Compliance declines between clinic visits.

Adherence to prescribed drug dosing regimens declined substantially during the interval between clinic visits and drug level tests. Using microelectronic monitors to observe pill-taking habits, 20 patients averaged 88% compliance before and 86% compliance after the visit, but this dropped to 67% compliance a month later. These data indicate that spot drug levels do not represent long-term "steady-state" drug serum concentrations.

Barbiturate-related connective tissue disorders.

Development of Dupuytren's contractures, frozen shoulder, Ledderhose's syndrome, Peyronie's disease, fibromas, and general joint pain has been linked in retrospective studies and case reports to the use of antiepileptic drugs. We undertook a prospective survey of the incidence of connective tissue disorders in 622 patients newly treated with carbamazepine, phenobarbital, phenytoin sodium, or primidone. Ten of the 406 patients who were treated for 6 months or more developed connective tissue disorders. All affected patients were taking a barbiturate (primidone, 4 patients; phenobarbital, 6 patients). Seven of the 10 problems occurred during the first year of treatment. These data are prospective evidence of a statistically significant relationship between barbiturate use and the development of connective tissue disorders, and timing of appearance.

Human GABA(B) receptor 1 gene: eight novel sequence variants.

GABA (gamma-aminobutyric acid) is the principal inhibitory neurotransmitter in the brain. The human GABA(B) receptor (GABBR1) maps to the human leukocyte antigen (HLA) region of chromosome 6. Its function and location in a susceptibility region for schizophrenia, epilepsy, and dyslexia make GABBR1 a candidate gene for neurobehavioral disorders. We report the characterization of GABBR1 gene mutations in 100 chromosomes from a mixed American population. Eleven distinct mutations were found, including two previously reported missense mutations (A20V and G489S) and a previously reported silent 1977 T>C transition. Here, we report four novel silent substitutions (39C>T, 1473T>C, 1476T>C, 1545T>C) and four novel intron variants. These DNA variants may be useful in association and linkage studies of neurobehavioral disorders, and in pharmacogenetic studies of drugs targeting GABBR1.

Vigabatrin: effect on brain GABA levels measured by nuclear magnetic resonance spectroscopy.

Vigabatrin is undoubtedly one of the most exciting anti-epilepsy drugs in use today. Many open and controlled clinical trials have confirmed that it is particularly effective in controlling partial epileptic seizures with or without secondary generalization. Vigabatrin acts to increase GABA levels in the presynaptic nerve terminal by inhibiting the activity of GABA-transaminase. There is no direct correlation between the blood or brain concentration of vigabatrin and its clinical effect, so monitoring vigabatrin levels is not predictive of patient response. However, it is possible to relate the activity of vigabatrin to levels of GABA in the brain, measured by nuclear magnetic resonance spectroscopy (NMRS). NMRS studies show that following administration of vigabatrin, brain concentrations of GABA rise to about 2-3 times their baseline values. This 'extra' GABA is held within the nerve terminal, and is only released during synaptic transmission. Although there appears to be a clear dose-response relationship up to 3 g/day, it is not well documented if higher doses result in proportionately higher brain GABA levels. This finding seems to support the results of clinical studies suggesting that the optimal dose of vigabatrin may be 3 g/day. There is also some evidence for a correlation between the concentration of GABA in the brain and the clinical outcome. Continuing investigations using NMRS aim to confirm these preliminary findings, and to determine the time course and extent of changes in brain GABA levels after vigabatrin administration.

Effect of valproate on cognitive functioning. Comparison with carbamazepine. The Department of Veterans Affairs Epilepsy Cooperative Study 264 Group.

OBJECTIVE: To assess the effects of carbamazepine vs valproate sodium on cognitive functioning in patients with epilepsy compared with normal control subjects. DESIGN: Patients with recently diagnosed, previously unmedicated seizures participated in a prospective randomized double-blind Department of Veterans Affairs multicenter study of the efficacy and toxicity of carbamazepine vs valproate. MAIN OUTCOME MEASURE: A behavioral toxicity battery was administered prior to treatment and again 6 and 12 months after the initiation of antiepileptic medication. RESULTS: There were no significant differences in the effect of carbamazepine vs valproate on motor speed and coordination, memory, or concentration and mental flexibility, and there was no significant decline in neuropsychological performance from pretreatment baseline levels for either drug. No significant differences in performance were found between patients with low (mean, 52.8 micrograms/mL) vs high (mean, 94.4 micrograms/mL) serum valproate levels within the therapeutic range. Patients treated with either carbamazepine or valproate did not show practice effects experienced by normal controls, a finding that may reflect a subtle compromise in cognitive functioning. CONCLUSION: The impact of carbamazepine and valproate monotherapy on cognitive functioning is similar: both drugs produce minimal negative effects compared with pretreatment baseline performance.

