Spinal Accessory Nerve Palsy and Whiplash
Spinal Accessory Nerve Palsy (SANP) is generally reported following surgical procedures in or around the posterior triangle of the neck. A team of researchers however, has encountered a SANP case following whiplash injury. Using this case report, they expound on the condition, touching on how the pain manifests and therapeutic approaches to treatment.
Patients commonly complain of the affected arm feeling heavy and moderate pain in the shoulders, possibly shooting out to the neck and arm. The intensity of the pain is usually heightened if the shoulder is unsupported, or if the patient is carrying or lifting heavy objects. Also, if the shoulder is elevated above its resting height during daily activities increased, pain may be experienced. To compensate, patients rely heavily on the forward and elbow flexion to accomplish the normal use of the shoulder. The authors have found some reluctance in a patient's admittance of pain, and warn:
"It has been the author's experience that patients often deny any shoulder dysfunction because of the use of such compensatory techniques. A high index of suspicion is needed on the part of the clinician to avoid overlooking hints of trapezius weakness by history."
The force and rate of time by which a nerve is stretched contributes heavily to producing nerve lesions. A great amount of force inflicted on a stretch over a period of time is bearable. If the span of time is rapid, however, the damage is dramatic. The authors link this aspect to whiplash injury:
"A sudden acceleration-deceleration event involving the cervical spine, as occurs in a typical whiplash injury, may subject the SAN to a very large force of stretch over a very rapid rate of time. The SAN is more prone to injury if the head is turned to the contralateral side prior to the event, as the ipsilateral nerve is put on stretch in this position."
To treat the condition, the authors advise alleviating the weight of the arm by taking it off the shoulder girdle—this will both decrease the pain and prevent over-stretching. It should be stressed to the patient to avoid carrying heavy objects, maintain good posture, and engage in a physical therapy regimen that normalizes the joint range of motion and muscle strength through targeted exercises or electrical stimulation:
"The treatment of SANP should be comprehensive and begin as early as possible. A high index of suspicion for SANP should be present following traction type injuries to the cervical spine. Early diagnosis and treatment of spinal accessory nerve palsy may lead to more effective pain relief and a better functional outcome."Bodack M, Tunkel R, et al. Spinal accessory nerve palsy as a cause of pain after whiplash injury: case report. Journal of Pain and Symptom Management 1998;15(5):321-328.