MRI Scan for the Ears: What an IAM Scan Looks For

An MRI of the internal auditory meati, usually shortened to MRI IAM, is a targeted MRI of the narrow channels that carry the nerves for hearing and balance from the inner ear to the brain. It is the scan most often used when someone has hearing loss or tinnitus in one ear and a clinician wants to rule out a growth on those nerves.

Most IAM scans are normal. The reason they are done is that a small number of people with these symptoms have an acoustic neuroma, a non-cancerous growth that is much easier to manage when it is found early.

What the scan is looking for

The main question is usually whether there is an acoustic neuroma, also called a vestibular schwannoma. The NHS describes it as a type of non-cancerous brain tumour that grows on the nerve used for hearing and balance. Symptoms tend to develop gradually and often include hearing loss that usually affects one ear, tinnitus, and unsteadiness or vertigo.

The NHS also notes that acoustic neuromas can be difficult to diagnose because the same symptoms can be caused by other conditions, such as Ménière's disease. That is why imaging is used to answer the question directly.

When NICE recommends an MRI IAM

NICE's guideline on hearing loss in adults recommends offering MRI of the internal auditory meati to adults with hearing loss and localising symptoms or signs, such as facial nerve weakness, that might indicate a vestibular schwannoma. It recommends considering the scan for adults with sensorineural hearing loss and no localising signs if a hearing test shows an asymmetry of 15 dB or more at any two adjacent test frequencies.

NICE's tinnitus guideline sets out a similar approach. It recommends offering MRI IAM to people with non-pulsatile tinnitus who have associated neurological, otological or head and neck signs, considering it for people with tinnitus in one ear or asymmetrical tinnitus, and not offering imaging to people with tinnitus in both ears and no other signs or symptoms. Pulsatile tinnitus, where the sound beats in time with your pulse, is handled differently and imaging is offered.

MRI or CT for ear problems

MRI shows nerves and soft tissue in detail without ionising radiation, which is why it is the first choice for looking at the hearing and balance nerves. NICE's tinnitus guideline recommends contrast-enhanced CT of the internal auditory meati for people who cannot have MRI, and CT of the temporal bone when a problem with the bone or middle ear is suspected, followed by MRI if the soft tissue needs a closer look.

What happens during the scan

You lie on your back with your head in a head coil, a frame that helps the scanner pick up a clear signal. You will be given ear protection because MRI is loud, and you need to keep your head still. The NHS says an MRI scan can take between 15 minutes and an hour depending on the area being scanned; a targeted IAM scan is usually at the shorter end, and the clinic will tell you what to expect. Some IAM scans include an injection of contrast dye.

Before any MRI you will be asked about metal in or on your body. This matters particularly for anyone with a cochlear implant or other ear implant, which may not be safe in an MRI scanner or may need special arrangements. Our guide to MRI with metal implants explains the safety checks.

Results and what happens next

Your images are reported by an appropriately qualified clinician and the report goes to whoever referred you. If an acoustic neuroma is found, the NHS explains that small tumours often just need to be monitored with regular MRI scans, with treatment generally only recommended if scans show it is getting bigger. Our guide to how long scan results take covers timings.

Having an MRI IAM privately

Because NICE's recommendations are based on the results of a hearing test, it is worth having an audiogram before an IAM scan if you have not already had one. Many MRI clinics accept self-referral after their own safety screening, but each clinic sets its own policy, and some ask for a referral from a GP, ENT specialist or audiologist for this scan.

Clinics listed on FindScan publish the price they charge and we show it as the clinic sets it. You can search MRI scans by location, and our MRI guides cover preparation, safety and costs.