Which approach is better: bilateral versus unilateral thalamic deep brain stimulation in patients with fragile X-associated tremor ataxia syndrome.

Fragile X-associated tremor ataxia syndrome (FXTAS) is a relatively recently described condition that is frequently misdiagnosed as essential tremor and then occasionally treated as such with deep brain stimulation (DBS) to the nucleus ventralis intermedius of the thalamus (Vim). Reports of ataxia worsening after bilateral Vim DBS in FXTAS patients are conflicting, and only five FXTAS patients treated with Vim DBS for intractable tremor have been reported in the literature, three of whom having undergone a bilateral procedure. We report a patient who underwent a staged Vim DBS procedure, with excellent contralateral hand tremor control and no worsening of ataxia after the first procedure, but immediate worsening of his ataxia after the second one, arguing in favor of a unilateral surgical approach for intractable tremor in FXTAS.