Cataplexy, transient episodes of bilateral muscle weakness with areflexia provoked by emotions, is a state highly specific to narcolepsy. Cataplexy is diagnosed based on clinical interview. Two screening tools have been developed recently but their usefulness has been limited because of length or current lack of psychometric data.
Used effectively even these screening tests require the interpreting physician to have an understanding of the typical features of cataplexy. Most physicians encounter patients with cataplexy fairly infrequently, making it difficult to gain proficiency in detecting cataplexy based on clinical interview alone.
Relatively little attention has been given to the differential diagnosis of cataplexy, which increases the likelihood of unnecessary sleep testing or false positive diagnosis.
A recent paper, to be published in the journal Sleep Medicine (available online 5 July 2005) describes six cases where cataplexy was initially diagnosed. In all cases the weakness spells were eventually not attributed to cataplexy. The presentation and characteristics of these cases have been presented as a means to discuss the differential diagnosis of cataplexy.
According to Lois E. Krahn, the author, these cases represent a diverse set of medical disorders including bradycardia, migraine, delayed sleep phase syndrome, conversion disorder, malingering and a chronic psychotic disorder.
The author concludes that a more in-depth understanding of the classic features of cataplexy should improve recognition of this fascinating state. Improved cataplexy recognition will enhance the appropriate usage of sleep tests and eventually increase the timeliness and accuracy of the diagnosis of narcolepsy with cataplexy.