Mary Tyler Moore, the actress best remembered for her roles on "The Dick Van Dyke Show" and "Mary Tyler Moore," will have surgery to remove a benign brain tumor called a meningioma, her publicist said Thursday. Moore's physicians have been monitoring the tumor for several years; it is not life-threatening and the iconic actress is expected to make a full recovery after the surgery at an undisclosed hospital.
Here's everything you might ever want to know about menigiomas.
Meningiomas, which account for a little over a quarter of all brain tumors, grow out of the meninges, the membranes that surround the brain and spinal cord. Technically, they are not really brain tumors because they don't originate in brain tissue, said Dr. Neil A. Martin, chair of neurosurgery at UCLA's Ronald Reagan Medical Center. They originate next to the bone of the skull in the dura or arachnoid tissues and grow inward, causing pressure on the brain. When they reach anywhere from 1-1/2 to 4 inches in size, they can cause sufficient pressure on the brain to produce neurological symptoms.
Meningiomas are most common in older women, but can strike at any age. Although about 5% turn cancerous, most are generally benign, slow-growing tumors that may require little treatment beyond close observation. They become a threat only when their size causes them to impinge on the brain itself, squeezing cells and creating adverse effects.
"No one knows for certain" what causes them, Martin said. "Most are sporadic and pop up out of nowhere, with no obvious cause." Radiation to the brain during childhood for treatment of childhood brain tumors, leukemia and lymphoma are known to increase the risk of meningiomas. During the 1950s, many children abroad were given low doses of radiation to the scalp to kill ringworms. To the surprise of doctors, "a remarkable number" of those children developed meningiomas two to three decades later. Female hormones are also thought to increase the risk. One form of neurofibromatosis, or "elephant man disease," also causes the tumors, but that is rare.
Symptoms usually begin unobtrusively, and can include blurred or double vision, headaches, hearing loss, memory loss and weakness in the arms and legs. As the tumors get bigger, they may produce seizures.
The most common treatment for meningiomas is surgery to remove the tumor. The success of the surgery may depend on where the tumor is located. If it lies at the top of the skull, removal is generally pretty straightforward and recovery is good. But if it lies along the base of the skull where blood vessels come in to feed the brain, "it is a much more difficult and complex operation to remove it surgically," Martin said. "It's much more likely that some of it will be left behind." That will require additional monitoring to determine whether the tumor starts to grow again, and may also require radiation therapy to destroy any tumor that remains.
Disturbance of blood vessels or other tissues during surgical removal can lead to seizures during recovery.
If pieces are left behind and keep growing despite repeated surgeries or radiation, the tumor can grow through the skull and protrude from the head. It can also metastasize to the lungs and elsewhere in the body.
Chemotherapy is generally not useful. "There is not a great medication, no great chemotherapeutic drug" for meningiomas, Martin said. Because growth of the tumors is thought to be influenced by female hormones, doctors have tried anti-hormonal drugs similar to those used for breast cancer, but without success.
Although Martin doesn't know the specific details of Moore's case, he said that "the chances are good she can have a surgical cure and resume normal activities within a couple of weeks." He noted that actress Elizabeth Taylor had a meningioma removed more than 15 years before she died and had no problems as a result.