Transcortical Surgery for Lateral Ventricular Brain Tumors

Overview

When a tumor occurs in one of the five regions of the brain’s lateral ventricle, or cavity, a procedure called a transcortical surgery technique makes it possible to remove these tumors, as well as vascular malformations or foreign objects. The key to a successful and effective transcortical surgery is an understanding of the functional anatomy, the location of the lesion and its blood supply.

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Tumors of the lateral ventricle are uncommon but not rare. Transcortical surgery is safe, often simpler than other alternatives, and provides excellent working space and flexibility in removing the tumor.

Tumors of the lateral ventricle are generally slow growing and can become large before causing symptoms. Symptoms occur after the tumor begins to impair the normal structure and function of the brain, generally develop late in the growth of the lesion and are often very nonspecific in nature.

Symptoms

Symptoms may include headache, imbalance, visual field deficits, memory difficulty, personality changes, cognitive impairment, weakness and seizures. Often, children with lateral ventricular tumors also have increased intracranial pressure, resulting in headache, vomiting and general malaise. Hemiparesis, or weakness on one side of the body, and seizure are also possible symptoms.

Indications of a ventricular tumor include obstruction of normal cerebrospinal fluid, the watery, colorless fluid that bathes and protects the brain and spinal cord pathways; compression of adjacent neural structures; or hydrocephalus, an accumulation of excess cerebrospinal fluid in the brain.

Diagnosis

Diagnosis of tumors in the lateral ventricle depends on several factors, including the patient’s age, tumor location and the lesion’s specific radiological characteristics. Radiological characteristics may be determined through CT scanning, MRI, MR angiography and angiography. MRI uses radio waves and a strong magnetic field rather than X-rays to provide clear and detailed pictures of internal organ tissues. Angiography is the radiographic, or X-ray, study of blood vessels.

Procedural Details

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There are many distinct transcortical approaches for the removal of a ventricular tumor. The various routes are based on location and size of the tumor, absence or presence of hydrocephalus and the extent of blood vessels supplying the tumor. Regardless of the unique characteristics of the tumor, there are several universal goals for the removal of any ventricular lesion.

Ultimately, the neurological surgeon must choose an approach that causes the fewest complications, offers the most working space and allows removal of as much tumor as possible.

Medications

All patients who undergo removal of a ventricular tumor require close supervision and expert care with an experienced operative and postoperative team following surgery. A stay in the intensive care unit is essential. Nurses and ICU intensivists, medical doctors specializing in hospital care, provide 95 percent of the postoperative care and are experienced taking care of patients with brain tumors.

Patients who exhibit persistent ventriculomegaly, increased size of ventricles in the brain, or subdural hygroma, excessive collection of fluid in the area of the brain beneath the tough membrane covering the brain and spinal cord, may require a catheter or shunt to help drain fluid. The patient receives antibiotics while the catheter or shunt is in place. Postoperatively, patients also receive anticonvulsant medication and are closely monitored and treated to maintain electrolyte balance.

Effectiveness

The potential for complications in the operative treatment of lateral ventricular tumors exists regardless of surgical approach but can be kept to a minimum if the surgeon has the proper team and experience in performing these surgeries. While some ventricular lesions may be removed via callosal sectioning, other tumors targeted by this route cannot be accessed without some form of cortical incision.

The complication rate of transcortical resections of lateral ventricular tumors is better than before the advent of microsurgical techniques, which use a special binocular microscope to operate on tiny, delicate or hard-to-reach tissues. The rate of complications is less than 10 percent at UW Medical Center.

Risks

There are some postoperative complications to lateral ventricular tumor resection that cannot be avoided, but can be anticipated and managed. In procedures where tumors are approached from the occipital lobe, patients experience temporary vision. Vision loss is less likely when undertaking a parietal or temporal lobe approach.

Patients may also suffer from epilepsy, a neurological disorder caused by abnormal, unpredictable electrical and chemical activity of neurons that cause brief episodes of diminished consciousness, following the removal of a ventricular lesion.

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The true incidence of epilepsy is hard to monitor, because many factors contribute to a seizure disorder. These may include tumor type, whether seizures existed before surgery, whether any portion of the tumor remains after surgery, the presence of a subdural hygroma or an electrolyte imbalance. Any patient who undergoes a craniotomy, a procedure in which a piece of the skull is removed to gain access to the tumor, is at risk for postoperative seizure.

Hemiparesis, or weakness on one side of the body, is also a potential complication of the transcortical approach. Most weakness is likely the result of removing the tumor during surgery and often resolves afterward. Permanent motor loss has been rare.

Language impairment may occur following surgery. This is possible if the tumor is based in the dominant hemisphere. The brain is physically divided into two halves, or hemispheres, with one hemisphere usually dominant compared to the other.

The left hemisphere is dominant in all right-handed people and the majority of left-handed people. Following the removal of a lateral ventricular tumor of the dominant hemisphere, about 10 percent of patients suffer new speech impairment or worsening of their preoperative deficit that may be temporary or permanent.

A subdural hygroma may form following surgery. This phenomenon is characterized by an excessive collection of fluid in the area of the brain beneath the dura and spinal cord. Patients with extraordinarily large tumors associated with ventriculomegaly are especially susceptible to developing a subdural hygroma. To alleviate the excess fluid, a shunt or temporary external drain is implanted.

Some patients who have undergone transcortical resection of a ventricular tumor may experience some form of meningeal irritation. Meningitis is an inflammation of the brain and spinal cord most often caused by a bacterial or viral infection and characterized by fever, vomiting, intense headache and stiff neck.

This condition is caused by the presence of blood products in the cerebrospinal fluid following surgery to remove a ventricular tumor. This type of chemical meningitis can be treated by administering pain medication followed by a tapered course of steroid medication.

Despite the risks associated with the transcortical resection of a lateral ventricular tumor, complication rates in the microsurgical era are much less than 10 percent. While this procedure is difficult, it is safe in experienced hands with advanced technology and microsurgical techniques.

Risks of not having this treatment

Brain tumor growth can lead to worsened symptoms and can make an operable tumor unsafe for surgery.

Brain tumors can grow to an inoperable size and symptoms may worsen and permanently damage crucial structures in the brain.

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