Should levetiracetam replace phenytoin for seizure prophylaxis after neurosurgery?

Efficacy and Tolerability of Levetiracetam versus Phenytoin after Supratentorial Neurosurgery. Milligan TA, Hurwitz S, Bromfield EB. Neurology 2008;71(9):665–669. BACKGROUND: Antiepileptic drugs are routinely given after craniotomy. Though phenytoin (PHT) is still the most commonly used agent, levetiracetam (LEV) is increasingly administered for this purpose. This retrospective study compared the use of LEV and PHT as monotherapy prophylaxis following supratentorial neurosurgery. METHODS: Patients receiving LEV monotherapy after supratentorial craniotomy were reviewed and compared to a control group of patients receiving PHT monotherapy. RESULTS: One of 105 patients taking LEV and 9/210 patients taking PHT had seizures within 7 days of surgery ( p = 0.17). Adverse drug reactions requiring change in therapy during hospitalization occurred in 1/105 patients taking LEV and 38/210 patients taking PHT ( p < 0.001). Among patients followed for at least 12 months, 11/42 (26%) treated with LEV vs 42/117 (36%) treated with PHT developed epilepsy ( p = 0.34); 64% remained on LEV, while 26% remained on PHT ( p = 0.03). CONCLUSIONS: Both levetiracetam (LEV) and phenytoin (PHT) were associated with a low risk of early postoperative seizures and a moderate risk of later epilepsy. LEV was associated with significantly fewer early adverse reactions than PHT and with a higher retention rate in patients who were followed for at least 1 year and developed epilepsy.

Choosing among antiepileptic drugs

Selecting an antiepileptic drug (AED) for treatment of seizures is daunting because there are now 20 from which to choose. Following simple principles allows a systematic approach to drug selection. Efficacy studies provide limited information. For initial monotherapy of partial seizures, high-level evidence exists for the efficacy of lamotrigine, carbamazepine, oxcarbazepine, and topiramate. For initial monotherapy of generalized seizures, high-level evidence is available for valproate, lamotrigine, topiramate, and oxcarbazepine. For initial monotherapy of absence seizures, high-level evidence exists for valproate, lamotrigine, and ethosaximide. All second-generation AEDs have efficacy as adjunctive therapy for partial seizures. AEDs are often useful for comorbid conditions or have properties that should be avoided in some groups. Thus, AEDs should usually be selected on the basis of comorbid conditions, including depression, migraine, chronic pain, obesity, and nephrolithiasis, or patient characteristics, especially for women of childbearing potential and older adults.

A frontal assault on the generalized nature of juvenile myoclonic epilepsy

Frontal Cognitive Dysfunction in Juvenile Myoclonic Epilepsy. Piazzini A, Turner K, Vignoli A, Canger R, Canevini M P. Epilepsia 2008;49(4):657–662. PURPOSE: The aim of the present study was to investigate the possible frontal cognitive dysfunction in patients with juvenile myoclonic epilepsy (JME) and to compare the results with those of patients with frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE), as well as with controls. METHODS: A total of 50 patients with JME, 40 patients with FLE, 40 patients with TLE, and 40 normal controls, all matched for age, education, and IQ, were administered tests to assess frontal functions (the Word Fluency Test and the Wisconsin Card Sorting Test [WCST]). All participants had a normal intelligence level based on the Wechsler Adult Intelligence Scale, and did not take medications other than antiepileptics (AEDs) or have a psychiatric history. RESULTS: Patients with JME had severe impairment in all administered tasks, similar to that of patients with FLE; TLE patients and controls followed in order. Multiple regression analysis did not disclose any significant effect of clinical variables on the cognitive deficits. DISCUSSION: These results clearly suggest that JME patients can show some frontal dysfunction, which may affect both epileptogenic features and cognitive processes. Further studies are needed to confirm these findings.

Intravenous lacosamide as replacement for oral lacosamide in patients with partial-onset seizures

PURPOSE

This multicenter, double-blind, double-dummy, randomized, inpatient trial evaluated the safety, tolerability, and pharmacokinetics of intravenous lacosamide as replacement for oral lacosamide in patients with partial-onset seizures.

METHODS

Patients were enrolled from an ongoing open-label extension trial of oral lacosamide and randomized (2:1) to either intravenous lacosamide and oral placebo or intravenous placebo and oral lacosamide. During the 2-day inpatient treatment period, patients received twice-daily doses of lacosamide equivalent to their current daily dose of oral lacosamide. The first 30 patients enrolled received infusions with 60-min durations and the next 30 received infusions with 30-min durations.

RESULTS

Of 60 patients randomized, 59 completed the trial. Treatment-emergent adverse events (AEs) were reported by 16 patients and included dizziness, headache, back pain, somnolence, and injection site pain. The tolerability profile of intravenous lacosamide was consistent with that of oral lacosamide. All AEs were considered mild or moderate in intensity, and no serious AEs or AEs leading to withdrawal were reported.

CONCLUSIONS

Intravenous lacosamide, administered as 60- or 30-min twice-daily infusions, showed a similar safety and tolerability profile to oral lacosamide when used as replacement therapy. Results from this trial support further investigation of intravenous lacosamide at shorter infusion durations.

