Table 1.

Characteristics of 10 patients with chronic therapy-resistant Parkinson's disease.

Patients	10
Bilateral pallidothalamic tractotomy (PTT): stage/one session	8/2
Time frame between first Unified Parkinson's Disease Rating Scale (UPDRS) and 1 year postoperative UPDRS after second side: mean ± SD, median (months)	36 ± 15, 33 (14–59)
Symptom duration [mean ± SD (min; max), median] (years)	10.2 ± 4.6 (7; 23), 9
Time interval between both PTTs [mean ± SD (min; max), median] (months)	20 ± 10 (5; 38), 16.5
Mean age at first treatment (years)	63 ± 5
Females	5/10
Ethnicity	9 Caucasians, 1 Indo-aryan
Preoperative mean modified Hoehn and Yahr stage (39) (min; max)	2.7 (1;4)
Mean modified Hoehn and Yahr stage (min; max) before second side	2.5 (2;3)
Retreatment of first PTT to increase lesion size and contralateral PTT in one session	4/10