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

BACKGROUND: People with cluster headache (CH) are frequently burdened by misdiagnosis or diagnostic delay. The peculiar somatic and behavioral changes characterizing patients with CH are not useful to improve diagnostic accuracy. In our clinical experience, we noticed a typical voice quality with low and croaking tone in patients with CH. In this cross‐sectional study, we evaluated, by digital voice analysis, whether it is possible to identify typical voice quality characterizing patients with CH compared with healthy controls (HCs). Furthermore, to investigate whether putative differences in voice characteristics could be underpinned by constitutional aspects or pathological processes of vocal cords, subjects underwent a videolaryngostroboscopy. Smoking habits and alcohol consumption were specifically investigated. METHODS: After conducting digital recording of the voices from both patients with CH and HCs in a soundproof insulated cabin in the laboratory of the Audiology Department, a set of voice parameters was analyzed. We included the measures of fundamental frequency, calculations of jitter and shimmer, and noise‐to‐harmonics ratios as well as quantities related to the spectral tilt (i.e., H1–H2, H1–A1, H1–A2, and H1–A3) in 20 patients with CH and in 13 HCs. A videolaryngostroboscopy was performed in all subjects. RESULTS: Patients with CH, explored during the cluster bout period, showed significantly lower second harmonic (H1–H2) values compared with HCs (−6.9 ± 7.6 vs. 2.1 ± 6.7, p = 0.002), usually characterizing the so‐called creaky voice. By using a laryngoscopy investigation, a significantly higher prevalence of mild to moderate vocal cord edema and laryngopharyngeal reflux signs were found in patients with CH (100% of patients with CH vs. 15% of HC, p < 0.001). CONCLUSION: 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.