Long-term association between seizure outcome and depression after resective epilepsy surgery.

OBJECTIVE: This study explored the association between long-term epilepsy surgery outcome and changes in depressive symptoms. METHODS: Adults were enrolled between 1996 and 2001 in a multicenter prospective study to evaluate outcomes of resective epilepsy surgery. The extent of depressive symptoms and depression case status (none, mild, or moderate/severe) were assessed using the Beck Depression Inventory (BDI) preoperatively and 3, 12, 24, 48, and 60 months postoperatively. A mixed-model repeated-measures analysis was performed, adjusting for covariates of seizure location, gender, age, race, education, and seizure control. RESULTS: Of the total 373 subjects, 256 were evaluated at baseline and 5 years after surgery. At baseline, 164 (64.1%) were not depressed, 34 (13.3%) were mildly depressed, and 58 (22.7%) had moderate to severe depression. After 5 years, 198 (77.3%) were not depressed, 20 (7.8%) were mildly depressed, and 38 (14.8%) were moderately to severely depressed. Five years after surgery, the reduction in mean change from baseline in BDI score was greater in subjects with excellent seizure control than in the fair and poor seizure control groups (p = 0.0006 and p = 0.02 respectively). Those with good seizure control had a greater reduction in BDI score than the poor seizure control group (p = 0.02) and borderline significant reduction compared with the fair seizure control group (p = 0.055). CONCLUSION: Although study participants had initial improvement in depressive symptoms, on average, after resective surgery, only patients with good or excellent seizure control had sustained long-term improvement in mood.

Zonisamide discontinuation due to psychiatric and cognitive adverse events: a case-control study.

OBJECTIVES: Zonisamide (ZNS) is an antiepileptic drug (AED) that has been associated with psychiatric adverse events (PAE) and cognitive adverse events (CAE); controlled studies evaluating these adverse events are limited. Our objectives were to 1) determine the incidence of PAE and CAE leading to the discontinuation of ZNS and 2) identify risk factors for PAE and CAE associated with the discontinuation of ZNS. METHODS: All patients exposed to ZNS at MINCEP Epilepsy Care between March 2000 and September 2008 were identified. Reasons for discontinuing ZNS were documented. Separate case-control studies were performed to identify risk factors associated with the discontinuation of ZNS due to PAE or CAE via multivariate binary logistic regression. RESULTS: A total of 544 patients were exposed to ZNS during the study period. PAE and CAE were the most frequently identified reasons for terminating ZNS therapy. The incidence of PAE severe enough to be associated with the discontinuation of ZNS was 6.9%; the incidence of CAE was 5.8%. Factors associated with termination of ZNS therapy due to PAE were past psychiatric history (p = 0.005), symptomatic generalized epilepsy (p = 0.027), and lower maximum ZNS serum concentration (mean = 17.9 mg/L vs 34.7 mg/L, p < 0.001). Independent variables associated with discontinuing ZNS due to CAE were greater number of concomitant AEDs (p = 0.011) and lower maximum ZNS serum concentration (mean = 16.6 mg/L vs 30.6 mg/L, p = 0.002). CONCLUSIONS: We have identified clinically relevant risk factors associated with the discontinuation of ZNS. Our findings support the concept that selected patients are relatively more vulnerable to CNS adverse events when exposed to ZNS.

Antiepileptic drug use and rates of hip bone loss in older men: a prospective study.

