Biomedical subjects

M R Sperling

Publications and source records attributed to M R Sperling.

At least 19 recordsLinked to original sources

PubMed1997

Clinical challenges in invasive monitoring in epilepsy surgery.

Invasive monitoring aids in selecting patients for epilepsy surgery. This article reviews the methods employed to obtain intracranial EEG, data interpretation, and problems that arise during intracranial investigations. The relative merits of depth, subdural, epidural, and foramen ovale electrodes are reviewed, and a strategy for their use is suggested. Characteristic interictal and ictal EEG findings are summarized, and the problems encountered in interpreting data are discussed.

Brain Mapping↗

PubMed1997

Seizures in temporal lobe epilepsy: I. Reliability of scalp/sphenoidal ictal recording.

We determined both (1) the reliability (reproducibility) of seizure onset location in patients with temporal lobe recorded with extracranial EEG and (2) if interictal spike (IIS) location influences that reliability. EEGs were recorded with the 10-20 system and sphenoidal electrodes. Between 1985 and 1993, 166 patients with suspected temporal lobe epilepsy were eligible for inclusion with a total of 734 seizures recorded. Each seizure onset was classified as either localized, lateralized, or nonlocalized. Individual patients were then grouped according to interictal spike location (i.e., unilateral, bilateral, or none) as well as by ictal onset reproducibility patterns (i.e., concordant, semiconcordant, conflicting, or nonlocalized) based on each patient's monitoring session. Seizure onset location was reproducible in 68% of the cases and variable patterns of seizure onset were seen in 32% of patients. Patients with unilateral IIS (68%) were more likely to have consistent ictal onset patterns than patients with bilateral IIS (27%). The first seizure more often predicted subsequent seizure onset patterns when it was localized than when it was nonlocalized. Of 18 patients with conflicting temporal lobe seizures, up to four seizures were necessary to detect independent bilateral temporal lobe seizures.

Adolescent↗

PubMed1997

A cost-effectiveness analysis of anterior temporal lobectomy for intractable temporal lobe epilepsy.

Patients with medically intractable temporal lobe epilepsy are potential candidates for anterior temporal lobectomy (ATL), in which epileptogenic temporal lobe tissue is localized and surgically removed. This surgical approach can eliminate or drastically reduce seizures in the majority of patients. The authors used a decision-analysis model to examine the cost-effectiveness of a surgical evaluation and treatment protocol for medically intractable temporal lobe epilepsy. This model compared a cohort treated with the new protocol with a continuation of their immediate preoperative medical management and projected these differences over the patient's lifetime. The Markov model incorporated postoperative seizure status, patient quality of life, death from surgical and natural causes, discounting, and the direct medical costs associated with outpatient evaluation, hospitalization, surgery, antiepileptic drugs, and lifetime outpatient treatment. The intent-to-treat analysis included patients who underwent evaluation but were not eligible for ATL. Sensitivity analyses were also performed on the variables in the model. Data from the baseline model indicated that evaluation for ATL provided an average of 1.1 additional quality-adjusted life years (QALYs) compared with continued medical management, at an additional cost of $29,800. Combining the clinical and economic outcomes yielded a cost-effectiveness ratio of $27,200 per QALY. This value is comparable to other accepted medical or surgical interventions, such as total knee arthroplasty ($16,700/QALY) or coronary artery balloon angioplasty ($40,800/QALY). Sensitivity analyses demonstrate that the results are critically dependent on postoperative seizure status and improvement in quality of life. Although further work is necessary to quantify the improvement in quality of life after epilepsy surgery better, the present data indicate that ATL for treatment of intractable temporal lobe epilepsy is a cost-effective use of medical resources.

Adult↗

PubMed1997

Epilepsy management. Issues in medical and surgical treatment.

After a single seizure, about 40% of patients have recurrence. The main features correlating with recurrence are cause, seizure type, EEG findings, family history of seizures and, possibly, the presence of a prior febrile seizure, Todd's paresis, and other abnormal neurologic findings. A number of medications are available for treatment. Withdrawal from medication is successful in 60% to 70% of patients. Several factors favor successful drug taper. These include a seizure-free status for at least 2 years during drug therapy, a single type of seizure (partial or generalized), young age at seizure onset, and an epilepsy syndrome with a tendency to remit. Surgery can be considered in certain patients with surgically remediable syndromes. Candidates typically have seizures that impair consciousness, that cause falling with injury, that have adverse psychosocial or social effects, and that persist after trials of three appropriate medications. A multidisciplinary evaluation should take place at a surgery center with experience and documented success. Favorable results from surgery can be expected in a large proportion of patients.

