Pain incidence in cervical dystonia is determined by the disease phenotype

Cervical dystonia (CD) is a movement disorder caused by prolonged contractions of the head and neck muscles resulting in abnormal postures and repetitive movements. Depending on the direction of the head and neck deviation, CD phenotypes are divided into torti-, latero-, antero-, and retro- impairments assessed in commonly used TWSTRS classification, or -caput and -collis according to the novel Col-Cap concept. Cervical pain, which pathophysiology has not been fully elucidated, affects more than 60% of CD patients. To date, none of the studies have investigated the risk of pain associated with the particular disease phenotype.

In this observational study data collection was based on the survey completion by the participants, analysis of the medical records, and physical examination with the use of proper scales (TWSTRS, Col-Cap, Tsui). Extended pain profile questionnaire included detailed questions about pain localization, character, and intensity.

We examined 60 patients suffered from CD; 66,7% of them reported cervical pain. Latero- as the only TWSTRS phenotype was associated with increased risk of pain occurrence (OR = 3,95; p < 0,05). Interestingly, each of two Col-Cap phenotypes correlated with cervical pain: -caput positively (OR = 3,78; p < 0,05) and -collis negatively (OR = 0,29; p < 0,05).

The risk of dystonic pain was highly differentiated within the particular CD phenotypes. The enhanced risk of cervical pain was observed in latero- (TWSTRS) and -caput (Col-Cap) phenotypes; conversely, -collis type (Col-Cap) was characterized by the lowest risk of cervical pain.