Complex regional pain syndrome type I (RSD): pathology of skeletal muscle and peripheral nerve.
BACKGROUND
Reflex sympathetic dystrophy (RSD) (recently reclassified as complex regional pain syndrome type I) is a syndrome occurring in extremities and, when chronic, results in severe disability and untractable pain. RSD may be accompanied by neurologic symptoms even when there is no previous neurologic lesion. There is no consensus as to the pathogenic mechanism involved in RSD. To gain insight into the pathophysiology of RSD, we studied histopathology of skeletal muscle and peripheral nerve from patients with chronic RSD in a lower extremity.


METHODS
In eight patients with chronic RSD, an above-the-knee amputation was performed because of a nonfunctional limb. Specimens of sural nerves, tibial nerves, common peroneal nerves, gastrocnemius muscles, and soleus muscles were obtained from the amputated legs and analyzed by light and electron microscopy.


RESULTS
In all patients, the affected leg showed similar neurologic symptoms such as spontaneous pain, hyperpathy, allodynia, paresis, and anesthesia dolorosa. The nerves showed no consistent abnormalities of myelinated fibers. In four patients, the C-fibers showed electron microscopic pathology. In all patients, the gastrocnemius and soleus muscle specimens showed a decrease of type I fibers, an increase of lipofuscin pigment, atrophic fibers, and severely thickened basal membrane layers of the capillaries.


CONCLUSIONS
In chronic RSD, efferent nerve fibers were histologically unaffected; from afferent fibers, only C-fibers showed histopathologic abnormalities. Skeletal muscle showed a variety of histopathologic findings, which are similar to the histologic abnormalities found in muscles of patients with diabetes.
van der Laan
L
L
Department of Surgery, University Hospital Nijmegen, The Netherlands.
ter Laak
H J
HJ
Gabreëls-Festen
A
A
Gabreëls
F
F
Goris
R J
RJ
D000328:Adult; D002196:Capillaries / Q000473:pathology; D005260:Female; D006801:Humans; D008062:Lipofuscin / Q000032:analysis; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009046:Motor Neurons / Q000473:pathology / Q000648:ultrastructure; D018485:Muscle Fibers, Skeletal / Q000737:chemistry / Q000473:pathology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000098:blood supply / Q000737:chemistry / Q000473:pathology*; D009336:Necrosis; D009412:Nerve Fibers / Q000473:pathology / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000473:pathology / Q000648:ultrastructure; D010525:Peripheral Nerves / Q000098:blood supply / Q000737:chemistry / Q000473:pathology*; D010543:Peroneal Nerve / Q000098:blood supply / Q000737:chemistry / Q000473:pathology; D012019:Reflex Sympathetic Dystrophy / Q000473:pathology*; D013497:Sural Nerve / Q000098:blood supply / Q000737:chemistry / Q000473:pathology; D013979:Tibial Nerve / Q000098:blood supply / Q000737:chemistry / Q000473:pathology
D008062:Lipofuscin