Abstract
We studied rhesus monkeys with hemiparkinsonism or bilateral parkinsonism produced by unilateral or bilateral intracarotid administration of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine. Using a standardized clinical rating scale, 4 hemiparkinsonian monkeys showed a 13 to 56% (mean, 36%) spontaneous improvement during an obsevation period of up to 25 weeks. Generally, recovery leveled off after 14 weeks. Four bilaterally parkinsonian monkeys showed a 5 to 42%(mean, 22percnt;) improvement over a period of up to 30 weeks. Our findings emphasize that spontaneous recovery is a potentially confounding characteristic of this monkey model when used for assessing novel antiparkinsonian therapies.