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Biomedical subjects

N Schaul

Publications and source records attributed to N Schaul.

At least 19 recordsLinked to original sources
PubMed2001

Oxcarbazepine (Trileptal) as monotherapy in patients with partial seizures.

OBJECTIVE: To evaluate the efficacy and safety of oxcarbazepine (OXC) as monotherapy for patients with uncontrolled partial seizures. METHODS: A multicenter, double-blind, randomized, parallel-group, dose-controlled monotherapy trial compared OXC at 2400 mg/day with OXC at 300 mg/day in patients with uncontrolled partial-onset seizures previously receiving carbamazepine (CBZ) monotherapy. During a 28-day open-label conversion phase, patients were tapered off CBZ and titrated to OXC 2400 mg/day. After a 56-day open-label baseline phase on OXC 2400 mg/day, patients entered a 126-day double-blind treatment phase in which they were randomized to continue OXC at 2400 mg/day or were down titrated over 6 weeks to OXC at 300 mg/day. Patients met the efficacy endpoint by completing the double-blind treatment phase or by meeting one of four predefined exit criteria. The primary efficacy variable was time to meeting one of the exit criteria. The secondary efficacy variable was the percentage of patients meeting one of the exit criteria in each of the two treatment groups. RESULTS: Of the 143 patients enrolled, 96 were randomized in the double-blind treatment phase. Time to meeting an exit criterion was significantly in favor of the OXC 2400 mg/day group (p = 0.0001). The median time to meeting an exit criterion was 68 days for the OXC 2400 mg/day Group and 28 days for the OXC 300 mg/day Group. In addition, the percentage of patients meeting one of the exit criteria was significantly lower for the OXC 2400 mg/day Group (p = 0.0001). Overall, OXC was well tolerated with the most common adverse events consisting of fatigue, nausea, ataxia, and headache. CONCLUSION: This trial demonstrated that OXC at 2400 mg/day is well tolerated and efficacious when administered as monotherapy in patients with uncontrolled partial onset seizures.

Adolescent↗
PubMed1998

New-onset psychogenic seizures after surgery for epilepsy.

BACKGROUND: The emergence of psychogenic seizures after surgery for epilepsy is not well recognized. OBJECTIVES: To identify the frequency of psychogenic seizures in an 11-year surgical experience and to characterize the patients with this complication. METHODS: Ninety-six patients underwent surgery for epilepsy between 1985 and 1996. The surgical database was reviewed and all patients who experienced postoperative psychogenic seizures were identified. Patients were characterized by sex, age, psychopathologic conditions, full-scale IQ, duration of epilepsy, surgical procedure, and operative complications. Patients were compared with the surgical group as a whole for these variables. SETTING: A comprehensive epilepsy center. RESULTS: Five patients were identified: 3 men and 2 women. Mean full-scale IQ was 73 (range, 66-82). Mean age was 29.8 years (range, 22-36 years). Three patients were diagnosed as having psychosis, 1 with borderline personality disorder and 1 with generalized anxiety. Operations included 4 anterior temporal lobectomies and 1 occipital lobectomy. Two patients experienced operative complications. Compared with the surgical cohort, patients had a higher frequency of preoperative psychopathologic conditions, lower mean full-scale IQ, and a greater occurrence of operative complications. CONCLUSIONS: (1) Patients can develop new-onset psychogenic seizures after surgery for epilepsy. (2) Low full-scale IQ, serious preoperative psychopathologic conditions, and major surgical complications may be risk factors. (3) Atypical postoperative seizures should be evaluated with video electroencephalographic monitoring before concluding that they are epileptic.

Adult↗
PubMed1998

The fundamental neural mechanisms of electroencephalography.

We are at an interesting time in the evolution of the EEG. Studies are opening the door to understanding the intrinsic neuronal properties and network operations responsible for the generation of EEG oscillations. I will review some of our knowledge regarding the physiology of the normal and abnormal EEG. Both epileptic and non-epileptic activity will be discussed. Less is known about the latter, because of difficulties in developing appropriate models. The major dichotomy for both types of EEG phenomenon will be focal and generalized (or widespread. Certain distinctive abnormal EEG patterns including burst suppression, periodic phenomena and intermittent rhythmic delta will also be addressed.