Evidence for functional impairment but not structural disease in benign rolandic epilepsy

Is Rolandic Epilepsy Associated with Abnormal Findings on Cranial MRI? Boxerman JL, Hawash K, Bali B, Clarke T, Rogg J, Pal DK. Epilepsy Res. 2007;75( 2 – 3 ):180–185. Rolandic epilepsy (RE) is designated an idiopathic epilepsy syndrome, and hence no lesional abnormalities are expected on MRI exam. Recent reports suggest that MRI abnormalities are not only common, but may be specific for temporal lobe epilepsy, and lateralized to the side of EEG discharges. However, no controlled study has been performed to test the hypothesis of association between MRI abnormalities and Rolandic epilepsy. We performed an unmatched case-control study to test the hypothesis of association between MRI abnormalities and Rolandic epilepsy, using 25 typical RE cases and 25 children with migraine. Two independent examiners rated the MRIs for abnormalities. Examiners were blinded to the study hypothesis and identity of case and control exams. Fifty-two percent of RE exams contained at least one abnormality: peri/hippocampal abnormality (one case), non-localized congenital malformation (seven cases), subcortical parenchymal hyperintensities (two cases), periventricular parenchymal hyperintensities (one case), dilated perivascular spaces (six cases). There was no difference between the number or type of abnormalities in cases and controls. No type of abnormality lateralized to the hemisphere from which the EEG spikes emanated. The odds ratio of association between MRI abnormalities and RE was 0.87, 95% CI: 0.18–4.33 after adjusting for potential demographic and technical factors. We conclude that routine cranial MRI abnormalities are common in RE, but no more common than in controls, and not specific for RE.

Memory and Phonological Awareness in Children with Benign Rolandic Epilepsy Compared to a Matched Control Group. Northcott E, Connolly AM, Berroya A, McIntyre J, Christie J, Taylor A, Bleasel AF, Lawson JA, Bye AM. Epilepsy Res. 2007;75(1):57–62.

Purpose

In a previous study we demonstrated children with Benign Rolandic Epilepsy have normal intelligence and language ability. However, difficulties in verbal and visual memory and aspects of phonological awareness were found compared to normative data. To address the methodological limitations related to the use of normative data, we compared the same cohort of children with Benign Rolandic Epilepsy to a matched control group.

Method

Controls ( n = 40) matched on age and gender to the Benign Rolandic Epilepsy cohort underwent neuropsychological assessment. The life functioning of the control group was assessed using a modified version of the Quality of Life in Childhood Epilepsy Questionnaire (QOLCE).

Results

The study confirmed the previous findings of memory and phonological awareness difficulties. In addition, the children with Benign Rolandic Epilepsy had significantly lower IQ scores than the matched control group. Paired sample t-tests showed that on 8 of 11 QOLCE scales, children with Benign Rolandic Epilepsy were rated by parents as having poorer life functioning compared to matched controls, including lower parental ratings on the subscales of memory and language.

Discussion

Benign Rolandic Epilepsy has an excellent seizure prognosis, but this study further emphasizes potential cognitive difficulties. Using an age and gender matched control group, the previous findings of memory and phonological awareness difficulties were validated. These problems in cognition were also identified by parents of children with Benign Rolandic Epilepsy as problematic and impacting upon the child's quality of life.

Transcranial magnetic stimulation and sleep deprivation as experimental tools: when sleep deprivation is too exciting

Sleep Deprivation Increases Cortical Excitability in Epilepsy: Syndrome-Specific Effects. Badawy RA, Curatolo JM, Newton M, Berkovic SF, Macdonell RA. Neurology 2006;67(6):1018–1022. OBJECTIVE: To use transcranial magnetic stimulation (TMS) to investigate the hypothesis that sleep deprivation increases cortical excitability in people with epilepsy. METHODS: We performed paired pulse TMS stimulation, using a number of interstimulus intervals (ISIs) on each hemisphere of 30 patients with untreated newly diagnosed epilepsy (15 idiopathic generalized epilepsy [IGE] and 15 focal epilepsy) and on the dominant hemisphere of 13 healthy control subjects, before and after sleep deprivation. RESULTS: Both hemispheres in patients with IGE and the hemisphere ipsilateral to the EEG seizure focus in those with focal epilepsy showed an increase in cortical excitability following sleep deprivation at a number of ISIs. This change in excitability was most prominent in the patients with IGE. Although there were minor changes after sleep deprivation in control subjects and the contralateral hemisphere in the focal epilepsy group seen at the 250-millisecond ISI, it was less than that in the other groups. CONCLUSIONS: Sleep deprivation increases cortical excitability in epilepsy; the pattern of change is syndrome dependent.

Effects of Sleep Deprivation on Cortical Excitability in Patients Affected by Juvenile Myoclonic Epilepsy: A Combined Transcranial Magnetic Stimulation and EEG Study. Manganotti P, Bongiovanni LG, Fuggetta G, Zanette G, Fiaschi A. J Neurol Neurosurg Psychiatry 2006;77(1):56–60. OBJECTIVE: To investigate the effect of sleep deprivation on corticospinal excitability in patients affected by juvenile myoclonic epilepsy (JME) using different transcranial magnetic stimulation (TMS) parameters. METHODS: Ten patients with JME and 10 normal subjects underwent partial sleep deprivation. Motor threshold (MT), motor evoked potential amplitude (MEP), and silent period (SP) were recorded from the thenar eminence (TE) muscles. Short latency intracortical inhibition (SICI) and short latency intracortical facilitation (SICF) were studied using paired magnetic stimulation. TMS was performed before and after sleep deprivation; EEG and TMS were performed simultaneously. RESULTS: In patients with JME, sleep deprivation induced a significant decrease in SICI and an increase in SICF, which was associated with increased paroxysmal activity. A significant decrease in the MT was observed. No significant changes in any TMS parameters were noted in normal subjects after sleep deprivation. The F wave was unchanged by sleep deprivation in both control subjects and in patients with JME. CONCLUSIONS: In patients with JME, sleep deprivation produces increases in corticospinal excitability in motor areas as measured by different TMS parameters.

