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.