Comparison of different modalities for detection of small fiber neuropathy.
OBJECTIVE
In general, large fiber sensory function is easier to assess than small fiber function both clinically and electrophysiologically. Therefore, small fiber sensory neuropathies are more difficult to diagnose. The relative sensitivities of different electrodiagnostic tests for small fiber neuropathy are not known. We sought to determine and compare the sensitivities of quantitative thermal sensory testing (QST), quantitative sudomotor axon reflex testing (QSART), and cardiovascular autonomic testing for diagnosis in patients with clinically suspected small fiber neuropathy.


METHODS
15 adult patients with clinically suspected small fiber sensory neuropathy underwent neurologic examination, QST, and QSART. Twelve also underwent cardiovascular autonomic testing.


RESULTS
80% had an abnormal neurologic examination consistent with small fiber neuropathy, while 93% had at least one abnormal quantitative test. QSART was most sensitive with 12 of 15 (80%) having abnormal studies while 10 of 15 (67%) had abnormal thermal thresholds by QST. Abnormal heart rate with deep breathing was detected in 9 of 12 (75%) patients.


CONCLUSIONS
Of the modalities tested, QSART was most sensitive in confirming the clinical suspicion of a small fiber neuropathy. Autonomic cardiovascular abnormalities were also common in our patients. Clinical examination and QSART may be optimal for screening patients for small fiber neuropathy.
Tobin
K
K
Department of Neurology, University of Pittsburgh, PA 15213, USA.
Giuliani
M J
MJ
Lacomis
D
D
D000328:Adult; D000368:Aged; D001369:Axons / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology* / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000502:physiology; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis* / Q000473:pathology; D012018:Reflex / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology; D012867:Skin / Q000294:innervation