Advances in the Management of Spinal Cord Tumors

Performing more than 3,000 neurosurgical procedures a year, the neurosurgery practice at Mayo Clinic is one of the largest neurosurgery practices in the United States. Patients can be evaluated and treated by a team of specialists in a matter of days rather than months.

Spinal cord tumors can be broadly classified by location relative to the spinal cord and the dura mater. Those outside the dural sac and cord are called extradural extramedullary tumors. Those within the dural sac but exterior to the cord are called intradural extramedullary tumors.

Because of their location within the dural sac and cord, intradural intramedullary tumors were considered inoperable as recently as a decade ago. Mayo Clinic neurosurgeons were among the first to resect such tumors and today, improved imaging and microsurgical techniques continue to advance surgery for tumors of this type.

Examples of anatomically classified spinal tumors

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Differential Diagnosis and Management: A Team Effort

The symptoms of spinal cord tumors vary and depend on a number of factors, including location, rate of tumor growth, involvement of skeletal structures of the spinal column, and whether the tumor is creating pressure against or invading the spinal cord or adjacent nerves.

Symptoms can include numbness, tingling, pain, sensory and motor impairments, and changes in bowel and bladder function. In children, spinal or vertebral column abnormalities such as scoliosis may be present as well.

Diagnosis can be difficult. Various conditions mimic tumors and vice versa. Possibilities include cystic formations, cavernous malformations, and dural arteriovenous fistulas. The symptoms associated with inflammatory conditions that affect the spinal cord, such as multiple sclerosis, and the nerve roots, such as chronic inflammatory demyelinating polyradiculoneuropathy, as well as viral, bacterial, or parasitic infections, and degenerative disorders of the nervous system, can also be confused with symptoms of tumor.

At Mayo Clinic, patients are usually seen first by a neurologist. "Our job is to sort out what's really going on, to decide when the neurologic disability — or threat of it — is severe enough to warrant intervention and the nature of that intervention," explains Daniel H. Lachance, M.D., neurologist at Mayo Clinic in Minnesota. He notes, for example, that some patients may have a tumor found incidentally on an MRI, but the symptoms are caused by another process — "a situation," he says, "that requires detailed explanation to the patient."

Other patients may come for treatment of a herniated disc only to find they also have a tumor. Still others may have had an attempted and nondiagnostic biopsy or other surgical intervention, or perhaps radiotherapy, yet have progressive disability with few answers as to why. "At Mayo," Dr. Lachance notes, "in these difficult situations, management decisions are greatly enhanced by the collaborative approach and the depth of experience among our team members."

The diagnostic and management team typically includes specialists from neurology, neuroradiology, and neurosurgery, but may also include experts in radiation oncology, medical genetics, orthopedics, physical medicine and rehabilitation, and other specialties.

Mayo Clinic's High-Field Imaging

MRI is one of the best tools for detecting the presence of a spinal cord tumor. Traditional MRI, however, may not always distinguish the type of mass present. Mayo is one of the few institutions to have high-field 3-Tesla MRI scanning, which can help distinguish tumor from other types of diseased tissue and can detect smaller tumors that may be missed on traditional MRI scans.

MRI of hemangioblastoma

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Surgical Advances

The most common spinal cord tumors in adults are ependymomas, relatively slow-growing tumors that account for approximately 60 percent of intramedullary tumors and tend to occur in patients 40 to 60 years of age. Approximately 40 percent of ependymomas occur in the lower spine.

"Our goal is to remove ependymomas in their entirety," says William E. Krauss, M.D., neurosurgeon at Mayo Clinic in Minnesota. "Improvement in microsurgical instrumentation and technique, combined with ultrasonic aspiration, gives us a very good success rate." If the tumor is growing rapidly or cannot be resected entirely, surgery is followed by radiotherapy.

3-Tesla MRI of astrocytoma

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Astrocytomas are the second most common type of intramedullary tumors in adults and the most commonly occurring type in children. Astrocytomas are typically found in the cervical and upper thoracic region of the spine. Tumors with well-defined borders may be removed surgically. Invasive tumors and those associated with progressive neurologic deterioration are usually managed through biopsy followed by radiation or stereotactic radiotherapy.

Monitoring Motor Function during Surgery

Monitoring sensory function through evoked potentials has long been a part of spinal tumor surgery. Approximately 10 years ago, Mayo Clinic began monitoring motor-evoked potentials as well.

Dr. Krauss explains, "The motor pathway is more difficult to monitor than the sensory pathway, because measurements of motor function can be suppressed by anesthesia. The expertise of our neuroanesthesia colleagues is critical to the successful use of this technology." Monitoring motor evoked potentials has improved the ability to preserve motor function in spinal cord tumor resection.

Stabilization of the Spine

In the past, spinal tumor resection could lead to profound deformities of the spine. Today, Mayo neurosurgeons work to stabilize the spine through spinal fusion or spinal reconstruction. Dr. Krauss notes, "We now have a much better knowledge of which patients are at risk for developing spinal deformities."

Dr. Lachance adds that many of the spinal reconstruction procedures performed at Mayo are extremely complex. The team involved in reconstruction may include surgeons from a number of subspecialties, such as orthopedic and thoracic surgery, who operate in tandem with neurosurgeons. This intraoperative collaboration is a benefit of Mayo's team approach.