Comparison of the efficacy of Dexmedetomidine versus Ketamine as an adjunct to Ropivacaine for Scalp nerve block during Awake craniotomy surgery- A Randomised Controlled Trial

Scalp nerve block (SNB) is an established technique for effective analgesia during awake craniotomy, but its analgesic duration is limited when local anesthetics are used alone. Adjuvants such as dexmedetomidine and ketamine may enhance block efficacy, though direct comparative evidence remains limited. This prospective trial randomized forty-six adult patients undergoing elective awake craniotomy to receive SNB with 0.5% ropivacaine with dexmedetomidine 1 µg/kg (Group RD, n = 23) or ketamine 0.5 mg/kg (Group RK, n = 23). The primary outcome was the time to request the first rescue analgesia. Secondary outcomes included onset of sensory blockade, postoperative pain scores, rescue analgesic consumption, hemodynamic variables, respiratory depression, psychosis, and time to discharge from the postoperative ward. The time to first rescue analgesia was significantly longer in Group RK compared with Group RD (18.67 [17.08–19.00] vs. 14.67 [12.92–15.08] hours; P = 0.001). Group RK demonstrated significantly lower postoperative pain scores at 6,10, and 16 h postoperatively ( P < 0.004) and reduced consumption of rescue analgesia ( P < 0.001). The onset of sensory blockade was comparable with a higher incidence of respiratory depression in Group RD ( P = 0.02). Group RK showed higher intraoperative heart rate and mean arterial pressure, though values remained within clinically acceptable limits. Ketamine (0.5 mg/kg) as an adjuvant to ropivacaine for SNB in awake craniotomy provides longer postoperative analgesia and reduced rescue analgesic requirements compared with dexmedetomidine, with a lower incidence of respiratory depression. Dexmedetomidine offers superior hemodynamic attenuation to noxious stimuli. Larger multicenter studies are warranted to establish optimal adjuvant selection. Clinical Trials Registry-India (CTRI): CTRI/2024/01/061259, https://ctri.nic.in/Clinicaltrials/pmaindet2.php?EncHid=OTY2NDQ=&Enc=&userName= Date of registration: 09/01/2024 Date of enrolment of first patient: 15/01/2024 Principal Investigator: Dr Ankur Luthra