The relationship between acute encephalopathy followed by permanent brain injury or death associated with further attenuated measles vaccine was evaluated in 48 children, ages 10 to 49 months, reported to the National Vaccine Injury Compensation Program, Rockville, MD. Of a total of 403 claims of encephalopathy and/or seizure disorder after measles, MR, MMR, mumps, or rubella vaccination during a 23-year period, 1970-1993, 48 met inclusion criteria, with acute encephalopathy of undetermined cause 2 to 15 days after vaccination, all following measles vaccine and none with mumps or rubella vaccine. A clustering of symptoms and peak onset of encephalopathy occurred on days 8 and 9. Fever, measles-like rash, and ataxia, associated with behavior changes and CSF pleocytosis, were the most frequent initial manifestations. Seizures occurred in 34, and rapidly progressed to coma in 29. Eight children died, and all survivors had chronic encephalopathy. The authors conclude that a causal relationship probably exists between measles vaccine and encephalopathy. 
COMMENT. A causal relationship between measles vaccination and severe and sometimes fatal encephalopathy, although rare, is cause for concern. Of 403 claims of vaccine-related encephalopathic complications, only 11% were accepted because of an arbitrary selection period of 15 days. It would be of interest to compare the numbers of cases occurring within 30 days, the selection period used in a previous report. Details of the symptoms described as ’behavior changes’ in survivors would also be of interest.
The incidence of post-infectious encephalitis complicating natural measles is estimated at 1 in 1000 cases, with a mortality of 10 to 20% and permanent CNS damage in the survivors. Thalamic syndrome and measles, and SSPE are reviewed in Ped Neur Briefs Jan 1998. The incidence of measles in the US increased in 1989-1991, especially in pre-school children with low immunization rates. With improved vaccination policies, indigenous measles since 1992 has been low, but the incidence of imported cases among immigrants or travelers returning to the US from under-developed countries has increased. A total of 1182 imported cases were reported by the CDC, 1983-1997. (Millichap, John J. Travel-related spread of disease. NWU Thesis, 1998). The importance of measles vaccination is obvious from these statistics, but the need for safer vaccines is also apparent.