Definition and Workup of Cataplexy
Cataplexy is defined as the sudden loss of muscle tone with strong emotion, while consciousness remains preserved throughout the episode, and is pathognomonic for narcolepsy type 1. 1
Definition and Clinical Presentation
- Cataplexy involves paresis or paralysis triggered by emotions (particularly laughter), with patients remaining conscious throughout the episode 1
- Episodes typically last less than 2 minutes and patients have no amnesia for the event, recalling everything that happened during the episode 1, 2
- Cataplexy is most commonly associated with and considered pathognomonic for narcolepsy type 1 1, 2
Adult vs. Pediatric Presentation
- In adults, cataplexy commonly presents as bilateral loss of muscle tone triggered by emotions 3
- In children, presentation differs significantly:
- Profound baseline facial hypotonia 4
- Active movement of the tongue and perioral muscles 4
- May present as loss of tone and/or complex hyperkinetic movements 4
- May occur without clear emotional triggers, unlike in adults 4
- Can resemble clonic, atonic, and/or myoclonic seizures, but without loss of consciousness 4
Diagnostic Workup
Clinical Assessment
- Document presence of emotional triggers, particularly laughter 1
- Confirm preserved consciousness during episodes 1
- Assess for association with other narcolepsy symptoms, particularly excessive daytime sleepiness 1
- Verify absence of post-ictal confusion (which would suggest epilepsy) 1
Laboratory and Specialized Testing
- First-line testing involves overnight polysomnography (PSG) followed by Multiple Sleep Latency Test (MSLT) 5
- Mean sleep latency ≤8 minutes and ≥2 sleep-onset REM periods on MSLT suggest narcolepsy 5
- CSF hypocretin-1 (orexin) testing can be performed in unclear cases:
Differential Diagnosis
Cataplexy vs. Epilepsy
- Epileptic seizures typically involve altered consciousness, while cataplexy preserves consciousness 1
- Patients with absence epilepsy remain upright during attacks, while cataplexy may cause falls 1
- Epileptic movements last approximately 1 minute, whereas cataplectic episodes are typically shorter 1
Cataplexy vs. Syncope
- Syncope involves loss of consciousness due to cerebral hypoperfusion, while cataplexy preserves consciousness 1
- Syncope is often preceded by prodromal symptoms like lightheadedness, which are absent in cataplexy 1
- Syncope has rapid recovery of consciousness, while cataplexy involves no loss of consciousness 1
Other Conditions
- Drop attacks: typically occur in middle-aged women who suddenly fall without loss of consciousness 1
- In children, cataplexy can be confused with neuromuscular disorders due to profound facial hypotonia 3
Management Approach
Referral Considerations
- Refer patients with suspected cataplexy to a sleep specialist for proper diagnosis and management 6
- Sleep specialists have expertise to differentiate narcolepsy from other causes of excessive daytime sleepiness 6
Pharmacological Treatment
- Sodium oxybate (Xyrem/XYWAV) is FDA-approved for cataplexy in narcolepsy for both adults and pediatric patients (7 years and older) 7
- Efficacy of sodium oxybate was established in randomized withdrawal studies showing significant worsening of cataplexy when switched to placebo 7
- Antidepressants (TCAs, SSRIs, venlafaxine) are commonly used off-label for cataplexy management 6, 2
Common Pitfalls and Caveats
- Failure to recognize cataplexy as distinct from seizures or other neurological conditions can lead to misdiagnosis 6
- Cataplexy in children can be mistaken for movement disorders such as Sydenham's chorea 3
- Inadequate treatment of both excessive daytime sleepiness and cataplexy components can worsen quality of life 6
- Isolated cataplexy without other narcolepsy symptoms can occur but is rare and presents diagnostic challenges 8