Gamma-Knife Stereotactic Radiosurgery for Large Vestibular

The Schwann cells that surround the vestibular nerve, which controls hearing and balance, give birth to benign tumours called vestibular schwannomas, sometimes referred to as acoustic neuromas. Symptoms including hearing loss, imbalance, facial numbness, and in extreme situations, brainstem compression, can result from these tumours’ gradual growth and eventual pressure against nearby brain structures.

Microsurgical excision has historically been used to treat big vestibular schwannomas. However, even for big vestibular schwannomas in properly chosen individuals, Gamma Knife Stereotactic Radiosurgery (GKRS) has become a less invasive and successful therapeutic option due to technological developments and a better understanding of tumour biology.

Gamma Knife Stereotactic Radiosurgery: What is it?

With little effect on nearby healthy tissue, Gamma Knife Radiosurgery is a non-invasive, image-guided treatment technique that targets a particular area of the brain with a highly concentrated radiation dose. No “knife” or incision is used, despite the name. It delivers a potent dose exactly to the tumour by utilising hundreds of coordinated gamma radiation beams that converge on a single location. The tumor’s DNA gets damaged as a result, which slows its growth and eventually causes it to shrink.

How Does It Operate?

Stereotactic guiding, which makes use of 3D imaging (MRI and CT scans) and a stereotactic frame or mask to guarantee the tumour is precisely targeted, is the secret to the Gamma Knife’s accuracy.

Important Steps in the Process:

Imaging & Planning: A 3D model of the tumour can be produced with the use of MRI/CT scans.
Treatment Planning: Using cutting-edge tools, neurosurgeons and radiation oncologists create a personalised treatment plan.
Positioning: To guarantee that the patient stays motionless, a stereotactic head frame or frameless mask is utilised.
Radiation Delivery: Depending on the size and dosage of the tumour, the patient rests in the Gamma Knife machine for 30 to 2 hours.
After the procedure, patients usually leave the hospital the same day and return home.

Gamma Knife Treatment for Large Vestibular Schwannomas

For small to medium-sized vestibular schwannomas, Gamma Knife Radiosurgery has long been used as a primary or adjuvant treatment. However, the strategy needs to be carefully considered when dealing with larger tumours (usually >2.5-3 cm in diameter).

Problems with Big Tumours:

Risk of brainstem compression
Increased risk of swelling (oedema) after treatment
Increased mass effect resulting in neurological manifestations

A Modern Method for Huge Tumours:

Fractionated or staged radiosurgery: To reduce side effects and give the brain time to adjust, radiation may be administered across several sessions rather than all at once.
Resection of the Subtotal Subsequent to GKRS: A frequently used approach involves removing a piece of the tumour physically in order to decompress the brainstem, and then controlling the remaining tumour using radiosurgery.
Selecting Patients Carefully: GKRS is not appropriate for all big vestibular schwannomas. Important factors to take into account include the patient’s age, symptoms, tumour size, location, and general health.

Gamma Knife Advantages for Big Vestibular Schwannomas

Non-invasive: doesn’t require general anaesthesia, scalpels, or incisions.
Preservation of Nerve Function: Compared to open surgery, there is a greater chance of protecting the hearing and facial nerves.
Short Recovery Time: Within one to two days, the majority of patients return to their regular activities.
Low Risk of Bleeding or Infection
Procedure for Outpatients

Risks and Adverse Effects

Even while Gamma Knife is thought to be safe, especially when handled by skilled individuals, possible adverse effects could include:

Immediately following the surgery, a headache or nausea
Momentary weakness or numbness in the face
Peritumoral oedema, or swelling surrounding the tumour, can cause symptoms like feeling dizzy or trouble balancing.
Delayed hearing loss, especially when there is a pre-existing hearing impairment
Frequent MRI follow-up is necessary to track tumour response and identify any postponed problems.

Results and Effectiveness

Several studies have demonstrated that, even in certain situations of massive vestibular schwannomas, Gamma Knife achieves tumour control rates of 90–95%. Most tumours stabilise or decline over months to years, however quick reduction is rare. Functional results are better than surgery, particularly when it comes to the preservation of facial nerves. Radiosurgery provides the best compromise between minimising bulk effect and preserving neurological function when paired with subtotal resection.

In conclusion

A new approach in the treatment of vestibular schwannomas is represented by Gamma Knife Stereotactic Radiosurgery. This non-invasive, precision-guided treatment can provide excellent tumour control with few side effects for large vestibular schwannomas, particularly in older patients or those with comorbidities. To identify the best course of treatment, a multidisciplinary examination involving neurosurgeons and radiosurgery specialists is essential if you or a loved one has been diagnosed with vestibular schwannoma, especially a large one.