Symptom duration and clinical features in painful sensory neuropathy with and without nerve conduction abnormalities.
BACKGROUND
The term "small fiber sensory neuropathy" (SFSN) refers to an axonal sensory polyneuropathy predominantly affecting cutaneous sensory modalities, often associated with pain and with no evidence of large fiber involvement. We hypothesized that, in most patients, SFSN is the earliest manifestation of a nonspecific axonal neuropathy and will usually progress to involve larger, heavily myelinated sensory and motor fibers. We sought indirect evidence of this through an analysis of the correlation between symptom duration and large fiber involvement in patients with painful sensory neuropathy (PSN).


METHODS
A clinical diagnosis of PSN was supported by nerve conduction studies or measurement of epidermal nerve fiber (ENF) density in 43 patients. Symptom duration was correlated with the frequency of large fiber loss as measured by nerve conduction abnormalities. The severity and extent of clinical signs and symptoms were also evaluated in subjects with and without electrodiagnostic abnormalities.


RESULTS
Patients with large sensory axon involvement had symptoms of longer duration than patients with SFSN. The frequency of electrodiagnostic abnormalities increased in direct proportion to disease duration. Patients with electrodiagnostic abnormalities also had more extensive pinprick sensory deficits, suggesting that small fiber loss was more advanced in this group as well.


CONCLUSIONS
In PSN, the incidence of large fiber involvement appears to increase in proportion to symptom duration. This represents indirect evidence that SFSN usually progresses to involve both large and small fibers within 2-10 years.
Walk
David
D
Department of Neurology, University of Minnesota, 420 Delaware Street SE, MMC 295, Minneapolis, MN 55455, USA. walkx001@umn.edu
Zaretskaya
Marina
M
Parry
Gareth J
GJ
D000328:Adult; D005260:Female; D006801:Humans; D006987:Hypesthesia / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology / Q000502:physiology; D036421:Nerve Fibers, Unmyelinated / Q000473:pathology / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D009437:Neuralgia / Q000473:pathology / Q000503:physiopathology*; D009475:Neurons, Afferent / Q000473:pathology / Q000502:physiology*; D010525:Peripheral Nerves / Q000473:pathology / Q000503:physiopathology*; D010523:Peripheral Nervous System Diseases / Q000473:pathology / Q000503:physiopathology*; D011446:Prospective Studies; D012026:Reflex, Stretch / Q000502:physiology; D013997:Time Factors