Table 1.

Characteristics of the included 18 studies. Standard deviation detailed where reported.

First author	Year	Study design	Intervention	Size	Follow-up duration, months (mean ± SD)	Pre-operative total TWSTRS score (mean ± SD)	Post-operative total TWSTRS score (mean ± SD)	% improvement
Munchau	2001	Prospective cohort study	SPD	26	16.7±12.6	47.0±10.0	31.0±13.0	34
Yianni	2003	Retrospective cohort study	DBS	6	18.9	57.8±8.2	23.0±9.1	60
Hung	2007	Longitudinal cohort study	DBS	10	31.9±20.9	53.7±17.2	23.2±11.6	57
Kiss	2007	Prospective single-blind study	DBS	10	12	14.7±4.2§	8.4±441§	NR*
Jeong	2009	Consecutive case series	DBS	6	18.7±11.1	60.5±3.6	15.8±4.3	74
Moro	2009	Crosssectional study	DBS	8	28.6±19.2	24.4±4.1§	11.1 ±2.6 §	57§
Huh	2010	Retrospective cohort study	DBS	24	29.5±18.6	25.6±8.9§	10.03±4.1§	38§
Cacciola	2010	Consecutive case series	DBS	10	37.6 ±16.9	55.7±8.3	17.6±13.4	68
Yamada	2013	Retrospective cohort study	DBS	7	63.5 ±38.2	21.3±4.9§	6.4±5.7§	NR*
Schjerling	2013	Randomized crossover trial	DBS	6	6	23.5±5.3§	14.5±9.6§	NR*
Sadnicka	2013	Case-control study	DBS	11	26±15	50.0±12.2	18.0±19.4	64
Witt	2013	Retrospective cohort study	DBS	28	33.7±25.0	53.5±10.3	24.2±15	55
Walsh	2013	Prospective single-blind cohort	DBS	10	21.5±4.6	54.5±12.4	29.0±14.4	47
Volkmann	2014	Randomized sham- controlled trial	DBS	32	19.9±3.7	45.9±9.9	27.8±14.5	40
Ostrem	2014	Prospective cohort study	DBS	7	12	36.0±9.7	31.8±8.8	12
Chung	2015	Retrospective cohort study	SPD	16	19.9±11.5	24.9±8.0	14.9±3.6	40
Wang	2015	Retrospective cohort study	SPD	648	33.4	54.7±18.3	31.1±11.6	43
Ostrem	2017	Prospective cohort study	DBS	16	36	41.0±18.9	18.8±14.8	54

^§TWSTRS severity sub-scores

^*not reported: percentage improvement unable to calculated from study data