Limbic Encephalitis: Types, Symptoms, Causes And Treatment
Limbic encephalitis is a rare medical condition in which various parts of the brain’s limbic system are inflated. The cause behind it may be a tumor or some autoimmune condition, resulting in psychiatric problems in the patient.
This disease has been of considerable interest in recent times because, although there are many neurological diseases that can present psychiatric symptoms, this is the one that goes unnoticed the most and its actual diagnosis ends up being a little late, sometimes misdiagnosing the patient. patient with schizophrenia.
Below we are going to take a more in-depth look at limbic encephalitis, its typologies, most common symptoms, diagnosis and current treatments.
Like all encephalitis, limbic encephalitis is a disease that is characterized by inflammation of the brain, in this case the parts that make up the limbic system. This disease is usually caused by autoimmunity problems, that is, the body enters a strange state in which the body produces antibodies against itself, in other words, it attacks itself causing varied symptoms, especially areas such as the hypothalamus. and the hippocampus.
Most cases of limbic encephalitis are caused by oncological disease, some type of cancer that affects the brain in one way or another, causing a wide repertoire of psychiatric symptoms. However, it is true that there are some cases in which there is no presence of any tumor, the probable cause of limbic encephalitis being some autoimmune disorder or infection.
The disease was first described by JB Brierley and collaborators in 1960 evaluating three cases of this medical condition. In 1968 the link between limbic encephalitis and cancer would be discovered, although today it is known that it is not always caused by oncological diseases. In fact, the existence of different subtypes of limbic encephalitis is known thanks to the detection of several antibodies involved, including anti-Hu, anti-Ma2 and anti-NMDAR.
Depending on whether or not there is a tumor behind its appearance, we speak of two types of limbic encephalitis: paraneoplastic and non-paraneoplastic. Paraneoplastic limbic encephalitis is one that is caused by some type of cancer or tumor and can be treated by removing and eliminating the tumor cells, while non-paraneoplastic limbic encephalitis is not due to cancer and is usually caused by some type of infection, autoimmune disorder, or other unidentified medical condition.
The most common types of cancer behind paraneoplastic limbic encephalitis are small cell lung cancer, testicular tumors, ovarian teratoma, Hodgkin lymphoma, and breast cancer. Likewise, within limbic encephalitis we can talk about another classification depending on whether the antibodies that appear in this autoimmune disease attack intracellular antigens or attack surface antigens:
Intracellular antigen antibodies
The best known is encephalitis associated with anti-Hu antibodies., associated with small cell lung cancer and which is typical of smokers aged 50 or 60 years. Anti-Ma-associated encephalitis, testicular tumors in young people, or lung or breast cancer in older adults is also found in this group.
Surface antigen antibodies
Within this group is anti-potassium channel antibody encephalitis, which is not usually paraneoplastic, although in 20% it is associated with oncological diseases, especially small cell lung cancer or a thymoma. Encephalitis mediated by anti-AMPA antibodies is also found, more common in women over 60 years of age, with lung, breast or thymoma cancer.
Another type of encephalitis that is very interesting for psychiatry is limbic encephalitis due to antibodies against NMDA receptors or anti-NMDAR encephalitis. This is among those mediated by antibodies against surface antigens and although it has been identified for a relatively short time, the conclusion is being reached that it could be the most frequent, in addition to having a better prognosis than the rest of paraneoplastic encephalitis.
The symptoms of limbic encephalitis, both paraneoplastic and non-paraneoplastic, can appear in a matter of days or weeks. It is considered that the presence of short-term memory deficits is the hallmark of the diseasebut it happens that on many occasions this sign goes very unnoticed or is directly ignored because there are many other symptoms also typical of the pathology that attract more attention in the psychiatric clinic:
It may also happen that the patient’s short-term memory is not evaluated because the patient arrives sedated to the consultation, probably after having suffered seizures, psychosis or general agitation. Since it is not possible to administer a memory test to someone who is under the effects of a sedative, this test is often omitted or left for later.
Diagnosis
As we said, although its distinctive sign is memory problems, this disease It is extremely difficult to diagnose, especially its non-paraneoplastic modality.. Since the rest of the symptoms attract more attention and are psychiatric in nature, it can be thought that what is happening to the patient is that he has a mental disorder rather than a neurological disease, which means that the correct diagnosis takes time to arrive and, in the meantime, The patient is admitted to a psychiatric hospital, thought to have schizophrenia or another psychotic disorder.
In order to detect limbic encephalitis, it is necessary to perform tests that analyze what types of antibodies are in the cerebrospinal fluid and whether the immune system is attacking the organism. Unfortunately, these types of tests are not usually done as a routine procedure and tests for some of the autoantibodies involved in the disease are not available on the market.
It also happens that many patients with limbic encephalitis are initially diagnosed with herpes virus encephalitis since both limbic and viral share symptoms and since antibody tests are not available, it is often assumed that it is caused by herpes simplex.
Treatment
In the case of paraneoplastic limbic encephalitis, treatment generally consists of immunotherapy and tumor removal., as long as possible. In this type of encephalitis, recovery will only occur when the tumor has been eliminated.
Regarding the pharmacological route and also applied to other encephalitis, we have intravenous immunoglobulin, plasmapheresis, corticosteroids, cyclophosphamide and rituximab.
