Heterotopic ossification as a complication of carbon monoxide intoxication.

PURPOSE Gait impairment due to encephalopathy and neuropathy has been reported in carbon monoxide (CO) intoxication. Heterotopic ossification (HO) as a cause of gait impairment after CO intoxication has never been reported. In this study we report a patient with HO after CO intoxication. CASE REPORT A 21 year-old woman developed HO after CO intoxication, which resulted in progressive difficulties in ambulation. Bone scan 3 months later revealed HO around bilateral femoral joints and extended to proximal thighs. Selective involvement of bilateral iliopsoas, tensor fascia lata, rectus femoris, sartorius, and quadriceps muscles were found by muscle magnetic resonance imaging. Surgical intervention improved ambulation. A repeated bone scan 6 months after the operation showed no focal recurrence. CONCLUSION CO intoxication can lead to HO through ischemic reperfusion injury. HO should be considered in patients with ambulation difficulties after CO intoxication. Excision of HO may be a treatment option to correct limitations in locomotion.