|Year : 2018 | Volume
| Issue : 2 | Page : 105-108
Role of cervical vestibular-evoked myogenic potentials in evaluating vestibular dysfunction in patients with Type II diabetes mellitus: A prospective institutional study
Sitaramaraju Kanumuri, Krishna Vemuru Chaitanya, Janardhan Nara, K Vasu Kumar Reddy
Department of ENT, Narayana Medical College and Hospital, Nellore, Andhra Pradesh, India
|Date of Web Publication||4-Sep-2018|
Dr. Krishna Vemuru Chaitanya
Department of ENT, Quarters No. 98, Narayana Medical College and Hospital, Chinthareddypalem, Nellore - 524 003, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Cervical Vestibular Evoked Myogenic Potentials (C VEMP) is new dimension of non-invasive investigation to evaluate integrity of Saccule and inferior vestibular nerve by means of sacculo-collic reflex. In this study, we intend to use cervical vestibular evoked Myogenic potential as tool to investigate prevalence of vestibular dysfunction in patients with type II diabetes mellitus. Objectives: To study the prevalence of vestibular dysfunction as measured by cervical Vestibular Evoked Myogenic Potentials in patients with type 2 diabetes mellitus. Results: Prospective study performed on patients presenting in Otorhinolaryngology department during 2013-2016. Patients in study with type 2 diabetes mellitus of greater than 5 years underwent vestibular assessment by using Cervical Vestibular Evoked Myogenic Potentials. It was observed that 4 (10.0%) patients had absent bilateral Cervical Vestibular Evoked Myogenic Potentials responses, 8(20.0%) patients had delayed Cervical Vestibular Evoked Myogenic Potentials responses with delayed p1 and n1 latencies. Discussion and Conclusion: In diabetic individuals who are asymptomatic in patients who never complained of giddiness, Cervical Vestibular Evoked Myogenic Potentials identified vestibular dysfunction in 25% of patients. In symptomatic diabetic mellitus individuals, Cervical Vestibular Evoked Myogenic Potentials was able to identify 33.3% of vestibular dysfunction, however in another 33.3% of patients where Cervical Vestibular Evoked Myogenic Potentials failed to identify.
Keywords: Cervical vestibular-evoked myogenic potentials, diabetes mellitus, vestibular deficiency
|How to cite this article:|
Kanumuri S, Chaitanya KV, Nara J, Kumar Reddy K V. Role of cervical vestibular-evoked myogenic potentials in evaluating vestibular dysfunction in patients with Type II diabetes mellitus: A prospective institutional study. Indian J Otol 2018;24:105-8
|How to cite this URL:|
Kanumuri S, Chaitanya KV, Nara J, Kumar Reddy K V. Role of cervical vestibular-evoked myogenic potentials in evaluating vestibular dysfunction in patients with Type II diabetes mellitus: A prospective institutional study. Indian J Otol [serial online] 2018 [cited 2019 Sep 21];24:105-8. Available from: http://www.indianjotol.org/text.asp?2018/24/2/105/240562
| Introduction|| |
Cervical vestibular-evoked myogenic potentials (cVEMPs) is a new dimension in vestibular system investigation; it is a noninvasive investigation to evaluate the integrity of saccule and inferior vestibular nerve by means of sacculo-collic reflex. Vertiginous attacks are common in patients with type II diabetes mellitus due to poor glycemic control. However, recent literature suggests the role of vestibular dysfunction for these vertiginous attacks.
Vestibulopathy, a term often suggestive of hypofunction in horizontal as well as vertical canals evidenced with electronystagmography (ENG) and cVEMP, does cause a significant problem in the elderly. The problem may cause oscillopsia during locomotion and/or head movements, which often causes unsteadiness. Many morphological studies have suggested that microvascular and connective tissue changes as well as alteration of inner fluid metabolism contribute to otolith injury in people with diabetes.
The application of cVEMP to study the function of otolith organ and integrity of inferior vestibular nerve in patients with diabetes is not eloquently reported earlier. In this study, we intend to use cVEMP as a tool to investigate the prevalence of vestibular dysfunction in patients with type II diabetes mellitus.
