Limbic encephalitis is a strange medical condition in which various parts of the cerebral limbic system swell. The cause behind it can be a tumor or an autoimmune disease, leading to psychiatric problems in the patient.
This disease has generated great interest in recent years because, although there are many neurological diseases that can present with psychiatric symptoms, it is the most unnoticed and its actual diagnosis ends up being a bit late, sometimes diagnosing in a way. erroneous to the patient with schizophrenia.
Below, we’ll take a closer look at Limbic Encephalitis, its types, most common symptoms, diagnosis, and current treatments.
What is limbic encephalitis?
Like all encephalitis, limbic encephalitis is a disease characterized by inflammation of the brain, in this case the parts that make up the limbic system. This disease is usually caused by autoimmune problems, that is, the body goes into a strange state in which the body makes antibodies against itself, that is, it s attack itself causing various symptoms, especially areas such as the hypothalamus and the hippocampus.
Most cases of limbic encephalitis are caused by cancer, a type of cancer that affects the brain in one way or another causing a wide range of psychiatric symptoms. However, it is true that there are cases in which there is no tumor, the probable cause of limbic encephalitis being an autoimmune disease or infection.
The disease was first described by JB Brierley and colleagues in 1960 when evaluating three cases of the disease. In 1968, the link between limbic encephalitis and cancer was discoveredAlthough today there is some evidence that it is not always caused by cancer. Indeed, different subtypes of limbic encephalitis are known to exist thanks to the detection of several antibodies involved, in particular anti-Hu, anti-MA2 and anti-NMDAR.
Classification of its types
Depending on whether or not there is a tumor we are talking about behind its appearance two types of limbic encephalitis: paraneoplastic and non-paraneoplastic. Paraneoplastic limbic encephalitis is caused by a certain type of cancer or tumor and can be treated by removing and removing tumor cells, while non-paraneoplastic limbic encephalitis is not due to cancer and is usually caused by a 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’s lymphoma, and breast cancer. Also, within limbic encephalitis, we can speak of another classification according to whether the antibodies that appear in this autoimmune disease attack intracellular antigens or attack those on the surface:
Intracellular antigenic antibodies
The best known is encephalitis associated with anti-Hu antibodies, Associated with small cell lung cancer and is typical of smokers aged 50 or 60. Also included in this group is anti-Ma-associated encephalitis, which originates from testicular tumors in young people or from lung or breast cancer in the elderly.
Antibody surface antigens
In this group is encephalitis with antibodies against potassium channels, which is generally not paraneoplastic, although in 20% it is associated with oncological diseases, especially small cell lung cancer or thymoma. Anti-AMPA-mediated encephalitis is also found, which is more common in women over 60 with lung, breast or thymoma cancer.
Another type of encephalitis very interesting for psychiatry is limbic encephalitis by antibodies directed against NMDA receptors or anti-NMDAR encephalitis. It is in the range of antibodies to surface antigens and although it has been relatively long since it was identified, it is concluded that it might be the most common, as well as have a better prognosis than other paraneoplastic encephalitis. .
Symptoms of limbic encephalitis, both paraneoplastic and non-paraneoplastic, can appear within days or weeks. We consider that the presence of short-term memory deficits is the hallmark of the disease, But it happens that in many cases this sign goes very unnoticed or is directly ignored by the fact that there are so many other symptoms also typical of the pathology that draw more attention to the psychiatric clinic:
- Sound issues
- Personality changes
- Auditory and visual hallucinations
- psychomotor agitation
- Orolingual dyskinesias
- affective disorders
- Obsessive-compulsive symptoms
- Loss of consciousness
It may also happen that the patient’s short-term memory is not assessed so that the patient arrives at the consultation sedated, possibly after experiencing seizures, psychosis or general agitation. Since it is not possible to administer a memory test to someone who is under the influence of a sedative, this test is omitted or left for later on many occasions.
As we said, although its hallmark is memory problems, this disease it is extremely difficult to diagnose, especially its non-paraneoplastic modality. As the other symptoms are more striking and psychiatric, one might think that what happens to the patient is that he has a mental disorder rather than a neurological disease, which means that the correct diagnosis is slow to arrive and, in fact, waiting, the patient. is admitted to a psychiatric ward suspected of having schizophrenia or another psychotic disorder.
In order to detect limbic encephalitis, tests should be done to analyze what types of antibodies are in the cerebrospinal fluid and whether the immune system attacks the body. Unfortunately, this type of test is usually not performed as a routine procedure and tests are not yet available for some of the autoantibodies involved in the disease not commercially available.
It also happens that many patients with limbic encephalitis are initially diagnosed with herpesvirus encephalitis since both limbic and viral symptoms share symptoms and the absence of antibody tests is often thought to be caused by herpes simplex.
In paraneoplastic limbic encephalitis, treatment usually consists of immunotherapy and tumor extraction., As soon as possible. In this type of encephalitis, healing will not occur until the tumor has been removed.
As for the pharmacological route and also applied to other encephalitis, we have intravenous immunoglobulin, plasmapheresis, corticosteroids, cyclophosphamide and rituximab.
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