Law‐Koune 2005.

Methods	Study design: randomized controlled trial (3 arms) Study duration: not reported Study setting: hospital, single centre, France
Participants	Adults undergoing elective supratentorial craniotomy for tumour resection (n = 80) Inclusion criteria ASA I to ASA III participants undergoing elective supratentorial craniotomy for tumour resection Exclusion criteria Inability to understand the visual analogue scale Previous scalp incision Intracranial hypertension Cerebrovascular disease Allergy to any study drug Regular opioid usage Surgery scheduled to start after 2 pm Mean age, range (years) 49 (18 to 80) Numbers allocated to each arm Group 1: scalp infiltration with either 0.375% bupivacaine with 1:200,000 epinephrine (n = 20) Group 2: scalp infiltration with 0.75% ropivacaine (n = 20) Group 3: scalp infiltration with 20 mL of saline (n = 40) Male gender Group 1: 8/20 (analysed patients) Group 2: 8/19 (analysed patients) Group 3: 16/37 (analysed patients)
Interventions	Technique and timing Scalp infiltration with 0.375% bupivacaine with epinephrine 1:200,000 versus scalp infiltration with 0.75% ropivacaine versus scalp infiltration with saline with epinephrine 1:200,000, before scalp closure Dosage 20 mL
Outcomes	Primary Total morphine requirement during the first 16 hours postoperatively Secondary Pain as measured by the visual analogue scale Sedation score: from ‘alert’ to ‘roused only by shaking': 1 to 5 Adverse events: nausea, vomiting, pruritis, urinary retention, need for antihypertensive medication, haematoma
Notes	Funding No funding source reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	A table of random numbers was used for randomization
Allocation concealment (selection bias)	High risk	Authors did not provide any details regarding how the allocation sequence was concealed.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote: ''the anaesthesiologist, surgeon, and patient were blinded to the solution''. However no details were provided regaining the method used or how or if its adequacy was assessed.
Blinding of outcome assessment (detection bias) All outcomes	High risk	No details were provided as to whether or not those assessing outcomes were blinded to treatments received.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	4 participants were excluded from the final analysis due to postoperative complications: 3 in the control group (2 due to unspecified neurological complications and 1 due to excessive sedation) 1 in the ropivacaine group (due to an unspecified neurological complication) The lack of an intention‐to‐treat analysis made the effect of their exclusion difficult to determine.
Selective reporting (reporting bias)	Low risk	Outcomes were reported as specified.
Other bias	Unclear risk	Small study