Comparison of tractography-assisted to atlas-based targeting for deep brain stimulation in essential tremor

BACKGROUND Direct targeting of the dentato-rubro-thalamic tract is efficacious in DBS for tremor suppression. OBJECTIVES We sought to compare outcomes and optimal stimulation parameters for tremor control using the technique of directly targeting the dentato-rubro-thalamic tract to those who underwent indirect targeting of the ventral intermediate nucleus thalamus. METHODS Twenty consecutive essential tremor patients obtained preoperative diffusion MRIs, where the dentato-rubro-thalamic tract was individually drawn and used to directly target the ventral intermediate nucleus of the thalamus during surgery. These patients were compared to an earlier cohort of 20 consecutive patients who underwent surgery using atlas-based coordinates. Baseline and 1-year postsurgery tremor amplitude using The Essential Tremor Rating Assessment Scale was recorded, as were the parameters needed for successful tremor control. RESULTS The indirectly targeted group had greater baseline and postop tremor severity relative to those directly targeted (baseline, 2.9 vs. 2.6; P = 0.02; postop, 1.1 vs. 0.8; P = 0.03). Mean voltage, pulse width, and frequency for optimal tremor control in the directly targeted group (38 electrodes) = 2.8 V, 80 μs, 153 Hz; the parameters for the indirectly targeted group (38 electrodes) = 2.9 V, 86 µs, 179 Hz (significantly greater, P