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Axon reflex flare and quantitative sudomotor axon reflex contribute in the diagnosis of small fiber neuropathy
Author(s) -
Namer Barbara,
Pfeffer Stefan,
Handwerker Hermann O.,
Schmelz Martin,
Bickel Andreas
Publication year - 2013
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.23543
Subject(s) - axon reflex , sudomotor , medicine , reflex , axon , nerve fiber , anesthesia , anatomy
Objective diagnosis of small fiber impairment is difficult. Methods We used the quantitative sudomotor axon reflex test (QSART) and axon‐reflex‐flare‐test in the foot and thigh of 46 patients with peripheral neuropathy to assess C‐fiber function in addition to conventional neurography and thermal threshold testing. Results In all patients, small fiber impairment was suspected because of abnormal warmth detection thresholds (76% of all tested) and/or pain in the feet. A total of 83% had reduced axon‐reflex flare areas and 17% lower QSART scores. Patients with pure small fiber neuropathy had higher rates of reduced flare areas (87.5%) and sweating rates (25.5%). There was no difference between patients with and without pain regarding thermotesting and axon‐reflex testing. Conclusions Both axon‐reflex tests are helpful to identify objectively patients with small fiber impairment. Afferent and efferent C‐fiber classes can be impaired differently. These tests detect small fiber impairment, but they cannot differentiate between painful and nonpainful neuropathy. Muscle Nerve 47: 357–363, 2013