Autonomic dysfunction and sleep apnea in olivopontocerebellar degeneration.

We studied ten men with olivopontocerebellar degeneration. Our findings of the autonomic deficits as manifested by orthostatic hypotension, impaired Valsalva's response, abnormal findings on cold pressor and mental arithmetic tests, and plasma renin and norepinephrine abnormalities in some patients with olivopontocerebellar degeneration suggested a defective central control of the sympathetic nervous system. Five patients had sleep apnea. Autonomic dysfunction and sleep apnea in olivopontocerebellar degeneration may result from degenerative lesions in the cerebellum and the brain stem.

Tiagabine therapy for complex partial seizures. A dose-frequency study. The Tiagabine Study Group.

OBJECTIVE: To evaluate the efficacy and safety of 2 regimens of tiagabine as add-on therapy for patients with complex partial seizures (CPSs) that are refractory to other treatment. DESIGN: Randomized, double-blind, placebo-controlled, add-on, parallel-group trial with an 8-week baseline period, 12-week experimental period (4 weeks of dose titration and 8 weeks of fixed-dose therapy), and 4-week termination period. SETTING: Twenty-six centers throughout the United States. PATIENTS: Three hundred fifty-one patients were enrolled, 318 were entered in the double-blind period, and 271 completed the study. INTERVENTIONS: Tiagabine, 16 mg 2 times per day (106 patients); tiagabine, 8 mg 4 times daily (105 patients); and placebo (107 patients). The doses of tiagabine were titrated in 3 steps to the fixed dose. MAIN OUTCOME MEASURE: The median change in the 4-week rate of CPSs from baseline to experimental period. RESULTS: The median change from baseline was -1.6 CPSs per 4 weeks in the group of patients who were given tiagabine 2 times per day, and it was -1.2 CPSs in the group of patients who were given tiagabine 4 time per day (P = .06 and P = .02, respectively, compared with placebo). The 4-week seizure frequency was reduced by 50% or more in 31% of the patients who were given tiagabine 2 times per day and in 27% of the patients who were given tiagabine 4 times per day vs 10% of the placebo-treated patients (P < or = .001 for each tiagabine-treated group compared with the placebo group). The most frequent adverse events involved the central nervous system and occurred in comparable proportions in the 3 treatment groups. Similar proportions of patients discontinued the study prematurely for adverse events. CONCLUSIONS: Tiagabine administered 2 and 4 times daily as add-on pharmacotherapy was effective in reducing CPSs in patients with epilepsy whose conditions were refractory to treatment with other antiepileptic agents, and it was well tolerated.

Challenging our past paradigm in the management of epilepsy.

Trial designs of antiepileptic drugs have been reviewed. Add-on trials that were used to obtain marketing approval for many of the new antiepileptic drugs provide useful information but have definite limitations. The new monotherapy trial designs offer greater promise both in the provision of safety and efficacy information for registration purposes as well as the clinical use of these new agents to physicians.

Neurophysiologic study of olivopontocerebellar atrophy with or without glutamate dehydrogenase deficiency.

By neurophysiologic investigations, we evaluated 20 patients with olivopontocerebellar atrophy (OPCA), comprising 8 with glutamate dehydrogenase (GDH) deficiency and 12 with normal GDH activity. We found sensorimotor, predominantly sensory axonal neuropathy distally in the legs, and peripheral auditory nerve dysfunction (prolonged wave I but normal interpeak latencies in brainstem auditory evoked response) in GDH-deficient patients. These findings seem distinctive enough to serve as the electrophysiologic marker for diagnosis and monitoring of treatment and progression of the disease. The pattern-reversal visual and median nerve somatosensory evoked responses did not differ among the patients and controls.

Rapid initiation of gabapentin: a randomized, controlled trial.