Animals↗
PubMed1997

Temporal lobe epilepsy: correlation of proton magnetic resonance spectroscopy and 18F-fluorodeoxyglucose positron emission tomography.

Proton magnetic resonance spectroscopy (MRS) has demonstrated reduction of N-acetylaspartate (NAA) in the epileptogenic temporal lobe. However, the correlation of NAA reduction with cerebral metabolic abnormalities is unknown in temporal lobe epilepsy (TLE). Proton MRS and 18F-fluorodeoxyglucose positron emission tomography (FDG/PET) were used to study 12 unilateral TLE patients with medically intractable seizures and 26 age-matched healthy volunteers. The epileptogenic temporal lobe of each patient was determined by both electroencephalography and FDG/PET. The NAA/choline-plus-creatine (NAA/(Cho+Cr)) ratio correlated significantly with the interictal glucose metabolism (r = 0.54, P < 0.01) in 12 TLE patients. The mean NAA/(Cho+Cr) ratio in the epileptogenic temporal lobe was significantly less than that in the contralateral side (P < 0.01), and less than that in normal control temporal lobes (P < 0.0001). These results suggest that quantitative MRS abnormalities reflect underlying metabolic pathology in TLE.

Adult↗
PubMed1997

Bilateral reductions in hippocampal volume in adults with epilepsy and a history of febrile seizures.

OBJECTIVES: To examine the degree and frequency of reductions in hippocampal volume in patients with temporal lobe epilepsy with and without a history of febrile seizures. METHODS: In vivo measures of hippocampal volume were computed from three dimensional gradient echo (FLASH) images in 44 patients undergoing comprehensive evaluations for epilepsy surgery. Twenty one patients (48%) reported a history of febrile seizures. The volumes from these patients were compared with those from 23 patients without a history of febrile seizures and 34 healthy controls. RESULTS: The febrile seizure group had significant reductions in volume, both ipsilateral (30% decrease) and contralateral (15% decrease), to the EEG seizure focus. Twelve of 18 patients with febrile seizures exhibited clinically significant ipsilateral volume reductions, defined as volumes falling 2 SD below the mean obtained from the control sample. Only four of 19 patients without febrile seizures exhibited this degree of reduction. No significant correlations were found between seizure variables (for example, duration of epilepsy, seizure frequency) and ipsilateral reductions in volume. However, a significant inverse correlation (r=-0.45, P<0.05) between seizure frequency and the volume of the hippocampus contralateral to the seizure focus was found in the febrile seizure group. CONCLUSION: These results suggest that a history of febrile seizures is associated with the finding of a smaller hippocampus on the side ipsilateral to the subsequent temporal lobe focus whereas chronic factors seem to be be related to pathology contralateral to the seizure focus.

Adolescent↗
PubMed1996

Psychogenic status epilepticus induced by a provocative technique.

We report a patient who developed sustained psychogenic seizures after undergoing a provocative technique (PT) for the diagnosis of psychogenic seizures. Because patients are at risk for severe agitation with PT, these diagnostic maneuvers should be used selectively, and the clinician should be prepared to deal with this complication.

Adult↗
PubMed1995

Prognosis and treatment of seizures in children with acute lymphoblastic leukemia.

