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Biomedical subjects

J C Sackellares

Publications and source records attributed to J C Sackellares.

At least 55 records · Page 3Linked to original sources
PubMed1987

Differential effects of isoflurane on human median nerve somatosensory evoked potentials.

The effect of isoflurane on median nerve somatosensory evoked potentials (MN-SSEPs) was studied in 15 patients. Anesthesia was induced with thiamylal and maintained with oxygen and isoflurane. MN-SSEPs were recorded in awake patients and after achieving 0.5, 1.0, 1.5, and 2.0% stable end-tidal concentrations of isoflurane. Peak latencies and amplitudes of EP, N13, and N20 and conduction times EP-N13, N13-N20, and EP-N20 were measured. Peak latencies of all components increased after all concentrations of isoflurane compared with control values. N20 peak latencies after 1% and 1.5% isoflurane differed significantly, whereas EP and N13 latencies showed no significant difference. No significant change in conduction time EP-N13 resulted from 1% and 1.5% concentrations of isoflurane compared with control values. Isoflurane increased conduction time N13-N20 significantly when compared with control values, and this increase was dose related. Amplitude of EP and N13 did not show significant change with 1% and 1.5% isoflurane when compared with control values. Amplitude of N20 decreased significantly following isoflurane anesthesia compared with control values, and the difference between 1% and 1.5% isoflurane recordings was also statistically significant. N20 was not discernible in one out of 14 patients after 1.5% and in three out of ten patients after 2% isoflurane. These results indicate that subcortical potentials are less affected by isoflurane anesthesia than cortical potentials. Amplitude reduction of cortical potentials was more noticeable than either prolongation of peak latency or conduction time.(ABSTRACT TRUNCATED AT 250 WORDS)

Evoked Potentials, Somatosensory↗
PubMed1987

Recombinant human tissue-type plasminogen activator therapy in acute thromboembolic stroke.

Systemic fibrinolytic therapy for acute stroke is no longer recommended because of resulting systemic fibrinolysis and the risk of intracerebral hemorrhage. Human tissue-type plasminogen activator (TPA) is a native enzyme that converts plasminogen to plasmin with subsequent clot lysis. The affinity for plasminogen is increased several-fold when the substrate is bound to fibrin. At appropriate dosage, "clot-specific" thrombolysis may be achieved at the surface of the thrombus without creating systemic fibrinolysis. The authors designed a study to evaluate the effect of intravenous TPA administered 2 hours after acute thromboembolic stroke in rats. This time course was chosen to simulate an analogous clinical situation. Middle cerebral artery embolic stroke was caused by intracarotid injection of 0.025 cc of human blood clot in 16 rats. Regional cerebral blood flow, measured by the hydrogen clearance technique, and electroencephalographic (EEG) recordings were obtained every 30 minutes for 5 hours after thromboembolism. Eight rats received a 1-hour infusion of intravenous TPA (1.5 mg/kg) 2 hours after injection of emboli. Ipsilateral blood flow increased significantly within 30 minutes after intravenous TPA and reached preembolic levels within 60 minutes. Blood flow did not improve in the eight control rats throughout the experiment. Power spectral analysis of the EEG recordings showed improvement in the treated group compared to the control group. Postmortem angiography revealed proximal middle cerebral artery occlusion in control animals and patent middle cerebral arteries in TPA-treated animals. Serum fibrinogen and fibrin split products were unchanged in both groups, indicating the absence of systemic fibrinolysis. There were no intracerebral hemorrhages. It is concluded that, in this rat model, TPA increases blood flow with subsequent improvement in the EEG recording after thromboembolic stroke without evidence of systemic fibrinolysis. Intravenous TPA may be useful in the treatment of acute stroke in man.

Animals↗
PubMed1986

Patients with partial seizures: evaluation by MR, CT, and PET imaging.

Fifty patients who experienced partial seizures were imaged with computed tomography (CT) and magnetic resonance imaging (MR); 14 of these also had imaging studies of local cerebral glucose metabolism with positron emission tomography (PET). Thirteen patients with attenuation abnormalities on CT scans also had abnormal signals on MR images; ten other patients had MR-image signal abnormalities but normal CT scans. In all seven patients undergoing PET who had MR-signal and sometimes also CT-attenuation abnormalities, areas of metabolic asymmetry were present. Positive PET scans were also seen in three patients with no evidence of abnormality on CT and MR studies. Focal cerebral substance loss on CT and MR studies, present in 21 patients, did not correlate well with electroencephalographic findings. MR is utilized as the initial imaging procedure in patients with partial seizures because it is more readily available and less invasive than PET and more sensitive than CT scanning.

Adolescent↗
PubMed1986

Personality of patients with pseudoseizures.

