SYNOPSIS The first large scale study of migraine epidemiology from a nationwide collaborative group was carried out in 22 Chinese rural and ethnic minority communities of 21 provinces of the People's Republic of China during 1985 in a well‐defined population of 246,812 inhabitants. On the day for which prevalence was calculated, January 1, 1985, there were 1703 cases of migraine, yielding a point prevalence ratio of 690/100,000. The prevalence ratio of migraine for females was higher than that for males. The overall sex difference in the prevalence ratio was significant (Z=26.57, P<0.0001), The prevalence began from the age before 10 years old, and monotonically increased until it had reached its peak at age 40–49, then decreased steadily. The geographic distribution of the prevalence has the tendency that the south is higher than the north, and the west is higher than the east. The incidence rate of new cases was 37/100,000 in 1984. The incidence rate reached its peak at age 15–19, then gradually decreased. Incidence before age 10 and after age 50 was rare. The incidence rate of migraine was higher in females than in males. Sex difference in the incidence rate was significant (Z=4.35, P<.0001}. Clinical Manifestations: In 804 cases with auras, 793 (46.56%) had visual disturbances, 11 (0.64°/o) had hemiparesis or hemiparesthesia. Concomitant nausea or vomiting occurred in 1,349 cases (79.21%). Among those 1703 cases with headache, 584 cases (34.29%) were unilateral, 791 cases (40.45%) were bilateral and 328 cases (19.26%) were uncertain. In duration of headache, 744 cases (43.69%) had less then 24 hours and 720 cases (42.28%) had 24 hours or longer. In the frequency of episodes, 818 cases (48.03%) had no more than once per month and 742 cases (43.57%) had more than once per month. Classification: There were 752 cases (44.16%) of prodromal type (classical) migraine, 929 cases (54.55%) of non‐prodromal type (common) migraine, 14 cases (0,82%) of cluster headache, 2 cases (0.12%} of hemiplegic migraine. Each of vertebrobasilar and ophthalmoplegic types had 3 cases (0.18%), Trigger Factors for Episodes: 678 cases (39.81%) were triggered by mental stress (tension, anxiety etc.), 509 cases (29.81%) by change of weather and 293 cases (20.88%) of females by menstruation.

Felbamate (2-phenyl-1,3-propanediol dicarbamate) has a favorable preclinical profile in animal models of epilepsy. We present the results of a double-blind, randomized, placebo-controlled clinical trial in patients with partial seizures. Criteria for entry included a requirement for four or more partial seizures per month despite concomitant therapeutic blood levels of phenytoin and carbamazepine. Fifty-six patients (mean age, 31.4 years; 32 men, 24 women) completed the trial. The mean seizure frequencies for the 8-week periods analyzed were felbamate = 34.9, placebo = 40.2. Felbamate was statistically superior to placebo in seizure reduction, percent seizure reduction, and truncated percent seizure reduction. The mean felbamate dosage was 2,300 mg/d. Plasma felbamate concentrations ranged from 18.4 to 51.9 mg/l, mean = 32.5 mg/l. Adverse experiences during felbamate therapy were minor and consisted primarily of nausea and CNS effects. This trial indicates that felbamate is safe and effective in the treatment of comedicated patients with severely refractory epilepsy.

The National Institutes of Health sponsored a randomized, double-blind, multicenter, placebo-controlled trial of flunarizine (FNR) in epileptic patients receiving concomitant phenytoin (PHT) or carbamazepine (CBZ). Because of FNR's long half-life (up to 7 weeks), a parallel rather than crossover design was used. Each patient received an individualized loading dose and maintenance dosage targeted at a 60-ng/ml plasma FNR concentration. Of 93 patients randomized, 92 provided seizure data for the full 25-week treatment period; one placebo-treated patient dropped out for personal reasons. Fifty-four patients received CBZ only, nine received PHT only, and 30 received both CBZ and PHT. Eighty-seven patients had a history of complex partial seizures, and 60 had secondarily generalized seizures. Eight patients discontinued FNR prematurely, all because of adverse neurologic or psychiatric signs or symptoms; depression was the specific cause in three cases. Calculated maintenance dosages, based on single-dose pharmacokinetic profiles, ranged from 7 to 138 mg/day (mean, 40 mg/day). Plasma FNR concentrations generally exceeded the target, with the highest concentrations observed immediately after loading; excluding the first three treatment weeks and all concentrations after a FNR dosage change, the median plasma FNR concentration was 71.7 ng/ml. The percent reduction from baseline seizure rate was statistically greater (p = 0.002) in the FNR-treated group (mean, 24.4%) than in the placebo-treated group (mean, 5.7%).

Twelve patients with intractable partial seizures [4 receiving carbamazepine (CBZ), 4 phenytoin (PHT), and 4 both] entered a study of the tolerability of flunarizine (FNR) at specified plasma concentrations. After an 8-week baseline period, a single-dose pharmacokinetic study was performed for each patient to calculate a loading dose and maintenance dosage necessary to achieve a target plasma FNR concentration of 30 ng/ml. The first 8 patients received the loading dose (as divided doses) during a 1-week hospitalization and the maintenance dosage for the ensuing 8 weeks. These patients proceeded to treatment periods with target concentrations of 60 and then 120 ng/ml, using doses based on an assumed linear relation between dose and plasma concentration. The last 4 patients were studied only at the 120- ng/ml target level. Results indicated that this procedure successfully approximated target levels of 30 and 60 ng/ml, but observed concentrations in the last period exceeded the 120-ng/ml target level and continued to increase with time, often necessitating a dosage reduction owing to intolerability. Calculated doses for a given target concentration varied by a factor of 12. The most frequently reported adverse experiences were sedation and increased fatigue; reports of dizziness, headache, and lethargy were also common. Based on this study, a target concentration of at least 60 but < 120 ng/ml is recommended for a controlled clinical trial of the antiepileptic efficacy of FNR.

After reaching an apparent steady state, plasma phenytoin (PHT) levels may then undergo inexplicable changes, a phenomenon called " pseudosteady state". We evaluated 13 pseudosteady -state periods in 10 inpatients with complex partial seizures. Eleven of the periods occurred after a change in PHT dosage and two after drug withdrawal. The pseudosteady -state period began 2 to 12 days (means = 5.7 days) after dosage change and lasted 5 to 10 days (means = 6.3 days), during which plasma PHT levels were stable (+/- 5%). Plasma PHT levels thereafter fluctuated spontaneously by greater than 25% for 5 to 22 days (means = 10.8 days). A final steady-state level was reached 13 to 31 days (means = 21.4 days) after the first dosage change. Falling plasma PHT levels increased seizure frequency in two patients, and a level of 52 micrograms/ml led to medication toxicity in another.