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What
can be treated
Clinical Indications
Pituitary Tumors
Arteriovenous Malformations
Gamma Knife surgery has proven highly effective in the treatment
of AVMs. More than 15,000 patients have been treated since
1971. The complete obliteration rate for AVMs (most of which
were considered unsuitable for microsurgery) is over 80% with
zero treatment mortality and minimal morbidity. This success
rate underscores the importance of Gamma knife treatment as
an alternative to microsurgery.
Multiple studies show that the clinical efficacy and the non-invasive
procedure makes it advantageous for patients medically unable
or unwilling to undergo conventional open surgery.The non-invasive
nature of the Gamma Knife treatment also helps when treating
centrally located lesions and those close to critical structures
such as the brain stem.
Trigeminal Neuralgia
Acoustic Neuromas
Significant success has been achieved in the treatment of
acoustic neuromas with Gamma Knife since the first statement
in 1969 by the late Professor Lars Leksell in Sweden. Several
published studies indicate effective management of acoustic
neuromas while still preserving cranial nerve function. According
to a recent study, a permanent growth control rate after Gamma
Knife surgery 80% was achieved with facial nerve function
preservation of nearly 100% and preservation of serviceable
hearing of approximately 70%.
With enhanced diagnostic imaging techniques, a growing number
of previously undetected acoustic neuromas are being identified.In
addition, noteworthy studies indicate that most of these tumours
enlarge within 1 to 2 years.
The challenge is to treat these tumors totally while preserving
full cranial nerve function and hearing. Results in a study
by the University of Pittsburgh, comparing microsurgery with
Gamma knife surgery, indicate the open microsurgery is associated
with a greater incidence of pre-operative or delayed facial
dysfunction and a decreased rate of preservation of the preoperative
level of serviceable hearing compared to Gamma Knife. This
further indicates the importance of Gamma Knife surgery for
acoustic neuroma patients.
Metastases Brain Tumor
It is currently estimated that around 20-30% of all patients
harbouring malignant disease develop metastases to the brain.The
established treatment modality for cerebral metastases has
been craniotomy and whole brain radiation therapy.The convenience
and efficacy of Gamma Knife procedures, however, has given
rise to an increasing use of this treatment for both single
and multiple metastases.Excellent results have been achieved
with the Gamma Knife, even for such traditionally radioresistant
tumours as melanoma.
Meningiomas
Although the accepted first line of treatment for meningiomas
is microsurgical removal, Gamma Knife surgery is being increasingly
used as a valuable adjunct, particularly in cases of subtotal
tumours removal.
For example, morbidity from intracavernous surgery may be
markedly decreased by planning in advance for a less aggressive
intracavernous surgical resection followed by delayed radiosurgery
to the intracavernous tumour residua.
Additionally, Gamma Knife surgery can result in a significant
reduction in recurrence rates and prevents reoperation in
up to 67% of patients with relatively low complication rates.This
includes tumours close to important structures such as the
brain stem and cranial nerves.
Astrocytomas
Glioblastomas
Expanding Indications The array of vascular malformations
and tumors currently treated with Gamma Knife surgery is continuing
to grow.As the ability to better visualize brain abnormalities
and functional disorders increases through advances in diagnostic
imaging and functional mapping of the brain, applicable for
the Gamma knife will continue to expand.
The uniformity and specificity of the Gamma Knife coupled
with its unique non-invasive approach makes it particularly
appropriate for an expanding role in neurosurgery. Treatment
for Parkinson's disease, trigeminal neuralgia, epilepsy, uveal
melanomas and intractable pain are just a few of the ongoing
research areas.
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