We studied personality features of 19 patients with pseudoseizures (PS) only. Scores on a personality inventory (MMPI) were compared with those of adults with generalized seizures and correlated to cognitive measures (Halstead-Reitan). Mean MMPI scores did not differ significantly, and no profile distinguished PS and epilepsy patients. MMPI abnormalities of PS patients were diverse and seldom characteristic of hysteria. Eight PS patients had cognitive impairment, two without MMPI evidence of personality disorder. These findings suggest that the etiology of pseudoseizures is multifactorial, involving different psychopathologies and sometimes cerebral dysfunction.

Adolescent↗
PubMed1985

Patients with pseudoseizures: intellectual and cognitive performance.

We compared cognitive and intellectual performance of patients with pseudoseizures (pseudoseizure-only group), pseudoseizures and epilepsy (mixed seizure group), and generalized epileptic seizures (generalized seizure group). The pseudoseizure-only group performed significantly better on all measures except those of simple motor function. There were no significant differences between those with mixed and generalized seizures. Therefore, cognitive and intellectual performances of patients with pseudoseizures are influenced by the presence or absence of concomitant epilepsy, and suggest that it is necessary to distinguish patients with and without epilepsy in studies of pseudoseizures.

Adolescent↗
PubMed1984

Nonlinear pharmacokinetics of CI-912 in adult epileptic patients.

We studied the pharmacokinetics of CI-912 (1,2-benziosoxazole-3-methanesulfonamide) in 10 adults with refractory partial seizures during an open-label pilot study. Plasma and whole blood concentrations were measured by a high-performance liquid chromatograph method after a single dose and up to and at steady state with one or two dosage regimens. Steady-state clearances averaged only 42% (range 20-60%) of single-dose clearances. Vm and Km values of the Michaelis-Menten equation were calculated for 9 of the 10 patients by a new method: Vm averaged 1,272 (range 500-1,973) mg/day and Km averaged 25.1 (range 9.23-52.5) micrograms/ml. The best initial dosage for a new patient is 300 mg CI-912 every 12 h.

Adult↗
PubMed1983

Effects of age of onset of partial and generalized seizures on neuropsychological performance in children.

Neuropsychological performance data from 106 children with epilepsy were evaluated to determine the effects of seizure type and age of onset. The performance of children with partial seizures (N = 49) was similar to that of children with generalized seizures (N = 57). Only one of 13 tests showed a significant difference between groups, with children with partial seizures performing better on that test. The effects of age of onset were also similar in the two seizure groups. Children whose seizures began before the age of 5 years performed significantly worse than children whose seizures began later on four measures (Verbal IQ, Performance IQ, Trails A, and Trails B) and performed more poorly, but not significantly so, on the other nine measures in the battery. A breakdown of the partial group into simple partial, complex partial, and secondarily generalized partial seizure groups found a significant difference between the groups on only one variable, but there were suggestions in the data that the performance of the partial secondarily generalized group was worse than the other two groups. These results indicate that variables associated with an early onset of seizures, regardless of type, place a child at risk for cognitive dysfunction.

Age Factors↗
PubMed1983

Improvement in neuropsychological performance in patients with refractory seizures after intensive diagnostic and therapeutic intervention.

Tests of cognitive, perceptual, motor, and memory function were administered to patients with refractory seizures before and after intensive treatment on a specialized epilepsy unit. Improved test performance related to withdrawal of barbiturates and an overall reduction in the number of antiepileptic drugs but not with reduction of seizure frequency.

Adolescent↗
PubMed1983

Cerebrally lateralized epileptogenic foci and performance on a verbal and visual-graphic learning task.

A set of verbal and visual-graphic learning tasks sensitive to differential cerebral hemisphere impairment was administered to 50 patients with epileptogenic focus localized in either the left or right cerebral hemisphere. Patients with left-hemisphere seizure-foci and those with generalized seizures performed the verbal task significantly more poorly than did patients with right-hemisphere epileptogenic foci. In contrast, there were no significant differences between groups on the non-verbal tasks. Results are discussed in light of findings in the literature relating cognitive dysfunction to epilepsy and with regard to the possible contribution of such dysfunction to patients' complaints.

Adolescent↗
PubMed1983

Antidepressant withdrawal syndromes: evidence supporting the cholinergic overdrive hypothesis.

The authors present case examples of the various antidepressant withdrawal syndromes. Substantial evidence supports the contention that these syndromes result from cholinergic overdrive; thus, they may have a common pathophysiological basis. Even paradoxical reactions on antidepressant withdrawal, such as mania, are consistent with the cholinergic overdrive hypothesis. If the cholinergic overdrive hypothesis of affective illness. The cholinergic overdrive hypothesis is both of considerable heuristic value and is further testable by the study of the tonic and phasic aspects of sleep and neuroendocrine parameters in the withdrawal state.

