An acoustic neuroma growing towards the skull base can interfere with the functions of other cranial nerves and vessels, which supply the brain and lead into the brain through the openings in the skull base.
If the 7th cranial nerve (nervus facialis) is impaired this leads to motor failures in the face, as this nerve is responsible for facial muscles, amongst other things. Facial paralysis or facial palsy are referred to here. With severe damage, the production of tear fluid and secretions from the nose and palate are affected. Eventually, the sense of taste in two thirds of the tongue will also suffer.
If the 5th cranial nerve (nervus trigeminus) is impaired this leads to sensation problems or facial pain. We're referring here to trigeminal neuralgia. The trigeminal nerve is also responsible for the jaw muscles. These symptoms occur less frequently because this cranial nerve passes somewhat further away from the cerebellopontine angle.
It is similar with the 9th cranial nerve (nervus glossopharyngeal) and 10th cranial nerve (nervus vagus). Impairments to these nerves lead to problems swallowing, painful swallowing and taste disorders in the rear third of the tongue, amongst other problems.
At the latest stage, the term «benign tumour» is absurd, when the acoustic neuroma has become so big that it fills the «reserve space in the brain», the cerebellopontine angle , and it presses on the cerebellum and the brainstem. These are areas that have vital functions for life for coordinated movement (cerebellum), breathing, heart and circulation as well as protective reflexes and the wakefulness function (brainstem). If the acoustic neuroma has become so large that it occludes the outflow of cerebral fluid (CSF) in the cerebellopontine angle and dams the cerebral fluid in the brain, the pressure in the head increases (occlusion hydrocephalus). Symptoms of this are: impaired movement coordination, severe walking difficulties and prone to falling, headaches at the back of the head, neck stiffness, vomiting, vision disorders, cognitive disorders. The lateral pressure on the brainstem can eventually lead to heart and circulation disorders, which can be life-threatening – and this is all without metastases!