Neurology Today Conference Reporter: MDS International Congress—Electrophysiology Adds Benefit to Diagnosis in Post-Hypoxic Myoclonus

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    June 17—Electrophysiology Adds Benefit to Diagnosis in Post-Hypoxic Myoclonus

    BY ED SUSMAN

     

    SAN DIEGO—The use of various electrophysiology diagnostic tools appears to differentiate patients with cortical- or subcortical-related post-hypoxic myoclonus and can change treatment decisions, researchers reported here on Tuesday at the 19th International Congress on Parkinson’s Disease and Movement Disorders.

     

    Jonathan Van Zijl, MD, a PhD candidate at the University of Groningen in the Netherlands, and colleagues analyzed outcomes in a small retrospective study that included 17 adult patients with documented post-hypoxic myoclonus, a hyperkinetic movement disorder that can occur after anoxic brain damage.

     

    “These were very ill patients who developed myoclonus [within five days] after cardiac arrest,” Dr. Van Zijl said. Only two of the patients survived.

     

    To help make the diagnosis, the researchers performed extra tests, using electroencephalography (EEG) and electromyography (EMG) studies along with video recordings, as well as clinical tests such as the Unified Myoclonus Rating Scale and Clinical Global Impression Scale. The electrophysiology tests were in place for at least 30 minutes, and were only used in patients where myoclonus had been observed.

     

    The two survivors were correctly diagnosed with cortical etiology through EEG and EMG, Dr. Van Zijl said, but the clinical evaluation failed to diagnose cortical etiology in one of the survivors.

     

    Dr. Van Zijl said that in patients with cortical etiology, he and his colleagues observed an event-related potential on EEG/EMG before the muscle jerk, which distinguished it from subcortical etiology. “The patients with cortical etiology have a relatively good prognosis,” he said. “Patients with the subcortical etiology have a bad prognosis. However, when you just look at the patient, it is quite difficult to distinguish these two types.”

     

    “This is a small but important study in a group of very sick patients,” said Alberto J. Espay, MD, FAAN, an associate professor of neurology at the University of Cincinnati Neuroscience Institute, who was not involved with the research. “It tells us that we are not as good as we think we are in diagnosing myoclonus just on the basis of clinical features.

     

    “It also indicates that the electrophysiological methods that we have available are important to use with our patients because we can get a sense of the type of myoclonus the patient has and its association with survival,” he added.

     

    “Determining the difference between cortical myoclonus and subcortical myoclonus is important because each of these categories of myoclonus is targeted by different drugs,” Dr. Espay said. “So if a doctor is better apprised of the type of myoclonus, he is more likely to select more effective treatment.

     

    “It is remarkable how many differences in opinion there can be among clinicians about the movement [disorder] in a patient,” he added. “Using these technologies is one way to mitigate the difficulties in making a diagnosis.”

     

    Dr. Espay noted that the treatments used in the Dutch study are routinely available and are inexpensive, but he pointed out that they are time-consuming and there are issues with reimbursement for conducting these studies, which may be related to underuse in some facilities.

     

    LINK UP FOR MORE INFORMATION:

    MDS International Congress abstract: The added value of neurophysiologic investigations in post-hypoxic myoclonus: http://bit.ly/NTCR-MDS-myoclonus


    http://journals.lww.com/neurotodayonline/blog/NeurologyTodayConferenceReportersMDSInternationalCongress/Pages/post.aspx?PostID=4
    Periode17-jun.-2015

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    Keywords

    • post-hypoxic myoclonus
    • electroencephalography