OBJECTIVE: To test the hypotheses that older community dwelling men taking non-enzyme-inducing antiepileptic drugs (NEIAEDs) and those taking enzyme-inducing antiepileptic drugs (EIAEDs) have increased rates of hip bone loss. METHODS: We ascertained antiepileptic drug (AED) use (interviewer-administered questionnaire with verification of use by containers) and measured hip bone mineral density (BMD) (using dual energy x-ray absorptiometry) at baseline and an average of 4.6 years later in a cohort of 4,222 older community-dwelling men enrolled in the Osteoporotic Fractures in Men study. Men were categorized as nonusers (no AED use at either examination, n = 4060), NEIAED user (use of NEIAED only at either examination, n = 100), or EIAED user (use of EIAED only at either examination, n = 62). RESULTS: After adjustment for multiple potential confounders (age, race, clinic site, health status, pain interfering with work or activity, physical activity, smoking status, alcohol use, total calcium intake, diabetes, chronic kidney disease, vitamin D supplement use, bisphosphonate use, selective serotonin reuptake inhibitor use, inability to rise from a chair, body mass index, and baseline BMD), the average rate of decline in total hip BMD was -0.35%/year among nonusers compared with -0.53%/year among NEIAED users (p = 0.04) and -0.46%/year among EIAED users (p = 0.31). Multivariable adjusted rate of loss was -0.60%/year among men taking NEIAED at both examinations, -0.51%/year among men taking NEIAED at one examination only, and -0.35%/year among nonusers (p for trend = 0.03). Findings were similar at hip subregions. CONCLUSION: Use of non-enzyme-inducing antiepileptic drugs was independently associated with increased rates of hip bone loss in this cohort of older community-dwelling men.

Worsening of quality of life after epilepsy surgery: effect of seizures and memory decline.

BACKGROUND: Surgery for intractable temporal lobe epilepsy usually controls seizures and improves health-related quality of life (HRQOL), but some patients experience continued seizures, memory decline, or both. The relative impact of these unfavorable outcomes on HRQOL has not been described. METHODS: We studied seizure control, memory change, and HRQOL among 138 patients in the Multicenter Study of Epilepsy Surgery (MSES), an ongoing, prospective study of epilepsy surgery outcomes. Seizure remission at 2 years and 5 years was prospectively determined based upon regularly scheduled follow-up calls to study patients throughout the follow-up period. HRQOL was assessed annually using the Quality of Life in Epilepsy Inventory (QOLIE-89). Memory decline was determined by change in verbal delayed recall from baseline to the 2- or 5-year follow-up. RESULTS: HRQOL improved in patients who were in remission at the 2-year or 5-year follow-up, regardless of memory outcome. Among those not in remission at both 2 and 5 years (25/138, 18%), HRQOL remained stable when memory did not decline (14/138, 10%), but HRQOL declined when memory did decline (11/138, 8%). These 11 patients had baseline characteristics predictive of poor seizure or memory outcome. Declines were most apparent on HRQOL subscales assessing memory, role limitations, and limitations in work, driving, and social activities. CONCLUSIONS: After temporal resection, health-related quality of life (HRQOL) improves or remains stable in seizure-free patients despite memory decline, but HRQOL declines when persistent seizures are accompanied by memory decline. These results may be useful in presurgical counseling and identifying patients at risk for poor psychosocial outcome following surgery.

Patient-perceived impact of resective epilepsy surgery.

OBJECTIVE: To evaluate the patient-perceived impact of resective epilepsy surgery, a key outcome to consider in evaluating such a highly invasive, elective procedure. METHODS: Impact measures obtained from 396 patients in a multicenter cohort study of resective epilepsy surgery included (1) willingness to undergo surgery if that decision could be made again and (2) the overall impact of surgery on the patient's life. Predictors of impact were analyzed using multivariate ordinal logistic regression. RESULTS: Of study participants, 73.8%, 77.4%, and 75.5% would definitely undergo surgery again and 78.2%, 80.2%, and 79.1% reported a very strong or strong positive overall impact of surgery at 3, 12, and 24 months. Multivariate ordinal logistic regression showed that seizure freedom predicted more positive perceptions at 3, 12, and 24 months (all p < 0.04). Becoming employed was uniquely associated with willingness to undergo surgery again and with overall impact at 24 months (all p < 0.05), but only a net 7% of the cohort improved their employment status. Right-sided resection (at 12 and 24 months, p < 0.005) and female gender (at 3 and 12 months, p = 0.006) were each positively associated with perceived overall impact. CONCLUSIONS: Most epilepsy surgery patients report a positive overall impact of the procedure on their lives and a high willingness to undergo surgery again if that choice could be made. Seizure-free individuals express consistently more positive perceptions of the procedure. Findings suggest that it is important to make early efforts to reintegrate epilepsy surgery patients into employment.

