Enlarging the spectrum of cluster headache: Extracranial autonomic involvement revealed by voice analysis.

Creaky phonation is a "physiological mode of laryngeal operation" usually underpinned by shortened and thickened vocal folds. Creaky voice phonation can be due to a vocal fold's reduced capability to become slack or flaccid secondary to vocal cord edema underpinned by laryngopharyngeal reflux affecting the phonatory mechanisms in patients with CH. The laryngopharyngeal reflux may represent a dysautonomic sign related to the increased parasympathetic tone during in-bout period, reinforcing the hypothesis of an extracranial autonomic dysfunction as part of CH clinical picture.