The objective of this study is to study the prevalence of vestibular dysfunction as measured by cVEMP in patients with type II diabetes mellitus.
| Materials and Methods|| |
This was a prospective study performed on patients presenting to otorhinolaryngology department during 2013–2016. A total of sixty people were selected for the study. A group of twenty normal nondiabetic individuals who were similar to the study group comprising of forty patients suffering from type 2 diabetes mellitus were studied to establish the normalcy values of cVEMP. These normative data of cVEMP were considered as the normative values and formed the standard criteria for comparison.
Forty patients in the age group of 20–60 years diagnosed with type II diabetes mellitus for >5 years were included in the study. Patients presenting with central nervous system disorders and diseases involving external or middle ear with limitation of neck movements; those presenting with a history of head-and-neck injury, a history of usage of drugs such as antiepileptics, muscle relaxants, a history of head-and-neck surgery; and those presenting with a history of usage of vestibulotoxic drugs were excluded from the study.
All the study population underwent regular neuro-otological examination which included otoscopy, pure-tone audiometry, fistula test, Dix–Hallpike test, cerebellar function tests, Unterberger's stepping test, timed up and go test, and ENG. Selected patients in the study within the age group between 20 and 60 years with type II diabetes mellitus of >5 years underwent vestibular assessment using cVEMPs.
The test was performed in an audiological sound-treated room with electrical isolation equipment. GSI Audera (version 2.6 software) Viasys Healthcare, Inc. Madison WI 53711-4497 with a desktop computer having ER-3A inserts ear phones as output transducers were used for performing the study. The patient on whom the test was being performed was asked to lie down on a couch and flex the head to 20°–30° opposite to gravity so as to contract the ipsilateral sternocleidomastoid muscle. Electrodes were placed such that the positive electrode was placed on sternocleidomastoid, negative on the sternum, and the ground electrode was placed on the forehead. Precautions were taken to maintain absolute silence and switching off of all the electronic devices which can interfere with the responses.
Short-duration tone pips (2-1-2 cycles, 5.1/s stimulus rate, 105 dB nHL stimulus intensity) at a frequency of 500 Hz were presented through a headphone on the ear being tested, and the EMG activity was recorded from the ipsilateral sternocleidomastoid muscle using surface electrodes. The test was repeated twice on both sides to look for better superimposition of the waveforms. The latencies of P1 and N1 were measured. The amplitude of the waveform obtained was also calculated by difference between the P1 and N1 (P1−N1).
cVEMPs are summation responses recorded from the contracted sternocleidomastoid EMG so as to reflect the repetitive summative relaxation of the SCM in response to synchronized acoustic stimulation of the ipsilateral ear/saccule. The saccule, though primarily a sensor of linear acceleration/gravity, also senses acoustic stimulation. Individual small-amplitude relaxation impulses are summated on a background of EMG activity. Acoustic stimulation of the saccule leads to minimal activity in the vestibulospinal fibers and subsequently the sternocleidomastoid muscle.
During the performance of the study, we considered the following criteria as markers for diagnosing vestibular dysfunction which included absent cVEMP response, prolonged p1 and n1 latencies (ms), and decreased p1−n1 interamplitude (μV). The results of cVEMPs were compared in the patients with type II diabetes mellitus and the normative data established from the cVEMP responses obtained from twenty normal, age-matched, nondiabetic patients.
| Results|| |
A total of sixty patients were taken up for the study, of which twenty patients were without a history of noninsulin-dependent diabetes mellitus (NIDDM) and forty patients were with a history of NIDDM. Of these patients, 28 (70.0%) patients were male and 12 (30.0%) patients were female. When the clinical symptoms of the patients were analyzed, vertigo was observed to be the most common symptom observed in 24 (60.0%) patients, followed by hard of hearing in 16 (40.0%) patients. Tinnitus was observed in six (15.0%) patients of our study.
cVEMPs were performed in twenty normal individuals and the normative data were established in the study population which were used as a reference guide to set up cVEMP testing and these data were used for interpretation of cVEMP responses in patients with type II diabetes mellitus. The values of normative data obtained in cVEMP were depicted in [Table 1].