Prospective assessment of levetiracetam pharmacokinetics during dose escalation in 4- to 12-year-old children with partial-onset seizures on concomitant carbamazepine or valproate

PURPOSE

To assess the multiple-dose pharmacokinetics of levetiracetam and its major metabolite ucb L057 in children with partial-onset seizures and determine whether it is affected by adjunctive carbamazepine or valproate. To correlate levetiracetam concentrations in plasma and saliva and to assess its safety and clinical response.

METHODS

Design was an open-label, multicenter study. Twenty-one children (4-12 years old) with epilepsy taking carbamazepine (13) or valproate (8) received adjunctive levetiracetam. Levetiracetam was initiated at 20 mg/(kg day) and titrated at 2-week intervals to 40 and then 60 mg/(kg day). Twelve-hour pharmacokinetics were determined at the end of each 2-week period. Efficacy was estimated from the partial seizure frequency per week and Global Evaluation Scale.

RESULTS

Levetiracetam was rapidly absorbed following oral dosing, with median t(max) of 0.5 h. Dose proportional increases were observed for C(max) and AUC((0-12)) over the dose range; t(1/2) was 4.9 h. Pharmacokinetics of levetiracetam and ucb L057 were not markedly different with concomitant carbamazepine or valproate; clearance was only 7-13% faster and AUC was decreased by only 15-24% in those on carbamazepine compared to valproate. Levetiracetam did not affect trough carbamazepine or valproate. Concentration in saliva and plasma were strongly correlated. Seizure frequency declined by 50% or more in 43% of subjects in the intent-to-treat population (n=21) and in 56% of those with seizures at baseline (n=16). Marked or moderate improvement occurred in 80% and 75% of patients based on Global Evaluation Scale ratings by investigators and parents/guardians, respectively. Levetiracetam was well tolerated.

CONCLUSION

Levetiracetam exhibits simple pharmacokinetics in children, with rapid absorption and dose-proportional kinetics. Small but not clinically relevant differences were observed between subjects receiving carbamazepine and valproate, suggesting significant dose adjustment is usually not necessary. This substantiates prior assessments that levetiracetam clearance is higher in children than adults, necessitating a higher dose in children on a mg/kg basis, and suggests it is useful add-on therapy for children with partial-onset seizures regardless of baseline therapy.

EEG Is an Essential Clinical Tool: Pro and Con

The authors debate whether routine EEG is an essential clinical tool for evaluation of a first seizure. One author suggests that because of the positive predictive value of interictal spikes for seizure recurrence, the EEG is a useful tool. The other author argues that since many clinicians would not treat after a single seizure, even if the EEG were abnormal, the EEG is not essential. Both authors agree that the EEG should only be ordered with forethought to answer a specific question.

Epilepsy in Football Players and Other Land-based Contact or Collision Sport Athletes

We discuss the impact of epilepsy on the lives of athletes involved in contact sports. Recommendations for epilepsy patients with regard to contact sports have changed over the years from avoidance to encouragement. It is conceivable that exercise could exacerbate seizures either directly, through hyperventilation, or indirectly by alteration of anticonvulsant levels. Seizures could also be injurious in contact sports, and recurrent minor head trauma could worsen epilepsy. However, evidence to the contrary abounds and very few case reports support these notions. Exercise benefits individuals with epilepsy in many ways including improved seizure control, mood, and quality of life. We suggest that athletes with epilepsy be evaluated on an individual basis, and follow sensible guidelines while participating in contact sports. There is no significant evidence to suggest that contact sports are harmful to athletes with epilepsy; however, common sense rules still apply.

Assessment of acute morbidity and mortality in nonconvulsive status epilepticus

OBJECTIVE

S: The natural history of nonconvulsive status epilepticus (NCSE) is not well defined, especially mortality and morbidity. The authors hypothesized that the mortality of NCSE is higher when NCSE is due to acute medical causes (systemic or neurologic) or associated with severe impairment of mental status or with acute complications, and lower when associated with generalized spike-wave (SW) discharges on EEG.

METHODS

The authors retrospectively identified 100 consecutive patients with NCSE from an EEG database. Data were collected from systematic review of medical records and actual EEG tracings. Specific etiologies were divided into three groups: acute medical, epilepsy, and cryptogenic.

