Pupillary autonomic dysfunction in multiple system atrophy and Parkinson's disease: an assessment by eye-drop tests

To compare pupillary autonomic dysfunction in multiple system atrophy (MSA) and Parkinson's disease (PD).

We administered eye-drop tests to 40 MSA patients, 40 PD patients with similar disease duration, and 20 age-matched healthy controls. Pupillary supersensitivity to a parasympathomimetic agent (0.05% pilocarpine hydrochloride) and to a sympathomimetic agent (0.02% dipivefrine hydrochloride) was examined by assessing changes in pupil diameter.

Pupillary supersensitivity to a parasympathomimetic agent (0.05% pilocarpine hydrochloride) and to a sympathomimetic agent (0.02% dipivefrine hydrochloride) was examined by assessing changes in pupil diameter. Pupillary supersensitivity to 0.05% pilocarpine was greatest among the PD patients (PD -23.1 +/- 14.4%, MSA -12.4 +/- 11.5%, control -9.5 +/- 8.2%, p < 0.05) but was not correlated with disease duration. Pupillary sensitivity to 0.02% dipivefrine was significantly greater in the PD and MSA patients versus controls (PD 10.5 +/- 12.0%, MSA 11.8 +/- 11.0%, control 3.1 +/- 5.8%, p < 0.05). MSA patients had pupillary sympathetic dysfunction from an early stage, whereas in PD patients it tended to gradually accelerate as the disease advanced. In MSA patients, pupillary sympathetic sensitivity to 0.02% dipivefrine was correlated with the severity of orthostatic hypotension during a head-up tilt test and with the elevation of systolic blood pressure during a noradrenaline infusion test. In PD patients, pupillary sympathetic sensitivity to 0.02% dipivefrine was correlated with a reduction of the heart-to-mediastinum (H/M) ratio using delayed-phase iodine-123 meta-iodobenzylguanidine ((123)I-MIBG) myocardial scintigraphy.

These data indicate that eye-drop tests can reveal differences in the progression of pupillary autonomic dysfunction in patients with MSA and PD.