Table 1 Clinical data.

Case number	Initial clinical presentation	DYT‐1 status	Evolution of dystonia (functional impairment prior to DBS insertion)	Age at GPi DBS insertion	Preoperative BFMDRS Severity/ Disability	Postoperative BFMDRS (6 months) severity/disability	% Improvement in severity/disability (functional ability)
Case 1	F, aged 10	Negative	Bilateral upper limb and	14 years	77/21	30/20 (34/20	61/5. Walked unaided;
	years.		truncal dystonia; unable to			at 18 months)	easier wheelchair
	Handwriting		walk, feed or wash unaided.				use; self‐care skills
	deterioration		Schooling affected				modestly improved
Case 2	M, aged 8	Positive	Limbs, trunk and laryngeal	15 years	66/10	10/5 (8/3 at	85/50. Almost normal
	years.		muscles affected; severe			13 months)	gait (in‐toe, right foot);
	Dystonia right		difficulties with walking,				independent care skills
	foot		feeding and washing.
			Schooling affected
Case 3	F, aged	Negative	Limbs, trunk, laryngeal	8 years;	103/28	36/10 (41/17	65/64. Walked and
	18 months.		and oromotor muscles	revision		at 36 months,	used wheelchair;
	Dystonia left		affected; unable to use	aged 9 years		after battery	independent care skills
	foot		wheelchair due to posture.	due to lead		change)
			Crawled to move; unable	displacement
			to stand or walk.	and
			Schooling affected	infection
Case 4	M, aged	Negative	Increased frequency of	10 years	85/17	62/9 (53/11	27/47. Paroxysmal
	14 months.		1–2 min episodes. Wheel‐			at 12 months)	dystonic episodes
	Paroxysmal		chair bound, unable to walk,				eradicated, walked
	dystonic		feed or wash unaided.				unaided; self‐care
	episodes		Schooling affected				skills improved

BFMDRS, Burke, Fahn and Marsden Dystonia Rating Scale; DBS, deep brain stimulation; GPi, globus pallidus internus.