Condition:
Hemangioblastoma
Contents:
What is a Hemangioblastoma?
How are hemangioblastomas diagnosed?
What are treatment options for hemangioblastoma?
What are the advantages of treating hemangioblastoma with stereotactic radiosurgery?
What are the disadvantages of treating hemangioblastoma with stereotactic radiosurgery?
How is CyberKnife® radiosurgery different from other radiosurgical systems?
What to expect after radiosurgery for hemangioblastoma
What are the possible complications of hemangioblastoma radiosurgery?
References
What is a Hemangioblastoma?
Hemangioblastomas are benign, highly vascular tumors that can occur in the brain and spine. Most hemangioblastomas occur as a single lesion. However, there are some patients who develop hemangioblastomas as part of a genetic syndrome called von Hippel Lindau disease (VHL).
Over their lifetimes, such patients develop multiple tumors within the brain and spinal cord. Nearly all brain lesions occur within the inferior back portion of the brain, known as the cerebellum. This part of the brain is especially important for balance and coordination.
Hemangioblastomas occur in two basic forms, solid and cystic. Solid tumors consist entirely of tumor cells. Cystic hemangioblastomas are composed of a generally small solid component, adjacent to an oftentimes much larger cystic portion of tumor.
With either form of hemangioblastoma, an enlarging tumor will press on the brain and can cause neurologic symptoms, such as headaches, weakness, sensory loss, balance and coordination problems, and/or hydrocephalus (a build up of spinal fluid). In rare cases, the tumor is discovered as an incidental finding during an evaluation for unrelated symptoms or another disorder.
How are hemangioblastomas diagnosed?
Hemangioblastomas can be diagnosed by either contrast CT or MRI scans of the brain or spine. On such studies, hemangioblastomas appear as bright white lesions within the brain or spine after intravenous contrast is administered. Hemangioblastomas can occasionally mimic other tumors, such as meningioma, brain metastases, or in some cases, an arteriovenous malformation.
Sometimes a cerebral angiogram aids in the diagnosis of hemangioblastoma, which have a characteristically profuse blood supply. In von Hippel Lindau disease, hemangioblastomas are inherited as a genetic disorder from either parent (dominant inheritance).
When a family history of von Hippel Lindau is present, there is a strong likelihood that other directly descended family members will be afflicted by this disorder.
What are treatment options for hemangioblastoma?
There are two basic treatment options for hemangioblastoma. Surgical resection involves operating on the brain or spine to physically remove a tumor. If a hemangioblastoma can be completely removed, and is not associated with von Hippel Lindau disease, then a patient is cured.
In the typical case of a cystic hemangioblastoma, only the solid portion of the tumor needs to be removed; the adjacent cyst that is drained during surgery, will eventually disappear once the tumor nodule is removed.
If the entire hemangioblastoma cannot be resected, then there remains a high likelihood that either the tumor will re-grow or that additional cysts may form. Any operation on the brain or spine is invasive and can be associated with risks, such as stroke, infection, anesthetic complication, or neurologic deficits. However, most hemangioblastomas can be safely removed with present day neurosurgical instrumentation.
As an alternative to an open operation, stereotactic radiosurgery can be used to target and destroy a hemangioblastoma(1).
A single radiosurgery session will result in the gradual death and eventual shrinkage of a treated lesion. In the case of cystic hemangioblastoma, only the solid portion of the tumor need be ablated with radiosurgery; cyst fluid gradually ceases to be produced and eventually the cyst decreases in size.
What are the advantages of treating hemangioblastomas with stereotactic radiosurgery?
The principle advantage of stereotactic radiosurgery relative to surgical resection of hemangioblastoma is that the former is noninvasive and does not carry the risks of conventional brain or spine surgery.
Furthermore, some hemangioblastomas are located in areas of the brain that are difficult to approach safely with conventional surgery. In such cases, radiosurgery may be a much safer option for the patient. Moreover, radiosurgery is an outpatient procedure, and does not require any recovery period before a patient can resume a normal lifestyle.
In patients with von Hippel Lindau disease, multiple hemangioblastomas tend to develop over time within both the brain and spine.
This situation very commonly necessitates that a patient undergo multiple operations over their lifetime. These operations even when successful, generally take their toll on the patient, often resulting in gradual disability. For these patients, stereotactic radiosurgery can be performed multiple times over the life of the patients to treat symptomatic hemangioblastomas when they occur, thereby preventing the need for numerous conventional
What are the disadvantages of treating hemangioblastomas with radiosurgery?
There are two main disadvantages to ablating hemangioblastomas with radiosurgery. First, radiosurgery typically takes from six months to a year to destroy a hemangioblastoma.
Therefore, if a tumor is large and causing significant symptoms from pressure on the normal brain, standard surgical resection is usually necessary. Even after aggressive radiosurgery for cystic hemangioblastoma, fluid continues to be produced within the cyst for several months after treatment.
Also, if the cyst becomes large, it too can cause symptoms. Such large cystic tumors can be symptomatic and require surgical drainage, even though the tumor is dying from radiation. Secondly, radiation may cause injury to the normal brain immediately adjacent to the treated hemangioblastoma (see complications of radiosurgery below).
How is CyberKnife® radiosurgery different from other radiosurgical systems?
Most radiosurgery systems require the use of a metal frame for accurate targeting. This device attaches to the patient’s head with four screws, each of which penetrates the scalp and anchors to the skull. Naturally, this technique results in pain for a patient.
In contrast, the CyberKnife® is “frameless”, thereby avoiding any patient discomfort, yet still maintaining comparable, if not superior targeting accuracy. Furthermore, other radiosurgery systems limit treatment to hemangioblastoma of the brain.
Since CyberKnife® radiosurgery is frameless, hemangioblastomas located anywhere in the spinal cord can also be treated safely.
What to expect after radiosurgery for hemangioblastoma
Radiosurgery for tumors, such as hemangioblastomas, is typically performed on an outpatient basis. Generally, a patient feels nothing during treatment. After radiosurgery, patients are followed with periodic brain or spine scans. Most radiosurgery centers perform a follow-up MRI scan after six months to monitor tumor shrinkage and look for any radiation side-effects in the adjacent brain.
Once it can be demonstrated over a few years time that a tumor is not growing (or is actually shrinking), the lesion is thought to be destroyed and further MRI scans need only be performed on a more limited basis.
What are the possible complications of hemangioblastoma radiosurgery?
The main potential complication of radiosurgery is the chance that radiation may destroy the tumor but injure the adjacent normal brain. Such damage is called radiation edema, or in severe cases, radiation necrosis. Particularly for small tumors, the likelihood of radiation injury to the brain is low.
The rate of complications is generally much lower than the risk of leaving the tumor untreated or undergoing an open surgical resection (2). The symptoms produced by radiation edema will often improve significantly with oral steroids.
References
- Chang SD, Main W, Martin DP, Gibbs IC, Heilbrun MP: An analysis of the CyberKnife: a robotic frameless stereotactic radiosurgical system. Neurosurgery. 2003 Jan: 52(1):140-7.
- Maciunas RJ, Galloway RL Jr, Latimer JW: The application accuracy of stereotactic frames. Neurosurgery. 1994 Oct: 35(4):682-94.
- Chang SD, Adler JR Jr, Martin DP: LINAC radiosurgery for cavernous sinus meningiomas. Stereotactic and Functional Neurosurgery. 1998: 71(1):43-50.