OBJECTIVE: To compare the tolerability of two different dose-initiation regimens of gabapentin for the adjunctive treatment of partial seizures. BACKGROUND: Patient compliance is a key feature of successful outpatient pharmacologic therapy for epilepsy, and one aspect of compliance is simplicity of initiation. By using a rapid titration rate, leading to a rapid therapeutic gabapentin dose, perhaps there could be an improvement with compliance. METHODS: Male or female patients, at least 12 years old, with a recent history of partial seizures with or without secondary generalization, were randomized to receive gabapentin (following a blinded placebo period of an undisclosed number of days) as either a Slow initiation (300 mg day 1, 600 mg day 2, then 900 mg/day) or a Rapid initiation (900 mg/day immediately following the placebo lead-in). RESULTS: Starting gabapentin therapy at an initial therapeutic dosage of 900 mg/day is well tolerated by patients with epilepsy and is as safe as initiating with a titration schedule over 3 days. Of the four most common adverse events (somnolence, dizziness, ataxia, fatigue), only one, dizziness, occurred more often in the nontitrated (Rapid initiation) group than in the titrated (Slow initiation) group. CONCLUSION: Initiation of gabapentin at 900 mg/day is as well tolerated as is a 3-day titration, except for a higher incidence of dizziness.

A double-blind, randomized trial of topiramate in Lennox-Gastaut syndrome. Topiramate YL Study Group.

OBJECTIVE: To evaluate the efficacy and safety of topiramate as adjunctive therapy for Lennox-Gastaut syndrome in a multicenter, double-blind, placebo-controlled trial. BACKGROUND: Conventional antiepileptic drugs are frequently ineffective against multiple-seizure types of Lennox-Gastaut syndrome. METHODS: Ninety-eight patients >1 year to <30 years of age, with slow spike-and-wave patterns on EEG, seizure types including drop attacks, and either a history of or active atypical absence seizures, were assigned to an 11-week, double-blind treatment phase with either topiramate or placebo. Topiramate was titrated to target doses of approximately 6 mg/kg/d. RESULTS: For drop attacks, the most severe seizures associated with this syndrome, the median percentage reduction from baseline in average monthly seizure rate was 14.8% for the topiramate group and -5.1% (an increase) for the placebo group (p = 0.041). Topiramate-treated patients demonstrated greater improvement in seizure severity than did placebo-treated patients based on parental global evaluations (p = 0.037). The percentage of patients with a > or = 50% reduction from baseline in major seizures (drop attacks and tonic-clonic seizures) was greater in the topiramate group (15/46 or 33%) than in the control group (4/50 or 8%; p = 0.002). The most common adverse events in both groups were CNS related; there were no discontinuations from topiramate therapy due to adverse events. CONCLUSIONS: Topiramate adjunctive therapy was effective in reducing the number of drop attacks and major motor seizures and in improving seizure severity as determined by parental global evaluation.

Pathology of olivopontocerebellar atrophy with glutamate dehydrogenase deficiency.

We report the neuropathologic findings in the first patient with recognized glutamate dehydrogenase (GDH) deficiency to come to postmortem examination. He had progressive cerebellar ataxia beginning at age 21. He died at age 47 of pulmonary emboli. Postmortem examination revealed pancerebellar, olivary, and mild pontine atrophy, demyelination of the posterior columns, degeneration of anterior horn and dorsal root ganglion cells, and reduction of myelinated fibers in the sural nerve. In addition, there was neuronal storage of lipopigment diffusely throughout the CNS and the autonomic neurons, with cell distention, atrophy, and loss in selected areas.

Oxcarbazepine (Trileptal) as monotherapy in patients with partial seizures.

