title: Median-radial sensory nerve comparative studies in the detection of median neuropathy at the wrist in diabetic patients.
abstract: OBJECTIVE
  Median-ulnar comparative studies (MUCS) play an important role in the electrodiagnosis of carpal tunnel syndrome, but in diabetes concomitant involvement of Guyon's canal (ulnar nerve compression at the wrist) would reduce the sensitivity of MUCS. This study tested the utility of median-radial comparative studies (MRCS) in diabetic patients.
  
  
  METHODS
  Anti-dromic MUCS and MRCS were prospectively performed in 120 patients with diabetes, and 64 normal controls. In 28 diabetic patients, latent addition using threshold tracking was performed in superficial radial sensory axons to estimate persistent nodal sodium currents.
  
  
  RESULTS
  MUCS was abnormal in 49% of the diabetic patients, and MRCS was abnormal in 58%. Median motor distal latencies were prolonged in 38%, and median sensory nerve conduction velocities were slowed in 40%. The longer latency differences in MRCS were associated with smaller persistent sodium currents, suggesting that intra-axonal sodium accumulation mediated by hyperglycemia enhances nerve compression.
  
  
  CONCLUSIONS
  MRCS appears to be the most sensitive electrodiagnostic test in the detection of median neuropathy at the wrist in diabetic patients. Nerve conduction slowing across the carpal tunnel may be associated with metabolic abnormalities under hyperglycemia.
  
  
  CONCLUSIONS
  Assessment of nerve conduction across the common entrapment sites could provide new insights into the pathophysiology of diabetic neuropathy related to metabolic factors.
authors: Department of Clinical Laboratory, Graduate School of Medicine, Chiba University, 1-8-1 Inohama, Chiba, Japan.
authors: Megumi
authors: M
authors: Imada
authors: Sonoko
authors: S
authors: Misawa
authors: Setsu
authors: S
authors: Sawai
authors: Noriko
authors: N
authors: Tamura
authors: Kazuaki
authors: K
authors: Kanai
authors: Kenichi
authors: K
authors: Sakurai
authors: Setsuko
authors: S
authors: Sakamoto
authors: Fumio
authors: F
authors: Nomura
authors: Takamichi
authors: T
authors: Hattori
authors: Satoshi
authors: S
authors: Kuwabara
mesh_terms: D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003929:Diabetic Neuropathies / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D020423:Median Neuropathy / Q000473:pathology* / Q000503:physiopathology; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology* / Q000528:radiation effects; D011826:Radial Nerve / Q000503:physiopathology*; D011930:Reaction Time / Q000528:radiation effects; D012189:Retrospective Studies; D012684:Sensory Thresholds / Q000502:physiology / Q000528:radiation effects; D014953:Wrist / Q000294:innervation*