OBJECTIVES: The pallidothalamic tract connects the globus pallidus internus with 
the ventroanterior and ventrolateral parts of the thalamus. Lesioning or 
stimulation of the pallidothalamic tract has ameliorating effects on dyskinesia 
and dystonia in patients with Parkinson disease. However, the effect of the 
procedure on dystonia due to other etiologies has not been reported.
METHODS: We retrospectively analyzed patients with dystonia who underwent 
unilateral pallidothalamic tractotomy between July 2017 and October 2018 at 
Tokyo Women's Medical University Hospital. The Burke-Fahn-Marsden Dystonia 
Rating Scale-Movement Scale was used to evaluate the severity of dystonia at 
three time points (before surgery, 3 months postoperatively, and the last 
available follow-up). Adverse events were also evaluated.
RESULTS: Eleven patients underwent unilateral pallidothalamic tractotomy, 
including 5 with generalized dystonia, 4 with segmental dystonia, and 2 with 
focal (cervical) dystonia. All patients had undergone unilateral pallidotomy 
before contralateral pallidothalamic tractotomy. The mean interval between the 
previous surgery (pallidotomy) and pallidothalamic tractotomy was 9.5 ± 3.1 
months. The mean follow-up period was 11.5 ± 4.2 months. The Burke-Fahn-Marsden 
Dystonia Rating Scale-Movement Scale scores at 3 months after pallidothalamic 
tractotomy (5.8 ± 8.4) and at the last available follow-up (5.6 ± 8.3, P < 
0.001) were significantly improved compared with that before pallidothalamic 
tractotomy (21.8 ± 16.3). The most common adverse event was reduced voice volume 
(6 patients), which was mild and did not interfere with the patient's daily 
activities.
CONCLUSIONS: This study suggests that pallidothalamic tractotomy can be an 
alternative treatment target for dystonia. A larger and longer prospective study 
is needed to elucidate the safety and efficacy of pallidothalamic tractotomy for 
dystonia.