Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of E.N.T

Background: Diabetes Mellitus (DM) and its complications are rapidly becoming the world{u2019}s most significant cause of morbidity and mortality. Most of patients with DM complain of imbalance and/or dizziness. Objective: The aim of this study was to study the changes of vestibular function in patients with DM and to correlate the severity of diabetes to different vestibular findings. Methods: Forty adult patients (mean age =49.12 ±9.03 years) with a confirmed diagnosis of DM underwent audio-vestibular assessment in the form of PTA, Immittancemetry, bedside examination of dizziness, VNG, cVEMP and SOT. Results of these tests were compared with those of 20 age and sex matched control subjects selected randomly. Both patients and controls were not known to have neither peripheral nor central vestibular disorders. The grade of neuropathy, level of HbA1c and duration of DM were compared with vestibular tests results. Results: Bedside examination was normal. Patients had high frequency SNHL, higher cVEMP threshold with longer P13 and N23 waves latency, less rations of SOT test, slower saccadic eye movement, and less gain of both smooth pursuit and optokinetic eye movements. Neuropathic patients had more delay in cVEMP waves and less SOM ratio than non-neuropathics. Patients with longer DM duration showed prolonged latency of saccades. Severity of neuropathy was correlated with delay in cVEMP waves and saccadic latency, while alternation of SOM ratio, saccadic velocity and OPK gain were correlated to glycemic control. Conclusions: Diabetic patients have a subclinical vestibular deficit that may appear with progression of DM complications. VSR is altered in diabetic patients, while the VOR is not significantly affected. Alternation of vestibular functions is related more to severity of neuropathy and glycemic control than duration of DM.

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