This randomized controlled trial will compare two commonly used techniques for performing spinal anesthesia, the median (midline) approach and the paramedian (lateral) approach, in adult patients undergoing elective orthopedic or urology surgery at Mayo Hospital, Lahore. Spinal anesthesia is widely used because it provides rapid pain control during surgery and avoids airway instrumentation. However, a recognized complication is post-dural puncture headache (PDPH), a headache that typically worsens on sitting or standing and improves on lying down. PDPH can delay mobilization, reduce oral intake, prolong hospital stay, and sometimes require additional treatment.

Eligible participants aged 18 to 65 years with American Society of Anesthesiologists (ASA) physical status I or II will be enrolled, and then allocated in a 1:1 ratio to receive spinal anesthesia using either the median or paramedian approach. To standardize the procedure, spinal anesthesia will be performed under aseptic technique at the L3 to L4 or L4 to L5 interspace using a 25-gauge Quincke spinal needle, followed by injection of a fixed dose of hyperbaric bupivacaine. Routine perioperative monitoring will be applied for all participants, and intra-operative blood pressure will be recorded at regular intervals to document hypotension.

The primary outcomes are the frequency and severity of PDPH. PDPH will be assessed using a structured checklist based on the International Classification of Headache Disorders, 3rd edition (ICHD-3) at 24 hours, 72 hours, and day 5 after the procedure by a trained assessor. Headache intensity will be recorded using a 0 to 10 Visual Analogue Scale, and categorized as mild, moderate, or severe. The hypothesis is that the frequency and severity of PDPH differ between the median and paramedian approaches in patients receiving spinal anesthesia for orthopedic or urology surgery.

Inclusion Criteria:

• Both gender (male and female) aged between 18 and 65.
• Adults undergoing elective orthopedics or urology procedures planned under spinal anesthesia.
• ASA status I or II.
• Ability to give informed consent and comply with postoperative assessment.

Exclusion Criteria:

• Any contraindication to spinal anesthesia, including infection at puncture site, coagulopathy or therapeutic anticoagulation, thrombocytopenia, severe hypovolemia or shock, raised intracranial pressure due to space occupying lesion, or suspected spinal canal infection.
• Known hypersensitivity to planned intrathecal local anesthetic or adjuvant drugs.
• History of chronic daily headache, migraine requiring regular prophylaxis, or headache at baseline on the day of surgery.
• Prior lumbar spine surgery, significant spinal deformity, or neurological disease affecting lower limb sensation that will interfere with neuraxial assessment.
• Inability to complete follow-up assessments due to impaired cognition, severe psychiatric illness, or major communication barrier.
• Emergency procedures.