Objective: Our aim was to report the etiology, management and outcome of patients with focal dystonia.

Background: Focal dystonia (FD) is characterized by involuntary muscle contractions in one body part. Task-specific dystonias are an important subgroup and are associated with significant functional disability.

Method: We conducted a retrospective study including patients consulting our department for FD, between 2006 and 2023, who received botulinum toxin (BTX) injections. Clinical characteristics, management and outcome were analyzed. Clinical improvement after botulinum toxin injections was assessed with the Patient Global Impression of Change Scale (PGIC-S) on follow-up and was considered significant for a PGIC-S of ≥5.

Results: Seventy-three patients were included with a sex ratio of 1,14. Mean age of onset was 40,8 [8-70] years of age. Dystonic movements involved the cervical region (spasmodic torticollis) in 36% (n=26), the eyelids (blepharospasm) in 27% (n=20), upper limbs in 10% (n=7), the oromandibular region in one patient, and vocal cords in one patient. Dystonia was task-specific in 26% (n=19). Etiologies were primary in 77% (n=56), and secondary in 33% (n=17) including a genetic cause (n=5), degenerative cause (n=9), a parenchymal lesion (n=2) and a psychogenic cause (n=1). All patients were treated with BTX injections. Mean dose was 140 U [40-470]. Significant improvement was noted in 41% (n=30) of patients with a mean time for improvement of 10 days [2-45] and a mean duration of 2 months [1-4] post injection. Patients with blepharospasm receiving pretarsal injections (n=6), had a PGIC-S of 7. Side effects were found in 19% (n=14) of patients, including local inflammation in two patients, headache in four patients and weakness in eight patients. Long term botulinum injections were necessary for all patients in order to maintain clinical improvement. Patients with task specific dystonia required higher doses of BTX (p=0,00) and exhibited more frequent side effects after injections (p=0,006) with muscle weakness in six out of nineteen patients.

Conclusion: Focal dystonias could significantly impact quality of life. Task-specific dystonias are especially hard to manage and require higher doses of BTX to relieve symptom which might result in more frequent side-effects.  

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MDS Abstracts - https://www.mdsabstracts.org/abstract/botulinum-toxin-treatment-for-focal-dystonia-in-a-tunisian-cohort/