Tremor is one of the clinical manifestations of
dystonia; however, there are no specific therapeutic trials evaluating the efficacy of treatments for dystonic
tremor (DT),
tremor associated with
dystonia or primary writing
tremor (PWT). We systematically reviewed the literature available up to July 2013 on the treatment of these
tremors and retrieved the data of 487 patients published in 43 papers detailing the effects of given interventions on
tremor severity. Treatment outcome was highly variable, depending on the specific type of intervention and
tremor distribution. No specifically designed studies were available for the treatment of
tremor associated with
dystonia. As for the other
tremors,
drug efficacy was generally disappointing and a moderate effect was only found with
anticholinergics,
tetrabenazine,
clonazepam, β-blockers and
primidone;
levodopa was only efficacious on
tremor due to
dopa-responsive dystonia. The largest amount of data was available for
botulinum toxin injections, which provided a marked improvement, particularly for the management of axial
tremors (head or vocal cords). In refractory DTs,
deep brain stimulation of several targets was attempted.
Deep brain stimulation of globus pallidus internus, thalamus or subthalamic area led to a marked improvement of dystonic axial or appendicular
tremors in most cases refractory to other treatments. Few other non-invasive treatments, for example,
orthotic device in PWT, have been used with anecdotal success. In conclusion, considering the lack of good-quality studies, future randomised controlled trials are needed. In absence of evidence-based guidelines, we propose an algorithm for the treatment of DT based on currently available data.