The palmomental reflex in Parkinson's disease. Comparisons with normal subjects and clinical relevance.

We tested 356 normal subjects and 109 parkinsonian patients for the palmomental reflex. The total incidence of the reflex was 16.3% in normal subjects, increasing with age. In parkinsonian patients, the overall incidence of the reflex was 71.5%, without clear effect of age. A positive correlation was found between degree of akinesia and incidence as well as intensity of the reflex. In the dyskinetic patients, the reflex was seldom elicited, and, if so, it was small. Modifications of the characteristics of the response could be disclosed in parallel with variations of the patient's clinical status. These findings suggest that the presence of a palmomental reflex in parkinsonian patients could indirectly reflect the decrease of dopaminergic activity in the nigrostriatal pathways.