Treatment options for acoustic neuromas

Wait and see is also known as “expectant” therapy that is following the patient with sequential scanning (with CT scan or MRI). More definitive treatment can be decided depending on the outcome of the follow-up scan. This form of management is generally adopted for those who are older (age 60 and up), people who are medically ill from other causes, and those who decline surgery.

PROS

• No immediate risks associated with the treatment (surgery or radiation)
• The decision is the right one if the tumour proves stable in its size without growth (unfortunately, we have no means of predicting the behaviour of the tumour)

CONS

• If the tumour shows significant growth during the follow-up period and surgery is contemplated, the potential risks of surgery can be higher because of the larger tumour size

A precise dose of radiation can be delivered to the tumour using what’s known as “stereotactic radiotherapy.” This form of radiation can be delivered by the GAMMA KNIFE or a LINAC unit. Both techniques are valid and comparable in radiation effects, dose delivery and accuracy. LINAC treatment is currently available in most large university teaching hospitals in Canada. In the Toronto area, it is available at the Odette Cancer Centre (OCC) and the Princess Margaret Hospital.

Radiation is delivered in small fractions over a period of 3-4 weeks. This has the advantage over single dose treatment, by delivering a larger accumulated dose while limiting side effects. Theoretically, radiation treatment could potentially stabilize tumour growth. Most tumours treated with radiation will show slight tumour reduction or no change in tumour size during the follow up period of 1-2 years. Its long-term effect in controlling tumour growth is not known. Up to 1/3 of the tumours will show growth in spite of radiation.

PROS

• Radiation could potentially delay or avoid the need for surgery
• Its overall risks with regards to serious neurologic complications are less compared with surgical treatment

CONS

Potential risks of radiation therapy include the following:

• Facial paralysis
• Facial numbness
• Hydrocephalus (rise in brain fluid pressure)
• Brainstem injury
• Hearing loss
• Hardening and scarring of tumour making surgery difficult (if the tumour continues to grow)
• The long-term effect of radiation therapy is unknown.

The aim of surgery is to completely remove the tumour; this is achieved in about 95 per cent of the cases. The chance of tumour regrowth (recurrence) is 2-5 per cent. If hearing is still present and useful, a hearing preservation operation is carried out with a suboccipital approach. Successful preservation of hearing is about 50%, with very small (intracanalicular) tumours, and about 30 per cent with tumours less than 1.5cm. If the hearing is poor or absent, a translabyrinthine approach is performed, sacrificing the inner ear en route to the tumour. Complete hearing loss is then expected on the operated side.

PROS

• A chance of complete tumour removal
• Potential hearing preservation with small tumours

CONS

Potential risks:

• Facial paralysis (depends on tumour size)
• Problems with eye closure (only with facial paralysis)
• Dizziness, unsteadiness (resolves over 6-8 weeks)
• Facial numbness (tumour larger than 2.5 cm)
• Double Vision (brief)
• Meningitis (1%)
• CSF-brain fluid leak (5%)
• Stroke (0.5%)
• Mortality: extremely low