The purpose of this randomised controlled study is to compare the haemodynamic changes and the degree of incisional bleeding after scalp infiltration of lidocaine and dexmedetomidine versus lidocaine and epinephrine for patients with hemi-facial spasm undergoing microvascular decompression.

Fifty-two patients were injected with 5 mL of 1% lidocaine with either dexmedetomidine (2 μg/mL) or epinephrine (1:100,000 dilution) to reduce scalp bleeding. Mean blood pressure and heart rate were recorded every minute for 15 minutes after scalp infiltration. The primary outcome was the incidence of predefined hypotension, which was treated with administration of 4 mg ephedrine as often as needed. The number of administrations and total amount of ephedrine administered were also recorded as a measure of the severity of hypotension. The neurosurgeon scored incisional bleeding by numeric rating scale from 0 (worst) to 10 (best).

The incidence of hypotension (68% vs. 34.8%, P = 0.02) and the frequency (P = 0.02) and total dose (P = 0.03) of ephedrine administered were lower in the dexmedetomidine group than in the epinephrine group. In addition, there was no difference in mean blood pressure between the two groups but heart rates were lower in the dexmedetomidine group (P = 0.01). Incisional site bleeding was better with epinephrine (median [interquartile range] of the numeric rating Score: 6 [4] in the dexmedetomidine group and 8 [2] in the epinephrine group; P < 0.001).

The dexmedetomidine-lidocaine combination may be recommended as a substitute for epinephrine-lidocaine for scalp infiltration in neurosurgical patients, especially neurologically compromised patients.