Neural conduction in visual pathways in newly-diagnosed IDDM patients

Vincenzo Parisi, Luigi Uccioli, Leoluca Parisi, Gaspare Colacino, Gianluca Manni, Guido Menzinger, Massimo G. Bucci

Research output: Contribution to journalArticlepeer-review


Objectives: Visual evoked potentials (VEPs) show abnormal responses in newly-diagnosed insulin-dependent diabetic (IDDM) patients. Electrophysiological methods allow one to dissect and explore different structures contributing to neural conduction in the visual pathways. The aim of our work was to assess whether the VEP abnormalities are due to impaired function of the retinal layers and/or a delayed conduction in the postretinal visual pathways. Methods: Simultaneous recordings of VEP and pattern- electroretinogram (PERG) were performed at two intervals (at entry of the study and after 3 months) in 14 newly-diagnosed IDDM patients (age: 24.8 ± 6.8 years; duration of disease: 3 ± 1.5 months), and in 14 agematched control subjects. Results: In comparison with control subjects, IDDM patients showed: VEP P100 latencies significantly delayed (P <0.01), a significant impairment of all PERG parameters (P <0.01) and retinocortical time (RCT, difference between VEP P100 and PERG P50 latencies) and latency window (LW, difference between VEP N75 and PERG P50 latencies) also significantly increased (P <0.01). All electrophysiological parameters were not significantly changed when retested after 3 months. No correlations were found between VEP P100 latency, RCT, LW and PERG parameters. Conclusions: Impaired PERG indicates an involvement of the innermost retinal layers; increased values of RCT and LW represent an index of delayed neural conduction in the postretinal visual pathways. Therefore two sources, one retinal (impaired PERG) and one postretinal (delayed RCT and LW), may independently contribute in to the abnormal responses of VEP observed in newly-diagnosed IDDM patients. Three months of relatively-stable metabolic control have not normalized the VEP and PERG impairment.

Original languageEnglish
Pages (from-to)490-496
Number of pages7
JournalElectroencephalography and Clinical Neurophysiology - Evoked Potentials
Issue number5
Publication statusPublished - Sep 1998


  • Diabetic retinopathy
  • Insulin-dependent diabetes
  • Latency window
  • Pattern electroretinogram
  • Retinocortical time
  • Visual evoked potentials
  • Visual pathways function

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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