Porras 2007.

Methods	A randomised double‐blind prospective study
Participants	Intervention: steroid rhizotomy Diagnostic criteria of patients included in the trial             Idiopathic trigeminal neuralgia with no response to pharmacological treatment Age mean (SD)  60.5 (13.1) Gender 3 male, 7 female Severity 8 to 10 on a scale of 0 to 10 Duration of condition mean (range) years Not available Number      10       Intervention: glycerol rhizotomy Diagnostic criteria of patients included in the trial    Idiopathic trigeminal neuralgia with no response to pharmacological treatment        Age mean (SD)  59 (7.3) Gender    3 male, 7 female       Severity 8 to 10 on a scale of 0 to 10 Duration of condition mean (range) years Not available Number         10
Interventions	Intervention: steroid rhizotomy Type of intervention  Percutaneous Gasserian ganglion block with 40 mg of methyprednisolone acetate Length of follow‐up 4 weeks Intervention: glycerol rhizotomy Type of intervention  Percutaneous Gasserian ganglion selective block with 0.4 cc of 100% glycerol Length of follow‐up 4 weeks
Outcomes	Primary outcome Pain relief at 4 weeks
Notes	Lack of data. Randomisation said to have been done but with no details. No allocation concealment. Very short trial
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No data given
Allocation concealment (selection bias)	Unclear risk	No data given
Blinding (performance bias and detection bias) All outcomes	Low risk	Stated that patients and doctors who did the VAS assessments were blind to the substance injected
Incomplete outcome data (attrition bias) All outcomes	High risk	Incomplete data
Selective reporting (reporting bias)	Unclear risk	incomplete data
Other bias	Unclear risk	No data given