Anticonvulsants↗

PubMed1997

Mossy fiber reorganization and its possible physiological consequences in the dentate gyrus of epileptic humans.

It is unlikely that MF reorganization is the cause of epilepsy, but it may affect the progression of the disease, i.e., the frequency or severity of seizures. We propose that early events, yet undiscovered, lead to an increased likelihood of excitability. This hyperexcitability, which initially may not be manifested in overt seizures, may erode vulnerable hilar neurons that serve an important inhibitory function, as illustrated in Fig. 6-15. As inhibition is lost, hyperexcitability reaches the level of clinically manifested seizures that are severe enough to lead to substantial loss of hilar neurons. When the loss of these cells is sufficiently high, MF reorganization occurs, first to neighboring hilar neurons and later to dendrites of granule cells (Fig. 6-15). Thus, the functional consequence of MF reorganization may provide a compensatory form of inhibition, as well as a circuit for feedback excitation. Although definitive evidence indicating that MF reorganization contributes to the acceleration or progression of epilepsy is missing, the findings to date are consistent with this hypothesis. In the event that reorganization contributes to the epileptic condition, treatments that reduce indicators of neuropathology may lead to a reduction of seizure frequency and severity. Evidence suggests that reorganization in the dentate gyrus may follow the pathways of neuronal processes of hilar neurons that have died. Thus, further study of the events that guide MF reorganization may hold important clues for developing methods for targeting regenerating axons following central nervous system injury.

Dentate Gyrus↗

PubMed1997

Predictors of intellectual performance in adults with intractable temporal lobe epilepsy.

The relationships of medical, developmental, social, and familial variables to intellectual performances (IQ scores) were assessed in a sample of 242 adult patients with intractable lateralized temporal lobe epilepsy. Lower IQ scores were associated with low patient and parent education. In addition to the significant contributions of nonneurological social and familial factors to IQ, early age at onset of regular seizures and presence of primary neurological dysfunction in the left cerebral hemisphere were also both independently related to lower IQ. The obtained results suggest that the occurrence of regular seizures during a critical period in early childhood neural maturation poses the greatest risk to cognitive development in the epilepsy population. Total duration of seizures, history of severe convulsive episodes, and the occurrence of another nonepileptic neurological problem in early childhood do not contribute significantly to delayed cognitive development.

Adolescent↗

PubMed1996

Temporal lobectomy for refractory epilepsy.

OBJECTIVE: To examine the long-term effectiveness of anterior temporal lobectomy for refractory epilepsy with regard to seizure control and related medical and psychosocial measures and to determine how patterns of early seizure recurrence relate to long-term prognosis. DESIGN: A cohort of patients prospectively followed up for 5 years after surgery. SETTING: Tertiary care comprehensive epilepsy center. PATIENTS: Eighty-nine patients with medically refractory epilepsy who were consecutively treated with anterior temporal lobectomy between 1986 and 1990. All patients had noninvasive preoperative evaluations, and 31 were evaluated with intracranial electrodes prior to surgery. MAIN OUTCOME MEASURES: Postoperative seizure frequency, neuropsychologic function, mortality, and postoperative employment status. RESULTS: Five years after surgery, 62 patients (70 percent) were seizure free, 8 (9 percent) had seizures on fewer than 3 days per year or exclusively had nocturnal seizures, 10 (11 percent) had greater than 80 percent reduction in seizure frequency, 5 (6 percent) had less than 80 percent reduction in seizure frequency, and 4 (4 percent) died of causes unrelated to surgery. The proportion of patients in each outcome class remained stable throughout the 5-year period. Fifty-five percent of seizure recurrences happened within 6 months of surgery, and 93 percent occurred within 2 years after surgery. Outcome at 1 year related only moderately well to outcome at 5 years. No significant cognitive or linguistic deficits occurred. All patients who died had persistent seizures after surgery. Underemployment and unemployment declined significantly after surgery, with improvement noted in seizure-free patients. CONCLUSIONS: Temporal lobectomy provides sustained seizure relief over 5 years to most patients who have surgery. Outcome at 2 years predicts long-term outcome. A seizure-free state is associated with reduced mortality and increased employment. Mere reduction in seizure frequency is not associated with improvement in those measures.

