HETEROTOPIC OSSIFICATION IN THE SETTING OF NEUROMUSCULAR BLOCKADE

Objective, Heterotopic ossification (HO) is a disorder characterized b y the formation of new bone in tissue that does not ossify under norma l conditions, We report a series of 6 cases in which HO occurred in th e setting of adult respiratory distress syndrome (ARDS). We wished to show that HO can occur after neuromuscular blockade and that these cas es might provide additional evidence that HO is influenced by neural m echanisms, Methods, Cases of HO were selected from the consultation se rvices at the Massachusetts General Hospital and the Brigham and Women 's Hospital, Affected patients all had ARDS and had been treated vith a neuromuscular blocking agent. Patients with a history of stroke, bur n, head trauma, spinal cord injury, or joint replacement were excluded from this study, Results. Heterotopic bone appeared around large join ts in a pattern identical to that seen in patients with paralysis, tra umatic brain injury, severe burns, or trauma, New bone formation was s elf-limited over a period of 1-2 years, Alkaline phosphatase and techn etium bone scan were sensitive ways of detecting early disease and mon itoring disease activity, Medical therapies had limited benefit, Surgi cal excision of mature new bone appeared to be the only definitive the rapy. Conclusion. Neuromuscular blockade in the setting of ARDS appear s to be an important risk factor for the development of HO, The simila rity of these cases of HO occurring in patients with brain or spinal c ord injury raises the possibility that neural mechanisms may be import ant in the pathogenesis of this disease. Whether the type of neuromusc ular blocking agent and the duration of use are important determinants of disease severity remains to be determined.