200 Section - Heterotopic Ossification Related Pyrexia in a Patient with Non-Traumatic Spinal Cord Injury

A 54-year-old man sustained a T4 AIS A spinal cord injury (SCI) secondary to an AVM haemorrhage treated by embolisation overseas. On day 83 post-onset, he developed a fever of 39.2°C. Comprehensive investigations, including blood cultures, urine MCS, chest X-ray, CT thorax/abdomen/pelvis, MRI spine, and gallium scan, showed no infection. CT revealed heterotopic ossification (HO) within the left psoas muscle and disuse osteopenia in the proximal limbs. A bone scan confirmed increased osteoblastic activity near the left lesser trochanter.

Indomethacin (25 mg TDS for six weeks from day 88) and a single zoledronic acid infusion (5 mg on day 96) were commenced. Although there was no local pain or swelling, he exhibited postural hypotension and thermoregulatory instability consistent with autonomic dysfunction. The fever was attributed to HO-related pyrexia. His temperature normalised within two days of commencing indomethacin. A brief recurrence occurred on day 104, with no further episodes.

Discussions: This case supports previous reports (Citak et al., 2016) identifying fever as an early sign of HO following spinal cord injury. However, unlike typical presentations, creatine kinase remained normal despite a markedly elevated CRP (221 mg/L). The severe fever was likely amplified by autonomic dysregulation of SCI.

Conclusions: HO should be considered in spinal cord injury patients with unexplained fever once infection is excluded. Correlating clinical presentation, imaging, and inflammatory markers is essential, even when CK is normal. Early diagnosis and treatment with indomethacin and bisphosphonate can limit HO progression, autonomic dysfunction and improve rehabilitation outcomes, particularly in those with autonomic instability.