Treatment of generalized dystonia

Abstract

The armamentarium for clinicians treating patients with generalized dystonia, previously restricted to only a few oral medications that often caused intolerable side effects, has been radically expanded in the past decade with the widespread application of deep brain stimulation (DBS). With DBS, patients who in the past would have been restricted to a life of severe motor disability from a young age can now lead lives with only minimal symptoms. Although DBS should therefore be considered as a treatment option for any patient with severe, medically refractory dystonia, important questions remain about patient selection, including what factors predict which patients will benefit from DBS, and when in the course of disease DBS should be performed. Reports show that patients with primary dystonia respond better than those with secondary dystonia, and limb and axial muscles may improve more than cranial dystonia. Some studies also suggest that shorter duration of disease may be associated with better outcomes. However, it is important to note that even among those thought to respond best to DBS, i.e. patients with primary generalized dystonia, there is a subset that will have significant and sustained clinical benefit with oral medications. It is therefore important that adequate trials of oral medications be attempted prior to referral for surgery. On the other hand, once it is clear that medical therapies are not providing significant benefit or are not well tolerated, children with disabling generalized primary dystonia should be referred quickly for DBS. The dramatic clinical improvement that can be seen with DBS can restore normal or near-normal functioning and avoid the physical and emotional costs of an extended period of decreased physical and social functioning. In general, a levodopa trial should always be considered as the first treatment at the time of presentation of any patient with childhood-onset limb dystonia, in order to exclude dopa-responsive dystonia. Once a diagnosis of primary generalized dystonia is established, we typically initiate treatment with trihexyphenidyl, titrating slowly up to a high dose. We then frequently add baclofen as a second agent. If clinical improvement at that point is inadequate and the dystonia is causing significant functional impairment, we then consider referral for DBS.