Skull pins are used to immobilize the head during craniotomy. Fixation of skull pins causes acute hemodynamic changes which may affect cerebral autoregulation and hence cerebral blood flow. Therefore, maintenance of stable hemodynamic parameters during skull pin placement under general anesthesia is crucial to ensure adequate cerebral perfusion and prevention of acute rise of intracranial pressure

Many different strategies have been used to minimize the hemodynamic responses to skull pin placement with varying results. Local anesthetic infiltration at pin application sites has been used but was always unsuccessful in obtunding the hemodynamic responses to skull pin placement. Dexmedetomidine, an alpha-2 adrenoceptor agonist, has been recently introduced as a sedative for patients on mechanical ventilation. In addition to its sedative effect; Dexmedetomidine has significant analgesic qualities and has been labeled as "analgesia-sparing". To the best of the investigator's knowledge, few studies investigated Dex use to suppress hemodynamic responses to skull pinning. The aim of the current study was to evaluate the lowest effective dose of Dexmedetomidine in attenuating the hemodynamic responses to skull pin placement for craniotomies. Lidocaine, administered subcutaneously at the head-holder pin sites, was more effective in preventing the blood pressure response to skull-pin than was deepening the level of anesthesia.

Inclusion Criteria:

• 120 Adult patients,
• undergoing elective craniotomy
• ASA I and II patients

Exclusion Criteria:

• patients undergoing craniotomy for emergency surgery,
• raised ICP,
• obese patients (body mass index >30 kg/m2 for males and 28 kg/m2 for females),
• patients having systemic comorbidities (cardiac, renal, hepatic, and endocrinal),
• hypertensive patients (including those detected after admission),
• patients undergoing intracranial aneurysm clipping