RESULTS

Of the 100 patients, 18 died. Fourteen of 52 patients in the acute medical group died, 1 of 31 in the epilepsy group died, and 3 of 17 in the cryptogenic group died. Mental status impairment was severe in 33, complications occurred in 39, and generalized SW discharges occurred in 36. Mortality rates were higher in patients 1) in the acute medical group (27%) vs the epilepsy (3%) and the cryptogenic (18%) groups (p < 0.02), 2) with severe mental status impairment (39%) compared to those with mild impairment (7%, p < 0.001), and 3) with acute complications (36%) when compared with those without complications (7%, p < 0.0002). The presence of generalized SW discharges on EEG did not correlate with mortality. Mental status impairment and etiology were independently associated with mortality (p < 0.001).

CONCLUSION

NCSE is associated with substantial mortality. Mortality is associated with an acute medical cause as the underlying etiology, severe mental status impairment, and development of acute complications, but not the type of EEG discharge.

Epilepsy

Seizures are common and are treated in all branches of medicine. Approximately 10% of the population will have one or more seizures during their lifetime. Seizures are symptoms that occur in acute illness, ie, provoked seizures, or in epilepsy, ie, unprovoked seizures. Epilepsy is any disorder in which spontaneous recurrence of unprovoked seizures is the main symptom. It is a common chronic neurologic disorder and affects 1% to 3% of the population. Classification of seizure type is important because it enables identification of the region of the brain where the seizure originated and guides initial diagnostic testing. Classification of epilepsy syndrome, rather than only type of seizure, is more important. Epilepsy syndromes are defined by many factors, including type of seizures, age at onset of seizures, family history of seizures, and findings at physical examination, electroencephalography (EEG), and neurologic imaging studies. Identifying the epilepsy syndrome provides insight into natural history, prognosis, diagnostic testing, and therapy of the disorder and facilitates communication between health care professionals. Understanding seizure type provides useful information even when the epilepsy syndrome cannot be classified. Many sudden events are easily confused with seizures, in particular, pseudoseizures, syncope, migraine, cerebrovascular disease, movement disorders, and sleep disorders. In most cases a detailed history and physical examination concentrated on the details of the event, and results of routine EEG and magnetic resonance imaging can aid in determination of which events are seizures. Video EEG monitoring is occasionally necessary to capture events to enable definitive determination of whether they are seizures and to further characterize them. Provoked seizures are treated with relief of the provoking factor. Antiepileptic drugs (AEDs) are not indicated. However, AEDs may be required to treat unprovoked seizures of new onset in patients at high risk for seizure recurrence or when a second seizure can have devastating psychosocial effects. High risk for recurrence is present when there is a history of brain insult, an EEG demonstrates epileptiform abnormalities, and magnetic resonance images demonstrate a structural lesion. AED therapy is the standard treatment for epilepsy, ie, two or more seizures. Selection of the appropriate AED depends on type of seizure and epilepsy present, and individual drug characteristics, including pharmacokinetics, side effects, dosing interval, and cost. All available AEDs except ethosuximide are effective as adjunctive therapy, and most are effective as initial monotherapy for partial seizures. Generalized seizures preferentially respond to valproate, lamotrigine, and topiramate, among other drugs. If trials of more than two AEDs do not control seizures, additional AEDs are unlikely to be effective, and the patient should be referred to an epilepsy center, where other treatment options, in particular, epilepsy surgery, can be offered. Epilepsy surgery renders 60% to 70% of patients with temporal lobe epilepsy free of disabling seizures.

Epilepsy and athletics

It may seem logical to place restrictions on athletes with epilepsy, but there are no studies to suggest that even contact sports exacerbate seizures, and there is ample evidence that exercise reduces seizure frequency and improves well-being. Thus, sports participation should generally be encouraged for epilepsy patients. The risk-benefit analysis for an individual patient is highly dependent on the athletic activity considered; type of seizure, the likelihood that a seizure will occur during the activity, and comorbid conditions. Water sports (scuba diving, swimming, boating), sports performed at heights (piloting, sky diving, climbing, horseback riding), and motor sports require specific considerations.

Clinical correlation of occipital intermittent rhythmic delta activity

Frontal intermittent rhythmic delta activity is associated with encephalopathy, and temporal intermittent delta activity is associated with epilepsy, but the importance of OIRDA (OIRDA) is less well defined. The authors reviewed retrospectively EEGs and medical records of 77 patients with OIRDA to determine whether they had epilepsy, acute encephalopathy, or another diagnosis. They compared the incidence of epilepsy in this population with a control group of 77 patients referred for EEG, matched for age, gender, and year of EEG. OIRDA was most commonly generalized, high amplitude, saw toothed, and reactive to eye opening, and with mean frequency of 2.89 +/- 0.50 Hz. Mean age was 8.1 +/- 4.5 years. Seventy-six of 77 patients were <or= 18 years old. Seizures were present in 69 OIRDA patients but only 41 control subjects (P < 0.0001). OIRDA compared with control subjects had more patients with GTCs (34 vs. 10; P < 0.0001) and absence seizures (25 vs. 6; P < 0.0001), but an equal number had partial seizures (30 vs. 27). Only one OIRDA patient had acute encephalopathy. OIRDA patients with seizures were younger (7.6 +/- 4.7 years vs. 12 +/- 6.9 years; P < 0.01) and more likely to evolve to spike-wave activity compared with OIRDA patients without seizures. OIRDA is present almost exclusively in children and is associated with epilepsy but not acute encephalopathy. OIRDA has clinical importance distinctly different from frontal intermittent rhythmic delta activity.