Adolescent↗

PubMed1996

Spike detection. I. Correlation and reliability of human experts.

A panel of 5 experienced electroencephalographers detected spikes in EEG trials from 40 epilepsy patients and 10 control subjects. 1952 spikes were detected, and detailed attribute scores were recorded. Statistics from the theory of measurement error are utilized to quantify the reliability and difficulty of the study. An extension of the Pearson correlation coefficient, called the detection correlation coefficient, is derived and used in recognition of the fact that readers agree on numerous non-spike regions. Spike perception is modeled with both dichotomous and continuous values. as expected, the study reliability is higher when using the continuous values. Standard sensitivity and specificity definitions are extended and applied to continuous-valued spike perception. A database of "panel scores" was created from the 5 reader scorings by merging spikes within 75 msec on each side. The average inter-reader correlation is 0.79 with a corresponding reliability of 0.95. Average spike attributes are calculated, and the resulting database can serve as a "gold standard" for testing computer algorithms or other readers.

Action Potentials↗

PubMed1996

Hippocampal cell distributions in temporal lobe epilepsy: a comparison between patients with and without an early risk factor.

Neuronal cell distributions were measured for anterior and posterior locations in the hippocampi of epilepsy patients who were seizure-free after temporal lobectomy. Patients were divided into two groups, those with an early risk factor, defined as a neurologic insult occurring in the first 4 years of life, and those with no early risk factor. Early-risk patients had lower hilar cell densities, lower granule cell densities, and fewer granule cells per millimeter, a measured related to total granule cell number, than to early risk patients. Moreover, each risk group had different anteroposterior density gradients for granule cells and hilar cells. These differences in cell distribution may arise from different patterns of cell loss of cell migration in the dentate gyrus during development. In the early-risk group, there was also a distinction between patients with a history of febrile convulsions without CNS infection and patients with a history of meningitis or encephalitis. These two subgroups had similar numbers of granule cells, However, the meningitis/encephalitis subgroup exhibited a wider granule cell layer, suggesting that the granule cell layer was more dispersed. Our results support the hypothesis of a predominantly anterior hippocampal insult in temporal lobe epilepsy (TLE). In nonepileptic hippocampus, the ratio of putatively excitatory granule neurons to putatively inhibitory hilar neurons is highest in the anterior hippocampus. This ratio may explain in part why the anterior hippocampus is more prone to cell loss and seizures.

Adult↗

PubMed1996

Significance of simple partial seizures in temporal lobe epilepsy.

We determined how localization of simple partial seizures (SPS) correlated with localization of complex partial seizure (CPS) in scalp/sphenoidal EEG and assessed prognosis after temporal lobe resective surgery in patients with an ictal correlate of SPS in scalp/sphenoidal EEG recordings. EEGs were recorded with the 10-20 system of electrode placement and supplemented with sphenoidal electrodes. Between 1985 and 1992, 183 patients with temporal lobe epilepsy (TLE) reported an aura (SPS) during inpatient monitoring; all were eligible for inclusion in our study. The EEGs during SPS showed ictal changes in 51 patients (28%, 117 SPS). Forty-four patients had unilateral temporal interictal spikes (IIS), and SPS and CPS always arose from the same region. Seven patients had bitemporal interictal spikes; SPS colocalized with CPS in 4 patients (57%), SPS were contralateral to CPS in 2 patients, and 1 patient had bilateral independent CPS but unilateral SPS. SPS accompanied by EEG ictal changes conveyed a favorable prognosis in patients who underwent epilepsy surgery. Scalp/sphenoidal recorded IIS but were less reliable in identifying the location of CPS onset in patients with bitemporal spikes.

Adult↗

PubMed1996

Coupling of cortical and thalamic ictal activity in human partial epilepsy: demonstration by functional magnetic resonance imaging.

