Subclinical neuropathy in children with IDDM: peripheral and central nerve functions: part I

ABSTRACT

Peripheral neuropathy is one of the major complications of diabetes mellitus. However the early natural history of this complication has not been well defined. Studying nerve functions in IDDM at an early stage was the aim of this work in order to evaluate the prevalence of neuropathy. The study included 20 insulin dependent diabetic patients, in addition to 10 healthy subjects of matching age and sex as a control group. Patients were subjected to full clinical evaluation which included detailed survey for neuropathic symptoms and signs, urine testing for microalbuminuria and repeated fasting blood glucose, with measurement of serum glycated hemoglobin [HbA[1c]]. Electrophysiological study included motor conduction studies of the median and deep peroneal nerves and sensory conduction studies of the sural and median nerves in addition to visual evoked potentials [VEPs]. Neuropathic symptoms were present in only 2 patients [10%] but nerve conduction studies revealed the presence of abnormalities in motor and sensory nerve functions which were more common in lower than upper extremities and more in motor nerve functions than sensory nerve functions. The duration of diabetes was a major determinant of the presence of peripheral nerve dysfunction also older age and more height were positively correlated with nerve dysfunction. Central nerve functions testing by visual evoked potentials [VEPs] demonstrated that although eyes of diabetic children showed no abnormalities in fundus examination, the implicit time of the P100 of the VEP, was significantly prolonged in eyes of IDDM cases with duration <5 years while the P100 amplitude was significantly reduced only in IDDM patients with duration of diabetes >10 years. These findings emphasize the importance of follow up and testing for subclinical peripheral and central neuropathy by repeated electrophysiological testing of children with IDDM