Acetylcholine↗
PubMed1981

Reduction of steady-state valproate levels by other antiepileptic drugs.

Steady-state plasma valproate (VPA) levels were analyzed in 37 children after 6 weeks of VPA therapy. Twenty-six patients were receiving other antiepileptic drugs in addition to VPA (experimental group). Eleven patients who received VPA alone served as controls. The mean VPA dose was not statistically different for the two groups (experimental group, 35.4 mg/kg/day, 11.6 SD; control group, 31.1 mg/kg/day, SD 6.6) The mean plasma VPA level was significantly lower for the experimental group (63.0 micrograms/ml, SD 21.8) than for the control (99.3 micrograms/ml), SD 23.3) (p less than 0.01). VPA level: dose ratio (LDR) was also reduced in the experimental group (1.92, SD 0.75) as compared to controls (3.26, SD 0.65) (p less than 0.01). Within the experimental group the VPA levels and VPA LDR were significantly reduced in patients receiving either phenytoin or phenobarbital. The data suggest that other antiepileptic drugs significantly alter the steady-state level to dose relationship for VPA.

Adolescent↗
PubMed1981

Intensive monitoring in refractory epilepsy.

Forty patients with intractable seizures were studied in an epilepsy unit for an average of 8 weeks with video-electroencephalographic telemetry and continuous observation by trained personnel. Drugs were administered on the basis of antiepileptic drug measurements and seizure classification determined by clinical observation and telemetry. Seizure frequency was reduced in 24 patients (60%). Unrecognized seizure types were identified in 8 patients (20%), and diagnostic classification was changed in 19 patients (47.5). At least one antiepileptic drug was eliminated in 25 patients (60%), and the average drug reduction per patient--0.60--was highly significant (p less than 0.01). In patients with seizures refractory to conventional out-patient and hospital management, improvement in diagnostic accuracy and refinement in observation techniques result in significant reduction of seizure frequency, elimination of drugs, and limitation of toxicity.

Adolescent↗
PubMed1980

Evaluation of childhood pseudoseizures using EEG telemetry and video tape monitoring.

Pseudoseizures, clinical events that superficially resemble epileptic attacks but which are not associated with central nervous system paroxysmal activity, are often difficult to differentiate from epileptic seizures. To evaluate the frequency and clinical manifestations of pseudoseizures in children with intractable seizures, children admitted to a Comprehensive Epilepsy Unit received prolonged simultaneous EEG telemetry and video recording. Pseudoseizures occurred in 11 of 53 pediatric patients admitted during the study period. Eight of the 11 patients with pseudoseizures also had documented epileptic seizures. Clinical characteristics of pseudoseizures and epileptic seizures documented by TEEG-VR were compared. Degree and duration of the postictal state, incontinence, combativeness, relationship to stress, and response to anticonvulsant medication were useful differentiating criteria. Pseudoseizures are not unusual in pediatric patients, often occur concurrently with epileptic seizures, and may be difficult to diagnose. However, careful clinical observation may offer clues in differentiating pseudoseizures from epileptic seizures.

Adolescent↗
PubMed1979

Myoclonus with electrocerebral silence in a patient receiving penicillin.

Multifocal myoclonus is a well-recognized complication of high doses of penicillin. In man, the site of origin of penicillin-induced myoclonus has not been clearly established, but there is evidence from animal studies that it may originate at a cortical, subcoritcal, or spinal level. We report a case of multifocal myoclonus occurring in a patient receiving large doses of penicillin. The myoclonus appeared when there was no clinical or EEG evidence of upper brain stem or cerebral function. The observations reported suggest that penicillin-induced myoclonus may occur in man and may originate at a caudal brain stem or spinal level.

Adult↗
PubMed1979

Stupor following administration of valproic acid to patients receiving other antiepileptic drugs.

Stupor is an unusual complication following the addition of valproic acid to other antiepileptic drugs. We report four such cases. Stupor occurred acutely in 3 patients and insidiously in the fourth. In the cases of acute toxicity, neither toxic levels of valproate nor significant elevations in blood levels of the other drugs occurred. In the fourth patient, stupor occurred concomitantly with a rise in the phenobarbital level. The electroencephalograms of all 4 patients revealed generalized high-amplitude rhythmic bisynchronous delta activity. Recovery occurred following discontinuation of valproic acid or other antiepileptic drugs. These observations suggest that stupor may occur as a result of drug interactions after the addition of valproic acid to other antiepileptic drugs.

Adolescent↗