Nine-year prospective efficacy and safety of brain-responsive neurostimulation for focal epilepsy

OBJECTIVE

To prospectively evaluate safety and efficacy of brain-responsive neurostimulation in adults with medically intractable focal onset seizures (FOS) over 9 years.

METHODS

Adults treated with brain-responsive neurostimulation in 2-year feasibility or randomized controlled trials were enrolled in a long-term prospective open label trial (LTT) to assess safety, efficacy, and quality of life (QOL) over an additional 7 years. Safety was assessed as adverse events (AEs), efficacy as median percent change in seizure frequency and responder rate, and QOL with the Quality of Life in Epilepsy (QOLIE-89) inventory.

RESULTS

Of 256 patients treated in the initial trials, 230 participated in the LTT. At 9 years, the median percent reduction in seizure frequency was 75% (p < 0.0001, Wilcoxon signed rank), responder rate was 73%, and 35% had a ≥90% reduction in seizure frequency. We found that 18.4% (47 of 256) experienced ≥1 year of seizure freedom, with 62% (29 of 47) seizure-free at the last follow-up and an average seizure-free period of 3.2 years (range 1.04-9.6 years). Overall QOL and epilepsy-targeted and cognitive domains of QOLIE-89 remained significantly improved (p < 0.05). There were no serious AEs related to stimulation, and the sudden unexplained death in epilepsy (SUDEP) rate was significantly lower than predefined comparators (p < 0.05, 1-tailed χ2).

CONCLUSIONS

Adjunctive brain-responsive neurostimulation provides significant and sustained reductions in the frequency of FOS with improved QOL. Stimulation was well tolerated; implantation-related AEs were typical of other neurostimulation devices; and SUDEP rates were low.

CLINICALTRIALSGOV IDENTIFIER

NCT00572195.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that brain-responsive neurostimulation significantly reduces focal seizures with acceptable safety over 9 years.

Evaluation of phenytoin serum levels following a loading dose in the acute hospital setting

PURPOSE

Due to the complex pharmacokinetic profiles of phenytoin (PHT) and fosphenytoin (FOS), achieving sustained, targeted serum PHT levels in the first day of use is challenging.

METHODS

A population based approach was used to analyze total serum PHT (tPHT) level within 2-24h of PHT/FOS loading with or without supplementary maintenance or additional loading doses among PHT-naïve patients in the acute hospital setting. Adequate tPHT serum level was defined as ≥20μg/mL.

RESULTS

Among 494 patients with 545 tPHT serum levels obtained in the first 2-24h after the loading dose (LD), tPHT serum levels of either

CONCLUSION

Close laboratory surveillance and PHT/FOS dose adjustments are recommended to ensure adequate and sustained tPHT serum levels early in treatment. Free serum PHT level is the preferred method of drug monitoring.

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Key Words

• Fosphenytoin
• Serum phenytoin level
• Status epilepticus

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MESH Headings

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Anticonvulsants/blood
• Anticonvulsants/therapeutic use
• Child
• Community Health Planning
• Epilepsy/blood
• Epilepsy/drug therapy
• Female
• Humans
• Male
• Middle Aged
• Phenytoin/blood
• Phenytoin/therapeutic use
• Retrospective Studies
• Statistics as Topic
• Young Adult

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Grants

• T32 ES007271 NIEHS NIH HHS
• TL1 TR002000 NCATS NIH HHS
• UL1 TR000042 NCATS NIH HHS
• UL1 TR002001 NCATS NIH HHS

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Depression but not seizure factors or quality of life predicts suicidality in epilepsy

The objective of this study was to determine prevalence and predictive risk factors of suicidality in a large sample of epilepsy outpatients. We prospectively examined 193 consecutive adult epilepsy outpatients for depression, including suicidal ideation. Demographic and epilepsy factors, medication toxicity and health-related quality of life were also evaluated. The prevalence of suicidal ideation within the past two weeks was 11.9%. Although medication toxicity, health-related quality of life and BDI scores were each associated with suicidal ideation in the bivariate analyses, only the BDI remained significant in the logistic regression analysis. About one-fourth of the subjects with suicidal ideation had no significant symptoms of depression. Recent thoughts of suicide are a common occurrence in the outpatient epilepsy clinic setting, but these are not predicted by gender, age, seizure factors, medication toxicity or self-perceived quality of life. Although depression is associated with suicidal ideation, about one-fourth of the suicidal subjects were euthymic or only mildly depressed.

