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Year : 2015  |  Volume : 21  |  Issue : 1  |  Page : 41-46

Incidental findings on magnetic resonance imaging in patients with tinnitus

1 Department of ENT and Head and Neck Surgery, SMGS Hospital, Government Medical College, Jammu and Kashmir, India
2 Department of Radiodiagnosis and Imaging, Government Medical College, Jammu and Kashmir, India

Date of Web Publication10-Mar-2015

Correspondence Address:
Dr. Rohan Gupta
Department of ENT and Head and Neck Surgery, SMGS Hospital, Government Medical College, Shalamar Road, Jammu and Kashmir - 180 001
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-7749.152861

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Introduction: Tinnitus is "a sound in one ear or both ears, such as buzzing, ringing, or whistling, occurring without an external stimulus." Magnetic resonance imaging (MRI) is a well-established, cost-effective investigation for the patients with tinnitus. Aim: The purpose of the study was to define the frequency of incidental findings on MRI scans, of patients with a history of tinnitus but with normal clinical examination, audiometry and otoacoustic emissions. Materials and Methods: A total of 62 patients were enrolled for the present study with a history of gradually increasing tinnitus and normal clinical ENT examination. All these patients underwent MRI scan to find out any lesion that would cause tinnitus. Results and Conclusion: In the present study, evaluation of MRI scans of 62 patients with gradually increasing tinnitus was done, with ipsilateral vestibular schwannoma and neurofibromatosis II being diagnosed in 1 patient (1.61%) each. Incidental findings were demonstrated in 26 cases (41.93%); with 8 cases (12.90%) of white matter lesions, 5 cases (8.66%) of vascular anomalies, 3 cases (4.83%) of arachnoid cyst, 2 cases (3.22%) of empty sella, 4 cases (6.45%) of sinus involvement, 2 cases (3.22%) of cerebral atrophy and 2 cases (3.22%) of vascular infarcts, though none of these findings were serious and neither warranted an urgent surgical intervention but a few cases required assessment by other specialties and were referred accordingly.

Keywords: Incidental, Magnetic Resonance Imaging, Tinnitus

How to cite this article:
Kalsotra P, Gupta R, Gupta N, Sharma R, Gupta S, Gupta GD. Incidental findings on magnetic resonance imaging in patients with tinnitus. Indian J Otol 2015;21:41-6

How to cite this URL:
Kalsotra P, Gupta R, Gupta N, Sharma R, Gupta S, Gupta GD. Incidental findings on magnetic resonance imaging in patients with tinnitus. Indian J Otol [serial online] 2015 [cited 2022 Sep 26];21:41-6. Available from: https://www.indianjotol.org/text.asp?2015/21/1/41/152861

  Introduction Top

Tinnitus is "a sound in one ear or both ears, such as buzzing, ringing, or whistling, occurring without an external stimulus." [1]

The number of people who complained of some form of tinnitus varies with how tinnitus is defined, what population is sampled, and how the subjects are questioned. [2] It is important to make a distinction between the presence of tinnitus, which may be universal (and normal), and the complaint of tinnitus, which suggests an abnormality. The severity of tinnitus varies from scarcely noticeable (by the patient) to an unbearable roar that drives some to suicide. [3]

The evaluation of a patient with tinnitus requires a detailed history to determine if the patient also has hearing loss, vertigo, or headache; a complete medical examination including a neurotologic physical examination; a comprehensive audiologic evaluation with hearing thresholds, word understanding (discrimination), and assessment of hyperacusis; [4] and often, imaging studies. Magnetic resonance imaging (MRI) is a well-established, cost-effective investigation for these patients [5] but only a small percentage of these scans reveal some form of causative pathology. MRI findings which are unrelated to the purpose of the examination are considered incidental findings. [6]

A growing body of literature exists in regards to incidental findings in various groups of patients. Mirza et al. [7] reported a frequency of 41% of incidental findings while examining MRI scans for cerebello pontine angle (CPA) tumors. Katzman et al. [8] reported on incidental findings in a large group of healthy volunteers with 18% occurrence of incidental findings and a 1.1% occurrence of clinically significant findings. Rotterdam study also concluded that incidental findings in the general population are quite common. [9]

The purpose of this study was to define the frequency of incidental findings on MRI scans, of patients with a history of tinnitus but with normal clinical examination, audiometry and otoacoustic emissions.

