Whiplash injury can result in pain, including neck pain, persistent headaches, and migraine [1]. Unfortunately, whiplash-associated pain is a subject of much debate in the medical community, given the difficulties associated with diagnosing and treating it [2]. Because a single effective treatment for whiplash injury does not exist, patients with acute whiplash-associated disorders often take pain medications to manage their conditions while hoping for spontaneous resolution [2]. Unfortunately, as time passes, the chance that a full recovery will never occur increases [2]. As a result, chronic pain and other symptoms are common among whiplash injury patients [2]. One potential treatment option for whiplash pain is nerve block.
Researchers have proposed the use of nerve block to treat whiplash-associated disorders and pain. Because nerve blocks can serve both diagnostic and therapeutic aims, they are versatile [3]. Evidence indicates that anesthetic blocks can help patients and providers identify the primary source of pain, supporting its diagnostic use [2]. Relatedly, patients whose pain sources were identified by nerve blocks may experience a high probability of relieving their pain after receiving radiofrequency neurotomy targeted at the nerves that are producing the discomfort [2].
Unfortunately, the diagnostic application of nerve blocks has its limitations. For one, validated criteria for choosing patients to receive diagnostic nerve blocks do not exist [2]. The nervous system is very complex, and pain can be difficult to understand in some cases. For example, patients may experience central sensitization, and pain location does not necessarily indicate which facet joints in the spine are symptomatic [2]. Furthermore, nerve blocks may produce false positives [2]. While medical teams can use techniques like repeated anesthetic block or double injection with different agents to eliminate false positives, these actions are not perfect [2].
As for the therapeutic uses of nerve block, researchers have focused on the effects on neck and head pain from whiplash injury. Persson et al. investigated how nerve blocks can treat neck pain [4]. Previous research indicated the possibility that whiplash injury damaged facet joints and capsules in the spine, which, in turn, produced pain [4]. By blocking the facet joints with local anesthetics, Persson and colleagues hypothesized that whiplash-related neck pain could be treated [4].
To test this hypothesis, the scientists recruited 47 patients suffering from whiplash-associated disorder [4]. Researchers first determined the location to target [4]. Then, Persson and colleagues injected bupivacaine near the joint [4]. When patients responded positively, the injections continued in a double-blinded sequence, one containing bupivacaine and the other saline [Persson]. Meanwhile, negative responses triggered the anesthetization of other levels of the spine in the neck [4]. The results indicated some success: 29% of patients were true positive responders, suggesting that nerve blocks may successfully treat pain in a significant percentage of cases [4].
While nerve blocks may not be a perfect diagnostic or therapeutic tool, strong evidence supports their use in identifying and treating whiplash pain.
References
[1] A. Eskilsson et al., “Decompression of the greater occipital nerve improves outcome in patients with chronic headache and neck pain — a retrospective cohort study,” Acta Neurochirugrgica, vol. 163, p. 2425-2433, July 2021. [Online]. Available: https://doi.org/10.1007/s00701-021-04913-0.
[2] M. Curatolo, “Pharmacological and Interventional Management of Pain After Whiplash Injury,” Journal of Orthopaedic & Sports Physical Therapy, vol. 46, no. 10, p. 815-930, October 2016. [Online]. Available: https://doi.org/10.1007/s12291-020-00909-2.
[3] B. Jung and N. Mehta, “Occipital Nerves,” in Pain. Switzerland: Springer, Cham, 2019, pp. 579-582. Accessed: Oct. 6, 2022. [Online]. Available: https://doi.org/10.1007/978-3-319-99124-5_128
[4] M. Persson et al., “Chronic Whiplash Associated Disorders (WAD): Responses to Nerve Blocks of Cervical Zygapophyseal Joints,” Pain Medicine, vol. 17, no. 12, p. 2162-2175, March 2016. [Online]. Available: https://doi.org/10.1093/pm/pnw036.