Subjective perception of cognition is related to mood and not performance

OBJECTIVE

Clinicians monitor cognitive effects of drugs primarily by asking patients to describe their side effects. We examined the relationship of subjective perception of cognition to mood and objective cognitive performance in healthy volunteers and neurological patients.

METHODS

Three separate experiments used healthy adults treated with lamotrigine (LTG) and topiramate (TPM), adults with epilepsy on LTG or TPM, and patients with idiopathic Parkinson's disease. Correlations were calculated for change scores on and off drugs in the first two experiments and for the single assessment in Experiment 3.

RESULTS

Across all three experiments, significant correlations were more frequent (chi(2)=259, P < or = 0.000) for mood versus subjective cognitive perception (59%) compared with subjective versus objective cognition (2%) and mood versus objective cognitive performance (2%).

CONCLUSIONS

Subjective perception of cognitive effects is related more to mood than objective performance. Clinicians should be aware of this relationship when assessing patients' cognitive complaints.

Subtraction ictal single-photon emission computed tomography coregistered to magnetic resonance imaging in evaluating the need for repeated epilepsy surgery

Object

The aim of this study was to determine whether ictal single-photon emission computed tomography (SPECT) is useful in localizing the site of seizure onset in patients in whom surgery for intractable epilepsy failed and who are being considered for repeated surgery.

Methods

Subtraction ictal SPECT coregistered to magnetic resonance imaging (SISCOM) studies were retrospectively analyzed in 58 patients who were being evaluated for possible repeated resection for intractable partial epilepsy between January 1, 1996, and October 31, 1999. All patients had persistent seizures subsequent to an initial resection and underwent another excision. The SISCOM-demonstrated abnormalities were classified as concordant, discordant, or indeterminate, compared with the localization of the epileptogenic zone revealed on video electroencephalography monitoring. The ability of SISCOM to predict operative outcome was also determined in patients who had undergone repeated surgical procedures.

The SISCOM studies revealed a localized hyperperfused alteration in 46 (79%) of 58 patients. Forty-one (89%) of these 46 patients had a SISCOM-demonstrated alteration in the hemisphere of the previous epilepsy surgery. Imaging changes in 33 (72%) of the 46 patients were at the site of the previous focal cortical resection. Eight (17%) of the 46 had SISCOM-demonstrated abnormalities remote from the lobe in which surgery had been performed but in the ipsilateral hemisphere. The hyperperfusion focus was in the contralateral hemisphere in the remaining five patients (11%). The site of the epileptogenic zone was concordant with the SISCOM focus in 32 (70%) of 46 patients. Twenty-six patients underwent repeated resection and were followed up for a mean of 44 months thereafter; 11 of these patients (42%) had a significant reduction in seizure tendency. Only five patients (19%) were seizure free. Ten (50%) of 20 patients with a concordant SISCOM focus compared with none (0%) of three patients with a discordant focus had a favorable surgical outcome (p = 0.23).

Conclusions

The SISCOM method might be useful in the evaluation of, and the surgical planning for, patients with intractable partial epilepsy in whom previous resective treatment has failed and who are being considered for reoperation.

Cognitive and behavioral effects of lamotrigine and topiramate in healthy volunteers

BACKGROUND

The relative cognitive and behavioral effects of lamotrigine (LTG) and topiramate (TPM) are unclear.

METHODS

The authors directly compared the cognitive and behavioral effects of LTG and TPM in 47 healthy adults using a double-blind, randomized crossover design with two 12-week treatment periods. During each treatment condition, subjects were titrated to receive either LTG or TPM at a target dose of 300 mg/day for each. Neuropsychological evaluation included 17 measures yielding 41 variables of cognitive function and subjective behavioral effects. Subjects were tested at the end of each antiepileptic drug (AED) treatment period and during two drug-free conditions (pretreatment baseline and 1 month following final AED withdrawal).

RESULTS

Direct comparison of the two AEDs revealed significantly better performance on 33 (80%) variables for LTG, but none for TPM. Even after adjustment for blood levels, performance was better on 19 (46%) variables for LTG, but none for TPM. Differences spanned both objective cognitive and subjective behavioral measures. Comparison of TPM to the non-drug average revealed significantly better performance for non-drug average on 36 (88%) variables, but none for TPM. Comparison of LTG to non-drug average revealed better performance on 7 (17%) variables for non-drug average and 4 (10%) variables for LTG.