Development and evaluation of biocompatible films of polytetrafluoroethylene polymers holding lithium phthalocyanine crystals for their use in EPR oximetry.

Electron paramagnetic resonance (EPR) oximetry is a powerful technology that allows the monitoring of oxygenation in tissues. The measurement of tissue oxygenation can be achieved using lithium phthalocyanine (LiPc) crystals as oxygen reporters. In order to have biocompatibility for the sensing system and to assure long-term stability in the responsiveness of the system, we developed films of Teflon AF 2400 with embedded LiPc crystals. These systems can be used as retrievable inserts or parts of an implantable resonator or catheter. Atomic force microscopy studies revealed that the surface of the films was regular and planar. The response to oxygen of the sensor (EPR linewidth as a function of pO(2)) remained unchanged after implantation in mice, and was not affected by sterilization or irradiation. The use of resonators, holding LiPc embedded in Teflon AF 2400, implanted in the gastrocnemius muscle of rabbits allowed the monitoring of oxygen during several weeks. Several assays also demonstrated the biocompatibility of the system: (1) no hemolytic effect was noted; (2) no toxicity was found using the systemic injection test of extracts; (3) histological analysis in rabbit muscle in which the films were implanted for 1 week or 3 months was similar to standard polyethylene biocompatible devices. These advanced oxygen sensors are promising tools for future pre-clinical and clinical developments of EPR oximetry. These developments can be applied for other applications of biosensors where there is a need for oxygen permeable membranes.

Epidemiological and medical aspects of epilepsy in the elderly.

Both the incidence and prevalence of epilepsy are high among the elderly. Cerebrovascular disease is the most common underlying cause, although as many as 25-40% of new epilepsy cases in the elderly have no obvious underlying etiology. Status epilepticus appears to occur more frequently in individuals greater than 60 years, and the morbidity and mortality of status epilepticus are significantly greater in this age group. Elderly patients with seizures, particularly complex partial seizures, present differently than younger adults, which can lead to misdiagnosis. Post-ictal confusion may last as long as 1-2 weeks in an elderly patient, as opposed to minutes in younger individuals. Adverse events are similar in symptomatology, but are more common in elderly patients and occur at lower doses and plasma drug concentrations. Neuropsychiatric disorders, such as depression and anxiety, are common in elderly patients with epilepsy, although often under-diagnosed and inadequately treated. The risk of osteoporosis is high among elderly women taking antiepileptic drugs, which underscores the importance of assessing bone health and treatment in this group. Management of the older patient with epilepsy requires an understanding of the etiologies and the medical and psychological aspects unique to this age group.

Changes in depression and anxiety after resective surgery for epilepsy.

OBJECTIVE: To determine changes in depression and anxiety after resective surgery. METHODS: Data from subjects enrolled in a prospective multicenter study of resective epilepsy surgery were reviewed with the Beck Psychiatric Symptoms Scales (Beck Depression Inventory [BDI] and Beck Anxiety Inventory [BAI]) and Composite International Diagnostic Interview (CIDI) up to a 24-month period. chi2 analyses were used to correlate proportions. RESULTS: A total of 358 presurgical BDI and 360 BAI results were reviewed. Moderate and severe levels of depression were reported in 22.1% of patients, and similar levels of anxiety were reported by 24.7%. Postoperative rates of depression and anxiety declined at the 3-, 12-, and 24-month follow-up periods. At the 24-month follow-up, moderate to severe levels of depression symptoms were reported in 17.6 and 14.7% of the patients who continued to have postoperative seizures. Moderate to severe depression and anxiety were found in 8.2% of those who were seizure-free. There was no relationship, prior to surgery, between the presence or absence of depression and anxiety and the laterality or location of the seizure onset. There were no significant relationships between depression or anxiety at 24-month follow-up and the laterality or location of the surgery. CONCLUSIONS: Depression and anxiety in patients with refractory epilepsy significantly improve after epilepsy surgery, especially in those who are seizure-free. Neither the lateralization nor the localization of the seizure focus or surgery was associated with the risk of affective symptoms at baseline or after surgery.

