Résumé
Background: Diabetes mellitus (DM) is a global pandemic affecting almost every organ in the body. Peripheral nervous system involvement in diabetes is well known but there are not many studies on central nervous system involvement. Visual evoked potential (VEP) is a sensitive, non-invasive test to detect central demyelination of optic nerve. The objective was to compare the visual evoked potentials in type-2 DM patients with that of healthy controls and to find out if any correlation is there with the duration and glycaemic control of the disease and to compare incidence of peripheral and central neuropathy in DM patients.Methods: Author included 50 DM patients and 50 age and sex matched controls. Patients with previous stroke, demyelination, diabetic retinopathy and other ophthalmological disorders were excluded. VEP was recorded using pattern reversal stimulation with EMG RMS MARK II machine and p100 latency was measured.Results: P100 latencies (ms) was significantly prolonged in diabetics with mean±SD of (111.24±5.28 ms) as compared to controls (101.30±1.66 ms) with p value <0.003. Also, there was significant correlation between duration of DM and P100 latency prolongation, but no significant correlation was present when compared with glycaemic control.Conclusions: Central neuropathy is very common in DM. It is related to duration of DM and not HbA1c unlike PNP which is related to both. Central neuropathy occurs even prior to development of retinopathy or PNP. Hence, VEP is a non-invasive and sensitive screening tool for early neurological involvement in DM.
Résumé
Objective: To study the central and peripheral neuropathy by electrophysiological tests in type two diabetes mellitus patients (DM-2) before symptomatic peripheral neuropathy. Methodology: DM-2 (n=30) and age- and sex-matched (n=30) healthy subjects (controls) with normal bilateral sural sensory nerve action potentials (SNAPs) were selected after informed written consent. Their 16-channel EEG records were transformed using Fast Fourier Transformation (FFT). EEG power spectra obtained were log-transformed and compared using student’s t-test. Results: DM-2 without symptoms of peripheral neuropathy had low amplitudes of bilateral sural SNAPs in comparison to the controls though they were above the normal cut-off values of ≥ 4 μV. In EEG, DM-2 had more beta power (p<0.05) at midline Fz (24.77±11.58 vs. 12.26±11.55,), Cz (33.04±19.41 vs. 17.65±19.51,), and Pz (30.34±16.54 vs. 16.13±15.57,) and at other sites (Fp2, F8, F4, C4, T4, T6, P4, O2, Fp1, F7, F3, C3, T3, T5, P3, and O1) during eyes-close condition. Similar differences in beta power were seen in eyes-open condition. The delta power was more (p<0.05) in DM-2 during eyes-close condition at midline Fz (64.64±34.54 vs. 47.37±22.47), Cz (73.87±45.07 vs. 51.73±25.58), and Pz (66.13±36.84 vs. 44.15±19.68) and at other sites (Fp2, F8, C4, P4, O2, Fp1, F7, T3, T5, O1). Similar differences in delta power were seen in eyes-open condition. Alpha activities were more (p<0.05) in DM-2 at some sites during eyes-open condition. Conclusion: Diffuse central neuropathy occurs along with the peripheral neuropathy in DM-2 as measured by the electrophysiological tests.
Résumé
We studied diabetic central neuropathy(DCN) that is not well-known neurologic disorder. for confirming its existence and then presenting objective diagnostic criteria and methods. Thirtysix diabetics(NIDDM: 30, IDDM: 6), men age 53.1 years, 21 males and 15 females, were com pared with 36 controls, mean age 51.5 years, 18 males and 18 females, electrophysiologically. First, we diagnosed peripheral polyneuropathy(PN) in diabetics by means of Diabetic Neuropathy Staging(DNS) developed at the University of Michigan and classified diabetics into two group; group I indicates diabetics with PN. group II diabetics without PN. Second, we studied central(cortico-cervical and cortico-lumbar) motor conduction time(CMCT) by means of magnetic motor-evoked potential (MEP) and central somatosensory conduction time by means of somatosensory-evoked potentials(SEP) stimulating on median and posterior tibial nerves. There were no significant differences(P>0.05) statistically in cortico-cervical CMCT between diabetics and controls. There were significantly more prolonged(P<0.01) in cortico-lumbar CMCT between diabetics and controls. In median nerve-evoked 3-channel SEP, N13-N20 (cortico-cervical) interpeak latency was significantly more prolonged(P<0.01) in diabetics than controls. In tibial nerve-evoked 2-channel SEP, P38-N22(cortico-lumbar) interpeak latency was significantly more prolonged(P<0.01) in diabetics than controls. In 30 patients(83.3%) of 36 diabetics, the study revealed central conduction delay in view of that above 2 or more abnormalities representing central conduction delay, that is, central neuropathy. In 10 patients(33.3%, M: 7, F:3) of diabetics with central neuropathy(30 patients), even though they had no PN, central conduction delay was revealed. Conclusively, in view of representing central conduction delay in 83.3% of patients, we believer that more active evaluations are needed in diabetics representing nonspecific central neurologic symptoms, for example, psychomotor slowing or cognitive dysfunctions, and MEP and SEP are useful in diagnosing DCN.