title: Myovascular innervation: axon loss in small-fiber neuropathies.
abstract: BACKGROUND
  Vascular denervation occurs in some neuropathies, but measurement of small perivascular axons has been difficult.
  
  
  METHODS
  We evaluated 31 consecutive patients who had both muscle and skin biopsies. We quantitated myovascular innervation by staining unmyelinated axons with peripherin and non-myelinating Schwann cells with neural cell adhesion molecule and comparing their areas.
  
  
  RESULTS
  Perivascular unmyelinated axon-Schwann (UAS) ratios correlated with axon density in skin (r = 0.679; P < 0.0001). Low UAS ratios (≤0.25) had a sensitivity of 90% and specificity of 91% for a clinical diagnosis of small-fiber neuropathy (P < 0.0001). Autonomic features were more common in patients with low perivascular UAS ratios (P = 0.002). A patient subgroup with myovascular, but not skin, denervation commonly had muscle discomfort and autonomic features.
  
  
  CONCLUSIONS
  UAS ratio measurements, comparing axons and associated non-myelinating Schwann cells, can quantitate perivascular innervation. Small-fiber neuropathies are often associated with myovascular denervation. Some patients with muscle discomfort have selective myovascular denervation.
authors.affiliation: Department of Neurology, Washington University School of Medicine in St. Louis, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri, 63110, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Dori
authors.forename: Glenn
authors.initials: G
authors.lastname: Lopate
authors.forename: Richard
authors.initials: R
authors.lastname: Keeling
authors.forename: Alan
authors.initials: A
authors.lastname: Pestronk
mesh_terms: D000328:Adult; D000368:Aged; D001369:Axons / Q000473:pathology*; D001706:Biopsy; D004916:Erythromelalgia / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012583:Schwann Cells / Q000473:pathology*; D012867:Skin / Q000294:innervation*; D013497:Sural Nerve / Q000473:pathology*
keywords: autonomic symptoms; muscle biopsy; muscle pain; small-fiber neuropathy; vascular innervation