title: Comparison of sudomotor and sensory nerve testing in painful sensory neuropathies.
abstract: OBJECTIVE
  To compare results of quantitative sudomotor axon reflex testing (QSART), dorsal sural, and sural sensory nerve testing in patients with painful sensory neuropathy (PSN).
  
  
  METHODS
  Fifty-six patients with symptoms and neurologic examinations consistent with PSN who had both autonomic and nerve conduction studies were identified from 376 patients with a clinical diagnosis of painful neuropathy. Cases were clinically categorized as large-fiber or small-fiber neuropathies by described criteria. The results of sural, dorsal sural, and QSART tests were then analyzed in relationship to these two clinical groups.
  
  
  RESULTS
  Evidence of unmyelinated fiber abnormalities by QSART was noted in 85% of clinical large-fiber and 69% of clinical small-fiber groups. Dorsal sural potentials were absent in all the large-fiber group but also in 52% of clinically classified small-fiber neuropathies. When QSART and dorsal sural abnormalities were combined, the identification of abnormalities in all the cases of PSN was 89% with 75% of cases (42) showing mixed large and small fiber abnormalities, 14% unmyelinated sensory fiber abnormalities (by QSART), and 11% normal studies.
  
  
  CONCLUSIONS
  This study demonstrates the value of combining both QSART and dorsal sural sensory testing in verifying the diagnosis of PSN. The majority of cases demonstrate involvement of unmyelinated C fibers as well as large/medium myelinated fibers, thereby separating mixed large- and small-fiber sensory neuropathies from those cases classified by clinical criteria solely as small-fiber neuropathy.
authors.affiliation: Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA. jkillian@bcm.edu
authors.forename: James M
authors.initials: JM
authors.lastname: Killian
authors.forename: Shane
authors.initials: S
authors.lastname: Smyth
authors.forename: Rudy
authors.initials: R
authors.lastname: Guerra
authors.forename: Ishan
authors.initials: I
authors.lastname: Adhikari
authors.forename: Yadollah
authors.initials: Y
authors.lastname: Harati
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004594:Electrophysiology / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D010146:Pain / Q000209:etiology; D010523:Peripheral Nervous System Diseases / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D012018:Reflex / Q000502:physiology; D012680:Sensitivity and Specificity; D011984:Sensory Receptor Cells / Q000502:physiology*; D013497:Sural Nerve / Q000503:physiopathology*; D055815:Young Adult