Paraspinal regional analgesic techniques in spine surgery—a narrative review

3.1 ESP block

The ESP block is a paraspinal myofascial plane block first described by Forero et al. [8] in 2016. It was used for thoracic analgesia in two patients with chronic thoracic neuropathic pain and two undergoing video-assisted thoracoscopic surgery. Ultrasound guidance is typically used for this technique, with local anesthetic deposited in the craniocaudal fascial plane between the erector spinae muscle and the transverse process of the vertebra. Local anesthetic diffusion anteriorly to the ventral and dorsal rami of the spinal nerves facilitates visceral and somatic analgesia [9]. ESP block is the most studied block for spine surgery among the nerve blocks reported in the literature. It has been used for different types of lumbar spine surgery such as microendoscopic surgery, discectomy, decompression surgery and posterior interbody fusion [10, 11, 12, 13]. In addition, ESP block has shown to have opioid-sparing effect in thoracolumbar scoliosis surgery using a bilateral, bi-level technique [14]. Elias et al. [15] reported in their systematic review that ESP blocks reduced postoperative pain and opioid consumption for lumbar spine surgery, but this effect was sustained only for the short term. They concluded that current evidence is insufficient to support the widespread use of ESP blocks for spine surgery [15].

Rizkalla et al. [16] reviewed 15 studies (5 randomized controlled trials (RCTs), 5 case series, 4 case reports and 1 retrospective study), noting that ESP blocks were consistently found to be a safe and effective method of analgesia for lumbar surgery with limited adverse effects [16].

To date, other systematic reviews are available [17, 18, 19, 20]. The most recent systematic review and meta-analysis by Oh et al. [19] included 12 RCTs (665 participants) who underwent lumbar spine surgery. ESP Block significantly reduced opioid consumption in the first 24 hours after surgery when compared with control. In addition, it lowered the pain scores for 48 hours after surgery, shorter length of hospital stay, and decreased the postoperative nausea and vomiting with increased patient satisfaction. Due to high heterogeneity, small sample size, variable block technique, and different local anesthetic concentration and volume, there is a still need for high quality of evidence to support these findings.

3.2 Retrolaminar block

The retrolaminar block with a catheter was first performed on the lamina of the thoracic vertebra in 2006 [21]. This approach was introduced to lower the risk of serious complications that thoracic epidural anesthesia and paravertebral blocks may cause, such as pneumothorax, hypotension, nerve damage, and dura puncture.

This is another superficial needle placement technique where the target is the plane between the erector spinae muscles and the lamina, but the target is more medial than the target of an ESP block. This block is performed from the cervical to lumbar levels and thus can be a useful anesthetic and analgesic technique for anterior lumbar interbody fusion (ALIF)/lateral lumbar interbody fusion (LLIF) [8, 22, 23].

A cadaver-based study of the retrolaminar block and ESP block spread found that the ESP block made the study dye spread more laterally. In contrast, the dye for the retrolaminar block spread vertically, suggesting a more efficient block of the dorsal rami with the retrolaminar block over the ESP. However, more thoracic spinal nerves were stained by the ESP block than by the retrolaminar block [24].

A continuous retrolaminar block has been reported as an effective pain management technique for breast cancer surgery [25, 26], rib fracture [27], video-assisted thoracoscopic surgery [28], and lumbar trauma [22], but thus far, there is no report available for spine surgery.

Although the retrolaminar block has been reported to be effective, clinical data are still insufficient. For example, thus far, no reports have investigated the optimal dose and concentration of local anesthetics for this block. Randomized clinical studies are needed to assess efficacy for spine surgery.

3.3 TAP block

Since the TAP block was first described in 2001 as an abdominal field block [29], it has been regarded as a safe pain management technique for the anterior abdominal wall, as part of a multimodal approach [30, 31]. The TAP block is commonly performed under ultrasound guidance [32]. TAP blocks are now used for pain control in patients undergoing large bowel resection, appendectomy, cesarean section, hysterectomy, renal transplantation, abdominoplasty, and iliac bone grafting [33].

TAP is an interfascial space between the transversus abdominis and internal oblique muscles, visualized with an ultrasound transducer [34, 35, 36].

The anterolateral abdominal wall is mainly supplied by the anterior rami of the spinal nerves originating from T6 to L1 [37]. Considering that the TAP block is a field block, they do not always coincide with the innervation area. Støving et al. [35] reported that its cutaneous sensory block area is nondermatomal and does not cross the midline.

Tsai et al. [36] standardized various expressions of TAP blocks used in previous studies into four categories based on the involved spinal nerves and the transducer positions: subcostal, oblique subcostal, lateral, and posterior TAP blocks. Among these categories, the appropriate approach for analgesia and anesthesia in ALIF and LLIF surgery would be to apply the lateral and posterior approaches together. Reisener et al. [38] conducted a large-sample, retrospective study in patients undergoing a single-injection TAP block under general anesthesia as part of their ALIF compared to those that did not. They reported that a single-injection TAP block was associated with a significantly shorter length of stay, less postoperative nausea/vomiting, and lower opioid consumption in the post-anesthesia care unit. Soffin et al. [30] also reported that a single-injection TAP block as a part of MMA for lumbar spine fusion was a feasible approach with high patient acceptance and no block related adverse events were observed [30].

