Since 1967 when the first Gamma Knife prototype was used to treat a patient, over 500,000 people worldwide have undergone Gamma Knife surgery with an excellent record of successful and safe treatment. There is a long tradition of this treatment in Sheffield where over 15,000 patients have been treated.
The Leksell Gamma Knife® Perfexion™ brings the latest advances in this technology to BMI Thornbury Hospital, whilst building on the experience gained over the last two decades in Sheffield.
Gamma Knife surgery is used exclusively for the brain, head and neck. Amongst others, it is highly effective in treating the following conditions:-
A ‘Secondary’ or Metastatic tumour is defined as a tumour which has spread distantly from the original or ‘Primary’ cancer site, through the blood circulation, lymphatic system or spinal fluid. This can involve either a single lesion (Metastasis) or multiple tumours (Metastases). Metastases can in theory spread to any point in the body, but for the purposes of Gamma Knife, only brain metastases are suitable for treatment.
As they are defined by the spread of tumours from one organ to another, metastases are different from ‘Primary’ brain tumours, which are tumours that start within the tissues of the brain. This is an important factor, as treatment options for Primary and Metastatic Brain tumours are often different.
These secondary tumours arise most commonly from primary carcinomas of the lung, breast, kidney, colon and melanomas of the skin, although it is possible for a number of other primary tumours to occasionally spread to the brain. Sex differences play a role with lung, colon and renal cancers accounting for 80% of metastatic brain tumours in men, and breast, lung, colon and melanoma cancers accounting for 80% of metastatic brain tumours in women. Independent of the Primary disease, successful results can be elicited from Gamma Knife Radiosurgery for metastases from a number of primary tumour sites.
Not all patients are suitable for Radiosurgery, as often it requires that there are only a low number of lesions within the head, all of which ideally are below a threshold volume, (as the larger the volume, the more healthy brain tissue will be treated). The location of the lesions within the brain may also play a deciding role in the most suitable treatment method for the patient. An important factor is also that any disease present in the rest of the body should be controlled, i.e. non-active.
Further information on brain metastases is available from:-
Meningiomas are one of the most common ‘brain tumours’, accounting for almost 1 in 5 of all primary brain tumours. Typically they are usually found in middle-aged or elderly adults, with an increased incidence in females.
They are identified as a tumour arising from the meninges, the outer membrane sheath covering the brain and spine. Meningiomas may occur in any part of the brain or spinal cord, but most commonly are found in the cerebral hemispheres of the brain. Although these are invariably slow growing and benign tumours, they can often cause significant symptoms due to their compressing and distorting the outer surface of the brain underneath where they are growing, leading to possible paralysis, speech or coordination problems and fitting.
Due to their slow-growth, meningiomas may often not be detected until of a significant size, sometimes out of the range that is suitable for Gamma Knife treatment. However, Gamma Knife can still play a role in the control of these tumours as it can either be used as the primary treatment for smaller lesions, or after surgery where complete removal was not possible or if a tumour has recurred post-surgery.
Further information on meningiomas is available from Meningioma UK.
A Neuroma is a tumour that arises from the cells of a nerve. Benign in nature, these are often slow growing and may present as sizeable by the time that symptoms such as declining hearing, tinnitus and loss of balance have become apparent.
The type of neuroma most often treated using Gamma Knife surgery is an ‘Acoustic Neuroma’, accounting for 8 out of 100 cases of primary brain tumours. They have an increasing incidence with age, and are often found more commonly in women. Some genetic conditions such as NF-II can also lead to an increased risk of Acoustic Neuromas. These tumours arise from the schwann cell lining of the vestibular or auditory nerve, hence are sometimes referred to as ‘Acoustic Schwannomas’, ‘Vestibular Schwannomas’ or ‘Vestibular Neuromas’.
Radiosurgery for acoustic neuromas is well established and can be useful in the treatment of both unilateral and bilateral neuromas. Although limited to the treatment of neromas below 4cm in diameter, radiosurgery can be planned to preserving any residual hearing in the side being treated.
Further information on acoustic neuroma is available from the British Acoustic Neuroma Association.
The pituitary gland is located at the base of the brain and secretes hormones to regulate growth and control most of the other hormone based systems in the body. As the pituitary consists of glandular tissue, any tumour arising from it is termed an ‘Adenoma’. Although all pituitary adenomas are benign, due to the pituitary’s important role in hormone regulation and the proximity of the optical apparatus to the base of the skull, pituitary tumours can cause growth disturbances, changes in hormonal balance and visual disturbances.
In cases where the pituitary tumour is of significant size or is in direct contact with the optic nerves, surgery may be the initial treatment method to ‘debulk’ the tumour before treating the remain tumour with Gamma Knife.
Further information on Pituitary Adenoma is available from the Pituitary Foundation.
There are other tumour forms that are also suitable for treatment depending on their size and location.
