Bilateral Ultrasound Guided Intramuscular Quadratus Lumborum Plane Block Versus Bilateral Lateral Quadratus Lumborum Plane Block in Controlling Postoperative Pain in Cancer Patients Undergoing Open Nephrectomy

Inclusion Criteria: * Age from 18 to 65 years. * Both sexes. * American Society of Anesthesiology (ASA) physical status II-III. * Body mass index (BMI): (20- 40) kg/m2. * Type of surgery: midline incision for unilateral open nephrectomy. Exclusion Criteria: * Patient refusal. * Age \<18 years or \>65 years * BMI \<20 kg/m2 and \> 40 kg/m2 * Known sensitivity or contraindication to drugs used in the study * Contraindication to regional anesthesia, e.g. local infection at the introduction site, pre-existing peripheral neuropathies and coagulopathy. * Physical status ASA IV * Patients on chronic analgesic therapy (daily morphine ≥30 mg or equivalent dose of other opioids or tramadol or any medication for neuropathic pain) * Patients with a history of drug abuse * Patients with neuropsychiatric diseases; patients with a history of chronic pain syndromes that may enhance sensitivity to pain, for example, fibromyalgia * All patients who are going to have severe intra- or post-operative bleeding or will require postoperative mechanical ventilation are also excluded from the study.