CONCLUSIONS

Lamotrigine produces significantly fewer untoward cognitive and behavioral effects compared to topiramate (TPM) at the dosages, titrations, and timeframes employed in this study. The dosages employed may not have been equivalent in efficacy. Future studies are needed to delineate the cognitive and behavioral effects of TPM at lower dosages.

Self-reported Seizure Frequency and Time to First Event in the Seizure Monitoring Unit

PURPOSE

To compare seizure frequency reported in the clinic with time to first diagnostic event during video-EEG monitoring. The effect of the artificial environment of the monitoring unit on self-reported seizure frequency was explored.

METHODS

The 155 consecutive patients were seen in the Washington University Epilepsy Center and subsequently underwent video-EEG monitoring during 2001. Of these, 112 had a diagnostic event during monitoring; 31 left without having a definite event; and 12 could not provide an estimate of seizure frequency in the clinic. The time to first event was compared with self-reported seizure frequency. The patients were then divided into three equal groups (tertiles) based on mean seizure frequency, and time to first seizure was compared between groups. Then the numbers of patients staying >7 days without ever having an event were compared between the low and high seizure-frequency groups. Finally, Kaplan-Meier survival curves were calculated.

RESULTS

No correlation was found between self-reported seizure rate and time to diagnostic event (r= 0.18; p = 0.06). Time to first event was 2.8 days in the low seizure-frequency group (mean, 2.2/month), 2.1 days in the medium (mean, 8.8/month), and 2.1 days in the high (mean, 24.1/month) groups, which were not significantly different (p = 0.19). Of patients in the low-frequency group, 79% had an event within 7 days.

CONCLUSIONS

In the artificial environment of the monitoring unit, self-reported outpatient seizure frequency is not an accurate predictor of duration of video-EEG monitoring required to make a definitive classification of clinical events and should not contribute to the decision as to whether to refer a patient for monitoring.

Correlation of Severity of FDG-PET Hypometabolism and Interictal Regional Delta Slowing in Temporal Lobe Epilepsy

PURPOSE

We investigated the association of severity of hypometabolism detected by positron emission tomography (PET) with [(18)F]fluorodeoxyglucose (FDG) and persistence of interictal EEG focal slowing in patients with refractory temporal lobe epilepsy.

METHODS

Eighty temporal lobes of 40 consecutive patients with intractable temporal lobe epilepsy (mean age, 43.5 years) were studied. All patients underwent video-EEG monitoring, magnetic resonance imaging (MRI), and FDG-PET. Patients with either normal MRI or with unilateral mesial temporal sclerosis, but no other structural abnormality, were included. Interictal EEG delta slowing was graded as none, infrequent (one episode or less/hour), intermediate (more than one episode/hour), or continuous. PET hypometabolism was graded as none, mild, moderate, or severe.

RESULTS

The severity of temporal lobe hypometabolism with PET was significantly correlated with the amount of delta activity in the interictal EEG, independent of MRI findings (Spearman r = 0.46; p < 0.0005).

CONCLUSIONS

This observation suggests related underlying pathophysiologic mechanisms for metabolic and electrical dysfunction in temporal lobe epilepsy.

Systematic screening allows reduction of adverse antiepileptic drug effects: a randomized trial

OBJECTIVE

To determine the effectiveness of systematic screening with a brief 19-item self-report instrument, the Adverse Events Profile (AEP), to reduce adverse effects of antiepileptic drugs (AEDs) and improve subjective health status.

METHODS

The authors performed a prospective randomized trial comparing the use of the AEP with usual care without the AEP. Sixty-two patients with an AEP score of >or=45 were enrolled from a consecutive group of 200 consenting adults with epilepsy.

RESULTS

The mean percent improvement in AEP scores was greater in the patient group for which clinicians received the AEP compared with the usual care group (25% vs 5%; p < 0.01). Mean change in Quality of Life in Epilepsy Inventory (QOLIE)-89 total scores was not different between groups, but for the entire sample QOLIE-89 change was greater for patients having a 15-point improvement in AEP scores than for those with a 0- to 15-point improvement or a worsened score (24 vs 12 vs 3; analysis of variance, p < 0.008). More patients in the AEP group had a >15-point improvement in QOLIE-89 score (p < 0.03). Use of the AEP was associated with a 2.8-fold increase (95% CI, 1.7 to 4.8) in AED modifications. No difference in seizure rates was observed.