OBJECTIVE: To evaluate the efficacy and safety of oxcarbazepine (OXC) as monotherapy for patients with uncontrolled partial seizures. METHODS: A multicenter, double-blind, randomized, parallel-group, dose-controlled monotherapy trial compared OXC at 2400 mg/day with OXC at 300 mg/day in patients with uncontrolled partial-onset seizures previously receiving carbamazepine (CBZ) monotherapy. During a 28-day open-label conversion phase, patients were tapered off CBZ and titrated to OXC 2400 mg/day. After a 56-day open-label baseline phase on OXC 2400 mg/day, patients entered a 126-day double-blind treatment phase in which they were randomized to continue OXC at 2400 mg/day or were down titrated over 6 weeks to OXC at 300 mg/day. Patients met the efficacy endpoint by completing the double-blind treatment phase or by meeting one of four predefined exit criteria. The primary efficacy variable was time to meeting one of the exit criteria. The secondary efficacy variable was the percentage of patients meeting one of the exit criteria in each of the two treatment groups. RESULTS: Of the 143 patients enrolled, 96 were randomized in the double-blind treatment phase. Time to meeting an exit criterion was significantly in favor of the OXC 2400 mg/day group (p = 0.0001). The median time to meeting an exit criterion was 68 days for the OXC 2400 mg/day Group and 28 days for the OXC 300 mg/day Group. In addition, the percentage of patients meeting one of the exit criteria was significantly lower for the OXC 2400 mg/day Group (p = 0.0001). Overall, OXC was well tolerated with the most common adverse events consisting of fatigue, nausea, ataxia, and headache. CONCLUSION: This trial demonstrated that OXC at 2400 mg/day is well tolerated and efficacious when administered as monotherapy in patients with uncontrolled partial onset seizures.

Oxcarbazepine monotherapy for partial-onset seizures: a multicenter, double-blind, clinical trial.

OBJECTIVE: To evaluate the safety and efficacy of oxcarbazepine (OXC) 2,400 mg/day versus OXC 300 mg/day monotherapy in patients with medically refractory partial epilepsy. BACKGROUND: OXC is primarily metabolized by reductase enzymes and, consequently, has a low propensity to inhibit or induce oxidative enzymes and a minimal potential for drug-drug interactions. The efficacy of OXC as monotherapy was shown in several comparative trials in patients with newly diagnosed epilepsy and in hospitalized patients undergoing evaluation for epilepsy surgery. METHODS: A multicenter, double-blind, randomized, parallel-group trial design was chosen to assess the antiepileptic efficacy of OXC as monotherapy in a refractory epilepsy patient population. Outpatients aged 12 years or older with inadequately controlled partial seizures, with or without secondarily generalized seizures, were enrolled. Patients finished the trial by completing the double-blind phase or by meeting one of four predefined exit criteria: a twofold increase in partial seizure frequency in any 28-day period relative to baseline; a twofold increase in the highest consecutive 2-day partial seizure frequency relative to baseline; occurrence of a single generalized seizure if none occurred during the 6 months prior to randomization; or prolongation or worsening of generalized seizure duration or frequency requiring intervention. Adverse events (AEs), vital signs, and clinical laboratory tests were evaluated. RESULTS: The percentage of patients meeting one of the exit criteria was significantly lower (p < 0.0001) for the OXC 2400 mg/day group (14/34; 41%) than the OXC 300 mg/day group (42/45; 93%). In addition, there was a significant difference in time to exit in favor of the OXC 2400 mg/day group (p = 0.0001). In the intent-to-treat analysis, 12% of patients in the OXC 2400 mg/day group were seizure-free compared with none in the 300 mg/day group. OXC was well-tolerated, with dizziness, fatigue, somnolence, and nausea being the most frequent AEs. Most of these AEs were transient and rated as mild to moderate in intensity. CONCLUSION: OXC is safe and effective in the treatment of patients with partial epilepsy previously receiving treatment with other antiepileptic drugs. The results of this trial are consistent with previous monotherapy trials with OXC.

Double-blind randomized trial of tramadol for the treatment of the pain of diabetic neuropathy.

