Apomorphine and levodopa challenge in patients with a focal midbrain lesion.

Three patients who presented with parkinsonian signs resulting from a focal midbrain lesion are reported. In all patients parkinsonian features occurred acutely and improved following acute challenge with apomorphine but not with levodopa. Remission of parkinsonian signs occurred spontaneously to a different degree. Inconsistent clinical response following administration of levodopa has been well documented in patients with focal midbrain lesions associated with parkinsonian signs; however, the efficacy of apomorphine has not been tested before. Anatomic or etiologic features do not allow us to predict in which cases parkinsonian signs secondary to a midbrain lesion would respond to levodopa or to dopamine agonists. A trial with apomorphine is warranted in all such cases.