Rare Disease — Alternating Hemiplegia of Childhood (AHC)
Unrelenting seizures. Developmental delays. Unpredictable hemiplegia. These are some of the symptoms that individuals with the very rare disease Alternating Hemiplegia of Childhood can experience. Read on to learn more about this disease.
What is a Rare Disease?
A rare disease is one that affects a small percentage of the population. There thousands of identified rare diseases that impact millions of people around the world. Each rare disease has its own unique cause and symptoms however there are some factors that most rare diseases have in common. As a small amount of the population has each specific rare disease, it is often difficult to get a timely and accurate diagnosis.
Interested in learning about rare diseases? Check out our blog on rare diseases for more information.
Today, I am going to be writing about one specific rare disease — Alternating Hemiplegia of Childhood (AHC). AHC is so rare that it is considered a one-in-a-million disease as there are few people with this diagnosis.
What causes AHC?
Alternating Hemiplegia of Childhood (AHC) is a neurological disease caused by a genetic mutation. AHC was first described in 1971 by doctors Simon Verret and John C. Steele. It is now known that AHC is caused in 2/3rd of cases by a mutation of the ATP1A3 gene.
The ATP1A3 gene is responsible for the production of the protein, ATPase, Na+K+ transporting, alpha 3 polypeptide, that is required for the normal function of nerve cells in the brain. This protein plays a role in the transport of sodium and potassium ions across a channel that connects nerve cells (neurons), helping to regulate brain activity. — Kathryn J. Swoboda MD, FACMG and Mario Merida, MD for the National Organization for Rare Disorders webpage.
What are the symptoms of AHC
AHC is characterized by recurrent events of hemiplegia (one-sided muscle weakness) which can impact either side of the body but may impact both sides (quadriplegia). Other common symptoms include nystagmus (repetitive, involuntary eye movement), seizures, muscle stiffness, and developmental delays.
Any one of these individual symptoms would send a parent into a panic. With AHC, these horrific symptoms can show before a child is 6 months old. I cannot fathom how terrified a family would feel seeing their newborn going through recurrent seizures. The “spells” of hemiplegia can be triggered by motor activity, emotion, or even temperature changes and the symptoms can last from minutes to weeks.
I can’t imagine worrying that playing with a child or giving them a bath may trigger an episode of hemiplegia or a seizure. The triggers can vary and they can vary from person to person and can be inconsistent.
Diagnosis for AHC
AHC is diagnosed by a physician following a thorough record review and case history as well as some specialized testing. There are general criteria that are explored as part of the diagnosis including:
- The onset of symptoms occurred before 18 months
- There are episodes of hemiplegia that impact both sides of the body
- Quadriplegia that occurs either as an isolated event or part of a hemiplegia attack
- Autonomic symptoms such as nystagmus
- Episodes dissipate with sleep
- Evidence of developmental delay or neurological abnormalities
- The symptoms experienced are not caused by and cannot be attributed to another disorder
Please check out the links below for more specific information regarding diagnostic criteria.
Though physicians and researchers have been aware of this condition for more than 50 years, AHC, like many other rare diseases, is still not well understood and can be difficult to diagnose. Symptoms of AHC can vary when considering the age of onset and the severity. The hemiplegia and seizures often seen with AHC can look like other disorders such as epilepsy. Additionally, as it is a “one in a million” disease, the sample size is extremely small.
To help with a differential diagnosis, a variety of specific tests such as magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), magnetic resonance spectroscopy (MRS), electroencephalogram (EEG), and other tests may be administered to rule in or out other condition. Additionally, genetic testing for mutations in the ATP1A3 may be done.
Treatment for AHC
There is no known cure for AHC. There is no or a specific therapy that exists for children who have been diagnosed with AHC. This is a very difficult fact that families struggle with as the symptoms can be severe and life threatening.
Currently, symptoms of AHC are treated and this often requires a team of specialists including the child’s primary care physician, physiatrists, neurologists, physical therapists, occupational therapists and speech pathologists. The team works together along with the family to create a plan individualized to treat the symptoms displayed by each child. As the treatment is individualized, it may vary from child to child with AHC.
Physicians may prescribe medication to reduce the frequency of episodes and anti-seizure medications. How effective the medications are is variable though. Medications may be effective but the effectiveness may change over time. Severe episodes of AHC, especially those that include epileptic seizures that cannot be controlled, can require hospitalization.
As there is no currently approved treatment for AHC, many children will undergo trials of different medications with the support of their physician to determine if the medication is effective in reducing the symptoms.
There are people living with AHC who are dependent on others for care, some that are wheelchair bound, and others are able to live semi-independently. The lifespan and level of independence can vary from person to person.
Where Can I Learn More About AHC?
Learning more about Alternating Hemiplegia of Childhood is one of the most important things you can do to support this community. Check out the links below and find them on social media to spread information to your community:
For Henry — One family’s journey to develop a treatment for their son, Henry, and others with AHC. Henry is the sweet boy in the picture above. I have been lucky to be his speech therapist and have learned everything I’ve written above to support his speech and language needs in speech therapy. Check out their website to learn more, support their mission, and to donate to their cause. Follow the family on Instagram as they share their their journey with AHC — ForHenryAHC
Cure AHC — The mission of Cure AHC is to financially support research and therapies, improve quality of life and strengthen connections to the global AHC community. Check out the work they are doing on their website and follow them on Instagram — CureAHC
Alternating Hemiplegia of Childhood Foundation (AHCF) — The AHCF provides opportunities for collaboration, the latest in AHC literature and research education, and resources to empower AHC families and healthcare professionals as they care for individuals with AHC. Check out their website to learn more about work they are doing and to donate to their organization. Follow them on Instagram — AHCKids
Summary
AHC is a very rare genetic disease with severe symptoms including recurrent events of hemiplegia, seizures, muscle stiffness, and developmental delays. The onset of symptoms typically occurs before 18 months of age and there is no known cure or standardized treatment for this condition.
The severity and type of symptoms vary from person to person and the symptoms can be triggered by motor activity, emotion, or even temperature changes.
As there is no known cure, symptoms are treated by a team of specialists. The team works together with the family to create a plan individualized to treat the symptoms displayed by each child.
The fact that there is no known effective treatment for this disease is terrifying for families. The disease impacts the child’s ability to experience a typical childhood as the family is constantly trying to avoid situations where a symptom will be triggered.
More research and support must be given to individuals who are doing work to find an effective treatment for AHC. Please check out the links in this article to learn more and to support individuals with AHC.
TLC Speech Therapy is a speech pathology private practice, headquartered in Boston, Massachusetts, that specializes in feeding, swallowing, and cognitive-communication skills in infants, children, teens, and adults.
We have experience support individuals with AHC and their families. For information about speech therapy or for a consult, check out our website at tlcspeechtherapy.com or contact us at hello@tlcspeechtherapy.com
Disclaimer :)
As a speech therapist and certified brain injury specialist, I have experience working with children and adults in all types of settings. The information in this article is meant to provide some general information about alternating hemiplegia of childhood. It is not meant as clinical advice. If you ever have any concerns, please consult with a physician.
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