Primary cervical dystonia and scoliosis: a multicenter case-control study

To study the distribution of prior scoliosis among patients with primary adult-onset cervical dystonia (CD) and matched control subjects.

Case and control subjects were selected among consecutive outpatients attending four Italian centers. Control outpatients were matched for age (+/-5 years), sex, and referral center. Information on prior scoliosis, other spine diseases, and family history of dystonia was obtained by a standardized questionnaire and supported by medical records. Conditional logistic regression models were used to adjust simultaneously for age, disease duration, and education level and to determine the independent association of exposure variables with the outcome.

Prior scoliosis developing in middle or late childhood or at around the puberty occurred more frequently among 72 case patients than among 144 neurologic control subjects. No subject reported conditions considered to be responsible for secondary scoliosis. The association of scoliosis and CD was not confounded by age, duration of disease, education level, other spine diseases, or family history of dystonia (adjusted odds ratio [OR] 6.8; 95% CI 1.5 to 29.5; p = 0.011). The OR of family history of dystonia (18.7; 95% CI 2.4 to 147.5; p = 0.005) fell to 11.7 (95% CI 1.3 to 103; p = 0.03) after controlling for scoliosis.

Prior scoliosis may increase the risk of developing CD. The observed decrease in the magnitude of the association between family history of dystonia and CD after controlling for scoliosis suggests a link between the two conditions.