The Mythology of Reflex Sympathetic Dystrophy and Sympathetically Maintained Pains

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.

Sympathetic skin response in patients with reflex sympathetic dystrophy

The sympathetic skin response (SSR) was recorded in four patients diagnosed with reflex sympathetic dystrophy (RSD) in one upper limb using Kozin's clinical criteria in conjunction with a three-phase bone scan. All patients had sustained cerebral vascular accidents and were classified as Stage I RSD. The SSR was recorded in both hands after each of ten contralateral median nerve surface stimulations and in both feet after each of ten contralateral peroneal nerve surface stimulations. Amplitude, onset latency, and number of phases were recorded for all responses in each limb. Mean amplitude, onset latency, and the number of phases of the five largest potentials were then determined. In all patients, there was a statistically significant difference in the amplitude and latency of the SSR in the involved limb compared with the uninvolved limb; mean amplitude of the involved limb was greater than the mean amplitude of the uninvolved limb (P < 0.001), and latency to onset of the SSR in the involved limb was shorter than that of the uninvolved limb (P < 0.001). There was no statistically significant difference in mean amplitude and latency between the involved side and uninvolved side responses as measured at the feet.