Head trauma in primary cranial dystonias: a multicentre case-control study.

BACKGROUND: The relationship between prior trauma and primary adult-onset dystonia is not well understood. Previous uncontrolled observations and exploratory case-control studies have yielded contradictory results.
OBJECTIVE: To analyse the association between cranial dystonia and prior head trauma.
METHODS: An ad hoc multicentre case-control study was performed using a semistructured interview to collect detailed information on the history of head trauma before disease onset in five Italian tertiary referral centres for movement disorders. The presence of a history of head trauma and of post-traumatic sequelae (loss of consciousness, bone fractures, scalp/facial wounds) before disease onset was recorded from 177 patients with primary adult-onset cranial dystonia and from 217 controls with primary hemifacial spasm matched by age strata and sex. Differences between groups were assessed by Mann-Whitney U test and Fisher's exact test, and the relationship between prior head trauma and case/control status was analysed by multivariate logistic regression models.
RESULTS: No association was found between vault/maxillofacial trauma and cranial dystonia. Most reported traumas occurred several years before disease onset. None of the main post-traumatic sequelae altered the chance of developing cranial dystonia compared with patients with primary hemifacial spasm, nor did head trauma modify the age at onset of cranial dystonia.
CONCLUSIONS: These results do not support prior head trauma as a possible environmental factor modifying the risk of developing late-onset cranial dystonia. The lack of association may have pathogenetic and medical-forensic implications.