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What

Children with paraneoplastic limbic encephalitis have memory loss, personality changes and seizures as a result of inflammation in the brain (any inflammation of the brain is known as encephalitis). The inflammation is caused by a tumor, though the tumor is usually not located in the brain.

Who

This syndrome only occurs in children who have a cancer of some sort. The tumor in children that is most often associated with this syndrome is neuroblastoma, though the problem can occur with any tumor. This is different than in adults, where paraneoplastic limbic encephalitis is almost always associated with a particular form of lung cancer. Even though the syndrome is always associated with a cancer, the cancer may not be identified, and many patients have symptoms of the encephalitis before they have any symptoms from the cancer. There have not been any risk factors yet described that would help figure out why some children with neuroblastoma get limbic encephalitis and others do not.

Signs and Symptoms

As mentioned, some children will be known to have a cancer before the onset of the encephalitis, but others will not. Regardless, children will begin to have personality changes, memory loss, and/or seizures. In addition, they may have weakness in arms or legs, or difficulty with balance or walking. This progresses over a number of weeks or months, and then usually stabilizes and does not get worse. However, the problems may become very severe before the syndrome stabilizes. The memory loss may affect both new and old memories. Depending on the type of tumor they have, children may also have other symptoms that are related to the tumor itself. There are a number of other syndromes that are very closely related with paraneoplastic limbic encephalitis that also have symptoms that affect the nervous system, such as overall weakness with Lambert Eaton myasthenic syndrome, rigid muscles with stiff person syndrome, or jerking eye movements or limb movements in opsoclonus-myoclonus syndrome. In fact any child may have features of any or all of these syndromes, as there is often overlap. Limbic encephalitis, however, refers specifically to symptoms like memory loss and personality changes.

Possible Causes

The body’s immune reaction to a tumor is believed to cause paraneoplastic limbic encephalitis. The immune system can recognize a tumor as being foreign tissue that does not belong in the body, and so it mounts an immune response against it. However, because the tumor is so similar to the body’s own normal tissues, some of the antibodies made can also react with normal tissues, including the brain. Particularly with lung cancers, an antibody against a protein called Hu is present, hence the alternative name for this syndrome, anti-hu paraneoplastic encephalitis. There is a wide range of other antibodies that researchers have identified that can help in diagnosing the disorder.

Diagnosis

The diagnosis is typically made by combining the signs and symptoms the child has with the results of an MRI of the brain, and with tests for the antibodies discussed above. Because many problems can have similar symptoms, it is also often important to do a variety of other tests to be certain that the child does not have some other disorder. If the child is found to have paraneoplastic limbic encephalitis, and does not have any known cancer, then it is important to search carefully for the underlying cancer. This is usually not as much of a problem in children as it is in adults.

Treatment

The treatment for the disorder is primarily the treatment of the underlying tumor. Even if the tumor is treated though, the memory loss, seizures or personality changes may or may not improve. A variety of treatments have been tried for these symptoms, focused on trying to reduce the immune response. These include steroids, and medications that suppress antibodies, like intravenous immune globulin (IVIG) and rituximab. None have been proven to improve the outcome though.

Prognosis

The prognosis in paraneoplastic limbic encephalitis is uncertain, and even less is known in children, as the syndrome is far more common in adults. The underlying tumor may be the most responsible for determining the mortality rate, but the encephalitis symptoms can be extremely debilitating. The symptoms may wax and wane over the course of the illness, and whether the patient recovers or not depends on how much damage has been done to the brain. Early treatment and successful treatment of the underlying tumor are the things most associated with improvement.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

The websites that exist addressing this disorder are almost entirely written for physicians. Currently, no patient-oriented sites that can be recommended exist.

Google Search for Paraneoplastic Limbic Encephalitis

References and Sources

Dropcho EJ. Update on paraneoplastic syndromes. Curr. Opin. Neurol. 2005;18:331-336. Farrugia ME, Conway R, Simpson DJ, Kurian KM. Paraneoplastic limbic encephalitis. Clin. Neurol. Neurosurg. 2005;107:128-131.