title: Morphological changes of the peripheral nerves evaluated by high-resolution ultrasonography are associated with the severity of diabetic neuropathy, but not corneal nerve fiber pathology in patients with type 2 diabetes.
abstract: OBJECTIVE
  To evaluate the morphological changes of the median and posterior tibial nerve using high-resolution ultrasonography, and the corneal C fiber pathology by corneal confocal microscopy in type 2 diabetic patients.
  
  
  METHODS
  The cross-sectional area, hypoechoic area and maximum thickness of the nerve fascicle of both nerves were measured by high-resolution ultrasonography in 200 type 2 diabetic patients, stratified by the severity of diabetic neuropathy, and in 40 age- and sex-matched controls. These parameters were associated with corneal C fiber pathology visualized by corneal confocal microscopy, neurophysiological tests and severity of diabetic neuropathy.
  
  
  RESULTS
  The cross-sectional area, hypoechoic area and maximum thickness of the nerve fascicle of both nerves in patients without diabetic neuropathy were larger than those in control subjects (P < 0.05 to P < 0.001), and further increased relative to the severity of neuropathy (P < 0.0001). All morphological changes of both nerves were negatively associated with motor and sensory nerve conduction velocity (P = 0.01 to P < 0.0001), and directly associated with 2,000-Hz current perception threshold (P = 0.009 to P < 0.001). The significant corneal C fiber pathology occurred before developing the neuropathy, and deteriorated only in patients with the most severe neuropathy. The association between the morphological changes of both nerves and corneal C fiber pathology was poor.
  
  
  CONCLUSIONS
  The morphological changes in peripheral nerves of type 2 diabetic patients were found before the onset of neuropathy, and were closely correlated with the severity of diabetic neuropathy, but not with corneal C fiber pathology.
authors.affiliation: Ishibashi Clinic Hiroshima, Japan.
authors.forename: Fukashi
authors.initials: F
authors.lastname: Ishibashi
authors.affiliation: Ishibashi Clinic Hiroshima, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Ishibashi Clinic Hiroshima, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Kojima
authors.affiliation: Ishibashi Clinic Hiroshima, Japan.
authors.forename: Asami
authors.initials: A
authors.lastname: Kawasaki
authors.affiliation: Ishibashi Clinic Hiroshima, Japan.
authors.forename: Aiko
authors.initials: A
authors.lastname: Kosaka
authors.affiliation: Ishibashi Clinic Hiroshima, Japan.
authors.forename: Harumi
authors.initials: H
authors.lastname: Uetake
keywords: Corneal C fiber pathology; Peripheral nerve ultrasonography; Type 2 diabetes