Cluster headache: a comparison of the proportions of abnormal recordings for several derived variables in tyramine pupillometry.

Tyramine pupillometry was performed in 27 cluster headache patients and in 45 healthy controls. Asymmetry variables, i.e. symptomatic(S)-nonsymptomatic(NS) side diameter difference and the ratios (S/NS, log NS/S or S/S+NS) displayed higher sensitivities than variables which express the function of the symptomatic and the nonsymptomatic side pupil separately. Thirty percent of patients had abnormal S-NS values at maximal pupillary dilatation. The statistical properties of different ratio variables are discussed and it is concluded that the transformed ratio (log(NS/S], anisocoria (S-NS) and the anisocoria index (S/S+NS) may be superior to the conventional S/NS ratio.