The goal of this clinical trial is to compare modified versus conventional thoracolumbar interfascial plane block for perioperative analgesia in lumber spine surgery.

The main question it aims to answer is:

• Whether modified thoracolumbar interfascial plane block is as effective as the conventional block for perioperative analgesia in lumber spine surgery.

60 patients were enrolled in the study, divided by simple random sampling into 3 groups.

Spinal surgeries are usually associated with marked postoperative pain that classically takes 3 days to recede.

Adequate perioperative pain control is significant for patients to encourage early mobilization and reduce postoperative adverse events. Discectomy, laminectomy, and spinal fixation are the most frequently performed spinal surgical procedures. Extensive dissection of tissues, ligaments, and bones is often performed during spinal surgeries, resulting in a significant degree of postoperative severe pain. Adequate pain management in these patients is challenging because most of them have already received ordinary analgesics and/or opioids to ameliorate preexistent chronic back pain. Pain following spine surgery can result from mechanical irritation, nerve compression, or postoperative inflammatory processes. It can be generated from different structures such as vertebrae, discs, ligaments, muscles, dural sleeves, and capsules of the facet joint. Innervation of these pain generators is from the dorsal rami of spinal nerves. Opioids are considered the standard method of analgesia and are commonly used as effective analgesics for the management of severe pain disorders. However, their widespread use is restricted because of their side effects such as nausea, vomiting, and respiratory distress, and acquired tolerance. Preemptive multimodal analgesic regimens that rely on the synergistic action of nonopioid agents given in lower doses have been used to improve postoperative pain management and reduce opioid consumption. Protocols for reducing pain after lumbar surgery recommend the use of regional anesthesia techniques to reduce opioid analgesic use to the minimum. Interfascial plane blocks have the potential to provide extended postoperative analgesia and to reduce opioid consumption and neuraxial-related motor block to a minimum. The use of thoracolumbar interfascial plane block TLIP block was first reported in 2015 by Hand et al. wherein they did a volunteer-based study and demarcated the area of sensory analgesia. Thereafter, Ueshima et al. reported two cases of spinal surgeries where TLIP block was administered. TLIP blocks the sensory component of the dorsal rami of the thoracolumbar nerves. These nerves emerge mainly through the interface between the multifidus (MF) and longissimus (LG) muscles. Blocking these nerves provides good analgesia after spine surgeries. TLIP modification where we inject the anaesthetics between the longissimus and iliocostalis muscles after having advanced the needles at a 15 angle in a medial to lateral direction. This modified method has several advantages. 1.Advancing the needle from a medial to lateral direction eliminates the risk of possible inadvertent neuraxial injection. 2.Injecting between the iliocostalis and longissimus muscles results in a dermatomal area of analgesia similar to that obtained with an injection made between the multifidus and longissimus muscles. Both conventional and modified techniques are assumed to be effective and safe.

The primary outcome measure is postoperative pain intensity expressed as A numerical rating scale (NRS) score at time zero (time of extubation), time 1 ( time of delivery to PACU), every 2 hours during the first 6 hours then every 6 hours during the first 24 hours.

Inclusion Criteria:

• Patients of both sexes admitted to the OR of Ain Shams University Hospitals for lumber disc surgery.
• Age 18 to 70 year old.
• ASA classification I and II.

Exclusion Criteria:

• Age <18 or >70 years.
• Declining to give written informed consent.
• History of allergy to the medications used in the study.
• Psychiatric disorder.
• ASA classification III-V.
• Patients with cerebrovascular accidents.
• Neuromuscular disorders, spine abnormalities.
• Spinal cord or head injuries.
• CNS tumours.