We reviewed the records of 127 consecutive pediatric patients with acute lymphoblastic leukemia (ALL) to determine the incidence, timing, etiologies, and recurrence rate of seizures in this population. Patients with ALL and seizures were identified retrospectively by review of the records of all pediatric ALL patients who were diagnosed and treated during the years 1983 through March 1993 in a large tertiary-care hospital. Seventeen patients (13%) developed one or more seizures. In 16 patients, seizures occurred during antileukemic treatment, and in almost all of them seizures were related to intrathecal methotrexate (IT MTX) or subcutaneous L-asparaginase treatment. One patient who developed a seizure while not receiving chemotherapy had a history of cerebral infarctions. In 8 patients, (47%), the initial seizure episode was associated with a cerebral lesion. One or more seizures recurred in 6 patients. Four of these patients had an isolated recurrence, in 3 patients < or = 3 months and in 1 patient < or = 6 months after the initial event. Two patients (12%) with static encephalopathy and neurological deficits developed a chronic seizure disorder. There is a significant risk of acute symptomatic seizures in pediatric ALL patients. Most seizures in these patients occur during the acute treatment phase and are most frequently related to side effects of chemotherapy. The long-term recurrence risk is low; recurrence occurs most often in patients with evidence of cerebral structural lesions and neurological deficits. Long-term antiepileptic drug (AED) therapy should be restricted to such patients.

Adolescent↗
PubMed1995

Postictal and chronic psychoses in patients with temporal lobe epilepsy.

OBJECTIVE: This study sought to elucidate the relation of clinical, neuropsychological, and seizure variables to chronic and postictal psychoses in patients with temporal lobe epilepsy. METHOD: Forty-four patients with treatment-refractory temporal lobe epilepsy were given formal psychiatric evaluations; 29 patients had no psychiatric disorder or a nonpsychotic disorder, eight patients had postictal psychoses, and seven patients had chronic psychoses. Comparisons of clinical, neuropsychological, magnetic resonance imaging, and seizure variables were made between the nonpsychotic and the psychotic patients and, secondarily, between the patients with transient postictal psychoses and those with chronic psychoses. RESULTS: Bitemporal seizure foci, clustering of seizures, and absence of febrile convulsions were associated with both postictal psychoses and chronic psychoses. Younger age at onset of epilepsy and lower verbal and full-scale IQs differentiated the patients with chronic psychoses from those with postictal psychoses. CONCLUSIONS: Patients with temporal lobe epilepsy with chronic and postictal psychoses show similar profiles of clinical and seizure variables, suggesting shared etiologic factors. These factors may increase the propensity to develop psychotic symptoms, while other factors, such as time of onset of epilepsy and underlying neuropathology, may determine whether transient or chronic psychotic symptoms develop. Even among patients with treatment-refractory temporal lobe epilepsy, a specific subgroup of patients, characterized by bitemporal seizure foci, an absence of febrile convulsions, and a history of clustering of seizures, appears to be particularly prone to develop psychotic disorders. A process similar to secondary epileptogenesis may be involved in the development of the psychoses.

Adult↗
PubMed1995

Cerebral metabolic topography in unilateral temporal lobe epilepsy.

OBJECTIVE: Fluorodeoxyglucose positron emission tomography (FDG-PET) studies of temporal lobe epilepsy (TLE) generally report interictal hypometabolism in the vicinity of the seizure focus. Yet, other evidence suggests that interictal metabolic abnormalities might extend to remote brain areas. We used FDG-PET to evaluate metabolism in selected regions distant from the focus in TLE. SUBJECTS: Twenty adult patients with medically intractable TLE were selected by criteria favoring a unilateral mesiobasal temporal focus. Structural imaging in this sample were normal except for medial temporal sclerosis in 13 patients. Twenty normal volunteers were controls. DESIGN: PET imaging was performed interictally. Regional glucose metabolism normalized by global metabolism was analyzed using t tests and correlation analysis. RESULTS: Ipsilateral to the seizure focus, metabolism was depressed compared with normal in the temporal pole (p = 0.001), but relatively elevated in the mesiobasal region (p = 0.005). Contralateral to the focus, metabolism was elevated in lateral temporal cortex (p = 0.0003) and mesiobasal regions (p = 0.0001). Metabolic correlation between ipsilateral and contralateral mesiobasal regions was similar in normal subjects (r = 0.74) and patients (r = 0.68). In contrast, correlations were abnormal between temporal poles and other temporal lobe subregions, both ipsilateral and contralateral to the seizure focus. CONCLUSIONS: Relative to normal values, both elevations and depressions of metabolism exist interictally in TLE. Such abnormalities, and accompanying changes in interregional correlations, may have wide spatial distribution. These findings are atypical among PET studies but are consistent with other physiologic, anatomic, and neuropsychological investigations of TLE.