  Materials and Methods Top

The present study was performed in the Department of Otorhinolaryngology and Head and Neck Surgery, SMGS Hospital, Government Medical College, Jammu, from January 2013 to June 2014 during which we enrolled 62 patients who presented with only one complaint of gradually increasing tinnitus with normal clinical otorhinolaryngologic examination including tuning fork tests, pure tone audiogram, tympanogram, brain evoked response audiometry and otoacoustic emission and showed no improvement with supplementary treatment in the form of methylcobalamin, zinc and ginkgo biloba. Among these 62 patients, we had 30 females and 32 males. Unilateral tinnitus was present in 54 (87.09%) patients and bilateral in 8 (12.90%) patients. MRI scan of internal auditory meatus (IAM), CPA, and brain was performed to find out any lesion that would cause tinnitus.

No ethics approval was needed for this study as the use of this imaging technique is considered as an integral part of the diagnostic approach to these patients. Patients undergoing MRI scanning had consented verbally to proceed with this examination both at time of arranging the scan and at the time of scanning.

  Results Top

Magnetic resonance imaging scans of 62 patients were evaluated (30 females and 32 males), with age ranging from 21 to 64 years.

34 scans (54.84%) were reported as completely normal.

Ipsilateral vestibular schwannoma was seen in 1 (1.61%) of the patients, and he was referred for neurosurgical evaluation and management.

Scan of 1 patient (1.61%) showed 2 small meningiomas arising from left parietal region, measuring about 12 mm × 11 mm and 7 mm × 5 mm [Figure 1] and also the presence of bilateral small vestibular schwannoma with the right measuring about 8 mm × 3 mm and left measuring about 4 mm × 3 mm [Figure 2]. Following this MRI spine was done but nothing significant was found. Neurological, opthalmological, and dermatological consultations were also insignificant. Therefore on the basis of clinical presentation and radiological imaging a diagnosis of neurofibromatosis II was made and as per the patients' request, she was referred to a higher centre.
Figure 1: (a) Axial T1-weighted postcontrast image showing two small enhancing meningiomas in left high parietal parasagittal location. (b) Coronal TI-weighted postcontrast image showing enhancing meningioma. (c and d) T1-weighted postcontrast left parasagittal images showing two small meningiomas

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Figure 2: Axial T1-weighted postcontrast image showing bilateral enhancing small acoustic neuromas

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Magnetic resonance imaging scans of 26 patients (41.93%) demonstrated various incidental findings with the most frequent incidental finding being hyperintensive white matter lesions (WML), seen in scans of 8 patients (12.9%) [Figure 3].
Figure 3: Fluid attenuated inversion recovery image (magnetic resonance imaging) axial section showing frontoparietal and periventricular hyperintensity in a 58-year-old male with tinnitus

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Five scans (8%) had vascular anomalies, with a loop of anterior inferior cerebellar artery (AICA) being present in four scans (6.45%) [Figure 4] and a loop of posterior inferior cerebellar artery in only 1 patient (1.61%).
Figure 4: (a) Axial view of T2-weighted scan magnetic resonance imaging (MRI) brain showing the origin of anterior inferior cerebellar artery (AICA) from basilar artery; (b) axial view of T2-weighted scan MRI brain showing the course of AICA; and (c) axial view of T2-weighted scan MRI brain showing loop of AICA compressing upon VII and VIII cranial nerves

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Three patients (4.84%) were reported as having arachnoid cyst (one in the temporal fossa, second in the CPA and another in the quadrigeminal cistern) [Figure 5]. These were considered innocuous, and no further action was warranted.
Figure 5: (a and b) T1- and T2-weighted magnetic resonance imaging images showing cerebrospinal fluid intensity lesion in left temporal region suggestive of arachanoid cyst

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Magnetic resonance imaging scans of 2 patients (3.22%) reported an empty sella with both these patients being obese females, who were sent for further investigation and management to the department of internal medicine.

Four patients (6.4%) were reported to have findings from one or multiple sinuses with findings ranging from simple mucosal thickening to pansinusitis.

