Our retrospective study included 159 scans of patients who presented with audiovestibular symptoms. All the patients underwent a clinical evaluation, pure tone audiogram, and tympanogram. Subsequently, they underwent an MRI scan of the IAM to exclude any intracranial pathology.
Up to 20% of the patients presenting to ENT department with audiovestibular symptoms are considered potential candidates for vestibular schwannoma screening . There are a few published guidelines for MRI imaging for vestibular schwannoma screening, but there is currently no national consensus on them .
Of note, only 27.2% of our scans were reported as completely normal. Papanikolaou et al. did a retrospective study on 200 MRI scans on patients presenting with audiovestibular symptoms and reported 52% scans being normal . Htun et al. also reported a similar statistics of having 49.5% scans entirely normal . Our study involved various radiologists and inter observer variation has to be taken into consideration.
Our study had a high incidence of small vessel disease and cerebral volume loss (35.2%). This can be due to the increased number of elderly population in our study. Notably, people aged 65 and over constitute 24% of the local population, in comparison with 18% nationally . Cerebral small vessel disease includes white matter lesions and lacunar infarcts and is associated with atherosclerosis, hypertension, diabetes mellitus, atrial fibrillation, and stroke .
Nineteen percent of our study population were found to have diseases in the mastoid/sinuses and post nasal space. However, none of them needed any further intervention. A large public health survey done in Norway on 982 participants chosen irrespective of their medical status found a high incidence of sinus diseases. Opacification in the paranasal sinuses was seen in two out of three participants, and mucosal thickening was seen in one out of two. Opacification of sinuses is common and can represent clinical challenges if misinterpreted and not correlated clinically .
Anatomical variants were found to be present in 9.4%. It can be difficult to assess the significance of these variants unless the radiologists highlights it as being clinically relevant. In a retrospective study of MRI scans of 2536 healthy young men (17–35 years), normal anatomical variants were present in 18.45% .
Vascular loop in IAM was seen in 8 patients. None of them required any surgical intervention. Vascular compression syndrome is believed to be due to close contact between a major artery and a nerve trunk over a prolonged period of time leading to localised demyelination and desynchronisation of impulses. A loop of the anterior inferior cerebellar artery seems to be most often involved, less so the posterior inferior cerebellar artery, the vertebral artery, or a vein .
Five patients (3.1%) were found to have vestibular schwannoma. Three were referred to a higher centre for further management and two were kept on surveillance. The detection rate of 3.1% in this study was slightly higher than other studies which reported rates of around 1% [6, 7]. This may be due to the fact that we get a concentrated group of patients already screened by the general practitioner and audiologist.
Strengths and limitations
Our study categorised the MRI reports into groups based on their clinical relevance. This can help otolaryngologists plan the management of patients with incidental findings. The limitation of our study was the possibility of inter observer variation in the MRI reports due to the reporting done by multiple radiologists.