CONCLUSIONS

Systematic screening for antiepileptic drug side effects may increase identification of toxicity and guide medication changes to reduce adverse effects and possibly improve subjective health status.

Selenium toxicity in sheep grazing reclaimed phosphate mining sites

Phosphate mining operations in southeastern Idaho have exposed selenium (Se) that was originally sequestered in the subsurface. Sheep grazing in these areas have died as a result of high Se concentrations in forage and water. This study was designed to monitor the health status of sheep grazing in a natural environment with known elevated levels of Se. A total of 72 Columbia x Suffolk sheep were divided into 3 treatment groups that included control (Con), low selenium (LoSe) and high selenium (HiSe). The baseline phase of the study was conducted in an area with normal background Se levels in forage and water, and was grazed for 3 w by all sheep groups. The sheep then were moved onto reclaimed mine areas to begin the 4-w exposure phase. This was followed by a 2-w depuration phase where sheep again received normal Se levels in forage and water. The Con group was held on areas with normal Se levels of forage (< 0.32 ppm Se dw) and water (< 1.70 ppb Se). The LoSe group was held in an area of elevated forage Se (< 13.0 ppm Se dw) and normal Se levels in their water (< 1.70 ppb Se) during the exposure phase. The HiSe group was held on mining areas with elevated Se forage (< 49.0 ppm Se dw) and drinking water (340 to 415 ppb Se). Whole blood and serum levels in the HiSe group peaked at 1.32 and 0.99 ppm mean Se, respectively. The LoSe group had mean whole blood and serum Se levels of 0.75 ppm on day 42 and 0.32 ppm on day 35 respectively. The Con group maintained low Se levels in both whole blood and serum that ranged from 0.05 to 0.14 ppm and 0.06 to 0.13 ppm respectively. The Se exposure in the HiSe group was estimated 0.26 mg Se/kg body weight/d. One sheep in the HiSe group died and was diagnosed with Se toxicosis based on clinical signs, histopathology and tissue Se levels. Se in liver (3.90 ppm), kidney (1.90 ppm) and skeletal muscle (0.70 ppm) were indicative of high to toxic Se exposure. Two other sheep necropsied after the exposure phase also had Se concentrations in liver, kidney and skeletal muscle representative of high or toxic Se exposure (5.50, 3.50 and 1.10 ppm Se), but these sheep had no gross or histopathological signs of illness. More research is needed on the toxicology of Se in sheep grazing natural settings.

The effects of remifentanil on epileptiform discharges during intraoperative electrocorticography in patients undergoing epilepsy surgery

PURPOSE

High-dose i.v. opioids (e.g., alfentanil, 50 microg/kg bolus) are known to increase the intraoperative reading of epileptiform activity during epilepsy surgery (ES), thereby facilitating localization of the epileptogenic zone (i.e., the site of ictal onset and initial seizure propagation). However, this phenomenon has not been studied with remifentanil (i.e., a novel ultra-short acting opioid). The purpose of the present study was to evaluate the effect of remifentanil on electrocorticography (ECoG) during ES.

METHODS

After Institutional Review Board approval, 25 adult patients undergoing elective ECoG-guided anterior temporal corticectomy were enrolled. At the time of ECoG, anesthesia consisted of inhaled isoflurane < or =0.1% (end-tidal) in 50% N2O, and i.v. fentanyl, 2 microg/kg/h and vecuronium. Patients were maintained at normocapnia and normoxia during ECoG. After acquisition of baseline ECoG, bolus remifentanil, 2.5 microg/kg i.v., was administered. The number of epileptiform spikes occurring 5 min before and after this bolus were compared by using a one-sided sign test; p values < or =0.05 were considered statistically significant.

RESULTS

When compared with baseline ECoG, bolus i.v. remifentanil significantly increased the frequency of single spikes or repetitive spike bursts in the epileptogenic zone while suppressing activity in surrounding normal brain.

CONCLUSIONS

During ES, remifentanil enhanced epileptiform activity during intraoperative ECoG. Such observations facilitate localization of the epileptogenic zone while minimizing resection of nonepileptogenic eloquent brain tissue. Although not specifically evaluated in this study, we speculate that remifentanil's short elimination half-life will facilitate neurologic function testing immediately after ES. Should this be the case, we envision remifentanil has the potential to supplant other opioids (e.g., alfentanil) during ECoG-guided ES.