Quality of life outcome is associated with cessation rather than reduction of psychogenic nonepileptic seizures

The outcome of psychogenic nonepileptic seizures (NES) is usually judged by recurrence of spells, but functional outcome or quality of life (QOL) is less well described. We tested the hypothesis that a decrease in NES recurrence yields corresponding improvement in QOL. Patients with NES were diagnosed with continuous video-EEG. We determined spell rate and QOL through a telephone interview at least six months after diagnosis. Thirty subjects consented to a follow-up interview (mean 17.4+/-1.5 months between diagnosis and interview). The rate of NES per week decreased significantly, and 10/30 (33%) had complete resolution. QOL, measured by the QOLIE-10 scale, did not improve proportionately with reduction in NES. However, subjects who reported a cessation of NES noted a significantly better total QOLIE-10 score (20.7+/-2.2) than those with continuing NES (27.4+/-1.6, P=0.02 by unpaired t test). Cessation rather than reduction of NES is associated with better QOL outcome.

Efficacy and safety of levetiracetam in children with partial seizures: an open-label trial

PURPOSE

To assess the efficacy and safety of levetiracetam (LEV) as adjunctive therapy in children with treatment-resistant partial-onset seizures.

METHODS

Children (aged 6-12 years) with treatment-resistant partial-onset seizures receiving one standard antiepileptic drug (AED) were eligible. After a 4-week baseline period, children received LEV in a 6-week titration phase (target dose, 40 mg/kg/day) followed by an 8-week evaluation phase. Seizure frequency during the evaluation period with individualized LEV doses (20-40 mg/kg/day) were compared with the 4-week baseline seizure frequency. Plasma concentrations of LEV and other AEDs were determined to evaluate potential drug interactions.

RESULTS

Twenty-four subjects enrolled and received LEV; 23 entered the evaluation phase, and 22 completed the evaluation phase. Compared with their baseline seizure frequency, 12 (52%) of 23 subjects entering the evaluation phase had their seizure frequency decrease by >50%. Two subjects remained seizure free during the entire evaluation period. LEV did not significantly affect plasma concentrations of any concomitant AED during this study, and no alteration of mean clinical laboratory values was observed. The most commonly reported adverse events were headache, infection, anorexia, and somnolence.

CONCLUSIONS

This open-label study of adjunctive LEV therapy (at 20-40 mg/kg/day) suggests that LEV is effective, safe, and well tolerated in children ages 6-12 years with treatment-resistant partial-onset seizures. A randomized, placebo-controlled, double-blind trial of LEV adjunctive therapy in children with treatment-resistant partial-onset seizures is needed and ongoing to confirm these open-label findings.

Pharmacokinetic study of levetiracetam in children

PURPOSE

The pharmacokinetics of the novel antiepileptic drug (AED) levetiracetam and its major metabolite, ucb L057, were studied in children with partial seizures in a multicenter, open-label, single-dose study.

METHODS

Twenty-four children (15 boys, nine girls), 6 to 12 years old, received a single dose of levetiracetam (20 mg/kg) as an adjunct to their stable regimen of a single concomitant AED, followed by a 24-h pharmacokinetic evaluation.

RESULTS

In children, the half-lives of levetiracetam and its metabolite ucb L057 were 6.0 +/- 1.1 and 8.1 +/-2.7 hours, respectively. The Cmax and area under the curve (AUC) of levetiracetam equated for a 1-mg/kg dose were lower in children (Cmax, norm=1.33 plus minus 0.35 microg/ml; AUCnorm=12.4 +/- 3.5 microg/h/ml) than in adults (Cmax, norm=1.38 +/- 0.05 microg/ml; AUCnorm=11.48 +/- 0.63 microg/h/ml), whereas the renal clearance was higher. The apparent body clearance (1.43 +/- 0.36 ml/min/kg) was approximately 30-40% higher in children than in adults. Levetiracetam was generally well tolerated.

CONCLUSIONS

On the basis of these data, a daily maintenance dose equivalent to 130-140% of the usual daily adult maintenance dosage (1,000-3,000 mg/day) in two divided doses, on a weight-normalized level (mg/kg/day) is initially recommended. Clinical efficacy trials in children are ongoing with dosages of 20 to 60 mg/kg/day.

Effects of benzodiazepines on triphasic waves: implications for nonconvulsive status epilepticus

Nonconvulsive status epilepticus (NCSE) is often diagnosed based on abolition of rhythmic sharp waves by benzodiazepines. It is possible that sharp waves resulting from metabolic (nonepileptic) encephalopathies may also respond to benzodiazepines and are potentially misdiagnosed as NCSE. The authors hypothesized that triphasic waves (TW) resulting from metabolic encephalopathy are abolished by benzodiazepines. They retrospectively identified patients with TW resulting from metabolic encephalopathy who had EEG recordings before, during, and after benzodiazepine administration. Benzodiazepines were given either because of the possibility of NCSE or for a medically indicated purpose. All patients were diagnosed definitively with a metabolic cause of encephalopathy and not NCSE. Ten patients (mean age, 59 years) met the criteria and were reviewed. TW resolved persistently in four patients and intermittently in six patients. Background activity slowed in five patients and was attenuated in five patients. Unresponsive patients did not arouse and three of five drowsy patients became less responsive. Rhythmic sharp waves resulting from metabolic encephalopathy are abolished by benzodiazepines, similar to NCSE, but without improvement in mental status. This suggests that definitive electrographic diagnosis of primary NCSE should not be based entirely on abolition of sharp waves by benzodiazepines. This also implies that gamma-aminobutyric acid neurotransmission is important in the expression of TW.

