Gelastic cataplexy is a sudden loss of muscle tone without loss of consciousness triggered by laughter. It’s a characteristic sign of a rare genetic disease called Niemann Pick disease type C.
“Gelastic” refers to laughter, and “cataplexy” is a sudden, temporary episode of muscle weakness that occurs while you remain conscious.
Gelastic cataplexy is often seen in people with Niemann Pick disease type C (NPC), which can onset from birth, childhood, or adulthood. The disease can lead to many complications, such as organ failure or neurological problems. The outlook can vary greatly between people.
Read on to learn more about gelastic cataplexy, including its causes, symptoms, and treatment options.
Cataplexy is thought to be a sleep-related phenomenon. It’s believed to be a brief episode of rapid-eye-movement sleep paralysis during wakefulness caused by changes to neurotransmitter levels that regulate sleep and postural tone.
Gelastic cataplexy has been reported in about half of people with NPC. This condition occurs in about 1 in 100,000 live births due to mutations in the NPC1or NPC2 genes.
NPC is in a group of disorders called lysosomal storage disorders. They lead to the buildup of cholesterol and fats in your cells.
Case studies
In a 2019 case study, researchers looked at a 14-year-old boy with parents who were first cousins who started to develop deteriorating ability to think and trouble walking at age 10. He also started developing atypical postures in his neck and limbs. Within the last year, he had developed gelastic cataplexy.
In another case study, researchers looked at a 10-year-old boy who had a 3-year history of fall episodes triggered by laughing. After a year, he started to develop delays in motor skills.
Gelastic cataplexy is characterized by sudden loss of muscle tone while laughing. This may result in:
- falling
- going limp
- slumping over
- appearing to have fainted
- injuries from falling
Other NPC symptoms
People with NPC can also have many other symptoms that vary significantly. They may develop at birth, in childhood, or adulthood.
Symptoms in newborns
Symptoms of NPC that may be present at birth or shortly after include:
- abdominal swelling (ascites)
- weak muscle tone
- enlarged liver and spleen
- jaundice
- thrombocytopenia
- lung disease
- liver failure
- difficulties with growth
Symptoms in infants
Symptoms that may be present in infants include:
- enlarged spleen or liver
- jaundice (yellowing of the whites of the eyes)
- weak muscles
- developmental delays
- speech delays
- difficulty swallowing
- stiff or rigid muscles
- trouble moving eyes up and down
Childhood symptoms
Childhood symptoms might include:
- enlarged spleen or liver
- history of prolonged jaundice as a newborn
- speech delays
- developmental delays
- clumsiness
- progressive loss of coordination
- involuntary muscle contractions
- speech difficulties
- trouble swallowing
- seizures
- gelastic cataplexy
- atypical eye movements
- hearing loss
- behavioral problems
Adolescent or adult symptoms
Symptoms that develop in adolescents or adults may include:
- enlarged spleen
- cognitive decline
- dementia
- learning disability
- psychiatric problems
- clumsiness
- progressive neurological symptoms like tremors or trouble walking
- difficulty speaking and swallowing
- atypical eye movements
Gelastic cataplexy can lead to injury from sudden loss of muscle tone. Also, NPC is a progressive degenerative condition that can cause many problems as it advances. End stage causes of death can include:
- lung failure
- uncontrollable epilepsy
- aspiration pneumonia, an infection caused by food entering your lungs
It’s important to seek medical attention if you or your child develops signs of gelastic cataplexy or NPC, such as:
- developmental delays
- seizures
- speech delays
- cognitive changes
- muscle problems
The symptoms of NPC can mimic those of many other conditions, including many other degenerative diseases. It requires a proper diagnosis and treatment to slow the disease’s progression.
Gelastic cataplexy is rare and a unique sign of NPC. Your doctor will likely suspect NPC if you or your child develops sudden muscle weakness during laughter.
Not everybody with NPC develops gelastic cataplexy. If you or your child has characteristic symptoms of NPC, your doctor might want to run blood tests. Blood tests can help doctors see if you have associated variants of your NPC1 or NPC2 genes.
Some signs that may have your doctor suspect NPC include:
- coordination problems (ataxia)
- intellectual disability or delayed development
- cognitive decline by age 40
- atypical muscle movements
- onset of schizophrenia-like symptoms
Niemann-Pick disease doesn’t have a cure, but medications may help you slow the progression of the disease and reduce your symptoms.
The oral medication miglustat (Zavesca) may help slow the progression of neurological symptoms associated with NPC. In the
The FDA also
Depending on your symptoms, you may also benefit from supportive therapies, such as:
- speech, physical, or occupational therapy
- nutrition therapy
- oxygen therapy
- treatment for specific symptoms like seizures
The life span of people with NPC varies from a few days to a few decades. Survival past age 5 is
If it develops past age 5, survival is expected to be 20 years or longer. Some people live to at
Gelastic cataplexy is a characteristic sign of NPC where you suddenly lose muscle tone when laughing. NPC is a rare genetic condition that can cause progressive neurological problems in childhood or adulthood.
If you or your child has gelastic cataplexy, your doctor will likely want to order a blood test to look for characteristic signs of the disease. Several medications can help slow its progression.