OBJECTIVE: The objective of this study was to evaluate the efficacy and safety of tramadol in treating the pain of diabetic neuropathy. BACKGROUND: The pain of diabetic neuropathy is a major cause of morbidity among these patients and treatment, as with other small-fiber neuropathies, is often unsatisfactory. Tramadol is a centrally acting analgesic for use in treating moderate to moderately severe pain. METHODS: This multicenter, outpatient, randomized, double-blind, placebo-controlled, parallel-group study consisted of a washout/screening phase, during which all analgesics were discontinued, and a 42-day double-blind treatment phase. A total of 131 patients with painful diabetic neuropathy were treated with tramadol (n=65) or placebo (n=66) tramadol, which were administered as identical capsules in divided doses four times daily. The primary efficacy analysis compared the mean pain intensity scores in the tramadol and placebo groups obtained at day 42 of the study or at the time of discontinuation. Secondary efficacy assessments were the pain relief rating scores and a quality of life evaluation based on daily activities and sleep characteristics. RESULTS: Tramadol, at an average dosage of 210 mg/day, was significantly (p < 0.001) more effective than placebo for treating the pain of diabetic neuropathy. Patients in the tramadol group scored significantly better in physical (p=0.02) and social functioning (p=0.04) ratings than patients in the placebo group. No statistically significant treatment effects on sleep were identified. The most frequently occurring adverse events with tramadol were nausea, constipation, headache, and somnolence. CONCLUSIONS: The results of this placebo-controlled trial showed that tramadol was effective and safe in treating the pain of diabetic neuropathy.

Follow-up study of risk factors in progressive supranuclear palsy.

The cause of progressive supranuclear palsy (PSP) is not known and has been little studied. The one previous controlled epidemiologic survey, performed at our center in 1986, found small-town experience and greater educational attainment as PSP risks, but, in retrospect, these results may have been produced by ascertainment bias. Since that time, several anecdotal reports have implicated heredity and various environmental exposures in the cause of some cases of PSP. To clarify the results of the previous study and to evaluate the more recently implicated candidate factors in a controlled fashion, we mailed a validated 69-item questionnaire to 91 personally examined patients with PSP and 104 unmatched controls with other neurologic conditions for which they had been referred to our tertiary neurologic center. We were able to match 75 subjects from each group by year of birth, sex, and race and subjected them to a separate matched-pair analysis. We allowed surrogates to supply any or all of the responses. Questions concerned hydrocarbon, pesticide, and herbicide exposure; urban/rural living; auto repair and other occupations; head trauma; educational attainment; maternal age; and family history of PSP, parkinsonism, dementia, and other neurologic conditions. A statistically significant finding was that patients with PSP were less likely to have completed at least 12 years of school (matched odds ratio = 0.35, 95% CI = 0.12-0.95, p = 0.022; unmatched odds ratio = 0.44, 95% CI = 0.21-0.89, p = 0.020). We hypothesize that this result may be a proxy for poor early-life nutrition or for occupational or residential exposure to an as-yet unsuspected toxin. Future studies should examine these potential risk factors in PSP.

Felbamate monotherapy for partial-onset seizures: an active-control trial.

We evaluated felbamate (FBM) monotherapy in 111 patients with uncontrolled partial-onset seizures in a multicenter, double-blind, parallel-group trial. During the 56-day baseline period, patients had at least eight partial-onset seizures and received one standard antiepileptic drug (AED) at a therapeutic level; a second AED was allowed if at a subtherapeutic level. Patients received either FBM 3,600 mg/d or valproate (VPA) 15 mg/kg/d. The baseline AED at therapeutic levels was discontinued by one-third decrements on study days 1, 14, and 28 and the sub-therapeutic AED, if any, was discontinued completely on study day 1. Study endpoints were completion of 112 study days or fulfilling one or more escape criteria. Criteria for escape relative to baseline were (1) twofold increase in monthly seizure frequency, (2) twofold increase in highest 2-day seizure frequency, (3) single generalized tonic-clonic seizure (GTC) if none occurred during baseline, or (4) significant prolongation of GTCs. The primary efficacy variable was the number of patients in each treatment group who met escape criteria. Thirty-seven patients on VPA and 18 on FBM met escape criteria (p < 0.001). Even when we considered FBM dropouts to have fulfilled escape criteria and VPA dropouts to have completed the 112-day trial, the treatment difference remained statistically significant (p = 0.039) in favor of FBM. Adverse experiences with FBM were all mild or moderate in severity. The frequency of adverse experiences was much lower during monotherapy. FBM monotherapy was effective in the treatment of partial-onset seizures with or without secondarily generalized seizures and demonstrated a favorable safety profile.

