Study	Reason for exclusion
AANTTAS 1990	Allocation: Not randomized
Adams 1993	Allocation: Not randomized
Adams 1995	Allocation: Random Participants: Adults with spasmodic dysphonia Interventions: Unilateral versus bilateral botulinum toxin injections
Adams 1996	Allocation: Not randomized
Aronson 1993	Allocation: Not randomized
Benninger 2001	Allocation: Not randomized
Bhattacharyya 2001	Allocation: Not randomized
Bielamowicz 2000	Allocation: Not randomized
Bielamowicz 2001	Allocation: Random Participants: Adults with abductor spasmodic dysphonia Interventions: Percutaneous versus transnasal injection of botulinum toxin
Bielamowicz 2002	Allocation: Not randomized
Blitzer 1985	Allocation: Not randomized
Blitzer 1988	Allocation: Not randomized
Blitzer 1991	Allocation: Not randomized
Blitzer 1992a	Allocation: Not randomized
Blitzer 1992b	Allocation: Not randomized
Blitzer 1998	Allocation: Not randomized
Brin 1988	Allocation: Not randomized
Brin 1989	Allocation: Not randomized
Brin 1998b	Allocation: Not randomized
Brin 2001	Allocation: Random Participants: Adults with spasmodic dysphonia Interventions: Unilateral versus bilateral botulinum toxin injections
Cannito 1994	Allocation: Not randomized
Ceballos 1992	Allocation: Not randomized
Courey 2000	Allocation: Not randomized
Crevier‐Buchman 1997	Allocation: Not randomized
Cyrus 2001	Allocation: Not randomized
Davidson 1996	Allocation: Not randomized
Devriese 1994	Allocation: Not randomized
Finnegan 1999	Allocation: Random Participants: Adults with spasmodic dysphonia Interventions: Botulinum toxin injections into both intrinsic and extrinsic laryngeal muscles versus botulinum toxin injections into intrinsic plus saline into extrinsic muscles
Fisher 1996	Allocation: Not randomized
Fisher 1999	Allocation: Not randomized
Ford 1990	Allocation: Not randomized
Ford 1992	Allocation: Not randomized
Galardi 2001	Allocation: Not randomized
George 1992	Allocation: Not randomized
Green 1992	Allocation: Not randomized
Inagi 1996	Allocation: Not randomized
Jankovic 1990	Allocation: Not randomized
Klap 1991	Allocation: Not randomized
Klap 1993	Allocation: Not randomized
Kobayashi 1993	Allocation: Not randomized
Koriwchak 1996	Allocation: Not randomized
Langeveld 1998	Allocation: Not randomized
Langeveld 2001	Allocation: Not randomized
Lees 1992	Allocation: Not randomized
Liu 1996	Allocation: Not randomized
Loven 1993	Allocation: Not randomized
Loven 1994	Allocation: Not randomized
Ludlow 1988	Allocation: Not randomized
Ludlow 1990	Allocation: Not randomized
Ludlow 1991	Allocation: Not randomized
Ludlow 1992	Allocation: Not randomized
Lundy 1998	Allocation: Not randomized
Maloney 1994	Allocation: Not randomized
Marion 1992	Allocation: Not randomized
Maurri 1992	Allocation: Not randomized
Mehta 2001	Allocation: Not randomized
Meleca 1997	Allocation: Not randomized
Miller 1987	Allocation: Not randomized
Murry 1995	Allocation: Not randomized
Papathanasiou 1997	Allocation: Not randomized
Poungvarin 1995	Allocation: Not randomized
Rhew 1994	Allocation: Not randomized
Rodriguez 1994	Allocation: Not randomized
Rontal 1991	Allocation: Not randomized
Rosen 1999	Allocation: Not randomized
Ruiz 1998	Allocation: Not randomized
Sapienza 2002	Allocation: Not randomized
Schonweiler 1998	Allocation: Not randomized
Smith 2000	Allocation: Not randomized
Teive 2001	Allocation: Not randomized
Thomas 2006	Allocation: Randomized Participants: Adult patients with adductor spasmodic dysphonia Interventions: Frozen versus fresh reconstituted botulinum toxin type A
Tish 2003	Allocation: Not randomized
Whurr 1993	Allocation: Not randomized
Whurr 1997	Allocation: Not randomized
Whurr 1998	Allocation: Not randomized
Wong 1995a	Allocation: Randomized Participants: Adults with spasmodic dysphonia Interventions: Botulinum toxin with vocalization versus botulinum toxin without vocalization
Wong 1995b	Allocation: Randomized Participants: Adults with spasmodic dysphonia Interventions: Botulinum toxin with vocalization versus botulinum toxin without vocalization
Zwirner 1991	Allocation: Not randomized
Zwirner 1992	Allocation: Not randomized
Zwirner 1993a	Allocation: Not randomized
Zwirner 1993b	Allocation: Not randomized
Zwirner 1997	Allocation: Not randomized