EPR spectrometer for clinical applications.

This article describes an EPR spectrometer specifically designed and constructed for EPR spectroscopy in humans. The spectrometer is based on a permanent magnet, suitable for measurements at 1200 MHz. The magnet has a full 50 cm gap between the poles, which facilitates accurate and comfortable placement of the subject for the EPR measurement at any location on the human body. The bridge includes features to facilitate clinical operations, including an indicator for phasing of the reference arm and a 2 level RF amplifier. Resonators with holders for each type and site of measurement have been developed that comfortably position the resonator and the patient and prevent artifacts due to motion. The initial applications for which the spectrometer has been designed are for oximetry using loops on the surface, oximetry using implanted resonators for measuring deep sites, and measurements in the teeth for determination of exposures to clinically significant doses of ionizing radiation.

Predicting long-term seizure outcome after resective epilepsy surgery: the multicenter study.

BACKGROUND: In a seven-center prospective observational study of resective epilepsy surgery, the authors examined probability and predictors of entering 2-year remission and the risk of subsequent relapse. METHODS: Patients aged 12 years and over were enrolled at time of referral for epilepsy surgery, and underwent standardized evaluation, treatment, and follow-up procedures. The authors defined seizure remission as 2 years completely seizure-free after hospital discharge with or without auras, and relapse as any seizures after 2-year remission. The authors examined type of surgery, seizure, clinical and demographic variables, and localization study results with respect to prediction of seizure remission or relapse, using chi2 and proportional hazards analysis. RESULTS: Of 396 operated patients, 339 were followed over 2 years, and 223 (66%) experienced 2-year remission, not significantly different between medial temporal (68%) and neocortical (50%) resections. In multivariable models, only absence of generalized tonic-clonic seizures and presence of hippocampal atrophy were significantly and independently associated with remission, and only in the medial temporal resection group. Fifty-five patients relapsed after 2-year remission, again not significantly different between medial temporal (25%) and neocortical (19%) resections. Only delay to remission predicted relapse, and only in medial temporal patients. CONCLUSION: Hippocampal atrophy and a history of absence of generalized tonic clonic seizures were the sole predictors of 2-year remission, and only for medial temporal resections.

Antiepileptic drug use increases rates of bone loss in older women: a prospective study.

OBJECTIVE: To test the hypothesis that older women with antiepileptic drug (AED) use have increased rates of bone loss. METHODS: AED use was ascertained and calcaneal and hip bone mineral density (BMD) measured in a cohort of 9,704 elderly community-dwelling women enrolled in the Study of Osteoporotic Fractures, and they were followed prospectively for changes in BMD. Current use of AED was assessed by interview, with verification of use from medication containers at baseline and follow-up examinations. Women were classified as continuous users, partial (intermittent) users, or nonusers. Rates of change in BMD were measured at the total hip and two subregions (average 4.4 years between examinations) and at the calcaneus (average 5.7 years between examinations). RESULTS: After adjustment for confounders, the average rate of decline in total hip BMD steadily increased from -0.70%/year in nonusers to -0.87%/year in partial AED users to -1.16%/year in continuous AED users (p value for trend = 0.015). Higher rates of bone loss were also observed among continuous AED users at subregions of the hip and at the calcaneus. In particular, continuous phenytoin users had an adjusted 1.8-fold greater mean rate of loss at the calcaneus compared with nonusers of AED (-2.68 vs -1.46%/year; p < 0.001) and an adjusted 1.7-fold greater mean rate of loss at the total hip compared with nonusers of AED (-1.16 vs -0.70%/year; p = 0.069). CONCLUSIONS: Continuous AED use in elderly women is associated with increased rates of bone loss at the calcaneus and hip. If unabated, the rate of hip bone loss among continuous AED users is sufficient to increase the risk of hip fracture by 29% over 5 years among women age 65 years and older.

