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Ask Nurse Lynn: Cataplexy Evaluation

Question:

Male, 1 year old, imprinting subtype

1 year old, non-deletion imprinting center defect- he has been having “episodes”. He will be playing and then lose all muscle control. Head bobbing, falls over, almost like a little drunk person. Which is not normal, he has extremely good muscle control, always on the move and in to everything. He crawls everywhere, standing and cursing along furniture. He had a two-day monitoring on EEG and it’s not seizures. Completed blood panel and everything came back normal. It would only happen once every few weeks but lately it’s been happening more and more. We didn’t know if this was a PWS thing, but we are lost. I have videos if needed.

Nurse Lynn’s Response:

What you are describing is something we do sometimes see in children with PWS even when EEGs and blood work comes back normal. One possible explanation is something called cataplexy. Cataplexy is a sudden loss of muscle strength that can happen while a child is fully awake. It can look like head bobbing, knees giving out, or the body going limp for a few seconds. It can be very scary to watch, but it is not the same as a seizure.

In children with PWS, cataplexy can happen because the part of the brain that controls sleep and muscle tone doesn’t work the same way as it does in other children. These episodes are often triggered by emotions like excitement, laughter, frustration, or even normal play. In babies and toddlers, it can be especially hard to recognize because they can’t tell us what they’re feeling. Instead, it may look like sudden clumsiness or weakness, even though they usually have good strength and motor skills.

It also makes sense that you’re noticing this more often now. These episodes can increase over time, especially as children become more active and expressive. While this can be frightening to see, it does not mean your child is in danger, but it does mean it should be taken seriously and followed closely.

A regular EEG can be completely normal in children with cataplexy, so a normal test does not rule this out. A neurologist or sleep specialist who understands Prader-Willi syndrome is usually the best person to help sort this out. Short video clips of the episodes, like the ones you mentioned, can be incredibly helpful for the medical team in making the right diagnosis and plan.

Resources:

Diagnosis and management of sleep disorders in Prader-Willi syndrome – PMC

https://www.pwsausa.org/wp-content/uploads/2022/09/Exploring-Disordered-Sleep-in-Prader-Willi-syndrome-September-2018.pdf

PWSA | USA Sleep Summit: Introduction to Sleep and Sleep Disorders in Children with PWS

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