Complex Focal Pain Syndrome: An Unusual Variant of Complex Regional Pain Syndrome.

Complex regional pain syndrome (CRPS) is a chronic neuropathic pain condition that is often overlooked by clinicians and typically occurs within an entire limb. There is considerable clinical variability in presentation among patients with CRPS. We report a case of extremely focal CRPS localized to the left small finger (LSF) following crush injury. A 48-year-old right-handed male presented with LSF stiffness and severe pain of three months' duration following crush injury. He endorsed severe allodynia and minimal flexion at the proximal interphalangeal and distal interphalangeal joints of the LSF. Physical examination was significant for overt shininess and edema isolated to the LSF. X-ray performed at the time of injury and three months after were devoid of any fracture or dislocation. Chronic focal pain syndrome (CFPS) may be a subset of CRPS that has yet to be documented in the literature.