The Trouble With Trauma in Ankylosing Spondylitis

June 25, 2014

This is the tale of a 51-year-old man with ankylosing spondylitis (AS) who fell backwards from standing height while climbing out of the bath, and landed on his back.

Stenhouse G, Ulbricht C, Khanna M. Picture Quiz: Spinal injury in ankylosing spondylitis. BMJ (2014) 348 doi: http://dx.doi.org/10.1136/bmj.g3849 16 June 2014

This is the tale of a 51-year-old man with ankylosing spondylitis (AS) who fell backwards from standing height while climbing out of the bath, and landed on his back. He went to the emergency department with neck pain. He had soft tissue discomfort at the mid-cervical spine but no midline bony tenderness.

His range of neck motion was limited, but this was usual for him. He was discharged with analgesia, but came back five days later because of ongoing pain.

The attending doctor recognized the greater risk of spinal injury in patients with AS and urgently requested cervical spine imaging. A lateral radiograph showed an unstable fracture dislocation at the level of C5/6 and extension into the posterior elements, along with vertical body fusion and marginal syndesmophytes typical of AS.

There is a low threshold for surgery in these patients, even though surgery is challenging, because non-surgical treatments have a higher complication rate. One large review found a mortality of 51% in the non-surgical group vs 23% in the surgical group, with age older than 70 a major risk factor.

This patient underwent surgery with open reduction and internal fixation of the fracture-dislocation using both anterior and posterior stabilization. He recovered uneventfully and was discharged, with an excellent functional recovery.

Patients with AS who present with even trivial trauma should be evaluated for acute spinal fractures using advanced imaging, even though they themselves may minimize the pain, having difficulty distinguishing it from the usual pain.

Spinal fractures are four times as common in AS, and unstable cervical fractures are associated with nearly twice the mortality in AS as in the general population. Most fractures traverse the intervertebral disk rather than the vertebral body, because the disk has reduced elasticity and the annulus fibrosus is calcified. This results is a rigid spine with limited ability to absorb impact. The risk is further increased by disuse osteoporosis as a result of immobility.

Magnetic resonance imaging (MRI) is preferable, because it is better at assessing the spinal cord and soft tissue, although computed tomography (CT) can also be used. One review found that 60% of cervical fracture dislocations were undetectable on initial radiographs, but CT has a sensitivity of 100% and specificity of 99%.

Guidelines of the College of Emergency Medicine (UK) and the National Institute for Health and Care Excellence recommend MRI or CT for patients with head or neck trauma with potential to injure the cervical spine. This includes AS, rheumatoid arthritis, and spinal stenosis.