Adjunctive therapy with oxcarbazepine in children with partial seizures. The Oxcarbazepine Pediatric Study Group.

OBJECTIVE: To evaluate the safety and efficacy of oxcarbazepine (OXC) as adjunctive therapy in children with inadequately controlled partial seizures on one or two concomitant antiepileptic drugs (AEDs). BACKGROUND: OXC has shown antiepileptic activity in several comparative monotherapy trials in newly diagnosed patients with epilepsy, and in a placebo-controlled monotherapy trial in hospitalized patients evaluated for epilepsy surgery. DESIGN: A total of 267 patients were evaluated in a multicenter, randomized, placebo-controlled trial consisting of three phases: 1) a 56-day baseline phase (patients maintained on their current AEDs); 2) a 112-day double-blind treatment phase (patients received either OXC 30-46 mg/kg/day orally or placebo); and 3) an open-label extension phase. Data are reported only from the double-blind treatment phase; the open-label extension phase is ongoing. METHODS: Children (3 to 17 years old) with inadequately controlled partial seizures (simple, complex, and partial seizures evolving to secondarily generalized seizures) were enrolled. RESULTS: Patients treated with OXC experienced a significantly greater median percent reduction from baseline in partial seizure frequency than patients treated with placebo (p = 0.0001; 35% versus 9%, respectively). Forty-one percent of patients treated with OXC experienced a > or =50% reduction from baseline in partial seizure frequency per 28 days compared with 22% of patients treated with placebo (p = 0.0005). Ninety-one percent of the group treated with OXC and 82% of the group treated with placebo reported > or =1 adverse event; vomiting, somnolence, dizziness, and nausea occurred more frequently (twofold or greater) in the group treated with OXC. CONCLUSION: OXC adjunctive therapy administered in a dose range of 6 to 51 mg/kg/day (median 31.4 mg/kg/day) is safe, effective, and well tolerated in children with partial seizures.

Topiramate. Clinical profile in epilepsy.

Topiramate, a sulfamate-substituted monosaccharide, is a new antiepileptic drug (AED) approved as adjunctive therapy for partial-onset seizures in adults. Topiramate is rapidly absorbed, has linear pharmacokinetics, minimal protein binding and a long half-life facilitating a twice-daily dosage regimen. Topiramate has little effect on the plasma concentrations of other AEDs with the exception of phenytoin, concentrations of which may increase in some patients when topiramate is added to the therapy. Topiramate metabolism is increased when administered with carbamazepine or phenytoin. In the absence of enzyme-inducing AEDs, topiramate is eliminated primarily by renal excretion, with 50 to 80% of a dose excreted as unchanged topiramate. In 6 double-blind, placebo-controlled trials, topiramate was shown to be well tolerated and effective as adjunctive therapy for partial-onset seizures in adults. Topiramate consistently reduced seizures across all patient groups defined by age, gender and baseline seizure frequency. Adverse effects were generally mild-to-moderate CNS-related effects and often resolved spontaneously or with slowing of topiramate titration and/or reduction of the dosage of concomitant AEDs. Clinical studies are currently evaluating the effectiveness and safety of topiramate as monotherapy and adjunctive therapy in children with partial seizures, in patients with Lennox-Gastaut syndrome and in patients with generalised tonic-clonic seizures of non-focal onset. Preliminary findings suggest that topiramate has a broad spectrum of clinical use.

