Averbuch‐Heller 1997.

Methods	Pharmacological interventions for acquired pendular and jerk nystagmus Allocation: double‐masked Masking: double‐masked Exclusions: 0 Losses: 1 Design: cross‐over RCT
Participants	Country: 4 sites in USA and Germany Number of participants randomised: 21 (15 with pendular nystagmus and 6 with jerk nystagmus) Age: 25‐73 years Gender: 10 female, 11 male Aetiologies: multiple sclerosis (9), degeneration (1), cerebellar atrophy (1), stroke (5), idiopathic (2), encephalitis (1), tonsillar herniation (1), AIDS (1) Ocular motility condition: acquired pendular nystagmus and horizontal jerk nystagmus Inclusion criteria: adult nystagmus Exclusion criteria: not specified
Interventions	Intervention 1: gabapentin Dose: 300 mg up to 900 mg/day Intervention 2: baclofen Dose: 10 mg up to 30 mg/day Duration: 2 weeks of intervention, 1‐2 weeks for wash‐out period, 2 weeks of intervention
Outcomes	Measurements: Landolt C, eye movement recordings, perceived motion of target, drug effects by participant recall Timepoints: Baseline, 2 weeks, 4 weeks and 6 weeks Adverse events: Drug intolerance, Increased ataxia
Notes	Health economic costs: not reported Quality of life measures: not reported Funding: USPHS grant E706717, Office of Research and development, Medical research Service, Department of Veteran Affairs and Evenon Arlington Fund and Deutsche Forschungsgemeinschaft Declaration of interests: Parke‐Davis Co provided transport and participant insurance fees in Germany Dates of study: not specified Trial registration ID: not specified
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not specified
Allocation concealment (selection bias)	Low risk	Quote: "Patients were randomly assigned to [gabapentin or baclofen]; these drugs were administered in opaque capsules that were identical in appearance, and both the primary investigators and the patients were blinded as to their identify". Judgment comment: primary investigators were masked which suggests that the allocation was concealed.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Patients were randomly assigned to [gabapentin or baclofen]; these drugs were administered in opaque capsules that were identical in appearance, and both the primary investigators and the patients were blinded as to their identify".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Patients were randomly assigned to [gabapentin or baclofen]; these drugs were administered in opaque capsules that were identical in appearance, and both the primary investigators and the patients were blinded as to their identify".
Incomplete outcome data (attrition bias) All outcomes	Low risk	21 people were recruited and 20 completed both 2‐week test periods. The one person who dropped out did so because of an unrelated condition.
Selective reporting (reporting bias)	Unclear risk	No access to study protocol or trials registry entry.
Other bias	High risk	Additional 'Risk of bias' assessment for cross‐over study Was the cross‐over design suitable: probably Was there a carry‐over effect: uncertain, no analysis done. Was only first period data available: no, first period data were not available Was the analysis correct: unclear, no estimates of effect reported Comparability of results with those from parallel‐group trials: no parallel group trials.