Pupillary dynamics in Parkinson's disease

Abstract

In 24 patients with Parkinson's disease (PKD), pupillary light reflexes and sensitivities to diluted solutions of adrenergics or cholinergics were measured by means of an infrared videopupillogram. Nine patients were in the cholinergic state (pupil area (PA) decreased, constriction as well as dilatation reduced) and four in the cholinolytic state (PA increased, constriction inhibited, dilatation activated). Seven patients showed physiological dilatation (PA increased, constriction and dilatation activated); some central mechanisms were thought to contribute to this. Four patients showed normal patterns.

As the state of PKD became more severe or the duration longer, the number of patients in the cholinergic state decreased and that with other reflex patterns (cholinolytic state or physiological dilatation) increased. Supersensitivity to cholinergics was prominent in the Yahr's 2nd grade patients, although supersensitivity to adrenergics was detected only in the 3rd grade patients. Drug medication had no statistically significant influence on the pupillary characteristics. The authors presume that cholinergic supersensitivity led to the cholinergic state in the early stage and that the cholinolytic state was induced in the process of losing supersensitivity to the patients' own acetylcholine. Sympathetic denervation supersensitivity was rare in the early or middle stages. Peripheral autonomic disorders were considered to progress in parallel with central disorders in patients with PKD.

Key Words:

• Parkinson's disease
• pupillary light reflex
• parasympathetic nerve
• denervation supersensitivity