|Table 1: Normal values of Cervical Vestibular Evoked Myogenic Potentials established from the study|
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In the group with forty known type II diabetes mellitus patients with >5 years of duration who underwent vestibular assessment using cVEMP and these responses were analyzed and compared with normative data established, it was observed that four (10.0%) patients had absent bilateral cVEMP responses, eight (20.0%) patients had delayed cVEMP responses with delayed p1 and n1 latencies, and 28 (70.0%) patients had normal cVEMP responses. Among the forty patients with NIDDM, eight patients showed delayed cVEMP responses. cVEMP responses (latencies) in these eight patients, when compared to the normative data established from the normal population, are delayed (p1 > 13.2 ± 1.27, n1 > 22.19 ± 1.54). Among 16 symptomatic NIDDM patients with normal cVEMP responses, eight patients showed positive results on performing Dix–Hallpike maneuver. Similarly, in 12 (30.0%) patients suffering from NIDDM, vestibular dysfunction was diagnosed by cVEMP. Eight patients (20%) with NIDDM and vertigo as complaints showed positive results on performing Dix–Hallpike maneuver and normal p1 and n1 latencies on performing cVEMP, these patients were investigated further with ENG and showed findings suggestive of benign paroxysmal positional vertigo.
When the cVEMP responses were analyzed based on symptoms in NIDDM patients, it was observed that 25.0% of asymptomatic NIDDM patients elicited delayed cVEMP responses, whereas 66.6% of symptomatic patients of NIDDM elicited normal VEMP responses. These results are analyzed in [Table 2].
|Table 2: Cervical Vestibular Evoked Myogenic Potentials Responses in Symptomatic and asymptomatic NIDDM Patients|
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| Discussion|| |
As normative data for cVEMP are not standardized for the study population, we have performed cVEMPs in twenty normal patients and established normative data. cVEMP responses of type II diabetes mellitus patients were compared with these normative data and assessed for any vestibular dysfunction. The results obtained from the present study suggest that the percentage of occurrence of cVEMPs in individuals with normal hearing sensitivity and no episodes of vestibular dysfunction is 100%.
Prior studies investigating caloric stimuli and rotational chair testing found fewer abnormalities in patients with type II diabetes mellitus, which may in part be due to the preservation of Type 2 vestibular hair cells, which are better suited to transduction of lower frequency stimuli. The results of our study confirm a higher prevalence of impaired vestibular performance in those patients with NIDDM using cVEMPs as a tool. This high prevalence of vestibular dysfunction in type II diabetes mellitus is also described in other observational studies such as Agrawal et al. who reported a prevalence of vestibular dysfunction in 35.4% and the odds are increased to 70.0% if the individuals are suffering from diabetes.
The latencies of p13 and n23 obtained in the current study were 13.2 ± 1.27 and 22.1 ± 1.54, respectively. These obtained values are similar to those obtained in other studies which are compared in [Table 3].
In this study, four (10%) patients with type II diabetes mellitus showed absent cVEMP responses. This result is less when compared to a study done by Ward et al., where in their study, 32% of patients with type II diabetes mellitus showed absent responses, the higher value is probably because of higher age group in their study.
In this study, 20% of the patients having diabetes mellitus had prolonged p1 and n1 latencies. Delayed cVEMP latencies in individuals with diabetes may be indicative of a neuropathy similar to the neurovascular damage seen in peripheral neuropathy in patients with diabetes mellitus, where prolonged latencies in nerve conduction studies are considered diagnostic.
The vestibular dysfunction in our study may pertain primarily to Type 1 vestibular hair cells resulting in the degradation of responses to transient stimuli measured in this study. In cVEMPs, the stimulus is thought to be primarily transduced via Type 1 vestibular hair cells. Type 1 vestibular hair cells are known to have greater sensitivity to ototoxic medication and to have increased likelihood of age-related degeneration. These findings suggest increased vulnerability of vestibular hair cells to oxygen deprivation or metabolic disturbances.
| Conclusion|| |
In diabetic individuals who are asymptomatic and never complained of giddiness, cVEMP identified a vestibular dysfunction in 25% of patients. In symptomatic diabetic mellitus individuals, cVEMPs was able to identify 33.3% of vestibular dysfunction; however, another 33.3% of patients where cVEMPs failed to identify were proved to be having vestibular dysfunction by ENG test. Thus, in symptomatic patients of diabetes, ENG always should be accompanied by cVEMPs. Due to the limited literature available about the prevalence of vestibular dysfunction in patients with NIDDM, our study remains informative.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]