<unk>  is a form of encephalitis.
In a small number of cases, the pathogens responsible for encephalitis attack primarily the<unk>  system (a collection of structures at the base of the brain responsible for basic autonomic functions), often causing memory deficits similar to those observed in Alzheimer's disease or Creutzfeldt-Jakob disease (although<unk>  does not cause the same cognitive deficits as these diseases.   Unfortunately for 20% of people with the diagnosis of<unk>  an MRI will not show any neurological abnormalities 
60% of the time,<unk>  is paraneoplastic in origin.  
Paraneoplastic<unk>  (PLE) is a particularly severe form of<unk>  caused by neoplasms most commonly associated with small cell lung carcinoma. Whereas the majority of encephalitides are viral in nature, PLE is often associated with cancer.   In fact, it is thought that up to 1 in 100 people with cancer have in fact got paraneoplastic<unk>  which is commonly misdiagnosed as neurological diseases such as Alzheimer's.
Limbic encephalitis
La Crosse encephalitis
Varicella zoster encephalitis
Herpes simplex encephalitis
Rasmussen's encephalitis
Japanese encephalitis
Eastern equine encephalitis
Bickerstaff's encephalitis