In the past year, researchers from Belmont University and the Middle Tennessee School of Anesthesia published two papers questioning whether dry needling the lumbar multifidi could put patients at risk for spinal canal injuries.1,2 The authors of the 2023 paper described that they aimed to determine if a solid filament needle could penetrate the ligamentum flavum at the T12/L1 interspace.1 The study was performed on a fresh-frozen, lightly fixed cadaver of an 88-year-old female in the prone position with ultrasound-guided dry needling. They concluded that a 0.30 x 50 mm needle inserted approximately 1.0 cm lateral to the spinous process of T12 and directed medially at a 22-degree angle could pass between adjacent vertebral laminae and penetrate the ligamentum flavum to enter the spinal canal.1 In other words, when needling in a lateral to medial direction, it is possible to create a potential subdural bleed and subsequent epidural hematoma. 
Several case reports have described epidural hematoma in the cervical spine,3,4 and the potential of a lumbar epidural hematoma does exist although to the best of our knowledge, it has not been described in the literature. Two large-scale retrospective studies of adverse events of dry needling did not encounter any spinal epidural hematomas or any major adverse events.5,6
The 2024 study repeated the previous study with an important modification.2 In this study, the researchers used a 0.30 x 40 mm needle and directed it in an inferior-medial angulation toward midline on a 77-year-old female donor. The needle was angulated 33 degrees from vertical with an 18-degree inferior angulation.2 In both studies, a needle was inserted until it reached the lamina after which additional needles were placed in very close proximity until a needle breached the ligamentum flavum and entered the spinal canal.1,2 Neither study reports how many additional needles were placed until the breach occurred. Both papers recommend the use of sonography during riskier dry needling procedures. Unfortunately, in the United States, most physical therapists do not have access to sonography even though the costs have decreased significantly during the last decade. In two recent dry needling courses conducted in the Myopain Seminars headquarters only 2 out of 28 physical therapists owned sonography equipment. In contrast, Spanish physical therapists routinely have ultrasound equipment (personal communication with Pablo Herrero, PT, PhD – November 4, 2024).
The true incidence of dry needling adverse events is not known as they are not being tracked and probably underreported.7 8 The two studies are important as they demonstrate that dry needling near the spine does carry potential risks. The studies included only two cadavers, which is sufficient to explore the feasibility of entering the epidural space, but no conclusions can be drawn about the optimal needling approach and the prevalence of such injuries.
When in doubt, stay out.
During a recent Dry Needling Dissection course, Jan Dommerholt prepared a brief anatomical video about dry needling the lumbar and thoracic multifidi. In this case, the distance from the skin to the lamina was approximately 8 cm which implies that the needles used in the two studies would be insufficient to reach the lamina.
The International Dry Needling Education and Training Advisory Group (IDNETAG) has considered dry needling of the multifidi and during that process, the IDNETAG members reviewed every article, case report, and study on the subject of dry needling of the multifidi. IDNETAG recommends placing the needle 10-15mm lateral to the spinous process, depending on the patient’s morphology. The needle is moved in a posterior to anterior direction directly over the bony posterior column between the level of the upper and lower borders of the spinous process of each vertebra of the lumbar spine, towards the lumbar vertebra laminae or in a medial and slightly caudal direction towards the lumbar spine. The target tissue is at the same level as that of insertion. Another approach targets tissues below the level of insertion with a medial, caudal and ventral angulation towards the bony laminae. There is no question that ultrasound-guided dry needling can offer substantial benefits over blinded dry needling. Our Belgium partners at Trigger teach all dry needling techniques with ultrasound guidance. Being aware of the potential risks is important. At the same time, there are no reported injuries associated with dry needling of the lumbar multifidi. Whenever a clinician is not certain about a needling approach, they should opt for another management option.
Jan Dommerholt, PT, DPT, President | CEO, Myopain Seminars