Evaluation of the potential interaction between felbamate and erythromycin in patients with epilepsy.

Effects of erythromycin on hepatic CYP450 3A4 isozymes can profoundly influence the metabolism of many therapeutic agents. An open-label, randomized, two-period, crossover study was therefore conducted to evaluate the pharmacokinetics of felbamate before and after a concurrent 10-day regimen (333 mg three times daily) of erythromycin. Patients were receiving either 3,000 or 3,600 mg/day felbamate monotherapy for treatment of epilepsy. Mean dose-normalized values for maximum concentration (Cmax) and area under the concentration-time curve (AUC tau) of felbamate were not statistically different in patients taking felbamate as monotherapy than in patients after erythromycin coadministration. Estimates of time to Cmax (tmax), minimum concentration (Cmin), apparent clearance (Cl/kg), average concentration (Cav), and degree of fluctuation (DFss) were likewise unchanged. The incidence of mild and moderate adverse events increased during coadministration of the two drugs. Because patients with epilepsy can not be treated with erythromycin alone, it could not be determined whether the adverse events were attributable to erythromycin or to the combination of the two drugs. Steady-state pharmacokinetic parameters of felbamate were not influenced by erythromycin coadministration.

Topiramate efficacy in infancy.

Topiramate is a sulfamate-substituted monosaccharide that has demonstrated efficacy as an antiepileptic drug in adults with partial onset seizures. Experience in children has been limited, but early reports have supported its safety and effectiveness in children as young as 2 years of age. In two infants ages 12 and 9 months, respectively, with partial seizures, the authors report excellent efficacy with good tolerability at doses up to 7.7 mg/kg. Although long-term safety and possible adverse sequelae have not been fully established in children, topiramate may represent an option for infants with high seizure frequency unresponsive to standard antiepileptic drugs.

Rufinamide for generalized seizures associated with Lennox-Gastaut syndrome.

BACKGROUND: Lennox-Gastaut syndrome is a catastrophic pediatric epilepsy syndrome characterized by multiple types of treatment-resistant seizures and high rates of seizure-related injury. Current available treatments are inadequate, leaving patients with few treatment options and opportunities. METHODS: We conducted a double-blind, randomized, placebo-controlled trial of the antiepileptic drug rufinamide in patients with Lennox-Gastaut syndrome. Eligible patients between 4 and 30 years of age had multiple types of seizures (including tonic-atonic and atypical absence seizures) with a minimum of 90 seizures in the month before baseline and a recent history of a slow spike-and-wave pattern on EEG. RESULTS: After a 28-day baseline period, 139 eligible patients were randomized; 138 patients received either rufinamide (n = 74) or placebo (n = 64) in addition to their other antiepileptic drugs. The median percentage reduction in total seizure frequency was greater in the rufinamide therapy group than in the placebo group (32.7% vs 11.7%, p = 0.0015). There was a difference (p < 0.0001) in tonic-atonic ("drop attack") seizure frequency with rufinamide (42.5% median percentage reduction) vs placebo (1.4% increase). The rufinamide group had a greater improvement in seizure severity (p = 0.0041) and a higher 50% responder rate compared with placebo for total seizures (p = 0.0045) and tonic-atonic seizures (p = 0.002). The common adverse events (reported by >or=10% of patients receiving rufinamide) were somnolence (24.3% with rufinamide vs 12.5% with placebo) and vomiting (21.6% vs 6.3%). CONCLUSIONS: Rufinamide was an effective and well-tolerated treatment for seizures associated with Lennox-Gastaut syndrome.

Randomized, multicenter, dose-ranging trial of retigabine for partial-onset seizures.

