord, subcortical, and cortical SEP's enhanced the certainty of detecting spinal cord dysfunction even though there was a significant number of false-negative and false-positive results. A marked change in the SEP's indicated a high chance of developing a neurological deficit (three or 43% of seven cases), and if there was no change the chance of any neurological postoperative deficit was extremely low (four or 1.87% of 213 cases). These data justify the use of intraoperative SEP monitoring.

Adolescent↗
PubMed1986

Effect of etomidate on the electroencephalogram of patients with epilepsy.

Etomidate was given intravenously to 12 epileptic patients undergoing craniotomy for surgical removal of their seizure focus. Electroencephalograms were recorded by means of subdural electrodes. Nine of the 12 patients showed an increase in epileptiform activity. In six of the nine patients, the activity was marked.

Adolescent↗
PubMed1985

The second sensory area in humans: evoked potential and electrical stimulation studies.

A patient with intractable seizures originating from a right frontal focus was evaluated for surgical treatment. This evaluation was carried out using a chronically implanted array of 96 stainless steel electrodes 1 cm apart and covering the perirolandic and frontal areas. Somatosensory evoked potentials and electrical stimulation of the subdural electrodes localized the primary sensory hand area. Evoked potentials of identical waveform but of lower amplitude and 2.4 ms longer latency were recorded in the inferior frontal gyrus immediately anterior to the face area of the motor strip. Electrical stimulation of that area elicited: (1) a "paralyzing" feeling in the left arm and face; (2) inhibition of rapid alternating movements of left fingers, left hand, and tongue; (3) inability to maintain a strong voluntary muscle contraction of the left hand or tongue; and (4) speech arrest. This appears to be the first report of a secondary sensory area in humans demonstrated by both electrical stimulation and evoked potential studies. Electrical stimulation showed that the secondary sensory area overlapped an area of complex motor control, suggesting that the secondary sensory area provides direct sensory feedback information for appropriate motor integration.

Adult↗
PubMed1985

Choosing an antiepileptic drug. The case for individualized treatment.

The range of drugs available for seizure control is broad, but selection of the drug and the dosage most likely to be effective for an individual patient is complex. In general, drug choice is determined by type of seizures involved and total daily dosage is based on milligrams per kilogram, so that plasma levels for all patients can be easily interpreted. Optimal seizure control is often possible with use of a single drug; in fact, in most patients with epilepsy, single-drug therapy is more effective than multiple-drug therapy and more desirable.

Adolescent↗
PubMed1985

Optimizing stimulating and recording parameters in somatosensory evoked potential studies.

Methods to increase the signal:noise ratio of evoked potentials are reviewed, dividing them into three groups: (1) increasing the number of stimuli averaged; (2) decreasing the noise (muscle relaxation, filters, intermittent artifact reject methods); and (3) increasing the amplitude of the signal (stimulus intensity, nerves stimulated, bilateral versus unilateral stimulation, stimulus modality, and montage). Examples of these different methods applied to recording of somatosensory evoked potentials are given, and it is concluded that, for optimal recording of somatosensory evoked potentials, a combination of all these methods should be used.

Electric Stimulation↗
PubMed1985

Ipsilateral trigeminal sensory responses to cortical stimulation by subdural electrodes.

Twelve patients with medically intractable epilepsy had plates of chronic subdural electrodes placed over the lateral and basal cortical hemispheres during evaluations for surgical therapy. During cortical stimulation, ipsilateral sensations involving any of the branches of the trigeminal nerve were noted in the eye, face, and mouth. Some responses could have been due to dural or direct trigeminal nerve trunk stimulation, but others were probably due to electrical stimulation of trigeminal fibers accompanying the pial-arachnoidal vessels. These fibers had been demonstrated in animals, but not in humans.

Adolescent↗
PubMed1985

Pattern evoked potentials (PEPs) in Parkinson's disease.

Controversy exists in the literature concerning whether Parkinson's disease (PD) results in prolongation of pattern evoked potential (PEP) responses. PEPs were obtained in 20 patients with PD. The latencies of the first major positive potential (P2) in response to independent left and right eye stimulation were evaluated. There was no statistically significant difference (group or individual) when patients with PD were compared with age-corrected controls. There was no difference in results in comparing patients with mild, moderate, and severe PD. These results contradict previous reports of markedly abnormal PEPs.

Aged↗
PubMed1985

Preservation of voluntary saccades after intracarotid injection of barbiturate.

We studied voluntary saccades in 44 patients undergoing Wada testing before surgery for intractable epilepsy. After intracarotid injection of barbiturate, and while they were hemiplegic, patients could still make voluntary saccades toward or away from the side of injection. Sustained ipsiversive deviation of gaze was not noted. Saccades made away from the side of injection were slower than ipsilateral saccades in only 3 of 10 tests. These data support the hypothesis of parallel, independent pathways from the frontal eye fields and from the superior colliculi to the brainstem reticular nuclei that generate saccades.

Amobarbital↗
PubMed1985

Treatment of acute focal cerebral ischemia and recirculation with d-propranolol.

The purpose of the investigation was to evaluate the effects of d-propranolol upon temporary cerebral ischemia followed by a period of reperfusion, that is, a situation analogous to major cerebral artery embolization. Twenty adult cats, lightly anesthesized with nitrous oxide, underwent 4 hours of right middle cerebral artery (MCA) occlusion and 2 hours of recirculation. Ten cats were untreated and 10 cats received d-propranolol, the weak beta-blocking isomer of racemic (d,l) propranolol. The d-propranolol was infused directly into the right carotid artery at doses of 2 mg/kg, given as a bolus immediately before MCA occlusion, and 0.33 mg/kg/hour, given continuously for 6 hours beginning immediately after MCA occlusion. Systemic arterial blood pressure was similar in both groups, but heart rate was transiently reduced in the treated group immediately after the bolus injection of d-propranolol and MCA occlusion. Regional cerebral blood flow (rCBF), measured by the xenon-133 clearance technique, was not significantly different in the ischemic, right hemisphere. Electroencephalographic (EEG) activity changes in the ischemic, right hemisphere were similar in both groups, but there was significant deterioration of EEG activity in the left, nonischemic hemisphere of untreated cats after MCA reopening. Swelling of the ischemic, right hemispheres was similar in both groups and more severe than in previous studies wherein there was no recirculation phase. Carbon perfusion and blood-brain barrier changes were also similar. The results of the study failed to show a protective effect despite theoretical beneficial actions of d-propranolol. Also, the study demonstrated that d-propranolol does not have a detrimental effect upon rCBF in acute focal cerebral ischemia.

Animals↗