(It is worth noting before you start reading that I have included explanations of hearing loss and possible audiograms but not actual examples. This is because clients with Multiple Sclerosis and Meningioma often present atypical audiograms.)
Those of us that have set up, or run direct referral services for MRI from audiology, will know that there are other findings that can cause hearing related red flags, and can be an unexpected finding post MRI.
Why this topic? I hear you ask, and why do you need to know? In audiology we expect various audiogram patterns and symptoms, given issues and disorders that are associated with the ear.
However, we know particularly with children there are some syndromes that you would not expect to have a hearing related component but they do, and this is the same for some other brain related disorders.
MULTIPLE SCLEROSIS (MS)
For example most people with multiple sclerosis don’t suffer hearing loss as a side effect , but a small percentage do, and it can be sudden hearing loss related (possible indication of an MS relapse episode). What most people with MS do suffer from are balance issues (around 50%) and auditory processing issues.
Processing Speech
Demyelination, causes a delay in neural timing along the central auditory nervous system. In addition, MS plaques frequently occur in the brainstem, which is a critical “relay station” for auditory information. So clients with MS will present with auditory processing issues that are worse in noise or complex auditory material, when they are overheated or tired. https://www.mssociety.org.uk/symptoms/hearing-problems
Balance
Our balance mechanism has connections through the inner ear to the brainstem and cerebellum as well where dizziness is perceived. Often it is the development of new plaques or an increase in size of old ones that will cause dizziness. https://mstrust.org.uk/news/expert/ask-expert-dizziness-and-balance
We also know that people with MS are particularly prone to a form of vertigo called benign paroxysmal positional vertigo, or BPPV. This is where small head movements like getting out of bed, bending down etc, cause sudden dizziness. It is caused by dislodged calcium crystals entering the semicircular canals. When you move your head these crystal can dislodge from the tiny hairs in your ear and cause the hairs to move, sending false signals to the brain that results in vertigo. Whilst MS doesn’t cause the BBPV, the demyelination affects the brain’s ability to properly process the incoming balance signals, making it harder for them to compensate for peripheral inner ear issue
Always ask yourself is this an audiogram I expect given a client’s history, does this make sense?
MENINGIOMA
Unfortunately, this is a true example of a delayed meningioma diagnosis: The client had a symmetrical cookie bite loss that wasn’t there in her teenage years or early 20’s; with bilateral tinnitus and intermittent balance issues.
If there was no family history of this. The hearing changes from normal hearing to a cookie bite loss over a period few years between the age of 30-40. This is a red flag even though technically the hearing and tinnitus were symmetrical.
The client had a meningioma which went undiagnosed for many years. Audiologists felt because the loss was symmetrical and the tinnitus bilateral that it didn’t warrant referral. The GP only referred when the client complained of facial numbness, more consistent dizziness and pins and needles.
But if they had listened closely to the client’s history there were red flags there. Normal hearing which started to change quickly. No family history of any type of hearing loss until post 50-60 years of age. Unexplained dizzy episodes, hearing aids not really being helpful. Two eminent neurologists weren’t impressed that audiology did not listen well enough and missed referring the client earlier!!
WHAT IS A MENINGIOMA?
Meningiomas, particularly those that occur in posterior cranial fossa or internal auditory canal, will/can cause hearing loss and tinnitus.
Like acoustic neuromas (A/N) they do this by compressing the eighth cranial nerve or the auditory pathway. Unlike A/N’s which start on the nerve sheath, meningioma’s start on the meninges, hence the name.
They like A/N’s grow slowly (so may often not be picked up for years), they are often benign, tumours, rarely cancerous.
Meningiomas arise from arachnoid cap cells that are sprinkled on the outer surface of the meninges. They are one of the more common types of primary brain tumours.
Meningioma are nearly twice as common in females than in males, rising to being three times more common in females between the ages of 35 and 54 years. Incidences of meningioma increase with age, particularly after the age of 65.
What is very interesting is that 40-60% of meningioma carry a mutation of Neurofibromatosis Type 2 gene. https://braintumourresearch.org/pages/types-of-brain-tumours-meningioma
Most meningiomas grow slowly and compress the central nervous system (CNS) at such a gradual rate that the CNS is able to accommodate this and any associated damage without displaying any symptoms for several years. When the client starts to display symptoms, the type of symptoms and how they present will depend on the location of the tumour. As it starts to grow it puts pressure on parts of the brain or spine nerves and blood vessels, hence some of the non-audiological symptoms. https://journals.sagepub.com/doi/10.1177/0145561319825712.
SYMPTOMS
Patients with meningiomas may present with the following:
1. Progressive sensorineural hearing loss because the meningioma is compressing seventh and/or eighth cranial nerves.
2. Most often one ear, but can be two – Bilateral hearing loss with meningiomas is rare and typically occurs when there are large tumours in the posterior fossa or cerebellopontine angle (CPA) which compress adjacent structures. Bilateral loss can manifest due to severe brainstem pressure.
3. Numbness, tingling, pain or weakness on one side of the face.
4. Non-specific vertigo symptoms
5. Tinnitus
6. Changes in vision – double vision, blurred vision
7. Headaches – that worsen over time
8. Tingling or pins and needles, weakness in arms or legs
9. Memory loss
10. Loss of smell
11. Seizures
12. Trouble with bowel and bladder control
What do Meningioma audiograms look like?
Cerebello-Pontine Angle (CPA) meningiomas will typically generally give a unilateral sensorineural hearing loss and tinnitus. Unlike A/N’s they often show audiograms with better preserved high-frequencies (the opposite to A/N’s). But like A/N’s the loss is progressive and slow.
Up to 20% of cases may present with a normal hearing test. Speech tests may show abnormalities like they do with A/N’s.
Key Audiometric and Vestibular Findings (CPA Meningioma)
• Severity: Range varies from normal to profound deafness.
• Tumor Size Influence: Tumors larger than 2 cm tend to produce greater low-frequency (250–1000 Hz) hearing impairment.
• Prevalence of Symptoms: Hearing loss and tinnitus are common, with about 20% of patients exhibiting normal audiograms despite having a measurable CPA
• Speech Audiometry (SDS): Often shows reduced discrimination, with normal speech understanding in approximately 50% of cases.
• Auditory Brainstem Response (ABR): Highly sensitive, showing abnormal results in nearly 100% of cases.
• Vestibular/Caloric Testing: Abnormal in 77% of cases, highlighting significant vestibular dysfunction alongside hearing loss.
• Dissociation (VEMP vs. Caloric): A distinctive finding often seen with large CPA meningiomas is abnormal O-VEMP (ocular) paired with relatively normal caloric responses, whereas schwannomas typically show abnormalities in both tests.
https://neupsykey.com/30-meningiomas-of-the-temporal-bone/