Parenteral antiepileptic/anticonvulsant drugs.

A large number of drugs can be given parenterally for the control of acute seizures, although many of these compounds are associated with serious adverse effects. Phenobarbital, the first antiepileptic drug (AED), has long been available in an injectable formulation. The sodium salt of phenobarbital is water soluble, and its parenteral formulation can be given for maintenance therapy or treatment of acute seizures. The introduction of phenytoin in 1938, and its subsequent parenteral formulation, represented a significant advance in AED therapy owing to its relative absence of sedation. However, the risk of adverse effects necessitates that the rate of phenytoin administration usually be limited to 50 mg/min. I.v. valproate has been used extensively but has not been approved for use in the United States, and its value for treating acute seizures is unclear. Several benzodiazepines have been used as adjunctive drugs for the treatment of epilepsy; given parenterally, they provide rapid CNS entry and prompt control of seizures, but their effect is short lived. Agents that have more hypnotic anesthetic properties are often used when the benzodiazepines or phenytoin alone or in combination fails.

Medical management of epilepsy in adults.

Optimal treatment of epilepsy in adults requires a tailored approach that weighs the efficacy of individual drugs in the specific diagnosis against the patient's risks for adverse events. Partial seizures, which are the most common seizure type in adults, can be effectively controlled by virtually all the standard and newer antiepileptic drugs (AEDs). For the generalized epilepsies, valproate remains the drug of choice. Data continue to accumulate regarding use of the newer agents. Overall, many of the newer AEDs may offer a better tolerability than the standard agents because of more favorable pharmacokinetic characteristics and lack of interactions with drugs other than AEDs. Serious adverse events have been associated with felbamate and lamotrigine, however, and more experience is needed with many of the other newer AEDs to better define their safety profiles. Monotherapy should be the goal when AED treatment is instituted for the adult with epilepsy. Dosage modification on the basis of seizure control and toxicity should be implemented, as well as single-drug trials with alternative AEDs, before resorting to polytherapy. With the introduction of several promising newer AEDs, safe and effective seizure control may become a reality for an increasing number of adults with epilepsy.

Current challenges in the treatment of epilepsy.

Significant progress in the classification, diagnosis, and pharmacologic management of epileptic seizures has occurred over the past two decades, but epilepsy remains a therapeutic challenge. Clinical studies show that most patients with epilepsy can have complete or almost complete seizure control with optimally managed monotherapy that employs a traditional antiepileptic drug (AED). About half of the remaining patients can obtain improved seizure control with combination antiepileptic drug therapy, but usually with more adverse effects. In the other half, seizures remain refractory to treatment with available antiepileptic drugs, or treatment remains problematic because of drug intolerance. Advances in understanding the pathogenesis of epilepsy and the mechanisms of action of antiepileptic drugs have provided a basis for the development of new AEDs that hold promise for difficult-to-treat patients. In this decade, a number of new AEDs that may overcome some of the disadvantages of traditional AEDs and offer clinicians and patients added therapeutic options will become clinically available. These will be more fully evaluated for their clinical potential to meet existing challenges of epilepsy treatment.

Isoprinosine in subacute sclerosing panencephalitis.

An open therapeutic trial of isoprinosine was conducted in 15 patients with subacute sclerosing panencephalitis (SSPE). Long-term remissions occurred in 5 (33 percent), with documented improvement sustained for 2 or more years. Another patient was in remission 9 months after starting treatment, and three patients had transient remissions or stabilization. The disease was unaltered in five patients who had rapidly progressive SSPE when treatment started. These results compare with an average remission rate of about 5 percent in several series of untreated cases of SSPE or in cases treated with other antiviral agents. Patients in remission continued to have elevated cerebrospinal fluid (CSF) IgG and measles antibody titers, with one exception. Isoprinosine was tolerated for several years without side effects, except for mild hyperuricemia.

