The effect of scalp block and local infiltration on the haemodynamic and stress response to skull-pin placement for craniotomy

Abstract

The insertion of skull pins into the periosteum induces not only a haemodynamic response but also an increase in stress hormones. We compared the effects of scalp-nerve block, infiltration anaesthesia, and routine anaesthesia during skull-pin insertion on haemodynamic and stress responses to craniotomy. Forty-five ASA I or II patients, scheduled for elective craniotomies, were enrolled in this prospective, randomized, placebo-controlled study. Anaesthesia was induced with thiopental (5 mg kg(-1)), fentanyl (2 microg kg(-1)) and vecuronium (0.1 mg kg(-1)), and was maintained with 50% N2O in oxygen and 1% isoflurane. Five minutes before head pinning, 0.5% bupivacaine was infiltrated at each pin-insertion site in group L. In group S, scalp block was performed by blocking the supraorbital, supratrochlear, auriculotemporal, occipital, and postauricular branches of the greater auricular nerves using 20 ml 0.5% bupivacaine. Opioids were used to control haemodynamic responses in group C (the control group). Heart rate and mean arterial pressure were recorded at regular intervals before and for 1 h after induction. Blood samples were collected for cortisol and adrenocorticotropic hormone analysis 5 min before induction and 5 and 60 min after pin-holder insertion. There were significant increases in heart rate and mean arterial pressure during head pinning in groups L and C compared with group S and also at the 1st, 2nd and 3rd minutes after pinning (P < 0.05). In group S, the reduced plasma cortisol and adrenocorticotropic hormone levels measured at the 5th and 60th minutes after pinning were significantly lower than those in groups L and C (P < 0.05). We conclude that scalp block using 0.5% bupivacaine blunts the haemodynamic and stress responses to head pinning better than routine anaesthesia or scalp infiltration with bupivacaine and should be considered in conjunction with general anaesthesia for craniotomy.