Gliomas– These tumours arise from the Glial cells within the brain and are malignant in behaviour. As they often demonstrated deep tissue spread, they are often more suited to the larger beams used in conventional radiotherapy, however, smaller tumours or areas of recurrence are sometimes suitable for Gamma Knife treatment.
Ocular Melanoma – These tumours arise from abnormal growth of the pigmented melanocyte cells found within the eyeball. Beyond surgical intervention involving removal of the eye in it’s entirety, Gamma Knife treatment can be designed to control the local tumour and preserve the vision. Gamma Knife can also be used after surgery to treat any remaining tumour or recurrence.
Glomus Jugulare – These are hyper-vascular tumours constructed of paraganglionic tissue which grow within the jugular foramen. Their growth and location can vary as they may grow up into the middle ear or down the neck following the vagus nerve. They often arise in middle age, and have a higher incidence in women. Symptom onset is often discrete and so the tumours can be of significant size at presentation. Although the insidious nature of presentation can often cause tumours to be at the limits of what it possible with Radiosurgery, the Perfexion model of the Gamma Knife is better suited for treatment of significantly inferior tumours, either as the sole treatment or combined with surgical intervention.
Other Tumour types which may be suitable for treatment with Gamma Knife include conditions such as Astrocytomas, Craniopharingiomas, Chordomas, Haemangioblastomas, Pinealocytomas, but this list is not exhaustive.
Further information is available from www.braintumouruk.org.uk
Trigeminal Neuralgia is a disorder associated with the Trigeminal nerve. It presents as a sudden onset severe shooting or burning facial pain that can occur spontaneously and may last for a few seconds or as consistent short bursts over a number of hours. The pain almost exclusively involves only one side of the face, more often the right-hand side.
The pain is often initiated by minor contact or muscle movement, and can even be stimulated by a gentle breeze on the skin. Suffers often report that they can go for long periods between attacks, sometimes weeks or even months.
The Trigeminal nerve splits into three sections, the first running above the eye and forehead, the second running along the cheek, side of the nose and teeth of the upper jaw, and the third which involves the lower jaw and teeth. Although Trigeminal Neuralgia can involve any of the three branches, it often affects the second and third branches.
Trigeminal neuralgia is thought to affect 8 in 100,000 people, and women appear to be more susceptible. Presentation often occurs in middle age, but in rare cases can begin in younger adults.
Further information on trigeminal neuralgia is available from Trigeminal Neuralgia Association UK.
Stereotactic radiosurgery is a suitable treatment for patients whose epilepsy is caused by an identifiable focus. Over the past 13 years many patients have been treated at Gamma Knife Centres world- wide, including Sheffield, who have epilepsy caused by a tumour or arteriovenous malformation.
Recently a small number of patients have been treated with radiosurgery, using the Gamma Knife, who had temporal lobe epilepsy (complex partial seizures) caused by mesial temporal sclerosis. This is a condition in which a small, approx. 5-7cc, volume of the brain becomes scarred and this change causes repeated epileptic fits. Many of these patients are not controlled with medication. Thorough evaluation is necessary to establish that their epilepsy originates from the medial part of the temporal lobe and to prove that the temporal lobe on the opposite side is sufficient to maintain memory. Currently these patients are offered an open operation (craniotomy) this operation is successful in 55% to 70%. The combined morbidity and mortality rates for surgery are about 5%. Gamma Knife radiosurgery was introduced as a minimally invasive alternative. However, as treatment with the Gamma Knife is aimed to stop function in the well defined volume of the brain which would be removed in the open surgery currently offered, only epileptic patients with such an identifiable focus can be treated. As a rule, this technique is appropriate when open surgery is contraindicated or unacceptable for the patient.
In theory, radiosurgery for mesial temporal sclerosis carries a small risk of visual field defect (blurring of vision in a quadrant of field in both eyes). The reduction of seizures comes slowly, after 1-3 years, and several patients have temporary side effects from local brain swelling. In addition, the possibility of late complications cannot be excluded at this point in time.
Experience with Gamma Knife surgery is short and only a limited number of patients have been treated. These patients remain under close supervision to establish safety and efficacy of the Gamma Knife treatment. The initial results are encouraging.
A cavernoma is a vascular abnormality consisting of a cluster of abnormal vessels occurring within the central nervous system, often ranging from microscopic in size to a number of centimetres. A cavernoma is made up of small structures, caverns, filled with blood. The outer layer of these cells often ‘leaks’ or haemorrhages blood into the surrounding tissue. Cavernomas that have bled previously are more likely to bleed again, especially in the next 24 months after the initial bleed.
Although Cavernomas may have no symptoms, they can cause symptoms similar to having a stroke, seizures, haemorrhages and headaches in addition to neurological symptoms such as limb weakness, vision or balance problems, or memory and attention problems. They are also known as cavernous malformations, cerebral cavernous malformations(CCM), cavernous venous malformations (CVM) or cavernous angioma.
Around 1 in 200 people may have at least one cavernoma, but only 30% of those will develop symptoms during their lifetime. Cavernomas more often present in adults than children, with symptoms starting between 20-30 years of age.