Eterobarb therapy in epilepsy.

A group of 27 patients with various types of epilepsy were selected for a 6-month double-blind crossover study to compare the anticonvulsant effect and toxicity of eterobarb and phenobarbital. No statistically significant differences in seizure frequency were found among the 21 patients who completed the 6-month trial, but three others, in whom status epilepticus developed during the crossover from eterobarb to phenobarbital, had to be removed from the trial. The study provided some indication that when eterobarb and phenobarbital were used in high dosage with corresponding high serum barbiturate levels (over 30 mug per milliliter), eterobarb had a superior therapeutic effect. Side effects from both drugs included tiredness, sleepiness, nystagmus, and infrequently ataxia, but serious systemic toxicity did not occur. This study showed that eterobarb is a safe and potent anticonvulsant comparable in efficacy to phenobarbital, and the superior results obtained in some patients with eterobarb therapy indicate that it is an effective alternative anticonvulsant.

Prognosis for total control of complex partial and secondarily generalized tonic clonic seizures. Department of Veterans Affairs Epilepsy Cooperative Studies No. 118 and No. 264 Group.

BACKGROUND: Two prospective observations of adults with symptomatic, localization-related (partial) epilepsy included 1,102 patients in VA multicenter studies (VA-118 and VA-264). Analyses assessed the likelihood of remaining seizure free for 12 and 24 months after initiating adequate antiepileptic drug therapy. METHODS: Patients were grouped as having only secondarily generalized tonic-clonic seizures (GTC), only complex partial seizures (CPS), or both types (MIXED) at entry. The cumulative proportion of patients remaining seizure free with standard antiepileptic drug therapy was determined by actuarial life table methods. RESULTS: At 12 months, 70% and 61% of GTC patients (VA-118 and VA-264, respectively) had no further GTC; 53% and 50% of MIXED, predominantly GTC patients had no further GTC, 21% and 28% of CPS patients had no further CPS and 98% and 91% were seizure free for GTC; 32% and 35% of MIXED, predominantly CPS patients had no further CPS, and 62% and 51% of patients with MIXED seizure types remained seizure free for CPS for 12 months after enrollment. CONCLUSIONS: The overall prognosis for control of seizures of any type for 12 months was best for those who had only GTC at entry (55% and 48%), worst for those who had only CPS at entry (23% and 26%), and intermediate for those with MIXED seizures at entry (32% and 25%) (all p < 0.0001). Prognosis can be based on the predominant seizure type in patients with multiple types.

Homocarnosine and seizure control in juvenile myoclonic epilepsy and complex partial seizures.

OBJECTIVE: To assess the relationship between seizure control and gamma-aminobutyric acid (GABA), homocarnosine, and pyrrolidinone levels in the visual cortex of patients with epilepsy taking valproate or lamotrigine. Previous studies suggested that poor seizure control was associated with low GABA and homocarnosine levels. METHODS: In vivo measurements of GABA, homocarnosine, and pyrrolidinone were made in a 14-cm(3) volume of the occipital cortex using (1)H spectroscopy with a 2.1-Tesla MR spectrometer and an 8-cm surface coil. Twenty-six adults (eight men) taking valproate or lamotrigine were recruited; 12 had complex partial seizures (CPS) and 14 had juvenile myoclonic epilepsy (JME). RESULTS: Median homocarnosine levels were normal for patients with JME and below normal for patients with CPS. Better seizure control was associated with higher homocarnosine levels for both groups. Median GABA was below normal for patients with JME, lower than for patients with CPS. Brain GABA was lowest in patients with JME even when seizure control was excellent. Pyrrolidinone levels were above normal in almost all patients with JME. CONCLUSIONS: Low GABA levels are associated with poor seizure control in patients with CPS, but not in JME. Higher homocarnosine levels are associated with better seizure control in both types of epilepsy.

Topiramate increases brain GABA, homocarnosine, and pyrrolidinone in patients with epilepsy.

