Acoustic neurinoma (ACN, vestibular schwannomas, cerebellopontine angle tumours) are benign tumours developing from the 8th cranial nerve (vestibulocochlear nerve). The 8th cranial nerve consists of two parts connecting the cochlea and the balance organ with the brain stem. The tumour forms on the vestibular nerve in the inner ear. Because there is not much space here, the close anatomical relationship between the two nerves generally means that patients experience symptoms of the balance organ and the cochlea at the same time.
The initial symptoms are dizziness, imbalance, loss of hearing or sudden deafness and tinnitus. Later on, other nearby cranial nerves may develop deficits. These can include numbness in the face and one half of the tongue, trigeminal pain (facial pain) and facial paralysis (as the facial nerve is affected). Very large tumours can also cause problems swallowing, double vision and symptoms of the brain stem. In rare cases the tumour leads to an accumulation of the cerebrospinal fluid causing hydrocephalus (water on the brain).
In patients with hereditary diseases such as neurofibromatosis (NF) , the tumours often appear bilaterally.
Most patients seek medical treatment as soon as they experience their first symptoms, so the diagnosis is made in an early stage while the tumour is still small.
For smaller tumours in particular radiosurgical treatment using the Gamma Knife represents an effective and less stressful treatment alternative. Large tumours (larger than ~ 3 cm) causing problems due to local pressure on the brain steam, still require an operation. This is the only option providing fast relief for the surrounding structures.
Unlike surgical tumour removal, the aim of radiosurgical treatment is to halt the growth of the tumour. This goal is achieved in more than 90% of cases. The cancerous tissue shrinks in approximately 50% of patients after 2-3 years. The occurrence of side-effects is extremely rare in comparison to operative procedures. A current evaluation of Krefeld data indicates a side-effect rate of less than 2% for the facial nerve (N. Facialis). Further worsening of the auditory nerve was found in only 20% of patients. Surgical resection harbours a 70-100% risk of further hearing loss. Left untreated, over 95% of all patients with acoustic neurinoma will lose their hearing on the affected side within 10 years of diagnosis.