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[Pupillometry in Menière's disease]
1Instituto di Clinica Otorinolaringoiatrica, Universita di Modena, Italy.
Abstract:
The autonomic dysfunction is one of the etiopathogenetic hypothesis of Ménière's disease. We have already described the presence of an anomalous pupillary contraction, induced by methacholine, during the attack stage of Ménière's disease, without cardio-vascular reflexes involving. We have now employed, in a larger number of cases, a new digital equipment with infrared lighting system, built by us. The pupillary area was measured in darkness by a personal computer in basal condition (time 0) and 10, 20, 30, 45, 60 minutes after methacholine instillation. We have observed 16 cases of Ménière's disease (during attack stage and free stage), 23 cases of other vertiginous disorders (during attack stage and free strage), 10 normal subjects (5 cases of these also during a caloric test). The pupillary contraction was always highest at 30 minutes after methacholine administration. Normal subjects didn't show anisocoria and the contraction was weak and symmetric. Caloric test modified only a little the pupillary response. We observed the same results in other vertiginous disorders. During free stage of Ménière's disease there was little basal anisocoria but the contraction was normal and symmetric. During attack stage of Ménière's disease the contraction was much more evident and higher on the affected side. Ménière's disease crisis is characterized by cholinergic pupillary hyperreactivity, that is not caused by labyrinthic reflexes. We suppose this autonomic dysfunction of central origin.
Insights
Ménière's disease attacks involve abnormal pupil responses to methacholine, indicating autonomic dysfunction. This cholinergic pupillary hyperreactivity, more pronounced on the affected side during attacks, suggests a central origin, not labyrinthine reflexes.
Area of Science:
- Neurology
- Ophthalmology
- Autonomic Nervous System Research
Context:
- Ménière's disease is hypothesized to involve autonomic dysfunction.
- Previous studies noted anomalous pupillary contraction during Ménière's attacks without cardiovascular involvement.
- A new digital infrared pupillography system was utilized for precise measurements.
Purpose:
- To investigate pupillary response to methacholine in Ménière's disease patients during attack and free stages.
- To compare these responses with other vertiginous disorders and healthy controls.
- To explore the potential central origin of autonomic dysfunction in Ménière's disease.
Summary:
- Pupillary area was measured post-methacholine instillation in 16 Ménière's disease cases, 23 other vertiginous disorder cases, and 10 controls.
- Ménière's disease attacks showed significantly higher and asymmetric pupillary contraction at 30 minutes, indicative of cholinergic hyperreactivity.
- This hyperreactivity, observed during attacks and not solely due to labyrinthine reflexes, supports a central autonomic dysfunction hypothesis.
Impact:
- The findings suggest cholinergic pupillary hyperreactivity is a key characteristic of Ménière's disease crises.
- This autonomic dysfunction appears to be of central origin, differentiating it from labyrinthine-induced responses.
- The study provides objective, quantifiable evidence for autonomic involvement in the pathophysiology of Ménière's disease.