It is a randomized control trial to compare the surgical plethysmographic index (SPI) response during a Mayfield head-holder insertion in neurosurgical patients who receive a scalp block versus those who do not receive the scalp block after induction of anesthesia with propofol with fentanyl and intubation with cis-atracurium.

Study design is a randomized controlled trial Participants include adult neurosurgical patients scheduled to have a Mayfield head-holder insertion for supratentorial craniotomy Intervention is a scalp block prior to a Mayfield head holder insertion. Comparison is 'no scalp block' Outcome is surgical plethysmographic index (SPI) responses during/after a Mayfield head holder insertion Sample size includes 30 cases (15 cases per arm)

The eligible neurosurgical patients will be randomly allocated, by a concealed randomization process, to receive or not to receive a scalp block after induction and intubation with propofol/fentanyl and cisatracurium. Surgical plethysmographic index, direct arterial blood pressure, heart rate (EEG), End tidal Carbondioxide, Bispectral/entropy (40-60) will be recorded every one minute before/after induction and intubation, before/after the scalp block, and before/after the Mayfield head-holder insertion. The Mayfield head-holder insertion will be performed by a neurosurgeon who will be blinded to the allocated groups.

Data analysis is performed to compare the change of SPI during and after the Mayfield head-holder insertion from the baseline in both groups by using repeated measure ANOVA at the significant level of 0.05.

Inclusion Criteria:

• patients will receive a Mayfield head-holder insertion for supratentorial craniotomy

Exclusion Criteria:

• History of chronic hypertension, Diabetes mellitus (DM), coronary heart diseases
• Receiving beta blockers
• BMI > 30
• Coagulopathy
• severe liver and renal diseases