Sacral Multifidus Plane/Sacral ESP Block
Nomenclature: Sometimes called the Sacral ESP, yet also occasionally referred to as the Sacral Multifidus Plane Block in the literature, the jury is still out whether this is one unique block or it will ultimately be considered two separate blocks. If history is anything to go on (think QL), the nomenclature will probably shift over time.
Indications: Perineal or perianal surgery, such as hypospadias and chordee repair, anal reconstruction, hemorrhoidectomy, anal fistulectomy, pilonidal sinus excision, gender reassignment surgery, and sacrococcygeal teratoma excision.
Special Considerations: A bilateral effect from a single midline injection (the longitudinal midline approach) is presented here, yet bilateral injections at the intermediate sacral crests are also effective.
Technique: Probe – Linear; Needle – In-plane
Patient Position: Prone or lateral.
Patient Positioning and Probe Orientation
Technique
Begin scanning by placing the ultrasound probe longitudinally over the midline of the sacrum. The median sacral crest, with it’s prominent tubercles, is identified (asterisks).
Sacral ESP Block (blue line): Needle entry is in-plane, from a cranial to caudad approach, directed towards the S3 level. Local anesthetic is deposited between the sacrum and the erector spinae muscle group, with visualization of separation of the fascial plane.
Sacral Multifidus Plane Block (pink lines): An alternative approach can be taken where two separate injections of local anesthetic occur in the same tissue plane as above, but just laterally to the midline. It begins with orienting the ultrasound probe transversely over the sacrum, and identifying the single median sacral crest. Just laterally lie the two intermediate sacral crests. The center of the probe is slid laterally to either of the intermediate sacral crests. The probe is once again rotated 90° to a parasagittal plane. Local anesthetic is injected between the intermedial sacral crest and overlying multifidus muscle. The technique is then repeated with injection in the facial plane over the contralateral intermedial sacral crest.
Potential Complications:
As with all peripheral nerve blocks, bleeding / infection at needle insertion site.
With no large vessels in this location, intravascular injection is rare.
With the bony sacrum as a fixed endpoint, damage to underlying structures is rare. Care must be taken not in inject directly into the posterior sacral foraminal, which lie lateral to the intermediate sacral crests.
Transverse Sacral Ultrasound Anatomy
Sagittal Ultrasound Images for Sacral ESP
(You can see the threadlike appearance of the aponeurosis of the multifidus muscle during the hydrodissection)
The sacral ESPB was first described for pilonidal surgery by Turger el al in 2019. Hamilton identified the need for anatomical nomenclature clarity in 2020, and reported that the block should be referred to as the sacral multifidus plane block, especially when one is applying bilateral injections over the intermediate sacral crests.
Blockade of the posterior branches of the sacral nerves as they course out of the dorsal sacral foramina makes intuitive sense, as this is where the local anesthetic is being deposited, yet more extensive coverage and spread appear to occur. Aksu and Gurkan first describe the longitudinal midline approach and it’s ability to provide effective analgesia for an infant undergoing hypospadias repair, and additionally hypothesized that epidural spread may occur, though the mechanism of this is not well elucidated. Asku et al. published another pediatric case for sacral teratoma excision in a 5yo and use the case to illustrate the potential for the sacral ESPB/MPB to replace the need for caudal anesthesia. Roy et al. also note that coverage is comparable to central neuraxial block, and includes pudendal and lumbar plexus spread. They note that it may be favored over epidural, caudal, and pudendal nerve blocks for coverage of the perineal area.
Motor weakness, in general, appears to be spared in case reports that assessed for it, however no cases have reviewed the specific implication of this block when nerve stimulation of the anus is of crucial importance, for example during anal-pull through procedures/anorectoplasty.
Pediatric dosing is discussed by Mahajan et al. They recommend 0.5-0.6ml/kg of 0.25% bupivacaine, yet note that others have used up to 1ml/kg. They report the need for 0.1ml/kg of local anesthetic per dermatome for infants and toddlers. We have had success with this block technique using 0.2% ropivicaine 0.5-1mL/kg, as well as mixtures of 0.25% bupivacaine with 1.5% liposomal bupivacaine (Chao et al.).
Kaya, C., Dost, B. and Tulgar, S., 2021. Sacral Erector Spinae Plane Block Provides Surgical Anesthesia in Ambulatory Anorectal Surgery: Two Case Reports. Cureus, 13(1).
Aksu C, Cesur S, Alparslan V, Kuş A. Is it time to replace caudal block: Above or below the bone? J Clin Anesth. 2020;61:109676.
Aksu C, Gürkan Y. Sacral Erector Spinae Plane Block with longitudinal midline approach: Could it be the new era for pediatric postoperative analgesia? J Clin Anesth. 2020;59:38-39.
Chao AP, Tafoya S, Saadai P, Hirose S. Opioid-free recovery after laparoscopic-assisted redo pull-through and loop ileostomy via sacral and thoracic erector spinae plane blocks. Journal of Pediatric Surgery Case Reports. 2021;74:102059.
Hamilton DL. The erector spinae plane block: Time for clarity over anatomical nomenclature. J Clin Anesth. 2020;62:109699.
Mahajan R, Gulati S, Gupta K, Jain K, Bloria S, JItendra M. Ultrasound‐guided sacral multifidus plane block for analgesia following excision of sacrococcygeal teratoma in two neonates. Anaesthesia Reports. 2021;9(1):81-84.
Roy R, Agarwal G, Patel A, Mohta A. Sacral multifidus plane block for post-operative analgesia in perianal procedures. J Clin Anesth. 2021;68:110060.
Tulgar S, Senturk O, Thomas DT, Deveci U, Ozer Z. A new technique for sensory blockage of posterior branches of sacral nerves: Ultrasound guided sacral erector spinae plane block. J Clin Anesth. 2019;57:129-130.