Initial outcomes in the Multicenter Study of Epilepsy Surgery.

OBJECTIVE: To obtain prospective data regarding seizures, anxiety, depression, and quality of life (QOL) outcomes after resective epilepsy surgery. METHODS: The authors characterized resective epilepsy surgery patients prospectively at yearly intervals for seizure outcome, QOL, anxiety, and depression, using standardized instruments and patient interviews. RESULTS: Of 396 patients who underwent resective surgical procedures, 355 were followed for at least 1 year. Of these, 75% achieved a 1-year remission at some time during follow-up; patients with medial temporal (77%) were more likely than neocortical resections (56%) to achieve remission (p = 0.01). Relapse occurred in 59 (22%) patients who remitted, more often in medial temporal (24%) than neocortical (4%) resected patients (p = 0.02). QOL, anxiety, and depression all improved dramatically within 3 months after surgery (p < 0.0001), with no significant difference based on seizure outcome. After 3 months, QOL in seizure-free patients further improved gradually, and patients with seizures showed gradual declines. By 12 and 24 months, overall QOL and its epilepsy-targeted and physical health domains were significantly different in the two outcome groups. (Anxiety and depression scores also gradually diverged, with improvements in seizure-free and declines in continued seizure groups, but differences were not significant.) CONCLUSION: Resective surgery for treatment of epilepsy significantly reduces seizures, most strikingly after medial temporal resection (77% 1 year remission) compared to neocortical resection (56% 1 year remission). Resective epilepsy surgery has a gradual but lasting effect on QOL, but minimal effects on anxiety and depression. Longer follow-up will be essential to determine ultimate seizure, QOL, and psychiatric outcomes of epilepsy surgery.

Discontinuation of levetiracetam because of behavioral side effects: a case-control study.

BACKGROUND: Levetiracetam (LEV) is a recently approved anticonvulsant with proven efficacy and safety in the treatment of partial seizures. LEV may cause behavioral abnormalities that can be severe and require discontinuation of this drug. Risk factors for discontinuing LEV have not been established. OBJECTIVE: To determine incidence of behavioral abnormalities severe enough to require discontinuation of LEV and identify risk factors for such behavioral abnormalities. METHODS: All patients treated with LEV at MINCEP between January 2000 and February 2002 constituted the study population (n = 553). Patients who had discontinued LEV for behavioral reasons were selected as index cases. Case controls were patients starting LEV immediately after the index case. Potential risk factors for LEV discontinuation included age, gender, cognitive function, history of psychiatric diagnosis, epilepsy syndrome, number of antiepileptic drugs, titration rate, maximum dose of LEV, and LEV level at maximum dose. RESULTS: Thirty-eight patients (6.9%) discontinued LEV because of behavioral abnormalities. Variables associated with LEV discontinuation included faster titration rate to maximal dose, history of a psychiatric disorder, and diagnosis of symptomatic generalized epilepsy. Patients who discontinued LEV owing to behavioral reasons had significantly lower maximum LEV doses than controls. CONCLUSIONS: This study identified variables associated with discontinuation of LEV due to behavioral abnormalities. Slower titration of LEV should be considered in those patients at higher risk of discontinuing LEV for behavioral reasons.

How long does it take for partial epilepsy to become intractable?

