Cataplexy is a sudden loss of limb tone which may lead to falls (drop attacks) without loss of consciousness, usually lasting less than 1 minute. Attacks may be precipitated by strong emotion (laughter, anger, embarrassment, surprise). Sagging of the jaw and face may occur, as may twitching around the face or eyelids. During an attack there is electrical silence in antigravity muscles, which are consequently hypotonic, and transient areflexia. Rarely status cataplecticus may develop, particularly after withdrawal of tricyclic antidepressant medication.
Cataplexy may occur as part of the narcoleptic syndrome of excessive and inappropriate daytime somnolence, hypnagogic hallucinations and sleep paralysis (Gélineau’s original description of narcolepsy in 1877 included an account of "astasia" which corresponds to cataplexy). Symptomatic cataplexy occurs in certain neurological diseases including brainstem lesions, von Economo’s disease (postencephalitic parkinsonism), Niemann-Pick disease type C, and Norrie’s disease.
Therapeutic options for cataplexy include: tricyclic antidepressants, such as protriptyline, imipramine and clomipramine; serotonin reuptake inhibitors, such as fluoxetine; and noradrenaline and serotonin reuptake inhibitors, such as venlafaxine.
Houghton WC, Scammell TE, Thorpy M. Pharmacotherapy for cataplexy. Sleep Medicine Reviews 2004; 8: 355-366