A total of 28 adult cases who were confirmed cysticercosis with or without cerebral involvements were treated with praziquantel at the daily dose of 3 x 25mg/kg for 3 to 7 consecutive days and was evaluated for tolerance and therapeutic effects in the trials clinically performed.The assessment of drug efficacy of praziquantel in the dermal cysticercosis was made by comparing the numbers of cysticercus nodules and histopathological findings of the biopsied parasites by means of light, scanning and transmission electron microscope. In the cerebral cysticercosis, the assessment was considered by the frequency of the episodes of convulsive seizure before and after treatment with praziquantel and by the findings of the disapearance or decreased densities of the lesions in C.T. scan in comparison with those of before and after treatment. The results were as follows: The cysticerci in the subcutaneous tissues began to disappear within one month of drug administration of 3 x 25mg/kg praziquantel over 3 to 7 days. Within 3 to 6 months most of the cysticerci had disappeared, although in some case a small number of cysticercus nodules remained even one year after treatment. Histological observation of the cysticerci biopsied at different times during the course of treatment revealed that morphological changes were already taking place within two weeks after the treatment. At the early stage of the treatment, small vacuoles were scattered along the basement layer in the tegumental syncytium of the scolex and neck regions. In the scanning electron microscopic observation, marked surface changes were present in the neck region with many bleb-like structures formed by the bursting of the large vacuoles in the tegumental syncytium. In the specimens biopsied at 2 or 5 weeks after treatment, the degenerations and necrosis of the tegumental syncytium were seen in all parts of cysticercus. In 12 cases of cerebral cysticercosis treated with praziquantel at the daily dose of 3 x 35 mg/kg for 3 or 4 consecutive days, there were no ceasing of the convulsive seizures during the 6 months follow-up. Among them 9 cases were given again the same doses of the drug for 4 or 7 days. In 7 of 9 cases, no more convulsive seizure was experienced over one or two years after the second time. At the same treatment the lesions of the brain C.T. scan disappeared, decreasd in size or calcified after treatment. In other 3 cerebral cysticercosis cases, complete cure was also obtained after the oral medication of praziquantel at the daily dose of 3 x 25 mg/kg for 7 consecutive days. In the treatment of cerebral cysticercosis with praziquantel, it was found that the concomitant oral medication of dexamethasone during the course of treatment was effective for preventing and minimizing the side-effects.
