Recently extension of malignant glioma to the spinal cord (meningeal gliomatosis: MG) has been described with increasing frequency as the advancement of the therapy for brain tumor. However, the study for clinicopathological features of MG has not been established and its therapy has still been difficult. We tried to produce experimental models of MG using nude mice and study experimental immunotherapy with human monoclonal antibody (CLN-IgG MoAb). U87-SC1 human glioma cells (5 x 10(5) in 20 microliters) were inoculated transcutaneously into the cisterna magna of BALB/c nu/nu mice using a 27-gage needle. Daily weights, neurological findings and survival time were examined. MRI scan was performed after neurological deterioration and histological examination was also performed after death. CLN-IgG MoAb was used for treatment and 15 nude mice which were inoculated with tumor cells into the cisterna magna (Day 0) were divided into three groups of 5 mice each. Group A was control group which received saline into the cisterna magna, Group B and C received 50 micrograms of CLN-IgG into the cisterna magna on Day 2 or Day 7 following inoculation of tumor cells. Efficacy of experimental immunotherapy was statistically evaluated by the difference of median survival time (MST) among three groups. All of the nude mice lost weight within 4 or 5 days after inoculation of tumor cells and developed paraplegia or tetraplegia with incontinence and died. MRI of the nude mice which showed neurological deteriorations revealed ventricular dilatation, infiltration of tumor cells to the spinal cord and spread of tumor cells into the subarachnoid space.(ABSTRACT TRUNCATED AT 250 WORDS)