Ankylosing Spondylitis & The Spine

There really are a lot of problems when you deal with a patient that has ankylosing spondylitis and has spine trauma or the sudden onset of neck or back pain. If we don’t pay attention to the ankylosing spondylitis patient with a spine trauma, then the outcome is not going to be good.


 Scenario:

A person with ankylosing spondylitis had a minor fall and has neck pain. You get an x-ray and the x-ray is negative (no obvious fracture) so you discharge the patient home after giving the patient a cervical collar and instruct the patient to follow up in the office in a week.

We want to make sure that we are not missing a fracture of the C-spine in a patient with ankylosing spondylitis. When you see a patient with ankylosing spondylitis and spine trauma, even a minimal spine trauma and even if the x-ray is negative, you need to hit the pause button and think about it.

Scenario:

Also, have a high index of suspicion for a fracture of the spine in patient with ankylosing spondylitis that has increased range of motion of the spine after a fall (the spine may be unstable). Do not send the patient home with a soft collar or a corset even if the patent does not have neurological deficit or even if the x-ray appears normal. This is the kind of patient that you will need to admit to the hospital and you will need to investigate the patient properly. The patient will probably need surgical stabilization.


Make sure you are dealing with a patient who has ankylosing spondylitis. To see this look at the x-ray. The patient will have bamboo spine. There will be marginal syndesmophytes and no large syndesmophytes in ankylosing spondylitis. There will be ossification of the intervertebral discs and involvement or fusion of the SI joints. HLA-B27 will probably be positive in the majority of cases. The rheumatoid factor will be negative. There will be limited chest expansion. The patients are at a high risk of occult vertebral fractures that are not easily seen on the x-rays. The x-ray is characteristic for recognizing the bamboo spine, for detecting SI joint involvement, but not very good at detecting the occult fracture. You must have a high index of suspicion for fracture in ankylosing spondylitis patients and you need to get further imaging of the spine, which can be CT scans or MRI. These fractures are not seen on x-rays. If the patient suffered a minimal trauma, low energy trauma, or experienced sudden neck pain or back pain, then rule out a fracture of the spine. The fracture in ankylosing spondylitis may not be seen at the time of initial presentation. Up to 50% of the fractures can be missed and delay of the diagnosis can occur in up to 20% of the patients. You need to get further imaging of the spine with CT scan or MRI even if the patient is neurologically intact. This occult fracture can displace, and the patient can have neurological deficit or deterioration if the patient is not diagnosed early and have proper stabilization. These fractures can be extremely unstable and are associated with a high risk of neurological deficit. Even if you image the entire spine, an occult fracture can be missed. If you are in doubt about ankylosing spondylitis, image the SI joints to establish the diagnosis, especially if the cause of pain is not clear. Patients with fractures of the c-spine and ankylosing spondylitis have a high rate of neurological deficit and mortality than other patients within the same age group. The neurological deficit with ankylosing spondylitis is over 50%. The mortality increases up to 2 years after the fracture, so when you hear that the patient suffered a minor fall or low energy fall and the patient has back pain or neck pain, then there is an occult fracture. If the patient has ankylosing spondylitis, then there is an occult fracture. This is an occult problem that we must diagnose. You may actually get the CT scan and it may not show anything, it may not clearly show the fracture, so then you get an MRI. CT scan and MRI complement each other. The fracture may be missed by one of these studies, so get the other study to either see or exclude the fracture. Usually the fracture appears to be minimally displaced (fracture is extension type) and may be associated with neurological deficit, for example loss of strength in the lower extremity. Neurological deficit can occur even after stabilization of the spine because of epidural hemorrhage. The MRI will clearly reveal the epidural hematoma. One of the principle concerns for ankylosing spondylitis is epidural hematoma. The fracture is highly unstable and has a high incidence of epidural hematoma due to disruption of the epidural veins and hypervascular epidural soft tissue in addition to a rigid spinal canal. The vertebral bodies are vascular and their canals are relatively enclosed, making it vulnerable to epidural bleeding. 

These patients that also have cardiac and pulmonary comorbidities. The mortality correlates with the older age group and an increased number of comorbidities. These fractures are highly unstable. The fractures is unstable because it extends across all three columns and creates two rigid segments that move independently from each other (chalk stick fracture). Because there is no mobility between the vertebrae, the fracture occurs as a transverse fracture of a long bone and it can be highly unstable. If you miss this condition, you can have neurological deficit and progressive deformity. Nonsurgical treatment will not work for this unstable fracture because it can lead to displacement and neurological deficit, so you will need to do multilevel stabilization, usually posteriorly. The treatment of epidural hematoma is posterior laminectomy and evacuation of the hematoma. You will also stabilize the spine fracture by posterior stabilization and fusion.

Author
Nabil Ebraheim, MD

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