Effect of Pregabalin on Optic Nerve Sheath Diameter in Craniotomy Patients.

When patients undergo brain tumor removal surgery (craniotomy), the pressure inside the skull may increase, which can lead to brain swelling and slower recovery. Currently, doctors measure this pressure using invasive monitors placed inside the brain, but these are not used for all patients. This study investigates whether a medication called pregabalin, given before surgery, can help reduce pressure inside the skull. Pregabalin is already approved for treating pain, anxiety, and seizures. The study will measure pressure indirectly using a simple, painless ultrasound of the eye (optic nerve sheath diameter), which is a validated non-invasive method to estimate intracranial pressure. Participants will be randomly assigned to receive either pregabalin 150 mg or a placebo (inactive pill) on the evening before surgery and again on the morning of surgery. The ultrasound measurement will be taken at four time points: before the first dose, before anesthesia induction, upon arrival to the intensive care unit, and 24 hours after surgery. Researchers will also measure pain levels, medication use, and recovery quality. The goal is to determine if preoperative pregabalin can safely reduce intracranial pressure and improve recovery in craniotomy patients.

Inclusion Criteria: 1. Age: 18-65 years 2. ASA status: I-III 3. Surgery Elective supratentorial craniotomy for tumor resection (meningioma, glioma, metastasis) 4. Anesthesia: General anesthesia with sevoflurane 5. Consent: Written informed consent obtained Exclusion Criteria: 1. Known hypersensitivity to pregabalin or gabapentinoids. 2. Pre-existing optic nerve pathology or glaucoma that could cause ONSD measurement interference. 3. Emergency surgery as No preoperative dosing window 4. Preoperative ICP elevation (suspected or confirmed) to avoid Baseline ICP abnormality 5. Severe renal impairment (CrCl \< 30 mL/min). 6. Preoperative use of gabapentinoids or benzodiazepines to avoid drug interaction/interference 7. Pregnancy or breastfeeding for Safety 8. Body mass index \> 40 kg/m² 9. History of substance abuse 10. Inability to cooperate with ONSD measurement