Distribution of seizure precipitants among epilepsy syndromes

PURPOSE

Previous studies of patient-reported seizure precipitants have not evaluated whether different epilepsy syndromes are differentially affected.

METHODS

Patients of a tertiary-care epilepsy center were consecutively surveyed with the use of a standardized questionnaire that lists precipitants that might trigger or exacerbate seizures (alcohol, caffeine, fasting, fatigue, fever or illness, flashing lights, heat or humidity, menstrual cycle, sleep, sleep deprivation, emotional stress, unknown, or other). Patients were classified into epilepsy syndromes according to International League Against Epilepsy criteria. Age and gender within groups defined by major precipitants were compared. Pearson's correlation was performed to evaluate common patterns of precipitants.

RESULTS

Of 400 patients, 62% cited at least one precipitant. In order of frequency, stress (30%), sleep deprivation (18%), sleep (14%), fever or illness (14%), and fatigue (13%) were noted by at least 10% of patients. Stress, fatigue, and sleep deprivation positively correlated, but sleep tended to negatively correlate with other major precipitants. Rankings of precipitants varied within epilepsy syndromes, with patients with temporal lobe epilepsy citing sleep infrequently compared with patients with other epilepsy syndromes. Menstrual effects were ranked highly within major precipitants among women over age 12 and were especially noted by women with temporal lobe epilepsy (28%).

CONCLUSIONS

Most patients with epilepsy identify a precipitant that triggers or exacerbates seizures. The high correlation of stress, sleep deprivation, and fatigue suggests that they act through common mechanisms to worsen seizure control. Through identification of the effect of both endogenous and exogenous precipitants among syndromes, more research and counseling can be directed to specific precipitants.

Status epilepticus: risk factors and complications

Status epilepticus is common and associated with significant mortality and complications. It affects approximately 50 patients per 100,000 population annually and recurs in >13%. History of epilepsy is the strongest single risk factor for generalized convulsive status epilepticus. More than 15% of patients with epilepsy have at least one episode of status epilepticus and low antiepileptic drug levels are a potentially modifiable risk factor. Other risks include young age, genetic predisposition, and acquired brain insults. Fever is a very common risk in children, as is stroke in adults. Mortality rates are 15% to 20% in adults and 3% to 15% in children. Acute complications result from hyperthermia, pulmonary edema, cardiac arrhythmias, and cardiovascular collapse. Long-term complications include epilepsy (20% to 40%), encephalopathy (6% to 15%), and focal neurologic deficits (9% to 11%). Neuronal injury leading to temporal lobe epilepsy is probably mediated by excess excitation via activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors and consequent elevated intracellular calcium that causes acute necrosis and delayed apoptotic cell death. Some forms of nonconvulsive status epilepticus may also lead to neuronal injury by this mechanism, but others may not. Based on clinical and experimental observations, complex partial status epilepticus is more likely to result in neuronal injury similar to generalized convulsive status epilepticus. Absence status epilepticus is much less likely to result in neuronal injury, and complications because it may be mediated primarily through excess inhibition. Future research strategies to prevent complications of status epilepticus include the study of new drugs (including NMDA antagonists, new drug delivery systems, and drug combinations) to stop seizure activity and prevent acute and delayed neuronal injury that leads to the development of epilepsy.

Midazolam treatment of acute and refractory status epilepticus

Generalized convulsive status epilepticus (GCSE) is a medical emergency requiring prompt resolution. Acute treatment is often delayed by difficulty in obtaining intravenous (i.v.) access. Refractory GCSE is often difficult to treat, and traditional therapy with barbiturates induces hypotension and respiratory depression and prolongs recovery. Midazolam is particularly useful for treating acute GCSE because it has an imidazole ring that is open at low pH, allowing it to be dissolved in aqueous solution for intramuscular injection, but closed at physiologic pH, increasing lipophilicity and rendering good intramuscular absorption, brain penetration, and fast onset of action. When given intramuscularly as a 0.2 mg/kg bolus, it has efficacy at least equal to that of i.v. diazepam, is well tolerated, induces little respiratory compromise, and has a shorter latency to onset of action. Therefore, it should be considered for the treatment of acute GCSE when i.v. access is problematic. For refractory GCSE, continuous i.v. midazolam infusion at 0.1-0.6 mg/kg/hr after a 0.2 mg/kg i.v. bolus is effective and has advantages over traditional therapies because it induces less hypotension and cardiorespiratory depression and can be easily titrated. Further prospective studies are needed to define the role of continuous i.v. midazolam compared to other contemporary therapies.

Conduction aphasia elicited by stimulation of the left posterior superior temporal gyrus

OBJECTIVE

Disruption of fascicular tracts that connect Wernicke's to Broca's areas is the classic mechanism of conduction aphasia. Later work has emphasised cortical mechanisms.

METHODS

To determine the distribution of language on dominant cortex, electrical cortical stimulation was performed using implanted subdural electrodes during brain mapping before epilepsy surgery.

RESULTS

A transient, isolated deficit in repetition was elicited with stimulation of the posterior portion of the dominant superior temporal gyrus.