OBJECTIVE: To measure the effects of topiramate on brain gamma-aminobutyric acid (GABA) in patients with epilepsy. BACKGROUND: Topiramate is a new antiepileptic medication with multiple putative mechanisms of action. In a recent meta-analysis of the newer antiepileptic drugs, topiramate was the most potent. Homocarnosine and pyrrolidinone are important metabolites of GABA with antiepileptic actions. METHODS: In vivo measurements of GABA, homocarnosine, and pyrrolidinone were made of a 14-cm3 volume in the occipital cortex using 1H spectroscopy with a 2.1-Tesla magnetic resonance spectrometer and an 8-cm surface coil. Twelve patients (eight women) with refractory complex partial seizures were studied while using topiramate. Nine epilepsy-free, drug-free volunteers served as control subjects. RESULTS: Topiramate increased mean brain GABA, homocarnosine, and pyrrolidinone concentrations in all patients. In paired measurements, brain GABA increased by 0.7 micromol/g (SD 0.3, n 7, 95% CI 0.4 to 1.0, p < 0.01). Homocarnosine increased by 0.5 micromol/g (SD 0.2, n 7, 95% CI 0.3 to 0.7, p < 0.001). Pyrrolidinone increased by 0.21 micromol/g (SD 0.06, n 7, 95% CI 0.16 to 0.27, p < 0.01). In two additional patients, GABA, homocarnosine, and pyrrolidinone increased after they were switched from vigabatrin to topiramate. CONCLUSIONS: Topiramate increased brain GABA, homocarnosine, and pyrrolidinone to levels that could contribute to its potent antiepileptic action in patients with complex partial seizures.

Treatment of seizures with medroxyprogesterone acetate: preliminary report.

Medroxyprogesterone acetate (MPA), a synthetic progesterone, was added to the antiepileptic drug regimen of 14 women who had uncontrolled seizures. Of the 11 women who developed amenorrhea, 7 reported fewer seizures during MPA therapy. Overall reductions in seizure frequency averaged 30% (n = 11), declining from a baseline 8.3 +/- 5.8 seizures per month to 5.1 +/- 4.1 seizures per month (p = 0.02). No serious side effects were encountered, but spotting was common. These preliminary data suggest further evaluation of MPA for catamenial seizures.

PIP: In Connecticut, physicians followed 19 women with tractable epilepsy for 3-5 months to determine baseline seizure frequency. 14 women agreed to enter a clinical trial evaluating synthetic medroxyprogesterone acetate's (MPA) ability to reduce seizure frequency by adding MPA to the usual antiepileptic drug regimen. They all received 10 mg MPA pills 2-4 times each day. 6 women who did experience amenorrhea later received 120-150 mg intramuscular MPA injections (Depo-Provera) every 6-12 weeks instead of oral MPA. The physicians followed the women for 12 months. 11 women eventually experienced amenorrhea and always had low levels of serum progesterone ( or = ng/ml). Seizure frequency fell significantly from a mean of 8.3 seizures/month before MPA administration to 5.1 seizures/month after MPA administration, equaling 39% fewer seizures (p = .02). 7 women who experienced obvious improvement had 52% fewer seizures on average (25-71%) reduction. All women who had fewer seizures did experience partial seizures, however. MPA did not affect the steady state levels of antiepileptic drugs. MPA levels were higher in women receiving oral MPA than they were in those receiving MPA injections (5.2 ng/ml vs. 2.6 ng/ml). Most women had some spotting, particularly during the first few months of the study. Some of these women discontinued treatment because of this side effect, especially women who did not appear to benefit from the treatment. Menstruation returned in 6-12 months in women receiving MPA injections. Further research on MPA's effect on catamenial seizures is needed.

Intracerebral masses in patients with intractable partial epilepsy.

One hundred ninety patients were considered for surgical treatment of uncontrolled partial seizures. Twenty-seven (15%) had intracranial mass lesions detected during preoperative evaluation. Seizures were present for a mean of 10 years. Sixty percent of the patients had prior negative radiologic studies. The lesions included 19 neoplasms and 8 non-neoplastic structural (non-atrophic) lesions. Refractory simple partial seizures and a changing neurologic examination were more commonly associated with neoplasms. Treatment included biopsy and radiation, mass resection, or subtotal lobectomy. Although any form of treatment gave better seizure control, patients undergoing subtotal lobectomy had more than 95% reduction in seizures.

A design for the prospective evaluation of the efficacy and toxicity of antiepileptic drugs in adults.

