Resemblance Between Cataplexy During Status Cataplecticus, Normal REM Sleep

Main Category: Sleep / Sleep Disorders / Insomnia
Also Included In: Neurology / Neuroscience
Article Date: 05 Feb 2007 - 21:00 PDT

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The first efforts to identify the neural structures and pathways underlying cataplexy during status cataplecticus in a narcoleptic patient, with the use of brain perfusion single photon emission computed tomography (SPECT), have led to the discovery that cataplexy during status cataplecticus, a case of prolonged cataplexy, partially resembles normal rapid eye movement (REM) sleep but without the other imaging characteristics of this state, according to a study published in the February 1st issue of the journal SLEEP.

The study, conducted by Dorothée Chabas, MD, PhD, of Université Pierre et Marie Curie-Paris, and Assistance Publique Hôpitaux de Paris, focused on a 68-year-old woman with hypocretin-deficient narcolepsy-cataplexy, who suffered status cataplecticus after having stopped clomipramine. The woman underwent a 99mTc-ethylcysteinate dimmer brain SPECT during an episode of cataplexy. This image was compared with her brain SPECT during an intervening asymptomatic period. Subtraction SPECT coregistered to magnetic resonance imaging (MRI)-determined anatomic areas differentially perfused during cataplexy and basal wakefulness state.

According to the results, the areas hyperactivated during cataplexy correspond on brain MRI with the cingular area, the left and right orbitofrontal cortex, the right temporal cortex and the right putamen, which are all activated during normal REM sleep. There was, however, no hyperactivation of the pons, amygdale or occipital cortex, other imaging characteristics of normal REM sleep.

"To my knowledge, this report is the first of imaging analysis comparing brain activation during a cataplectic episode with a nonsymptomatic state in the same subject," said Chabas. "Previous imaging studies have failed to show structural changes in the brain of narcoleptic patients, but functional changes could be demonstrated. The method used in this particular study analyzed functional features specifically related to the mechanisms of cataplexy. Picturing brain activity during cataplexy, a transient and unpredictable neurologic state, is challenging. It is, however, easier to study cataplexy during status cataplecticus."

The National Heart Lung and Blood Institute estimated that nearly three out of four people with narcolepsy also have cataplexy, a major symptom of narcolepsy, which is characterized by a sudden, bilateral loss of muscle tone (and possible fall) with preserved consciousness. It is usually triggered by emotions. Mild attacks of muscle weakness can cause:

* Head nodding

* Drooping eyelids

* Difficulty speaking

* Difficulty moving arms or hands or a weakened grip

* Buckling of the knees

Persons who think they might have a sleep disorder are discussed to discuss the problem with their primary care physician, who will refer them to a sleep specialist.

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SLEEP is the official journal of the Associated Professional Sleep Societies, LLC, a joint venture of the American Academy of Sleep Medicine (AASM) and the Sleep Research Society.

http://sleepeducation.com/, a Web site maintained by the AASM, provides information about the various sleep disorders that exist, the forms of treatment available, recent news on the topic of sleep, sleep studies that have been conducted and a listing of sleep facilities.

Contact: Jim Arcuri
American Academy of Sleep Medicine

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