[Paraneoplastic limbic encephalitis: a difficult-to-diagnose condition].
BACKGROUND
Paraneoplastic syndromes can be defined as manifestations in distant places of tumors or metastasis, which are not related with tumoral growth. Most of these syndromes are caused by substances secreted by the tumor, that mimic natural hormones, or interfere with plasma proteins.


METHODS
The rate of paraneoplastic syndromes with neurological manifestations is less than 0.5/100,000 per year, and affect about 0.01% of cancer patients. The pathogenesis of neurological paraneoplastic syndromes is attributed to humoral autoimmunity, due to the existence of a great variety of antibodies in relationship with the neurological alterations associated. Nevertheless, the absence of antibodies does not exclude a neurological paraneoplastic syndromes, just as antibodies may be found without a neurological paraneoplastic syndrome. The characteristic symptoms of paraneoplastic limbic encephalitis are confusion of acute onset, mood changes, hallucinations, loss of short term memory, and seizures; these symptoms generally develop in days or weeks, but may present suddenly. Image studies, cerebral spinal fluid evaluation, and serologic tests are the most useful in diagnosing a neurological paraneoplastic syndrome. The treatment requires two different approaches. The first one is through the suppression of the immune response generated by neurological damage. The second, is by removing the tumor as the source of the antigen. The latter is often the only effective treatment.


CONCLUSIONS
The paraneoplastic limbic encephalitis is an unusual and hard to diagnose entity, which can easily be confused with psychiatric problems. An early diagnosis and treatment is very important to avoid nonreversible neuronal damage.
Ramos-Rivas
M
M
Facultad Mexicana de Medicina, Universidad La Salle, Tlalpan, Mexico. melva_r2@hotmail.com
Rojas-Velasco
G
G
Acuña-Hidalgo
R
R
Márquez-Valero
O A
OA
Arellano-Bernal
R H
RH
Castro-Martínez
E
E
D000906:Antibodies / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D015551:Autoimmunity / Q000276:immunology*; D006801:Humans; D020363:Limbic Encephalitis / Q000175:diagnosis* / Q000209:etiology / Q000276:immunology* / Q000473:pathology; D009369:Neoplasms / Q000150:complications / Q000276:immunology; D013577:Syndrome
D000906:Antibodies; D000951:Antigens, Neoplasm