Yoshimura 1992

Methods	Randomised, double‐blind, cross‐over study.Method of randomisation: not mentioned.Data analysed on an intention to treat.Location: one centre in US.Duration: cross‐over at 1 month (minimum).
Participants	Eleven participants were enrolled. 3 participants were male and 8 participants were female. Mean age was 50 years (37‐68). Mean duration of symptoms was 5.2 years (1.5‐12). Six participants had facial weakness ipsilateral to the spasm. None of the participants had received previous treatment with Botulinum toxin type A (BtA). All had been treated with medications without success. One participant had undergone surgical microvascular decompressive procedures without lasting benefit.Inclusion criteria: not mentioned.Exclusion criteria: not mentioned
Interventions	The participants were randomly assigned to 4 sets of injections. Three of these injections were of BtA (formulation Botox) using 3 different doses (low, intermediate, and high dose), and one injection was of placebo (saline). Muscles were selected for injection based on clinical involvement. For each participant, the site of injections was kept constant. BtA dose was determined for each participant on the basis of the number of muscles involved, frequency and severity of the spasms. The average dose ranged from 2.5 to 10 units per muscle. Doses of one‐half (low dose) and twice this dose (high dose) were administered on different occasions. The total dose administered to participants at any one time varied between 5 and 90 units. BtA was diluted to a concentration of 2.5 to 5 units per 0.1ml. Participants were not reinjected until any response to the previous injection (as determined by both the patients and physicians) had been lost.
Outcomes	The primary efficacy outcome was patient self assessment of global improvement on a 10‐point scale. Secondary efficacy outcomes included the physician assessment of improvement (using a 10‐point scale to characterize the frequency of spasms, number of muscles involved, and severity of spasms), and adverse events. All outcomes data were collected at week 4 after injections. Author's also looked at duration of improvement (defined as the time for the patient to return to subjective and objective baseline after each injection).
Notes	There was 1 withdrawal after 2 injections due to concerns about facial weakness caused by BtA. Two other withdrawals occurred because of domestic reasons after 3 and 1 injection sessions, respectively.After this blinded controlled trial, an additional 95 participants were enrolled in an open trial of BtA injections. The results of this uncontrolled phase are not considered.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear