Abnormal movements in complex regional pain syndrome: assessment of their nature

Abnormal movements may be a clinical feature in complex regional pain syndrome (CRPS), but their basic nature is unclear. Between August 1989 and September 1998, patients fulfilling diagnostic criteria for CRPS (I or II) and displaying abnormal movements were entered into a prospective study. Fifty-eight patients, 39 women and 19 men, met entry criteria; 47 had sustained a minor physical injury at work. The patients exhibited various combinations of dystonic spasms, coarse postural or action tremor, irregular jerks, and, in one case, choreiform movements. Patients underwent rigorous clinical and laboratory evaluation aimed at characterizing their neurological disturbance. Surprisingly, no case of CRPS II but only cases of CRPS type I displayed abnormal movements. In addition to an absence of evidence of structural nerve, spinal cord, or intracranial damage, all CRPS I patients with abnormal movements typically exhibited pseudoneurological (nonorganic) signs. In some cases, malingering was documented by secret surveillance. This study highlights abnormal movements in CRPS as constituting a key clinical feature that differentiates CRPS I from CRPS II. They are consistently of somatoform or malingered origin, signaling an underlying psychoneurological disorder responsible for the entire CRPS profile.