BACKGROUND: Much remains unknown about the natural history of intractable localization-related epilepsy, including how long it typically takes before intractability becomes evident. This information could guide the design of future studies, resolve certain discrepancies in the literature, and provide more accurate information about long-term prognosis. METHODS: Individuals evaluated for resective surgery for refractory localization-related epilepsy were prospectively identified at the time of initial surgical evaluation at seven surgical centers (between 1996 and 2001). The latency time between onset of epilepsy and failure of second medication and history of remission (>/=1 year seizure-free) before surgical evaluation were examined with respect to age at onset, hippocampal atrophy, febrile seizures, and surgical site. RESULTS: In the 333 patients included in the analysis, latency time was 9.1 years (range 0 to 48) and 26% reported a prior remission before surgery. A prior remission of >/=5 years was reported by 8.5% of study participants. Younger age at onset was strongly associated with longer latency time (p < 0.0001) and higher probability of past remission (p < 0.0001). In multivariable analyses, age at onset remained as the most important explanatory variable of both latency time and prior remission. CONCLUSIONS: A substantial proportion of localization-related epilepsy may not become clearly intractable for many years after onset. This is especially true of epilepsy of childhood and early adolescent onset. If prospective studies confirm these findings and the underlying mechanisms behind these associations become understood, this raises the possibility of considering interventions that might interrupt such a process and some day prevent some forms of epilepsy from becoming intractable.

Distribution of partial seizures during the sleep--wake cycle: differences by seizure onset site.

OBJECTIVE: To evaluate the effects of sleep on partial seizures arising from various brain regions. METHODS: The authors prospectively studied 133 patients with localization-related epilepsy undergoing video-EEG monitoring over a 2-year period. Seizure type, site of onset, sleep/wake state at onset, duration, and epilepsy syndrome diagnosis were recorded. Periorbital, chin EMG, and scalp/sphenoidal electrodes were used. A subset of 34 patients underwent all-night polysomnography with scoring of sleep stages. RESULTS: The authors analyzed 613 seizures in 133 patients. Forty-three percent (264 of 613) of all partial seizures began during sleep. Sleep seizures began during stages 1 (23%) and 2 (68%) but were rare in slow-wave sleep; no seizures occurred during REM sleep. Temporal lobe complex partial seizures were more likely to secondarily generalize during sleep (31%) than during wakefulness (15%), but frontal lobe seizures were less likely to secondarily generalize during sleep (10% versus 26%; p < 0.005). CONCLUSIONS: Partial-onset seizures occur frequently during NREM sleep, especially stage 2 sleep. Frontal lobe seizures are most likely to occur during sleep. Patients with temporal lobe seizures have intermediate sleep seizure rates, and patients with seizures arising from the occipital or parietal lobes have rare sleep-onset seizures. Sleep, particularly stage 2 sleep, promotes secondary generalization of temporal and occipitoparietal, but not frontal, seizures. These findings suggest that the hypersynchrony of sleep facilitates both initiation and propagation of partial seizures, and that effects of sleep depend in part on the location of the epileptic focus.

Incidence and risk factors in sudden unexpected death in epilepsy: a prospective cohort study.

OBJECTIVE: To determine incidence of and risk factors for sudden unexpected death in epilepsy (SUDEP). METHODS: Three epilepsy centers enrolled 4,578 patients and prospectively followed these patients for 16,463 patient-years. The cohort was screened for death annually. Deaths were investigated to determine whether SUDEP occurred. Potential risk factors were compared in SUDEP cases and in controls enrolled contemporaneously at the same center. RESULTS: Incidence of SUDEP was 1.21/1,000 patient-years and was higher among women (1.45/1,000) than men (0.98/1,000). SUDEP accounted for 18% of all deaths. Occurrence of tonic-clonic seizures, treatment with more than two anticonvulsant medications, and full-scale IQ less than 70 were independent risk factors for SUDEP. The number of tonic-clonic seizures was a risk factor only in women. The presence of cerebral structural lesions and use of psychotropic drugs at the last visit were not risk factors for SUDEP in this cohort. Subtherapeutic anticonvulsant levels at the last visit were equally common in the two groups. No particular anticonvulsant appeared to be associated with SUDEP. CONCLUSIONS: These results support the idea that tonic-clonic seizures are an important proximate cause of SUDEP. This information creates a risk profile for SUDEP that may help direct preventative efforts.

