A quick loss of muscle tone brought on by laughter that does not result in unconsciousness is known as gelastic cataplexy. It is a defining feature of Niemann Pick disease type C, a rare hereditary illness.

“Cataplexy” is a quick, transient episode of muscle weakness that happens while you are still conscious, and “gelastic” is the word for laughter.

Niemann Pick disease type C (NPC), which can start at birth, in childhood, or in maturity, is frequently associated with gelastic cataplexy. Numerous consequences, including organ failure and neurological issues, can result from the condition. Individuals may have rather different outlooks.

Continue reading to find out more about the causes, signs, and available treatments for gelastic cataplexy.

Gelastic cataplexy causes and risk factors

It is believed that cataplexy is a sleep-related condition. Changes in the levels of neurotransmitters that control sleep and postural tone are thought to be the cause of this brief episode of rapid-eye-movement sleep paralysis during waking.

Approximately 50% of individuals with NPC have been documented to have gelastic cataplexy. Because to mutations in the NPC1 or NPC2 genes, this disorder affects roughly 1 in 100,000 live births.

NPC belongs to a class of illnesses known as lysosomal storage diseases. They cause lipids and cholesterol to accumulate in your cells.

Case studies

In a case study published in 2019, researchers examined a 14-year-old child whose parents were first cousins who began to exhibit declining cognitive function and difficulty walking at the age of 10. Additionally, he began to exhibit unusual neck and limb positions. He had gelastic cataplexy within the past year.

In a different case study, scientists examined a 10-year-old kid who had experienced falls that were brought on by laughter for three years. A year later, he began to exhibit motor skill deficits.

Gelastic cataplexy symptoms

The hallmark of gelastic cataplexy is an abrupt loss of muscular tone during laughter. This could lead to:

• falling
• going limp
• slumping over
• appearing to have fainted
• injuries from falling

Other NPC symptoms

There are a wide range of additional symptoms that people with NPC may experience. They could emerge at birth, as a child, or as an adult.

Symptoms in newborns

NPC symptoms that can appear at birth or soon after include:

• abdominal swelling (ascites)
• weak muscle tone
• enlarged liver and spleen
• jaundice
• thrombocytopenia
• lung disease
• liver failure
• difficulties with growth

Symptoms in infants

Infants may exhibit the following symptoms:

• 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

The following symptoms can appear in adults or adolescents:

• 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

Potential complications of gelastic cataplexy

Damage from an abrupt loss of muscular tone can result from gelastic cataplexy. Additionally, NPC is a degenerative disorder that worsens over time and can lead to a variety of issues. Among the end-stage causes of death are:

• lung failure
• uncontrollable epilepsy
• aspiration pneumonia, an infection caused by food entering your lungs

When to get medical help

If you or your kid exhibit any of the following symptoms of gelastic cataplexy or NPC, it’s critical to get medical help:

• developmental delays
• seizures
• speech delays
• cognitive changes
• muscle problems

Numerous degenerative diseases and other ailments can have symptoms similar to those of NPC. To reduce the disease’s course, a correct diagnosis and therapy are necessary.

Diagnosing gelastic cataplexy

Gelastic cataplexy is an uncommon and distinct symptom of NPC. If you or your kid have abrupt weakening in your muscles when laughing, your doctor is likely to consider NPC.

Gelastic cataplexy does not develop in all NPC patients. Your doctor may wish to do blood tests if you or your kid exhibit the typical symptoms of NPC. Doctors can determine whether you have related variations of your NPC1 or NPC2 genes by using blood tests.

The following are some indicators that your doctor might detect NPC:

• coordination problems (ataxia)
• intellectual disability or delayed development
• cognitive decline by age 40
• atypical muscle movements
• onset of schizophrenia-like symptoms

Gelastic cataplexy treatment

Although there is no known treatment for Niemann-Pick disease, there are drugs that can help manage symptoms and delay the disease’s progression.

The progression of neurological symptoms linked to NPC may be slowed by the oral drug miglustat (Zavesca). The FDA authorized the oral drug arimoclomol (Miplyffa) in the fall of 2024Trusted Source to treat neurological symptoms in people older than two who were using the enzyme inhibitor miglustat.

Levacetylleucine, commonly known as Aqneursa, was recently licensed by the FDA for use in adults and children who weigh more than 33 pounds (14.9 kg).

Additionally, depending on your symptoms, supporting therapy like:

• speech, physical, or occupational therapy
• nutrition therapy
• oxygen therapy
• treatment for specific symptoms like seizures

Living with gelastic cataplexy

People with NPC might live anywhere from a few days to several decades. If symptoms start in infancy, survival past age five is uncommon. Early infancy deaths are frequently caused by liver or lung issues.

It is anticipated that survival will be 20 years or more if it arises after age 5. Some individuals survive to be at least 60 years old.

Takeaway

One of the hallmarks of NPC is gelastic cataplexy, a condition in which laughing causes an abrupt loss of muscular tone. A uncommon genetic disorder called NPC can lead to increasing neurological issues in both childhood and adulthood.

Your doctor will probably want to conduct a blood test to check for the disease’s hallmark symptoms if you or your kid have gelastic cataplexy. A number of drugs can help slow its progression.