Encephalitis lethargica following Bartonella henselae infection

Cat Scratch Disease-associated Encephalitis Followed by Parkinsonism

Cat scratch disease (CSD) is a zoonotic infection caused by Bartonella henselae typically resulting in self-limited regional lymphadenopathy. Encephalitis is a complication with a supposedly benign prognosis, but we encountered an exceptional case. A 19-year-old Japanese woman presented with status epilepticus. She was diagnosed with CSD-associated encephalitis based on her history of contact with a kitten and a high titre of serum IgG to B. henselae. Multimodal treatment ameliorated her encephalitis, but neurological sequelae including spastic paraparesis, persisted. After several months, she developed age-disproportionate parkinsonism inconsistent with a neurodegenerative disease. In conclusion, CSD-associated encephalitis can result in severe neurological sequelae and post-encephalitic parkinsonism.

A role for pathogen risk factors and autoimmunity in encephalitis lethargica?

The encephalitis lethargica (EL) epidemic swept the world from 1916 to 1926 and is estimated to have afflicted between 80,000 to one million people. EL is an unusual neurological illness that causes profound sleep disorders, devastating neurological sequalae and, in many cases, death. Though uncommon, EL is still occasionally diagnosed today when a patient presents with an acute or subacute encephalitic illness, where all other known causes of encephalitis have been excluded and criteria for EL are met. However, it is impossible to know whether recent cases of EL-like syndromes result from the same disease that caused the epidemic. After more than 100 years of research into potential pathogen triggers and the role of autoimmune processes, the aetiology of EL remains unknown. The epidemic approximately coincided with the 1918 H1N1 influenza pandemic but the evidence of a causal link is inconclusive. This article reviews the literature on the causes of EL with a focus on autoimmune mechanisms. In light of the current pandemic, we also consider the parallels between the EL epidemic and neurological manifestations of COVID-19. Understanding how pathogens and autoimmune processes can affect the brain may well help us understand the conundrum of EL and, more importantly, will guide the treatment of patients with suspected COVID-19-related neurological disease, as well as prepare us for any future epidemic of a neurological illness.

Encephalitis lethargica in 5 South African children

The clinical features and cognitive outcome in 5 South African childhood cases of sporadic encephalitis lethargica seen between 2002 and 2006 are discussed. All children presented with an acute encephalopathic illness complicated by sleep disturbance, extrapyramidal and neuropsychiatric symptoms. Diagnosis was based on shared clinical features with other cases described in the literature and exclusion of known infective, biochemical and metabolic causes of acute childhood encephalopathy. The negative findings on neuro-imaging in all cases strongly supported the diagnosis. All children survived but 3 cases became learning disabled and all required cognitive rehabilitation after recovery. The cases demonstrate that encephalitis lethargica does indeed occur among South African children. The condition should be considered in any previously well child that presents with an acute encephalopathic illness with prominent extrapyramidal and neuropsychiatric symptoms and negative infectious, biochemical, autoimmune, metabolic and radiologic investigations. Recognition is important as it allows counseling of parents regarding the protracted course but generally favorable outcome of the condition.