What is Schwannoma ?
Nerves are covered with Schwann cells. Tumor arising from it is called as Schwannoma. The cause of vestibular schwannoma is unknown. There is no environmental predisposing factor. Sometimes theses tumours are seen in inherited conditions like Neurofibromatosis type -2.
Are these tumours malignant?
These are benign tumors don’t spread to any other site.
What are the clinical features of Schwannoma?
Schwannoma arising from any nerve impair function of that nerve. Generally, these tumours arise from covering of vestibulocochlear nerve which helps in hearing and balancing. Initially patient starts complaining of hearing loss, ringing in the ear(tinnitus), dizziness. As tumour start increasing in size it compresses facial nerve leading to deviation of mouth and difficulty in eye closure. As tumour increases further it involves lower cranial nerves causing nasal regurgitation while swallowing. Hence timely intervention can arrest further neurological deterioration.
Are these tumours treatable?
Smaller tumours less than 3 cm can be treated with GKRS, a form of radiotherapy. It controls growth rate of tumour. It requires close follow up and regular interval MRI of patient to monitor increase in size.
Larger tumour requires surgery where part of bone behind ear is removed and tumor is decompressed with microscope under nerve monitoring.
At present there is no medicine at present to halt the growth of tumour .
Is surgery life threatnenig ?
Main aim of surgery is maximum safe resection while preserving the function of involved nerves. Ideally it is done under Neuromonitoring of involved nerves. Sometime it may not be possible to identify and separate nerve from tumor. In such cases patient may experience loss of involved nerve function.In that case patient may have facial deviation to one side , difficulty in eye closure, difficulty in swallowing and nasal regurgitation while drinking or repeated salivary micro aspiration into lungs leading to pneumonia. To avoid this, temporary tracheostomy may be required. Patient may have to put on ryles tube (tube through nose) to feed for shorter duration which may get prolong in case of non-improvement.
What will be the prognosis of patient ?
Removed completely with acceptable preserved nerve function, will have good prognosis and near normal life.
Patient with nerve deficit may require physiotherapy to regain control over swallowing and speech.
Residual tumour requires repeated follow up to check size which may require radiotherapy.
Fig.1.: Vestibular Schwannoma involving 7th-8th nerve complex with cerebellar and brainstem compression.