Scalp Nerve Blocks for Post-Craniotomy Pain

Inclusion Criteria: * adults aged 18 years and over; * patients scheduled for elective craniotomy under general anaesthesia for one of the following surgeries: * resection of a supratentorial brain tumour, * clipping of an un-ruptured supratentorial cerebral aneurysm, * excision of a supratentorial arterio-venous malformation (AVM), * removal of an epileptic focus under general anaesthetic. * ASA physical status \< IV. Exclusion Criteria: * history of significant coronary artery disease (NYHA class III or IV) which would contraindicate the use of epinephrine; * presence of pain related to the intracranial pathology (e.g. tumour pain) since it could make difficult the discrimination between the tumour pain itself and the surgery related pain; * current history of alcohol abuse or recreational drug abuse; * active psychotic disorder; * history of chronic pain requiring chronic opioids use (patients on opioids for \> 2 weeks); * known or suspected addiction to narcotic substances; * presence of any acute distracting pain; * history of migraines; * inability to understand or incapacity to use the VAS; * proven or suspected allergy to local anaesthetics; * craniotomy incision extending beyond the field of the block; * predicted need for postoperative ventilation; * history of scalp paresthesia or scalp scarring that may preclude normal nerve anatomy; * previous craniotomy or cranial irradiation; * history of malignant hyperthermia, which would contraindicate the anaest…