Spotlight on Encephalitis lethargica

In this article, Dr. Garg of King George’s Medical University in Lucknow, India discusses encephalitis lethargica, a mysterious epidemic disease of the 1920s and 1930s that was better known as the “sleepy” or “sleeping” sickness. It is associated with the subsequent development of postencephalitic parkinsonism, a condition that was popularized in Oliver Sacks 1973 book, Awakenings, and the 1990 movie of the same name.

Encephalitis lethargica evolved to have many manifestations other than a “lethargic type,” including types that were primarily characterized by insomnia and/or movement disorders. In the acute stage, encephalitis lethargica was characterized by intractable somnolence, which was then attributed to abnormalities of the diencephalon. Since then, anatomical localization of sleep is focused in the subcortical brain.

Differentiating points from idiopathic Parkinson disease include young age of onset, oculogyric crises, altered sleep-wake cycle, respiratory disturbances, and pyramidal signs. Pathologically, there is diffuse involvement of gray matter of the brain dominantly, the diencephalon, and the mesencephalon. There has been extensive debate about a possible role of the “Spanish” H1N1 influenza A pandemic virus in the development of encephalitis lethargica, but this relation has not yet been established. MR signal abnormalities in the substantia nigra, thalamus, hippocampus, and subcortical white matter of the frontal lobes have been described. No definite treatment is available. Prognosis is variable. Many of the survivors had permanent neurologic sequelae and were completely akinetic.

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Spotlight on Movement disorders associated with autoimmune encephalitis

Movement disorders are prominent in the clinical presentation of many autoimmune disorders. They are common in over 50% of cases in children but less so in adults. Nonetheless, the subacute onset of a new movement disorder in a subject older than 50 years of age should prompt the suspicion of a possible autoimmune disorder.

With this article, Dr. Anelyssa D’Abreu of Rhode Island Hospital/Alpert Medical School of Brown University provides not a comprehensive review of autoimmune encephalitis but, rather, focuses on disorders in which movement disorders are an integral part of disease symptomatology.

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Spotlight on Acute necrotizing hemorrhagic leukoencephalitis

Acute hemorrhagic leukoencephalitis of Weston Hurst is at the extreme end of the spectrum of demyelinating diseases. It typically follows a viral upper respiratory infection and evolves rapidly to coma and death. “Ball and ring” hemorrhages appear in the centrum semiovale of the brain, associated with mononuclear and neutrophil infiltrates, surrounded by demyelination spreading out from fibrin-filled venules. In this clinical summary, Anthony Reder MD, Professor of Neurology at the University of Chicago, addresses these issues and suggests that IL-17, a cytokine that attracts neutrophils, may be important in pathogenesis.

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MedLink Neurology authors are always at work to bring you broad and up-to-date coverage of neurology topics. We are pleased to highlight clinical summaries that have been recently added or updated and to introduce the authors who write these authoritative articles. We hope you enjoy these overviews and appreciate the contributions of our more than 450 authors who keep MedLink Neurology the premier information resource for neurologists.

Spotlight on Headache associated with intracranial infection

Headache is usually the first and the most frequently encountered symptom in intracranial infection. It is usually generalized (but may be predominantly frontal); it may radiate down the neck and back and into the extremities, and it is severe and unremitting. Encephalitis is characterized by headache, fever, alteration of consciousness, focal neurologic deficit, and seizures (usually focal). Because the brain parenchyma has no sensory receptors, the headache of encephalitis and brain abscess may result from the meningeal inflammation that often accompanies these processes, including a nonspecific response to fever, increased intracranial pressure, or a mass-effect producing traction on pain-sensitive intracranial structures. The most common causes of brain abscesses are otorhinogenic. Physical signs of meningeal inflammation do not help clinicians rule in or rule out meningitis accurately.

In this clinical summary, Dr. Jong-Ling Fuh of Taipei Veterans General Hospital and National Yang-Ming University School of Medicine discusses the clinical presentation and diagnosis of headache associated with intracranial infection.

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MedLink Neurology authors are always at work to bring you broad and up-to-date coverage of neurology topics. We are pleased to highlight clinical summaries that have been recently added or updated and to introduce the authors who write these authoritative articles. We hope you enjoy these overviews and appreciate the contributions of our more than 450 authors who keep MedLink Neurology the premier information resource for neurologists.