The primary complication of spinal cord injury (SCI) is loss of motor function in some or most of the body. However, the generalized nerve damage caused by SCI can lead to a host of other post-injury complications. For instance, an injured spine can cause dysregulated nerve input in any organ below the injury level. Cervical SCI (which occurs in the neck) in particular is associated with disrupted function of the heart, which relies on neurons to beat at a steady, healthy pace. These disruptions can cause cardiac arrhythmia, a potentially dangerous irregularity in heartbeat.

While the association between cervical SCI and cardiac arrhythmia is well known, less research has investigated the relationship between heartbeat and thoracic SCI (which occurs in the mid-back back). A collaborative international study investigated this question by analyzing the heartbeats of 55 patients with acute traumatic SCI, 44 of whom had cervical injury and 11 of whom had thoracic injury. Each patients’ heart rhythms were continuously monitored for 24 hours at six time points: immediately following hospital admission, once a week for the first month, and once at six months post-injury. The research team analyzed these cardiac recordings to identify intermittent episodes of sinus bradycardia (slowed heartrate).

They compared recordings captured from cervical SCI and thoracic SCI patients, finding that:

• In the month immediately after SCI, mean heartrate was lower in the cervical injury group than in the thoracic injury group.
• By six months, there were no significant differences in arrythmia at six months after SCI.
• About 1 in 3 patients still experienced bradycardic arrythmias at the six-month mark.

These results indicate that thoracic SCI confers similar risk of cardiac arrhythmia relative to cervical SCI. Given that arrhythmia persisted in both groups at six months post-injury, clinicians are encouraged to consider the first six months to be a critical window for cardiac rehabilitation. Going forward, researchers hope to extend the study period to include the 12 months following SCI to determine cardiac outcomes in the first year after injury.

Balthazaar SJT, Sengeløv M, Bartholdy K, et al. Cardiac arrythmias six months following traumatic spinal cord injury. The Journal of Spinal Cord Medicine. (July 2021).