Cerebral atrophy was seen in the MRI scans of 2 patients (3.22%).

Two scans (3.22%) had vascular infarcts one in basal ganglia and other in the parietal lobe cortex [Figure 6] and [Table 1].
Figure 6: Fluid attenuated inversion recovery image axial view showing hyperintensity in right parietal lobe; and (b) diffusion-weighted imaging magnetic resonance imaging axial section at same level shows diffusion restriction in the above-mentioned lesion suggestive of middle cerebral artery territory infarct

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Table 1: Incidental findings in MRI

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  Discussion Top

Initially all the patients presenting with the chief complaint of gradually increasing tinnitus to our outpatients department underwent a full otolaryngologic clinical evaluation, vestibular clinical examination, pure tone audiometry, tympanogram, auditory brainstem response and otoacoustic emission study but only those patients were included in the study whose clinical examination and all other investigations as mentioned above were normal. Subsequently, these patients underwent an MRI scan of the IAM, CPA and brain in order to exclude any intracranial pathology and finally the present study included the evaluation of MRI scans of 62 patients.

Magnetic resonance imaging (with thin transverse and coronal T1- and T2-weighted images through the temporal bones and transverse images through the entire brain) is the study of choice for imaging of patients with tinnitus. [10] In patients with a unilateral nonpulsatile tinnitus, the most important pathology to exclude is a retrocochlear lesion and contrast-enhanced MRI is the most appropriate study to be performed. [11] Acoustic neuromas appear as iso-to hypointense on T1-weighted images and hyperintense on T2-weighted images with intense enhancement on gadolinium contrast administration. [12] Modern MRI scanners are considered to reach 100% sensitivity for acoustic tumor screening, without enhancement. However, further imaging with enhancement is needed to confirm the diagnosis. [13] In the present study T1-weighted sections with gadolinium enhancement and T2-weighted high resolution 2 mm sections through the IAM and 4 mm sections through the brain were performed.

In the present study, 54.84% MRI scans were reported to be normal, and a similar number is also reported by other studies done to investigate audiovestibular symptoms. [7],[14]

Twenty-eight MRI scans demonstrated positive findings in the present study with an ipsilateral vestibular schwannoma being detected in one of the patients and 1 patient was reported as having bilateral meningioma with bilateral vestibular schwannoma which was diagnosed as neurofibromatosis II. Neurofibromatosis II is a rare syndrome characterized by bilateral vestibular schwannomas, multiple meningiomas, cranial nerve (CN) tumors, spinal tumors and eye abnormalities [15] and this case was referred to higher center for further management.

The remaining 26 (41.94%) MRI scans revealed positive findings, however these could not be directly related to the investigated symptoms, therefore they were considered as incidental findings. [6] These findings are consistent with the study by Mirza et al. [7] who reported 41% incidental findings and Papanikolaou et al. [14] who reported 47.5% incidental findings.

In the present study, the most common finding was subcortical white matter (WM) hyperintensive foci, commonly referred as WML (12.9%). White matter hyperintensities lesions on T2-weighted and fluid-attenuated inversion recovery brain MRI are very common findings in elderly cohorts and their prevalence increases from 15% at the age of 60% to 80% at the age of 80. [16],[17] Mainly located in the periventricular WM and perivascular spaces, they can also be detected in deep WM. The exact nature of WML is still not defined, however, currently, the consensus is that they may well be ischemic in nature. This concept has been studied in relation with various cardiovascular factors, with hypertension being the most common. [18] Studies have shown WML to be associated with impairment in memory, [19] motor performance, balance, and gait. [20] But in the present study none of the patients had any of such impairment but all these patients were advised to get a general physician consultation done.