OBJECTIVE: To evaluate the efficacy and safety of retigabine 600, 900, and 1,200 mg/day administered three times daily as adjunctive therapy in patients with partial-onset seizures. METHODS: A multicenter, randomized, double-blind, placebo-controlled trial was performed. After an 8-week baseline phase, patients were randomized to a 16-week double-blind treatment period (8-week forced titration and 8-week maintenance) followed by either tapering or entry into an open-label extension study. Primary efficacy was the percentage change from baseline in monthly seizure frequency and compared across treatment arms. Secondary efficacy comparisons included the proportion of patients experiencing >/=50% reduction in seizure frequency (responder rate), emergence of new seizure types, and physician assessment of global clinical improvement. Safety/tolerability assessments included adverse events (AEs), physical and neurologic examinations, and clinical laboratory evaluations. Efficacy analyses were performed on the intent-to-treat population. RESULTS: Of the 399 randomized patients, 279 (69.9%) completed the double-blind treatment period. The median percent change in monthly total partial seizure frequency from baseline was -23% for 600 mg/day, -29% for 900 mg/day, and -35% for 1,200 mg/day vs -13% for placebo (p < 0.001 for overall difference across all treatment arms). Responder rates for retigabine were 23% for 600 mg/day, 32% for 900 mg/day (p = 0.021), and 33% for 1,200 mg/day (p = 0.016), vs 16% for placebo. The most common treatment-emergent AEs were somnolence, dizziness, confusion, speech disorder, vertigo, tremor, amnesia, abnormal thinking, abnormal gait, paresthesia, and diplopia. CONCLUSION: Adjunctive therapy with retigabine is well tolerated and reduces the frequency of partial-onset seizures in a dose-dependent manner.

Magnetic stimulation in the diagnosis of lumbosacral radiculopathy.

Five patients presenting with sensory-motor disturbances consistent with a clinical diagnosis of L5 or S1 radiculopathy were studied. All had conventional nerve conduction tests and electromyography. The lumbosacral roots were stimulated in the lumbosacral region by using the Cadwell MES-10 Magneto-electric stimulator. The compound muscle action potentials were recorded bilaterally by surface electrodes applied to the soleus and tibialis anterior muscles. The latencies to the affected muscles were significantly prolonged. The appropriate root dysfunction was confirmed at operation or by the imaging techniques. It was concluded that surface stimulation of the lumbosacral roots by a magnetic coil is a potentially useful technique for the non-invasive evaluation of the function of the lumbosacral roots.

Felbamate monotherapy: controlled trial in patients with partial onset seizures.

Felbamate (FBM) monotherapy was evaluated in 44 patients with uncontrolled partial onset seizures in a unique, single-center, randomized, double-blind, parallel-group trial. During the 56-day baseline period, patients were required to have at least 8 seizures and to be receiving only one standard antiepileptic drug (AED) at a therapeutic level; a second AED was allowed if at a subtherapeutic level. Patients were randomized to valproate (VPA), 15 mg/kg, or to FBM, 3,600 mg/day. In the treatment phase, previous AEDs were discontinued by study day 28 (by one-third decrements on study days 1, 14, and 28). Study end points were completion of 112 study days or the fulfilling of escape criteria. Criteria for escape relative to baseline were: two-fold increase in monthly seizure frequency, two-fold increase in highest 2-day seizure frequency, single generalized tonic-clonic seizure (GTC) if none occurred during baseline, or significant prolongation of GTCs. The predetermined primary efficacy variable was the number of patients escaping in each treatment group. Nineteen patients on VPA and 3 on FBM met escape criteria (p less than 0.001, chi-square test). When overall seizure frequency among study completers was compared with baseline, the FBM group had a 50 to 65% reduction in seizure frequency. FBM adverse experiences were all mild or moderate in severity, and the incidence of adverse experiences was lower in monotherapy. FBM monotherapy was effective in the treatment of partial onset seizures with or without generalization and demonstrated a favorable safety profile.