Adolescent↗
PubMed1994

Cerebellar atrophy in patients with long-term phenytoin exposure and epilepsy.

OBJECTIVE: Cerebellar atrophy has been noted in patients with phenytoin exposure. This finding has been attributed by some investigators to seizures, but by others to phenytoin. Previous studies included patients with mental retardation and convulsive seizures. We undertook a study in a group of nonretarded patients with partial epilepsy to better elucidate the cause of the cerebellar atrophy. DESIGN: Case control study. SETTING: Referral population from an epilepsy center. PATIENTS: Thirty-six patients with partial epilepsy and long-term phenytoin exposure were selected from a consecutive sample of admissions to an epilepsy center. Patients with histories of ethanol abuse, perinatal distress, anoxia, status epilepticus, or neurodegenerative disorders were excluded. Age- and sex-matched controls were selected from a pool of healthy volunteers and patients who had undergone magnetic resonance imaging for complaints of headache and dizziness. INTERVENTIONS: All patients and controls underwent magnetic resonance imaging. MAIN OUTCOME MEASURE: Degree of cerebellar atrophy. RESULTS: The magnetic resonance imaging scans were reviewed in a blind fashion. A rating was assigned to each scan based on the degree of cerebellar atrophy. Cerebellar atrophy was significantly more pronounced in patients than in controls. No correlation was found between cerebellar atrophy and variables reflective of seizure severity or degree of phenytoin exposure. CONCLUSIONS: Cerebellar atrophy may be seen in phenytoin-exposed patients with epilepsy in the absence of generalized tonic-clonic seizures or preexistent brain damage. Whether it is the phenytoin or the seizures that play the primary etiologic role remains unanswered. These factors may be synergistic.

Adult↗
PubMed1993

Neuroradiological manifestations of focal polymorphic delta activity in children.

To examine the neuroradiological and clinical correlations of focal continuous polymorphic delta activity (PDA) in children, we reviewed the records of patients with continuous PDA that was either focal or lateralized to one hemisphere. Of 2571 electroencephalograms (EEGs) performed between July 1, 1988, and December 31, 1990, a total of 125 records from 87 patients revealed continuous PDA. Eighty of these patients had neuroimaging performed either by computed tomographic scan (n = 59) or by magnetic resonance imaging (n = 38) within 8 weeks of the EEG. Twenty-two patients (28%) showed no abnormalities on neuroimaging, 16 patients (20%) showed diffuse abnormalities, and 42 patients (52%) showed focal abnormalities that correlated with the EEG findings. Most (18 of 22) patients with no neuroradiological abnormalities presented to the hospital with seizures from various causes. The presence of focal spikes or additional focal EEG abnormalities did not differ significantly among the three imaging groups. Generalized EEG abnormalities and multifocal spikes were significantly more common among the patients who had generalized abnormalities on neuroimaging. Focal continuous PDA without correlated changes on neuroimaging occurred in 48% of patients, which is much higher than what has been reported in adults.

Adolescent↗
PubMed1990

Pathogenesis and significance of abnormal nonepileptiform rhythms in the EEG.

In this article the present state of knowledge of physiological mechanisms underlying nonepileptiform EEG abnormalities is reviewed. Focal and widespread slow waves, background activity abnormalities, and bursts of rhythmic slow activity are discussed. Clinical and experimental data accumulated over the past four decades suggest that polymorphic slow activity is generated in cerebral cortex by layers of pyramidal cells and is probably due to partial deafferentation from subcortical areas. Unilateral background activity changes are probably due to thalamic dysfunction, and bilateral paroxysmal slow activity is due to abnormal thalamocortical circuits combined with cortical pathology. The fact that pathologic slow-wave phenomena are longer in duration than the average postsynaptic potential is also discussed.