CONCLUSION

This finding suggests that cortical dysfunction, not just white matter disruption, can induce conduction aphasia.

Control of primary angiitis of the CNS associated with cerebral amyloid angiopathy by cyclophosphamide alone

Corticosteroids combined with cyclophosphamide are currently recommended for primary angiitis of the CNS. The authors report a 71-year-old man with primary angiitis of the CNS and amyloid angiopathy who responded to cyclophosphamide without steroids, suggesting that corticosteroids may not be needed in all cases of primary angiitis of the CNS.

Responses of deep entorhinal cortex are epileptiform in an electrogenic rat model of chronic temporal lobe epilepsy

We investigated whether entorhinal cortex (EC) layer IV neurons are hyperexcitable in the post-selfsustaining limbic status epilepticus (post-SSLSE) animal model of temporal lobe epilepsy. We studied naive rats (n = 44), epileptic rats that had experienced SSLSE resulting in spontaneous seizures (n = 45), and electrode controls (n = 7). There were no differences between electrode control and naive groups, which were pooled into a single control group. Intracellular and extracellular recordings were made from deep layers of EC, targeting layer IV, which was activated by stimulation of the superficial layers of EC or the angular bundle. There were no differences between epileptic and control neurons in basic cellular characteristics, and all neurons were quiescent under resting conditions. In control tissue, 77% of evoked intracellular responses consisted of a short-duration [8.6 +/- 1.3 (SE) ms] excitatory postsynaptic potential and a single action potential followed by gamma-aminobutyric acid-A (GABAA) and GABAB inhibitory post synaptic potentials (IPSPs). Ten percent of controls did not contain IPSPs. In chronically epileptic tissue, evoked intracellular responses demonstrated prolonged depolarizing potentials (256 +/- 39 ms), multiple action potentials (13 +/- 4), and no IPSPs. Ten percent of epileptic responses were followed by rhythmic "clonic" depolarizations. Epileptic responses exhibited an all-or-none response to progressive increases in stimulus intensity and required less stimulation to elicit action potentials. In both epileptic and control animals, intracellular responses correlated precisely in morphology and duration with extracellular field potentials. Severing the hippocampus from the EC did not alter the responses. Duration of intracellular epileptic responses was reduced 22% by the N-methyl--aspartate (NMDA) antagonist (-)-2-amino-5-phosphonovaleric acid (APV), but they did not return to normal and IPSPs were not restored. Epileptic and control responses were abolished by the non-NMDA antagonist 6, 7-dinitroquinoxaline-2-3-dione (DNQX). A monosynaptic IPSP protocol was used to test connectivity of inhibitory interneurons to primary cells by direct activation of interneurons with a stimulating electrode placed near the recording electrode in the presence of APV and DNQX. Using this protocol, IPSPs similar to control (P > 0.05) were seen in epileptic cells. The findings demonstrate that deep layer EC cells are hyperexcitable or "epileptiform" in this model. Hyperexcitability is not due to interactions with the hippocampus. It is due partially to augmented NMDA-mediated excitation. The lack of IPSPs in epileptic neurons may suggest inhibition is impaired, but we found evidence that inhibitory interneurons are connected to their target cells and are capable of inducing IPSPs.

Sleep deprivation activates epileptiform discharges independent of the activating effects of sleep

An electroencephalogram (EEG) recorded after sleep deprivation (SDEEG) in epilepsy patients often discloses epileptiform discharges (ED) when routine EEG (REEG) does not, but since sleep alone activates ED, activation during SDEEG may result merely from the induction of sleep. We retrospectively investigated whether SDEEG is useful when REEG containing wakefulness and sleep fails to show ED. Subjects were patients with definite or highly probable epilepsy whose REEG lacked ED and who later underwent SDEEG. All had wakefulness and at least stage II sleep during both REEG and SDEEG. Patients with ED on REEG were specifically excluded to avoid including patients with activation due merely to the occurrence of sleep. Patient and EEG characteristics were studied, including duration of wakefulness and each sleep stage and timing and characteristics of ED. Fifteen of 29 patients (52%) had activation on SDEEG; exclusively during wakefulness in 1, exclusively during sleep in 6 and in both wakefulness and sleep in 8. Activation rates were not significantly different between wakefulness (9, 60%), stage I (11, 74%) and stage II (11, 74%). EEG characteristics were similar for REEG and SDEEG, except that total EEG duration and stage II sleep were longer in SDEEG than in REEG, which did not influence activation by a logistic regression model (p > 0.05). We conclude that sleep deprivation activates ED independent of the activating effects of sleep and therefore is useful in evaluation of suspected epilepsy even when REEG contains sleep.

