One of the functions of the eight cranial nerve on which an acoustic neuroma normally grows is the maintenance of balance. Unsteadiness can develop in people with an acoustic neuroma before any treatment intervention. It is an almost universal symptom for anyone who has had surgical removal of their tumour, and may occur after radiosurgery.
The slow growth of an acoustic neuroma as it presses on the balance nerve will decrease the information that it carries from the involved ear to the brain, which is required for the brain to process how to retain our balance. However, because the growth is usually slow, the brain can adjust the input from the ‘good’ ear and learns to compensate to keep both sides in balance.
After treatment it takes time for the body to adapt to the changes in balance – usually a minimum of eight weeks but it may take many months. As the balance in the ‘good’ ear compensates, unsteadiness will, in the vast majority of cases, improve.
When an acoustic neuroma patient experiences unsteadiness, it usually occurs with quick head movements, but this can also occur when standing up too quickly or when reaching above head height. A quick turn can overwhelm the system.
Without full information from the vestibular (balance) system, the brain is very dependent on input from the visual system to sense our ‘place in space’. Because of this, acoustic neuroma patients may find their balance difficulties are greater in conditions of darkness or low lighting.
To aid recovery, the balance system needs to be stimulated and that means movement of the head, eye and body, both slow and fast. A qualified person may be able to set and supervise a rehabilitation exercise programme to help with this. But many patients can well do this for themselves – often with the support of family or friends.
Imbalance and dizziness can be unpleasant and frightening but they are rarely dangerous. With help you can find practical solutions to most of the problems caused and the effects of your life can hopefully be kept to a minimum.