The design for the comparative evaluation of the efficacy and toxicity of phenobarbital, phenytoin, primidone, and carbamazepine is outlined. A double-blind prospective study of a sufficient number of patients can determine the optimum drug to use initially for partial and generalized tonic-clonic seizures in adults. The rationale for methods defines the major parameters that should be addressed in order to determine optimum drug for longterm seizure therapy. Major problems in the function of such a project include aspects of sample size attainment, screening/recruitment, non-drug-related losses, and adjustments to the ongoing protocol. The design, with modifications, can be used to study other antiepileptic drugs and other types of seizures.

Human brain GABA levels rise rapidly after initiation of vigabatrin therapy.

OBJECTIVE: The purpose of this study was to measure changes in brain GABA after a single oral dose (50 mg/kg) of vigabatrin in patients with intractable epilepsy. BACKGROUND: Vigabatrin is a safe and effective antiepileptic medication designed to increase brain GABA by irreversibly inhibiting GABA-transaminase. Serial measurements showed that brain GABA levels increased from 1.0 (SEM, 0.07) to 2.4 mmol/kg (SEM, 0.09) in patients who were regularly taking vigabatrin (50 mg/kg/day divided into two doses). METHODS: In vivo measurements of GABA in human brain were made using 1H magnetic resonance spectroscopy. We used a 2.1-T NMR spectrometer and an 8-cm surface coil to measure a 13.5 cm3 volume in the occipital cortex. RESULTS: Brain GABA increased by more than 40% within 2 hours of administration of a single 50 mg/kg oral dose of vigabatrin from 0.95 (SEM, 0.07; n = 7) to 1.34 mmol/kg (SEM, 0.13). By the next day, brain GABA increased further to 1.44 mmol/kg (SEM, 0.08). Levels declined gradually to 1.16 mmol/kg (SEM, 0.14) by day 5 and 1.03 mmol/kg (SEM, 0.10) at day 8. The patients reported no side effects and were calm but not drowsy. CONCLUSIONS: A single oral dose of vigabatrin rapidly increased brain GABA without side effects. Once-a-day dosing should be as effective as divided doses.

Measurement of carbamazepine and carbamazepine epoxide in the human brain using in vivo microdialysis.

We report the first study of carbamazepine and carbamazepine-10,11-epoxide concentrations determined by using intracerebral microdialysis in three patients undergoing depth electrode studies for the evaluation of medically intractable epilepsy. Very small microdialysis catheters, affixed to and inserted with the depth electrodes, sampled drug concentration in the extracellular environment. We perfused artificial extracellular fluid continuously, and varied the perfusion rate to permit estimation of the absolute drug concentration in the extracellular space. Serum samples were obtained simultaneously. The relation between dialysate and extracellular concentration (recovery fraction) depended, in vivo but not in vitro, on the relative lipophilicity of the compounds, suggesting that diffusion of the drug within the brain is a major determinant of microdialysate drug concentration. When this is taken into account, the steady-state extracellular concentrations of these compounds closely mirror their unbound serum concentrations.

Episodic aphemia and epileptic focus in nondominant hemisphere: relieved by section of corpus callosum.

A patient had right hemiparesis since infancy. At age 31, she had recurrent right focal motor and sensory seizures. In prolonged focal seizures, she could not speak but retained most other language-related functions. Intracarotid cerebral amytal testing demonstrated right hemisphere speech. Left intracarotid amytal injection stopped a typical attack. Complete section of the corpus callosum abolished the aphemic episodes and reduced the frequency and intensity of the focal seizures. Focal seizure activity in the left nondominant hemisphere appears to have caused restricted functional disturbance in the right dominant hemisphere.

Effects of corpus callosum section on secondary bilaterally synchronous interictal EEG discharges.

We studied the effect of corpus callosum section on secondary bilaterally synchronous interictal EEG discharges in 13 patients with partial and secondarily generalized seizures before and after partial or complete section of the corpus callosum. Bilaterally synchronous discharges were completely eliminated in one patient. In 12 patients, there was a distinct reduction in frequency. Our clinical experience agrees with experimental data to suggest that epileptic discharges follow pathways, both across the corpus callosum and/or down to diencephalic/mesencephalic structures, before there is bilateral spread.