Table 1. Study type, intervention, sample size, and patient age range of included studies.

Study	Country (year)	Study type	No. of patients	Patient age (yr)	Intervention
Van de Kerkhove et al.23	Belgium (2012)	Retrospective cohort, consecutive patients	10 male, 41 female	Mean±SD 47±14	Gabapentin 75 mg qd to 1,200 mg daily over 4 wk
Ryan et al.6	Australia (2014)	Case report	1 male, 1 female	A 61-year-old female	1,800 mg/day for 1 mo
				A 69-year-old male	1,800 mg/day for 3 mo
Bastian and Bastian24		Retrospective case series	12	Range 23–80	Median final dose 1,350 mg
Ting and Na22	China (2016)	Randomized, placebo-controlled patient blinded trial	Gabapentin: 11 male, 19 female; placebo: 8 male, 18 female	Range 18–65	Gabapentin 300–1,800 mg/day vs. placebo for 12 wk; included a 6-day dose escalation, 8-wk treatment, a 6-day dose reduction
				Gabapentin: mean 50.5 Placebo: mean 52.2
Lee and Woo14	USA (2005)	Prospective case series, consecutive	9 male, 17 female	Mean±SD 51.2±17.0; range 14–80; median 50.5	Gabapentin 100–900 mg daily >4 wk, nonresponders stop at 4 wk, responders continue dose for 3 mo and then reduction
Ryan et al.17	Australia (2012)	Randomized, double-blinded, placebo-controlled trial; note that patients and research staff were blinded; investigators assessing outcomes were not blinded; block randomization, sex stratified	Gabapentin: 12 male, 20 female; placebo: 10 male, 20 female	Gabapentin: mean±SD 62.7±14.0; placebo: mean±SD 60.9±12.9	Gabapentin 300–1,800 mg/day vs. placebo for 84 days; included a 6-day dose escalation, 8-wk treatment, a 6-day dose reduction
Mintz and Lee15	Canada (2006)	Case series, consecutive status unknown	6 female	Mean 59; range 34–77	Gabapentin 100 mg bid to 1,600 mg daily dose

qd: once daily; bid: twice a day.