Central Nervous System Abnormalities in Complex Regional Pain Syndrome (CRPS): Clinical and Quantitative Evidence of Medullary Dysfunction

OBJECTIVE:Sensory and motor abnormalities are common among patients with complex regional pain syndrome(CRPS). The purpose of the present study was to define and characterize these abnormalities and to develop a hypothesis regarding the area of the central nervous system from which they derive. DESIGN:Data were acquired from study subjects using clinical examination and quantitative assessment of neurological function. Subjects were divided into four groups. CRPS patients were differentiated into two groups based on the presence or absence of sensory deficit on the face to clinical examination. The other two groups were composed of patients with other chronic pain syndromes and normal individuals without chronic pain or disability. Clinical and quantitative data were compared between groups. PATIENTS:One hundred forty-five CRPS patients, 69 patients with other pain conditions, and 26 normal individuals were studied. RESULTS:A high incidence of trigeminal hypoesthesia was observed in CRPS patients. CRPS patients with trigeminal hypoesthesia manifested bilateral deficits of sensory function, with a predominant hemilateral pattern. These patients also manifested bilateral motor weakness with a more prominent hemiparetic pattern. Both sensory and motor deficits were greatest ipsilateral to the painful side of the body. These features differed significantly from those of CRPS patients lacking clinical trigeminal deficit, other pain patients, and normals. A lower cranial nerve abnormality (sternocleidomastoid weakness) and a myelopathic feature (Hoffman's reflex) were more common in CRPS patients with trigeminal hypoesthesia. CONCLUSIONS:Nearly half of CRPS patients had abnormalities of spinothalamic, trigeminothalamic, and corticospinal function that may represent dysfunction of the medulla. One-third of the remaining CRPS patients had neuroimaging evidence of spinal cord or brain pathology. The majority of CRPS patients in this study have measurable abnormalities of the sensory and motor systems or neuroimaging evidence of spinal cord or brain dysfunction.