Alpha Rhythm↗
PubMed1990

Periodic EEG patterns: classification, clinical correlation, and pathophysiology.

In this article, we review periodic EEG patterns, which have been classified into four different types based on their interval duration (short or long) and topographic distribution (lateralized, bilaterally independent, or diffuse and synchronous). The four patterns are: (1) periodic lateralized epileptiform discharges; (2) bilateral independent periodic lateralized epileptiform discharges; (3) periodic short-interval diffuse discharges; and (4) periodic long-interval diffuse discharges. We also discuss morphology, etiologies, and clinical correlates of each pattern and possible pathophysiological mechanisms of periodicity.

Brain Diseases↗
PubMed1986

Structural determinants of electroencephalographic findings in acute hemispheric lesions.

We studied electroencephalograms and computed tomographic scans of 54 patients with acute hemispheric strokes. Electrographic parameters evaluated included field, amplitude, frequency, persistence, and reactivity of focal or lateralized slow-wave activity. Ipsilateral and contralateral background activity were also assessed. Structural and clinical features studied were lesion size, density, mass effect, location, tissue involvement, deep structure involvement, level of consciousness, and outcome. The data were analyzed using computer sorting and the chi 2 test. The field, amplitude, and frequency of focal slow-wave abnormalities generally failed to show a specific association with structural details. Continuous focal abnormalities correlated with large lesions (p less than 0.05), mass effect (p less than 0.05), and altered state of consciousness (p less than 0.05). Reactive focal abnormalities were associated with small lesions (p less than 0.05) and the absence of mass effect (p less than 0.02). Ipsilateral background activity abnormalities correlated with lesion size (p less than 0.001) and mass effect (p less than 0.01). Attenuation of ipsilateral background activity was more important than irregularity. Abnormal background activity contralateral to the lesion side was associated with alteration of consciousness (p less than 0.05).

Adult↗
PubMed1981

Generalized, bilaterally synchronous bursts of slow waves in the EEG.

Forty-two patients who had bursts of spontaneous, bilaterally synchronous slow waves during the waking state in an otherwise normal EEG were compared with 42 age-matched control subjects with normal EEGs. The study group had a significantly higher incidence of diffuse encephalopathy than did the control group. They also had a higher incidence of alterations of consciousness. None of the patients in the study group had focal, deep midline lesions. This study indicates that generalized, bilaterally synchronous slow bursts in the EEG are significant abnormalities that in the majority of cases are associated with a mild to moderate diffuse encephalopathy rather than with a lesion limited to deep midline structures.

Adolescent↗
PubMed1981

The EEG in deep midline lesions.

We studied the electroencephalograms (EEGs) of 154 patients with well-defined diencephalic, mesencephalic, or posterior fossa lesions. Electrographic and clinical parameters were statistically evaluated. The results indicated considerable overlap of EEG abnormalities from different subcortical sites. Focal or lateralized abnormalities were relatively specific, suggesting a diencephalic lesion, whereas bilateral paroxysmal slow-wave disturbances were unspecific and not of precise diagnostic significance. There was no specific feature in this series to clearly distinguish the EEG pattern in deep midline lesions from that seen with diffuse cortical and subcortical encephalopathies.

Adolescent↗
PubMed1978

The electromicrophysiology of delta waves induced by systemic atropine.

Delta waves in the EEG can be induced by the intravenous administration of atropine. In cats we have investigated with several computer averaging programs the relationship of extracellular unit discharge to the EEG on the surface and within the cortex. We have also studied the laminar profiles and the vertical current density profiles of these slow waves. Our results indicate that surface-positive delta waves are related to events associated with excitation of cortical neurons, while surface-negative delta waves are related to a decreased probability of unit firing suggesting the possibility of inhibition. Laminar analysis of atropine-induced slow waves indicated that these were probably generated by pyramidal cells in a similar way to delta waves induced by brain lesions. These results suggest that a disturbance in cholinergic input to the cortex might be responsible for delta waves in the EEG.

Animals↗