A continuous TAP block may provide effective analgesia in abdominal surgery such as cesarean section and renal recipients [39, 40, 41, 42]. However, it has not been reported whether a continuous TAP block provides an additional analgesic effect compared to a single-injection TAP block in spine surgery. Therefore, studies comparing single injection and continuous infusion technique for pain management are needed.

3.4 TLIP block and modified TLIP block

The TLIP block is one block within the paraspinal interfacial plane (PIP) blocks family [43]. In this block, the needle is advanced in a lateromedial orientation between the multifidus and longissimus muscles of the thoracolumbar spine. The TLIP block was first described by Hand et al. [44], for postoperative pain control following lumbar surgeries. This block is less likely to cause a ventral rami blockade than an ESP block since local anesthetic is administered farther away from the nerve roots.

The modified TLIP block, proposed as the lumbar longissimus plane block [43], was described as an alternate method that would reduce the risk of neuraxial nerve injury by advancing the needle in a mediolateral orientation with a local anesthetic administered between the longissimus and iliocostal muscles [45]. A modified TLIP block is performed lateral to the standard TLIP block and may be technically easier. Chen et al. [46] performed a randomized controlled trial (RCT) comparing TLIP block and control (0.9% saline) in 60 patients who were scheduled for lumbar spinal fusion surgery. They found that patients who received a preoperative bilateral single shot TLIP block had significantly decreased opioid and anesthetic consumption, short postoperative hospital stay, and no significant differences in postoperative complications compared to the control group [46]. Ozmen et al. [47] performed a RCT where 90 patients scheduled for lumbar disk surgery were divided into a control group and a modified TLIP block group, and pain scores and opioid use were evaluated during the first postoperative 24 hours [47]. They concluded that pain scores and opioid consumption were superior in the modified TLIP group.

There are few studies comparing different types of blocks in spine surgery. Wang et al. [48] compared ESP block, TLIP, and control group (no block) in lumbar spine fusion [48]. Both ESP block and TLIP block provided better analgesia and reduced opioid consumption up to 48 hours after surgery when compared with control.

Ciftci et al. [11] studied patients who underwent lumbar decompression surgery. They divided the patients in 3 groups: ESP block; mTLIP block; control group. ESP block and mTLIP block provided better analgesia and less opioid consumption than control in the first 24 hours. However, there was no superiority between ESP block group and mTLIP group.

4.1 Multifidus cervicis plane block and inter-semispinal plane block

The multifidus cervicis plane block primarily intends to block the dorsal rami of cervical spinal nerves and has been utilized successfully in cervical laminoplasty [49]. However, in elderly patients it is sometimes difficult to identify the correct injection plane, leading to the development of the inter-semispinal plane block where local anesthetic is deposited between the semispinalis cervicis and semispinalis capitis muscles [50]. The authors identified the inter-semispinal block as a more superficial block compared to the multifidus cervicis plane block and noted equivalent effects in a comparative pilot study involving healthy volunteers. Its superficial location also improves the safety of the block as there is less likelihood of puncture of the dorsal artery or injection into intrathecal space. A prospective RCT was performed for use of inter-semispinal plane block for postoperative analgesia following cervical spine surgery and demonstrated decreased 24-hour postoperative analgesic consumption and lower pain scores in the first 12 postoperative hours [51].

4.2 Superficial cervical plexus block

There is one RCT that has studied the use of superficial cervical plexus blocks in patients undergoing anterior cervical discectomy and fusion [52]. Forty-six patients were randomized to either receive a superficial cervical plexus block or no block. Authors noted that although the early quality of recovery improved when measured by a 40-item quality of recovery questionnaire, both groups had similar opioid consumption and discharge times.

4.3 Cervical ESP block

Elsharkawy et al. [53] performed a cadaveric study of ultrasound guided cervical ESP blocks performed posterior to the transverse process of C6 or C7 consisting of a 20 mL injectate that contained India ink [53]. Dissection was performed demonstrating craniocaudal and medial-lateral dye spread. The authors noted that the C5, C6, C7 roots of the brachial plexus and dorsal rami were consistently stained and suggested that this type of block could be utilized for patients undergoing cervical spine surgeries. However, they also noted that the phrenic nerve was stained in 3 of the 10 injections performed. The concern for potential bilateral phrenic nerve block may preclude the use of bilateral cervical ESP blocks for cervical spine surgery. A recently published prospective, randomized controlled, double blinded study randomized 86 patients receiving posterior cervical spine surgery to regional anesthesia with ESP block versus a control group [54]. The ESP block demonstrated less intraoperative opioid consumption, muscle relaxant use, surgical duration, intraoperative blood loss, postoperative pain, and earlier mobilization.