Persistence of deep-tendon reflexes during partial cataplexy

Objective: Deep-tendon reflexes are abolished during generalized cataplexy, but whether this is the case in partial cataplexy currently remains unknown. Partial cataplexy may mimic other neurologic/psychiatric phenomena, and knowledge of the reflexes status may provide information for differential diagnosis. We assessed whether deep-tendon reflexes are persistent during partial cataplexy. Methods: Five drug-free patients with typical diagnoses of narcolepsy and clear-cut partial cataplexy were diagnosed in Reference Narcolepsy Centers in France and Italy. Biceps and patellar reflexes were elicited by physicians in charge and video-documented during cataplexy. Reflexes were assessed several times for each patient in different conditions and for various localizations of cataplexy. Results: The absence of tendon reflexes and complete loss of muscle tone during generalized cataplexy was confirmed, but the persistence of those reflexes during several partial cataplectic attacks at different ages, gender, localization of cataplexy (upper limbs, face) and reflexes (biceps, patellar) in drug-naive or withdrawal conditions was documented. Conclusion: The persistence of tendon reflexes during several partial cataplexy episodes contrasts with their absence during generalized cataplexy. This discovery has clinical implications: the persistence of tendon reflexes does not rule out cataplexy diagnosis for partial attacks, whereas their transient abolishment or persistence during generalized attacks indicates cataplexy or pseudocataplexy, respectively.