【 摘 要 】
The most important non-transmissible diseases (NTD) for public health in Latin America and the Caribbean region are cardiovascular diseases, cancer and diabetes mellitus (DM). Of these, DM is considered an economic, social and personal burden for institutions and families.1 The current world diabetic population is about 135 million people,2 a number that might reach 221 million by 2010.3 This increase will be significant in Latin America, as 80% of life-years lost due to DM-caused incapacity occur in developing countries.4Estimates for 2025 show that there may be about 11 million diabetics in Brazil, an increase of more than 100% compared to the current number (five million diabetics).3A multicentric study on the prevalence of DM in nine Brazilian capital cities between 1986 and 1988 in the urban population aged between 30 and 69 years revealed that the prevalence of DM is 7.6%. It is believed that a longer life span has led to an increased prevalence of DM.5DM may be defined as a metabolic disorder in which a relative or absolute insulin deficiency causes chronic hyperglycemia.6Metabolic alterations in DM alter the carbohydrate, lipid and protein metabolism in the human body. The disease interferes with the metabolism of glucose and other energy-producing substances.7The etiological classification of glucose disorders by the World Health Organization is based on work done by the National Diabetes Data Group (NDDP) in the United States of America. The NDDP suggests classifying DM and other states of glucose intolerance into three subclasses, as follows: type 1, type 2 and secondary diabetes associated with another identifiable condition or syndrome.8DM is considered the main cause of blindness, of end-stage renal failure and of non-traumatic amputation during the productive age. DM increases the risk of cardiovascular and cerebral diseases 2 to 7-fold, and is also an important cause of neonatal morbidity. Recent data have shown that most of the debilitating complications of the disease may be avoided or delayed by the prospective treatment of hyperglycemia and of cardiovascular risk factors.8Glucose metabolism significantly influences the physiology of the inner ear, which is very active metabolically.9-13The inner ear does not store energy, so minor variations in blood glucose affect its function and cause balance disorders.9-13 Altered inner ear metabolism may lead to potassium transfer from the endolymph to the perilymph and an opposite movement of sodium. This mechanism may cause vertigo, tinnitus, hypoacusis and ear fullness.13Various studies14-16 have shown that both the peripheral and central vestibular systems may be altered in type 1 DM patients.The aim of this study was to investigate vestibulocochlear manifestations in patients with type 1 DM. MATERIAL AND METHODSThirty patients (17 males and 13 females) aged between 7 and 56 years (mean age - 25.7 years) with a diagnosis of type 1 DM were assessed.The study was a cross-sectional contemporary cohort trial in which patients were assessed independently of the type and duration of treatment.The study was approved by the institutional Research Ethics Committee (protocol number 009/2005).Patients signed the free informed consent form before undergoing the following procedures:Clinical historyA questionnaire was applied, emphasizing otoneurological signs and symptoms, and the personal and family history. Patients with other diseases besides type 1 DM were excluded.Otorhinolaryngological evaluationThis assessment was one to exclude conditions that might interfere with auditory tests.Audiological evaluationConventional pure tone audiometry was done using an Interacoustics AC 40 audiometer and TDH 39P earphones (thresholds in dB NA). The speech recognition threshold was done followed by the percentage rate of speech recognition, in an acoustic booth to avoid interference from extraneous noise. The degree and type of hearing loss were classified according to Davis and Silverman17 and Silman and Silverman.18Acoustic immitance testingThis procedure was done to assess the integrity of the ossicular and the tympanic systems; it is based on the tympanometric curve and investigation of the acoustic reflection. The equipment was an Interacoustics AZ-26 impedance meter and TDH 39P earphones. Jerger’s19 criteria were used to interpret the results.Vestibular assessmentPatients underwent the following tests that are part of the vestibular assessment based on vectoelectronystagmography (VENG):Unrecorded:Open eye unrecorded positional nystagmus was investigated to investigate the presence of nystagmus and/or vertigo associated with bodily changes, based on Brandt and Daroff’s20 maneuver. Open eye spontaneous and semispontaneous nystagmus in frontal gazing and at 30° to the right, to the left, upwards and downwards was done.Recorded:A Berger VN316 three-channel thermosensitive device was used for measuring VENG. Skin around the orbits was cleaned using an alcohol solution; on each patient an active electrode was placed on the lateral angle of each eye and on the frontal midline, forming an isosceles triangle (electrolytic paste was used for fixation). This setup made it possible to check horizontal, vertical and oblique eye movements. This form of VENG provided us with precise measurements of the slow component angular velocity (vestibular correction) of nystagmus. A Ferrante rotating descending pendular rotating chair, a Neurograff model EV VEC visual stimulator and a Neurograff model NGR 05 air otocalorimeter were used at air temperatures of 42°C, 20°C and 10°C for caloric tests.The following ocular and VENG labyrinth tests were done according to Mangabeira-Albernaz, Ganança and Pontes’s21 criteria:* calibration of ocular movements: regularity of tracings were assessed to enable comparisons between studies.* testing of spontaneous nystagmus (open and closed eyes) and semispontaneous nystagmus (open eyes): the presence, direction, inhibiting effect of ocular fixation (IEOF) and the maximum slow component angular velocity (SCAV) of nystagmus were assessed.* pendular tracking test: the presence and type of curve were assessed;* optokinetic nystagmus test: the presence, direction, maximum SCAV with clockwise and anticlockwise movement of the light source were assessed, and the preponderant direction of nystagmus was calculated.* investigation of pre- and post-rotatory nystagmus by the pendular swing rotatory test with stimulation of the anterior, lateral and posterior semicircular canals: the presence, direction, frequency after anticlockwise and clockwise rotation and calculation of the preponderant direction were noted.* investigation of pre- and post-caloric nystagmus: done with the patient’s head and trunk tilted backwards by 60° for adequate stimulation of the lateral semicircular canals. Stimulation time for each ear was 80 sec per ear at each temperature (42°C, 20°C and 10°C) and responses were recorded with eyes closed and then with eyes open to observe IEOF. The direction, absolute values of SCAV and calculation of the preponderant direction and labyrinthic predominance of post-caloric nystagmus. RESULTSPatient complaints, the clinical history and habits are shown on Tables 1 and 2. Audiological tests revealed alterations in three cases (10 %), as follows: one
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