In the latest Case Record of the Massachusetts General Hospital, a 19-year-old man presented with otalgia, slurred speech, and ataxia 1 month after an episode of infectious mononucleosis. Otalgia improved after myringotomy and antibiotic therapy, but ataxia worsened and cognitive impairment developed.
The Guillain-Barre syndrome is the most common cause of postinfectious ataxia, but this is due to a sensory ataxia manifested by impaired proprioception and the loss of deep-tendon reflexes.
• What are the infectious causes of cerebellar ataxia?
Infectious causes of cerebellar ataxia include encephalitis, meningitis, abscess, and infectious or parainfectious acute cerebellar ataxia. Many infections and vaccinations have been associated with acute cerebellar ataxia. The most common preceding infection is varicella, which usually occurs in younger children. In older children and young adults, infectious mononucleosis is the most commonly identified preceding infection. Acute cerebellar ataxia has also been associated with upper respiratory infections and gastroenteritis. It may sometimes represent direct infectious encephalitis but is more commonly a parainfectious and presumably indirect immune process.
• How can encephalitis associated with EBV be differentiated from EBV-associated cerebellar ataxia?
Encephalitis associated EBV infection may occur with or without clinically evident infectious mononucleosis but is usually accompanied by headache and fever. It may affect any or multiple parts of the brain, but the cerebellum is the most frequently isolated location. Images from MRI scans may show T2-weighted hyperintense foci with or without enhancement, or the images may be normal. A specimen of CSF may reveal a lymphocytic pleocytosis or a normal profile, and a polymerase-chain-reaction assay of the CSF for EBV and an EBV-antibody test are positive in many cases. In contrast, postinfectious or parainfectious EBV-associated acute cerebellar ataxia is preceded by infectious mononucleosis by 1 to 3 weeks. Examination reveals predominant cerebellar motor symptoms, although cognitive dysfunction is also common. MRI scans are typically normal, but the images may reveal T2-weighted hyperintense foci. A CSF specimen is usually normal; EBV antibodies are present systemically but are absent in the CSF.
Morning Report Questions
Q: What is the cerebellar cognitive affective syndrome?
A: The cerebellar cognitive affective syndrome is characterized by deficits in executive function, visuospatial impairment, linguistic difficulties, and impairments in emotional modulation (e.g., blunted affect).
Q: What is the prognosis of EBV-associated postinfectious cerebellitis, and how should it be treated?
A: The prevailing opinion is that acute ataxia in both children and adults is self-limited, with complete recovery likely, and thus should be managed conservatively, though according to the authors, some patients may have permanent sequelae. Up to one third of affected children have symptoms and signs that resolve slowly over a period of many months, and some have permanent clinical syndromes that affect motor control and behavioral, social, and cognitive deficits. In adults who are older than 60 years of age, permanent impairment has been reported in association with imaging evidence of cerebellar atrophy. The authors’ recommendation is to treat patients who are not showing improvement by the end of the first week of cerebellitis, who have cognitive or emotional symptoms, or both. The treatment may include plasmapheresis or intravenous immune globulin.