Lower limb involvement in adult‐onset primary dystonia: frequency and clinical features

Background and purpose: Despite the growing number of reports describing adult‐onset primary lower limb dystonia (LLD) this entity has never been systematically evaluated in the general population of patients with primary adult‐onset dystonia. Methods: From outpatients with adult‐onset primary dystonia attending nine Italian University centres for movement disorders we consecutively recruited 579 patients to undergo a standardized clinical evaluation. Results: Of the 579 patients assessed, 11 (1.9%) (8 women, 3 men) had LLD, either alone (n = 4, 0.7%) or as part of a segmental/multifocal dystonia (n = 7, 1.2%). The age at onset of LLD (47.9 ± 17 years) was significantly lower than the age at onset of cranial dystonias (57.9 ± 10.7 years for blepharospasm, and 58.9 ± 11.8 years for oromandibular dystonia) but similar to that of all the other adult‐onset primary dystonias. The lower limb was either the site of dystonia onset (36.4%) or the site of dystonia spread (63.6%). In patients in whom LLD was a site of spread, dystonia seemed to spread following a somatotopic distribution. Only one patient reported a recent trauma involving the lower limb whereas 36.4% of the patients reported pain at the site of LLD. Only 64% of our patients needed treatment for LLD, and similarly to previously reported cases, the most frequently tried treatments was botulinum toxin and trihexyphenidyl. Conclusion: The lower limb is an uncommon but possible topographical site of dystonia in adulthood that should be kept in consideration during clinical evaluation.