In vivo EPR dosimetry of accidental exposures to radiation: experimental results indicating the feasibility of practical use in human subjects.

Low frequency electron paramagnetic resonance (EPR) provides the potential advantage of making accurate and sensitive measurements of absorbed radiation dose in teeth in situ, i.e. without removing the teeth from the potential victim. The potential limiting factors for making such measurements are: (1) whether low frequency EPR is sufficiently sensitive to detect radiation-induced signal in human teeth; (2) whether sufficient sensitivity can be maintained under in vivo conditions. In this manuscript, we summarize results indicating that this approach is feasible. Using 1.2 GHz EPR spectroscopy, we found that the lower limit for these measurements in isolated human teeth is 0.2 Gy or lower. Measurements of radiation-induced EPR signals in the teeth of living rats were achieved with sufficient sensitivity to indicate that, when taking into consideration the larger mass of human teeth, similar measurements in human teeth in situ would provide sensitivity in the dose range for potential accidental exposures. We estimate that the current lower limit for detecting radiation doses in human teeth in situ (in vivo) is 0.5-1.0 Gy; this would be sufficient for determining if a person has been exposed to potentially life threatening doses of ionizing radiation. The limiting factor for sensitivity appears to be background signals rather than signal/noise, and there are feasible means to overcome this problem and further increase sensitivity. The additional instrumental developments required to make an effective in vivo EPR dosimetric spectrometer for the measurements in teeth in human subjects in situ, seem quite achievable.

Relationships between seizure severity and health-related quality of life in refractory localization-related epilepsy.

PURPOSE: To evaluate relationships between self-report measures of seizure severity and health-related quality of life (HRQOL) in people with refractory localization-related epilepsy. METHODS: A sample of 340 adults enrolled in a seven-center, prospective study of resective epilepsy surgery completed baseline questionnaires that included the Quality of Life in Epilepsy (QOLIE)-89 and a seven-item adaptation of the National Hospital Seizure Severity Scale. Associations between QOLIE-89 summary measures and both the total seizure severity scale score and individual seizure severity items were assessed, after adjustment for seizure frequency. RESULTS: The seizure severity measure had adequate scale score variability and reliability in this sample. Correlations between individual items in the scale did not exceed 0. 43. Product-moment partial correlations between the seizure severity scale and QOLIE-89 summary measures ranged from -0.17 to -0.29 (all p values <0.01). Of the seven seizure severity items, the average time before individuals perceived they were "really back to normal" after their seizures was broadly related to all domains of HRQOL (r values ranged from -0.16 to -0.30; p values <0.01). Severity of injury during seizures was the only other item having more than minimal associations with HRQOL, and it was selectively related to the physical health measure. Higher frequency of falls during seizures was modestly related to less employment. CONCLUSIONS: This seizure severity measure assesses constructs that are generally distinct from HRQOL, except for moderate and broad associations between HRQOL and patient's perceptions of the average duration of recovery time after seizures. Recovery time may potentially be a useful clinical indicator of seizure severity that reflects meaningful impairment of HRQOL in adults with frequent seizures.

Kinetics of chromium(V) formation and reduction in fronds of the duckweed Spirodela polyrhiza--a low frequency EPR study.

The uptake of chromate by the duckweed Spirodela polyrhiza was investigated with atomic absorption spectroscopy and the reduction of Cr(VI) to Cr(V) was measured using low frequency EPR spectroscopy. The biphasic kinetics of the uptake was fitted to parameters of a proposed kinetic model. Another model was developed to simulate chromate reduction. The first step of chromate reduction was found to be much faster than the uptake of Cr(VI) from the free space. Most probably, this step occurs already in the cell wall or on the cell membrane surface. Further reduction of Cr(V) to Cr(III) was estimated to be slower. The disappearance of the Cr(V) signal, following transfer of the plants into a Cr-free solution, lasted several tens of hours; the kinetics was mono- or biexponential depending on the length of Cr loading. The rate constants for Cr reduction in living plants were determined for the first time.