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Does anisocoria by clonidine reflect a central sympathetic dysfunction in cluster headache?
M Fanciullacci1, U Pietrini, B M Fusco
1Institute of Internal Medicine and Clinical Pharmacology, University of Florence, Italy.
Clinical Neuropharmacology
|February 1, 1988
Summary
Cluster headache (CH) patients exhibit altered pupil responses due to sympathetic nervous system defects. Tyramine and clonidine tests reveal a less active pain-side pupil, suggesting a localized sympathetic deficit in cluster headache.
Area of Science:
- Neurology
- Ophthalmology
- Pharmacology
Background:
- Cluster headache (CH) is associated with reduced pain-side sympathetic activity.
- The precise location of this sympathetic defect (central nervous system vs. peripheral neurons) remains unclear.
Purpose of the Study:
- To investigate the localization of sympathetic nervous system defects in cluster headache patients.
- To differentiate between central and peripheral sympathetic dysfunction affecting the pupil.
Main Methods:
- Administered 2% tyramine (norepinephrine releaser) and 0.10 mg clonidine (central sympathetic inhibitor) to cluster headache patients and healthy controls.
- Assessed pupillary diameter changes (mydriasis and miosis) and anisocoria (pupillary asymmetry).
- Evaluated the effect of clonidine pretreatment on tyramine-induced mydriasis in cluster headache patients.
Main Results:
- Tyramine induced asymmetric mydriasis in CH patients, with the pain-side pupil dilating less.
- Clonidine caused more pronounced bilateral miosis in CH patients than controls, especially on the pain side.
- Clonidine pretreatment enhanced tyramine-induced anisocoria in CH patients by increasing dilation only in the pain-free pupil.
Conclusions:
- Findings suggest a permanent sympathetic defect in the pain-side pupil of cluster headache sufferers.
- This defect likely involves reduced sympathetic tone in both central nervous system nuclei and peripheral neurons innervating the pupil.