title: Axon reflex flare and quantitative sudomotor axon reflex contribute in the diagnosis of small fiber neuropathy.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Physiology and Pathophysiology, University of Erlangen, Universitätsstr. 17, 91054, Erlangen, Germany. namer@physiologie1.uni-erlangen.de
authors.forename: Barbara
authors.initials: B
authors.lastname: Namer
authors.forename: Stefan
authors.initials: S
authors.lastname: Pfeffer
authors.forename: Hermann O
authors.initials: HO
authors.lastname: Handwerker
authors.forename: Martin
authors.initials: M
authors.lastname: Schmelz
authors.forename: Andreas
authors.initials: A
authors.lastname: Bickel
mesh_terms: D001369:Axons / Q000502:physiology*; D004558:Electric Stimulation; D004568:Electrodiagnosis / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D009460:Neurologic Examination; D010146:Pain / Q000503:physiopathology; D017288:Pain Threshold / Q000502:physiology; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis*; D010543:Peroneal Nerve / Q000502:physiology / Q000503:physiopathology; D012018:Reflex / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D013497:Sural Nerve / Q000502:physiology / Q000503:physiopathology; D013546:Sweating / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology* / Q000503:physiopathology; D013697:Thermosensing / Q000502:physiology