Modified Thoracolumbar Interfascial Plane Block vs Retrolaminar Block for Pain in Lumbar Spine Surgeries

Pain after lumbar spine surgery arises from disruption of paraspinal muscles, ligaments, and bony structures, with innervation from dorsal rami of spinal nerves. Opioids remain the cornerstone of postoperative analgesia but carry adverse effects. The mTLIP block targets the fascial plane between longissimus and iliocostalis muscles, while the Retrolaminar block deposits local anesthetic on the posterior surface of the vertebral lamina. Both target the dorsal rami. This study will compare both techniques regarding opioid consumption, pain scores, time to first rescue analgesia, block performance metrics, side effects, functional recovery, and patient satisfaction.

• Morphine (Drug), also known as Morphine Sulfate: Rescue analgesic administered intravenously at a dose of 0.1-0.2 mg/kg every 2-4 hours as needed for breakthrough pain (NRS > 3), with a maximum dose of 10 mg per administration.
• Bupivacaine (Drug), also known as Bupivacaine Hydrochloride: Local anesthetic used in the block solution (0.25%, 15 mL per side).
• Dexamethasone (Drug), also known as Dexamethasone Sodium Phosphate: Adjuvant added to the block solution (8 mg per side) to prolong analgesia.
• Magnesium Sulphate (Drug), also known as Magnesium Sulfate: Adjuvant added to the block solution (300 mg of 10% per side) to prolong analgesia.
• Modified Thoracolumbar Interfascial Plane Block (Procedure), also known as mTLIP Block: Ultrasound-guided injection between the longissimus and iliocostalis muscles at the L3 level.
• Retrolaminar Block (Procedure), also known as RLB: Ultrasound-guided injection on the posterior surface of the vertebral lamina at the L3 level, deep to the erector spinae muscles.

Primary outcomes

• Total morphine consumption in the first 24 hours postoperatively [24 hours postoperatively]: Cumulative morphine dose (mg) administered as rescue analgesia during the first 24 postoperative hours

Secondary outcomes

• Pain intensity by Numerical Rating Scale (NRS) [At 2, 4, 8, 12, 18, and 24 hours postoperatively]: Pain intensity assessed using a 10-point Numerical Rating Scale (0 = no pain, 10 = worst pain imaginable)
• Time to first rescue analgesia [First 24 hours postoperatively]: Time from local anesthetic injection until the patient first requests additional pain-relieving medication (NRS > 3)
• Block performance time [During block procedure]: Time required to perform the block procedure
• Onset of sensory block [Within 20-30 minutes after injection]: Time from local anesthetic injection until loss of sensation in the desired dermatomes
• Opioid-related side effects [24 hours postoperatively]: Incidence of postoperative nausea and vomiting (PONV) assessed by PONV impact scale (0 = none, 1 = mild, 2 = moderate, 3 = severe), sedation, and respiratory depression
• Patient satisfaction score [24 hours postoperatively]: Patient satisfaction assessed using a 4-point scale (4 = excellent, 3 = good, 2 = fair, 1 = poor)
• Incidence of chronic pain [3 to 6 months postoperatively]: Chronic pain will be assessed at 3 months postoperatively via a structured follow-up (telephone interview or outpatient clinic visit). Patients will be asked whether they experience persistent or recurrent pain at or around the surgical site lasting more than 3 months after surgery. Responses will be recorded as "Yes" or "No," and the proportion of patients answering "Yes" will be reported as the incidence of chronic pain, according to the IASP definition (pain persisting or recurring for more than 3 months).
• Time of ambulation [First 24 hours postoperatively]: Time to first mobilization after surgery

Sex: All, ages: 21 Years to 65 Years

Inclusion Criteria:

* Age between 21 and 65 years
* ASA physical status I or II
* BMI < 30 kg/m²
* Scheduled for elective two-level lumbar spine surgery (discectomy/decompression)
* Expected duration of surgery less than 3 hours
* Patient's acceptance and written informed consent

Exclusion Criteria:

* Infection at block site
* Known allergy to used drugs
* Coagulation disorder
* History of psychiatric illness
* Pre-existing neurological deficits
* Presence of any metastasis
* Previous lumbar spine surgeries
* Patients on previous opioid therapy

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• Mohamed Shehta Mohamed Ali, M.B.B.CH, Principal investigator, Zagazig University
• Tarek Gaafar, Prof, Study chair, Zagazig University
• Sanaa Eltohamy, Prof, Study chair, Zagazig University
• Khadeja Elhossieny, Assist Prof, Study chair, Zagazig University