Most of the experience with thalamotomy is with patients with generalized dystonia. Several studies looked specifically at the effect of the procedure on Cervical Dystonia (CD). The combined number of patients reported in the four largest studies is very small, around 50. Benefit varied from minimal to excellent. Onset of improvement was delayed by a couple months from surgery. Patients who achieved maximum benefit were the ones with "horizontal" torticollis. Those with pronounced muscle hypertrophy and cervical scoliosis did worse. The majority of studies concluded that, in order to achieve meaningful improvement, patients required a bilateral procedure due to bilateral neck muscle involvement. The bilateral procedure generally is associated with a higher complication rate, specifically speech and swallowing dysfunction, which has precluded wide application of thalamotomy of surgery for Cervical Dystonia (CD).