PURPOSE: To localize metabolic coupling between a cortical seizure focus and other brain regions by using functional magnetic resonance imaging (fMRI) data of ictal events obtained in a patient with frequent partial seizures involving his right face. METHODS: Cross-correlation analysis was used to examine time-dependent alterations in regional signal intensity that correlated with signal-intensity changes from a well-characterized cortical seizure focus in a patient with frequent partial seizures. RESULTS: Signal changes in the left ventrolateral thalamus showed a high degree of temporal correlation with signal changes in the left frontal cortical seizure focus, demonstrating close corticothalamic coupling of metabolism. CONCLUSIONS: A significant role for thalamocortical interactions in the pathophysiology of epilepsy has been suggested by studies in animal models and human patients. This finding provides further support for the integral involvement of the thalamus in human focal epilepsy and underscores the potential for identifying neuronal networks by using cross-correlation analysis of fMRI data.

Adult↗

PubMed1995

Language before and after temporal lobectomy: specificity of acute changes and relation to early risk factors.

We evaluated language functions in 154 patients with left hemisphere speech dominance undergoing anterior temporal lobectomy (ATL). Measures of phonemic and semantic fluency, confrontation naming, repetition, comprehension, and reading were administered before and 3 weeks postoperatively. Patients were grouped by focus (left, LT; right, RT) and presence of early risk factors for development of seizures (ER, early risk, < or = 5 years; NER, no early risk): (LT-ER, n = 45; RT-ER, n = 49; LT-NER, n = 27; RT-NER, n = 33). Preoperatively, the LT group showed a selective naming deficit as compared with the RT group. Postoperatively only the LT-NER group showed significant overall decline in language. For this group, the change was attributable to a selective decline in naming as compared with other functions. These data indicate that there is a specific risk to naming after dominant ATL for adult temporal lobe epilepsy (TLE) patients with a left hemisphere focus and the absence of an early risk factor for the development of seizures.

Aphasia↗

PubMed1995

Cerebral blood flow during spike-wave discharges.

We used the 133xenon method to assess cerebral blood flow (CBF) during generalized spike-wave discharges in a patient with an uncommon form of generalized epilepsy with persistent spike-wave discharges. CBF measurements were made under four conditions with repeated measures: normal EEG, continuous theta state, continuous spike-wave state at rest, and continuous spike-wave discharges during performance of a cognitive activation task. CBF was mildly reduced (5.7%) during the theta state and decreased further (12%) in the spike-wave state. Although globally diminished, CBF was less decreased in the frontal lobes and more decreased in the parietal lobes during spike-wave discharges. CBF increased to baseline levels during the cognitive activation task. The decrease in CBF suggested that the generalized spike-wave discharges caused a net decrease in cortical metabolic demand and neuronal activity. The differences in lobar CBF during spike-wave discharges may reflect lobar disparities in neuronal firing patterns. The theta state noted is novel and intermediate between normal and spike-wave.

Cerebrovascular Circulation↗

PubMed1995

Comparison of mesial versus neocortical onset temporal lobe seizures: neurodiagnostic findings and surgical outcome.

We compared historical features, surface EEG findings, results of intracarotid sodium amobarbital memory testing (IAT), and outcome after anterotemporal lobectomy (ATL) in patients with mesiotemporal lobe seizure onset with those with more diffuse temporal lobe seizure onset (intracranial EEG). Forty-eight patients evaluated consecutively between July 1985 and October 1991 with both scalp/sphenoidal and intracranial EEG were shown to have seizures originating in one temporal lobe. No patients had temporal lobe tumor or vascular malformation. Thirty-seven of the 48 patients had seizure onset in the amygdala/hippocampus (amyg/hipp). Eleven of the 48 had either temporal neocortical onset or simultaneous amyg/hipp and neocortical onset. Patients with mesial onset seizures were more likely to have lateralized memory impairment on IAT (p = 0.05). We noted a trend toward a difference in age of first risk for epilepsy between the two groups (p = 0.09) but not for a difference in any specific risk factor. There were no significant differences in surface EEG interictal findings. Unlike in previous studies, comparison of outcome between the two groups showed no difference in seizure-free outcome. Sudden unexpected death (SUD) was more frequent in neocortical seizure patients who were not seizure-free (p < 0.05).

Adolescent↗

PubMed1995

False lateralization of temporal lobe epilepsy with FDG positron emission tomography.