Responses of the superficial entorhinal cortex in vitro in slices from naive and chronically epileptic rats

1. The main purposes of this study are to characterize the intracellular and extracellular responses of cells in superficial layers of entorhinal cortex (EC) in chronically epileptic animals, determine whether their altered physiology is dependent on being connected to hippocampus, and investigate whether there is evidence of augmented excitation and inhibitory interneuron disconnection. 2. Functional connectivity was maintained between the hippocampal area and the EC in vitro in a combined rat hippocampal-parahippocampal slice preparation by slicing with a vibratome at a 30-deg angle to the base of the brain. Three groups of animals were studied: naive animals, animals that had experienced a previous episode of (nonconvulsive) self-sustaining limbic system status epilepticus (SSLSE) induced by electrical stimulation resulting in a chronically epileptic state, and animals in an electrode control group. In chronically epileptic rats and the electrode control group, studies were done on tissue contralateral to the side of electrode implantation. 3. Extracellular and intracellular recordings were made from the superficial layers of EC. Neurons in the superficial layers of the EC were activated by stimulation of the deep layers within the EC or the angular bundle adjacent to the EC, which contains axons from EC neurons. Responses could be elicited by antidromic and synaptic mechanisms by stimulation at either site. In addition, a monosynaptic protocol was used that involved direct activation of interneurons with a stimulating electrode placed near the recording electrode in the presence of the ionotropic glutamate blockers D(-)-2-amino-5-phosphonovaleric acid (APV) and 6,7-dinitroquinoxaline-2-3-dione (DNQX). 4. Responses were collected over a range of stimulus intensities, from very low to high intensities, to construct input/output function (I/O) curves. Amplitudes and durations were measured at the lowest stimulus intensity that elicited a maximum responses. 5. Extracellular field potential responses from electrode controls did not differ from naives qualitatively with respect to morphology of field potential responses or quantitatively with respect to response duration and amplitude. Field potential responses in tissue from post-SSLSE rats differed markedly in morphology from naive and electrode controls, being more complex, significantly longer in duration, and decreased in amplitude. These epileptiform responses were shortened markedly by blockade of N-methyl-D-aspartate (NMDA) receptors with APV, but this manipulation did not convert responses to a normal morphology. These responses were abolished by blockade of non-NMDA mediated ionotropic glutamate receptors with DNQX. 6. During intracellular recordings of neurons in slices from both control and epileptic animals, neurons were quiescent under resting conditions in the absence of electrical stimulation. 7. Intracellular responses in electrode controls were identical to naive, and together were considered "controls." In control tissue, evoked intracellular responses were similar to those previously described and most commonly consisted of an excitatory postsynaptic potential (EPSP) that was blocked partially by the NMDA-receptor antagonist APV, followed by hyperpolarizing potentials, which were identified electrophysiologically and pharmacologically as gamma-aminobuturic acid-A (GABAA)- and GABAB-receptor-mediated inhibitory postsynaptic potentials (IPSPs). EPSPs were blocked completely by DNQX. 8. In chronically epileptic tissue, evoked intracellular responses differed markedly from responses in control animals, exhibiting all-or-none prolonged paroxysmal depolarizing events with multiple superimposed action potentials in response to a single shock. These depolarizing events were reduced in duration and amplitude, but not abolished, in APV. IPSPs were not seen or markedly reduced at all stimulus intensities. These intracellular responses never resembled control responses. Intracellur responss correlated precisely in morphology and duration with extracellular field potentials. (ABSTRACT TRUNCATED)

Primary angiitis of the central nervous system associated with cerebral amyloid angiopathy: report of two cases and review of the literature

Early diagnosis is essential for the effective management of primary angiitis of the CNS (PACNS), but the presence of cerebrovascular amyloid angiopathy (CAA) may complicate the pathologic diagnosis since nonvasculitic inflammatory reactions can accompany CAA. We report two patients with PACNS associated with CAA in whom the progression of symptoms ceased during combined corticosteroid/cyclophosphamide therapy. One patient had prominent eosinophilic vasculitis and eosinophilic CSF pleocytosis. Based on review of reported cases, features supporting the diagnosis of symptomatic vasculitis in these patients include subacute progression of mental status changes and multifocal deficits, elevated ESR and CSF protein, and multifocal nonhemorrhagic lesions on imaging studies. We conclude that combined disease (PACNS/CAA) is similar to PACNS and probably occurs more frequently than expected by coincidence. The presence of CAA should not alter the treatment strategy in patients presenting with symptoms and laboratory studies consistent with PACNS.

Pathophysiology of status epilepticus

The cellular and molecular pathophysiology of status epilepticus (SE) provides a conceptual framework for understanding clinical scenarios and prospectively designing logical therapies. SE is a dynamic process that evolves over time in a predictable manner with an established sequence of EEG, motor, physiologic, and cellular changes. Neuronal injury and death are the result of processes intrinsic to the brain, mediated by a complex neurotoxic cascade consisting of multiple serial and parallel processes. The risk of cell injury depends also on the overall pathophysiologic profile, including the presence of alterations resulting from SE and occurring independent of SE. On neurophysiologic grounds, we divide SE into "spike-wave" and "nonspike-wave" forms. Spike-wave "absence" status epilepticus carries a low risk of epileptic brain damage, and therapy should be adjusted accordingly. All nonspike-wave SE has a theoretical basis for epileptic brain damage, but the actual risk is variable. There is a significant known risk of cell injury during generalized convulsive SE, a variety of nonspike-wave SE, so aggressive treatment is warranted to prevent sequelae. There is also a theoretical basis for epileptic brain damage in nonspike-wave nonconvulsive SE, but prospective studies are needed to determine which of these patients warrant aggressive therapy. Based on pathophysiologic principles, future treatment of nonspike-wave SE may use a combination of anti-ictal agents, including gamma-aminobutyric acid agonists and N-methyl-D-aspartate antagonists, as well as various neuroprotectants.