Encephalitis lethargica is a rare disease that attacks the brain, causing extreme fatigue and sometimes leading to coma. A worldwide epidemic of encephalitis lethargica occurred between 1917 and 1928 for no apparent reason, disappearing just as mysteriously. Isolated cases continue to occur, and the disease has been the subject of substantial research to learn more about its origins and how to treat it. Treatment is currently focused on stabilizing the patient, and no cure is available.
The cause of encephalitis lethargica is not understood. Some researchers suspect it may be an immune reaction, based on a history of past infections in many patients with the disease. Scientists have been unable to identify a specific disease vector or pathophysiology, however, making the disease very hard to treat. It was popularized in Awakenings, a book by neurologist Oliver Sacks. Sacks notably identified levadopa as a successful treatment for patients rendered catatonic by encephalitis lethargica.
Patients with encephalitis lethargica usually complain of headache and high fever. They may develop tremors and personality changes, particularly psychosis. As the disease progresses, the patient becomes extremely fatigued and eventually falls into a coma. Patients may adopt stress positions while in a comatose state, such as facial grimaces or flexed limbs. The patient cannot be awoken and may remain in this state for years. Some patients recover, waking up and gradually developing more energy and strength. Other patients may wake up, but remain in a catatonic state, unable to interact or respond.
Doctors initially suspected that encephalitis lethargica was associated with psychological symptoms like stress reaction or avoidance. As the epidemic in the early 20th century began to spread, doctors realized that it was definitely physical in nature, even if the mechanisms of the disease were not known. Several researchers worked independently on the disease, resulting in duplicated research in several instances. As researchers began to interact and exchange information, they realized they were working on the same disease, even if they were using different names to describe it.
The unusual nature of encephalitis lethargica makes it very difficult to research, as people have limited numbers of patients to work with if they want to explore causes and treatment approaches. The diagnosis may be missed in the early stages because doctors often have no experience with the disease. When it is identified, patients and family members may want to consider treatment from a specialist in neurology, and can explore open research and clinical trials to see what kinds of treatment options are available.