We report 2 patients in whom visual interpretation of interictal positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) suggested false lateralization of an epileptic focus. PET scans were interpreted as showing diffuse left temporal lobe hypometabolism in 1 patient and lateral temporal hypometabolism in the other. However, seizures began in the right mesial temporal lobe in both patients, and both responded favorably to right temporal lobectomy. In 1 patient, the intracranial EEG showed continuous asymptomatic subclinical seizure activity emanating from the right amygdala. These limbic discharges probably caused unrecognized right temporal lobe hypermetabolism. In the other case, quantitative analysis of metabolic rates showed conflicting mesial and lateral metabolic indexes. Frequent mesial interictal discharges might have increased lateral temporal metabolism. We conclude that asymptomatic epileptiform activity may alter temporal lobe metabolism and that quantitative PET analysis helps clarify contradictory visual PET interpretations.

Adult↗

PubMed1995

Interictal single-photon emission computed tomography in partial epilepsy. Accuracy in localization and prediction of outcome.

The role of interictal brain single-photon emission computed tomography (SPECT) was examined using (99mTc)- labeled hexamethylpropyleneamine oxime (HMPAO) in refractory partial epilepsy. The accuracy with which SPECT localized an epileptic focus and whether it predicted long-term postoperative seizure relief were assessed. Twenty patients were evaluated, 14 of whom ultimately had anterior temporal lobectomy with follow-up ranging from 41 to 56 months. A single-headed gamma camera was used. The interictal SPECT showed ipsilateral temporal hypoperfusion in 8 (47%) of 17 patients with temporal lobe epilepsy and showed either multilobar hypoperfusion or no perfusion defects in the rest. The sensitivity and specificity were similar in patients with a more complex clinical picture who required intracranial electrodes and those who did not. Presence or absence of temporal lobe hypoperfusion did not correlate with postoperative seizure relief. It is concluded that interictal SPECT with 99mTc-HMPAO with a single-headed gamma camera does not add useful information in preoperative localization or predicting postoperative seizure relief.

Adolescent↗

PubMed1995

The syndrome of frontal lobe epilepsy: characteristics and surgical management.

We reviewed the historical features, preoperative diagnostic evaluation, operative procedure, and surgical outcome in 16 patients with refractory frontal lobe epilepsy. Clinical expression of the epilepsy varied widely, particularly with respect to seizure characteristics, although high monthly seizure frequency and absence of a risk factor for epilepsy before age 5 occurred more often than in reported in temporal lobe epilepsy patients. Seizures often caused early bilateral movements, were brief, and lacked oroalimentary automatisms and a prolonged postictal state. Both the interictal and ictal scalp EEGs had relatively poor sensitivity and specificity and often either contained no epileptiform abnormalities or were misleading. MRI usually identified structural lesions when these were present, although it was negative in two patients with tumors. In the absence of an MRI lesion, intracranial EEG usually identified the area to be resected, although it too provided misleading information in one case. Surgical procedures consisted of focal resections with or without anterior corpus callosotomy, or of corpus callosotomy alone. Nearly all patients improved after surgery, with a majority (67%) becoming seizure-free (average follow-up, 46 months). Preoperative seizure frequency correlated with seizure relief after surgery, as did age of seizure onset, whereas presence of tumor did not. We conclude that frontal lobe epilepsy warrants aggressive investigation and that surgical treatment often can be successful.

Adolescent↗

PubMed1995

Occupational outcome after temporal lobectomy for refractory epilepsy.

We evaluated employment after temporal lobectomy for refractory epilepsy in 86 patients (3.5 to 8 years of follow-up). Seventy-three patients qualified for the work force before and after surgery. Unemployment rates declined after surgery (18 patients [25%] unemployed before surgery, eight patients [11%] unemployed after surgery), and underemployment also tended to diminish. Improvement in occupational status related strongly to the degree of postoperative seizure relief. Seizure-free patients fared better (no unemployment, little underemployment) than patients with some seizure-free years and some years with seizures after surgery, whose high underemployment level persisted. Patients with seizures in each year after surgery fared worst (despite reduced seizure frequency), with increased unemployment after surgery. Age at surgery also influenced vocational outcome in patients who were unemployed before surgery. Historical, educational, cognitive, and behavioral measures did not correlate with vocational outcome. Employment gains came slowly; unemployed patients took up to 6 years to obtain work after surgery. Of 13 students at the time of surgery, 11 have graduated and nine are now employed. We conclude that seizures play a large role in limiting employment, and that by alleviating seizures, temporal lobectomy improves employability in people with refractory epilepsy. Surgery thereby provides benefit to individuals with epilepsy by increasing financial independence and to society by reducing unemployment.

Adult↗