Hearing loss
Hearing loss is the most common symptom in vestibular schwannoma, present in more than 90% of patients (1). It usually has a gradual onset. However, in 15% of cases, patients may present with sudden sensorineural hearing loss, which can be alarming. Hearing loss can also fluctuate. Over time, the hearing usually worsens, ending in total deafness in the affected ear. Due to the trend nowadays to perform more MRI scans, tumours are picked up when smaller and hearing may thus still be unaffected.
Impaired word recognition
Word recognition or speech discrimination is the ability to identify and understand words quickly and accurately when listening. It is a crucial skill for comprehension. Patients with a vestibular schwannoma often experience decreased word recognition, meaning they have difficulty understanding speech even though they can hear it (2). This can be more pronounced than expected based on their level of hearing loss alone. Less than 50% of patients with small tumours and up to 70% of people with larger tumours may complain of reduced word recognition.(3).
Tinnitus
Tinnitus is the perception of ringing or buzzing sounds in the ears without any external sound source. It is a common finding in up to 70% of patients with vestibular schwannoma. The tinnitus experienced by these patients may have different characteristics, such as constant or intermittent, high or low-pitched, and in one or both ears.
While tinnitus is most commonly caused by hearing loss, patients with vestibular schwannoma do not necessarily have to suffer from hearing loss to experience tinnitus. Therefore, any patient presenting with one-sided tinnitus or experiencing new-onset tinnitus should be investigated for a vestibular schwannoma(4).
Balance problems
Balance problems are common in patients with vestibular schwannoma, with over 50% experiencing some form of imbalance. (4). This is especially prevalent in patients with larger schwannomas. Symptoms of balance issues can range from subtle imbalances and difficulty walking in darkness to more severe instability and a tendency to fall.
A large vestibular schwannoma can grow to a size where it presses on the cerebellum, a brain region controlling balance and coordination. This pressure can result in symptoms such as difficulty maintaining balance when walking, known as ataxia, or a tendency to fall to one side due to impaired coordination. Additionally, the compression on the cerebellum can cause an intention tremor, which is a tremor that occurs when a person is attempting to perform a specific movement. These symptoms can significantly impact a person’s ability to walk and perform activities of daily living.
In some cases, patients may also experience vertigo, which can further exacerbate their balance problems. These issues can significantly impact a patient’s quality of life.
Dizziness
Dizziness is the sensation of disturbed or impaired spatial orientation without a false or disturbed sense of motion (6). Long-term dizziness occurs commonly in over 60% of patients with vestibular schwannoma (5). Female patients, advanced age, pre-treatment dizziness or headache and a history of migraine increase the risk of dizziness. Dizziness significantly contributes to impaired quality of life.
Headache
Headaches can occur in up to 50% of patients with vestibular schwannoma (3). With large tumours, patients may also experience nausea and vomiting. Raised intracranial pressure due to large end-stage tumours pressing on the brain typically leads to headaches.
Vertigo
Vertigo is the sensation of self-motion when no self-motion is occurring or the sensation of distorted self-motion during an otherwise normal head movement(6). It is often accompanied by nausea and balance issues. It occurs as the presenting symptom in around 20% of patients with vestibular schwannoma and smaller tumours are more likely to cause this symptom (7). Vertigo spells can appear suddenly and without warning. Such acute onset spells can be dangerous, even life-threatening and significantly impact a patient’s quality of life and daily activities. This can include driving ability and working capacity and, in some cases, even restrict specific professions such as flying for pilots.
Trigeminal nerve
The trigeminal nerve (fifth cranial nerve) can be impacted by larger vestibular schwannoma leading to symptoms like facial numbness, pain, and difficulties with chewing and swallowing. While trigeminal involvement occurs in less than 10% of patients with vestibular schwannoma, it can result in significant discomfort and functional limitations in affected individuals(3).
Facial nerve
Facial nerve weakness is rare in vestibular schwannoma even in large tumours (8). It occurs in 1% – 2,2% of patients if not treated. If facial nerve weakness is present in a small tumour, a facial nerve neuroma, a different kind of tumour, should be considered. Further involvement of the facial nerve leading to taste disturbance, dry eye, incomplete eye closure, or twitching of the facial muscles is even rarer. It is essential to realise that this relatively low risk should not be a significant indication for timeous active treatment with surgery or radiation.
Earache
Earache is a rare presenting symptom in vestibular schwannoma. Instead, patients with vestibular schwannoma are more likely to complain of ear pressure. Earache can also be due to referred pain from other nearby nerves, making it essential for healthcare providers to evaluate all possible root causes of ear discomfort in patients with suspected vestibular schwannoma.
Speaking, swallowing and tongue problems
A larger vestibular schwannoma can press on the lower cranial nerves, including the glossopharyngeal nerve (ninth), the vagus nerve (tenth), and the hypoglossal nerve (twelfth). This pressure can lead to difficulties with speaking and swallowing and tongue weakness (10).
With the increasing frequency of MRI scans being performed, vestibular schwannomas are detected at earlier stages when they are smaller. These small tumours are less likely to cause speaking, swallowing, and tongue movement symptoms.
