The role of MRI in the diagnosis of audio-vestibular pathology

Introduction and objective: Vestibular schwannoma is a benign, slow-growing tumor that appears in the myelin sheath surrounding the vestibular nerve. These tumors represent 6% of all intracranial tumors and 85% of tumors in the cerebellopontine angle. The most common initial symptom is unilateral hearing loss, followed by unilateral tinnitus, instability, vertigo, headache, and, in certain cases, facial paresthesia or facial paralysis. All of these symptoms depend on the size and location of the tumor. Currently, the diagnosis of these tumors is made through a complete medical history, complementary audiological and vestibular tests, and, as an imaging test, an MRI. According to the American College of Radiology (ACR), the MRI of the skull base and internal auditory canals is the gold standard for diagnosing vestibular schwannoma. This can be performed with and without contrast (usually Gadolinium) and allows the detection of very small tumors. Our objective with this article is to provide scientific evidence that enables professionals to diagnose vestibular schwannomas and optimize hospital resources. Method: From a total sample of 685 patients, all medical records of them who had been requested an MRI for audiovestibular symptoms (hearing loss, tinnitus, vertigo, facial paralysis, and others) were reviewed. A descriptive and observational study was carried out, showing the symptoms experienced by each patient, the reason for requesting the imaging test, the final diagnosis, and the type of MRI used. With all this information, a database was created, and the results were analyzed statistically. Results: Regarding the MRI results, 8% of the sample presented a lesion on the MRI that was probably the cause of the audiovestibular symptoms. Regarding the location of the lesions found in the total sample, focusing on the cerebellopontine angle, 5.2% did present a lesion in this location. In bivariate comparison, unilateral hearing loss, instability, and neurological focalization were significantly associated with a higher risk of finding lesions in the MRI that justified the clinical presentation. Unilateral pulsatile tinnitus, unilateral hearing loss with a difference of >70dB in PTA, and instability increased the probability of finding lesions in the MRI. Discussion: MRI has been a significant advancement in the diagnosis of vestibular schwannomas and cerebellopontine angle pathology. However, the easy access to this test has led to an increase in the number of incidental findings and MRIs without pathological findings. This needs the development of protocols and algorithms to support professionals in deciding whether or not to request CAI MRIs. Conclusions: With this article, we aim to contribute to decision -making when requesting an MRI and, thereby, improve the use of hospital resources. It is essential to detail the audiovestibular symptoms of patients in the medical history and with complementary tests. With our results, new lines of research could be initiated to clarify the relationships between, for example, cerebellopontine angle tumors, their symptoms, and their size, and, on the other hand, to develop future action protocols.