Five (8%) MRI scans reported vascular anomalies, loop of AICA was found in four scans, and a loop of posterior inferior cerebellar artery was found in the scan of 1 patient. The loop of the vessels was in close contact with the facial and vestibulocochlear nerves, and such vascular loops are not uncommon findings in various anatomical studies. [21] Hoekstra et al. [22] studied 321 patients with chronic tinnitus and found AICA loops in 70 (23%) patients and concluded that AICA loops are often encountered on an MRI scan but rarely relate to the tinnitus and should thus be considered incidental findings. In MRI studies, the incidence of AICA loops in contact with the eighth CN was nearly the same in symptomatic and asymptomatic patients (25% and 21.4%, respectively) [23] hence they are included in incidental findings while Nowé et al. [24] stated that nonpulsatile tinnitus may result from a microvascular compression at the cisternal segment of the eighth CN and showed a correlation between the clinical presentation of nonpulsatile tinnitus (high and low pitch) and perceptive hearing loss. Nowé et al. [24] and De Ridder et al. [25] found a strong correlation between the presence of vascular loops in the IAC seen on MRI and pulsatile tinnitus and theorized that pulsatile tinnitus is caused by direct transmission of pulsations to the cochlea via a resonance effect in the petrous bone. Nowé et al. [24] stated that the resolution of symptoms after microvascular decompression surgery should be accepted as a confirmation of their theory. The wide discrepancies among the studies may be explained by interobserver differences that can alter the results of estimation or evaluation of the various types of audiovestibular diseases in different studies. After a detailed discussion regarding the MRI findings, the treatment modalities and expected outcomes, the patients refused any further interventions.

Three (4.84%) MRI scans were reported as having arachnoid cyst (one in the temporal fossa, second in the CPA and another in the quadrigeminal cistern). The size of the lesions was small hence these were considered innocuous and no further action was warranted; thus, a routine follow-up examination was suggested.

Four patients (6.45%) presented findings related to their sinuses. Sinus findings in various MRI series performed for nonsinonasal complaints appear to be quite common with the prevalence of incidental sinus abnormalities being between 29.5% and 85.2% on MRI. [26] Del Rio et al. [27] concluded in their study that incidental sinus changes on MRI is a common finding, however, they bear little association with symptoms while Nazri et al. [26] found a significant correlation between the MRI sinus findings and patients' symptoms. Currently, the consensus is that these findings need to be clinically correlated when interpreting scans of the sinuses. In our series, none of our patients were treated on the basis of the scan results.

Two (3.22%) patients presented with cerebral atrophy. Similar findings were seen in the study by Papanikolaou et al. [14] who reported 5.5% scans with cerebral atrophy. Scahill et al. [28] observed the effect of age on global and regional brain volumes in healthy individuals and their work showed that there is a significant decrease in the cross-sectional volume of whole brain with the advance of age, a finding also confirmed by our study. Cerebral infarcts were seen in 2 (3.22%) patients with one infarct seen in basal ganglia and other in parietal lobe cortex. Both these patients were referred to the department of neurology. It was seen in various studies that brain atrophy, ventricular dilatation, and WML had no significant effects on the prevalence of tinnitus but Sugiura et al. [29] reported that cerebral infarctions in the basal ganglia, thalamus and pons were associated with tinnitus.

Two (3.22%) patients presented with an empty sella on MRI scan, both these patients were obese females and were referred to the department of internal medicine. Saindane et al. [30] in their study evaluated patients with definite idiopathic intracranial hypertension (IIH) and patients with "empty sella" reported on brain MRI and found that IIH and incidental empty sella turcica groups had statistically similar sellar, pituitary, and infundibular measurements. The patients with IIH were significantly younger than the patients with incidental empty sella turcica; were more likely to report headache and visual complaints; showed greater mean scalp thickness and neck soft tissue thickness; and were more likely to have an orbital finding suggestive of IIH and thus concluded that significance of the MRI finding of an empty sella turcica can be determined using a combination of clinical and imaging findings.

  Conclusion Top

Imaging is an integral component in the workup of tinnitus. The great sensitivity of the MRI as an investigative tool for the clinician allows the detection of previously undetectable pathologies and anomalies. In the present evaluation of 62 MRI scans of patients with gradually increasing tinnitus, we diagnosed a rare case of neurofibromatosis II, incidental findings were demonstrated in 26 cases (41.94%); though none of these findings were serious and neither they warranted an urgent surgical intervention, but a few cases required assessment by other specialties and were referred accordingly. It is, therefore, the responsibility of the otolaryngologist to assess the clinical findings, inform the patient and if required refer the patient to other specialties.

  References Top

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]

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