Asymmetric Hypsarrhythmia: Clinical Electroencephalographic and Radiological Findings

Authors

  • Ivo Drury,

    Corresponding author
    1. EEG Laboratory and the Departments of Neurology and Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Ahmad Beydoun,

    1. EEG Laboratory and the Departments of Neurology and Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Elizabeth A. Garofalo,

    1. EEG Laboratory and the Departments of Neurology and Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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  • Thomas R. Henry

    1. EEG Laboratory and the Departments of Neurology and Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A.
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Address correspondence and reprint requests to Dr. I Drury at EEG Laboratory, University Hospital 1B300/0036, 1500 E. Medical Center Dr., Ann Arbor, MI 48109-0036, U.S.A.

Abstract

Summary: Twenty-six children (16 boys and 10 girls) with hypsarrhythmia and infantile spasms (IS) were studied at the University of Michigan EEG Laboratory in a 4-year period. Six (2 boys, 4 girls), had asymmetric hypsarrhythmia with a preponderance of both slowing and epileptic form activity over one hemisphere. All 6 had the symptomatic form of IS, 4 with dysplastic conditions, 1 with porencephaly from a cerebral infarct, and 1 with hypoxic-ischemic encephalopathy. Five children had focal abnormalities on either physical examination or imaging studies. Four had the highest amplitude slowing and most epileptiform activity ipsilateral to the lesion, in 1, it was contralateral. Asymmetric hypsarrhythmia constituted 23% of cases with hypsarrhythmia examined at our EEG laboratory. The significant success in surgical therapy for some children with IS indicates the importance of identifying focal hemispheric abnormalities even if they are not apparent clinically. EEG may suggest focal changes not detected clinically or radiologically.

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