What is Alternating Hemiplegia Of Childhood

Alternating Hemiplegia of Childhood (AHC) is a rare, complex neurological disorder characterized by recurrent, transient episodes of paralysis that shift from one side of the body to the other. These episodes, which often involve weakness, abnormal eye movements, and dystonia, typically begin in early infancy and can vary significantly in duration and frequency.

What are the primary symptoms of Alternating Hemiplegia of Childhood?

The hallmark of Alternating Hemiplegia of Childhood is the "alternating" nature of the paralysis, where the weakness switches sides or involves both sides of the body. Symptoms often appear before 18 months of age and can be triggered by stress, temperature changes, or specific foods. Common clinical features include:

• Recurrent hemiplegia (paralysis of one side of the body).


• Oculomotor abnormalities, such as nystagmus (involuntary eye movement) or strabismus (crossed eyes).


• Dystonic episodes or painful muscle contractions.


• Developmental delays and cognitive impairment.


• Autonomic nervous system disturbances, such as excessive sweating or skin color changes.

What causes Alternating Hemiplegia of Childhood?

Alternating Hemiplegia of Childhood is primarily caused by a mutation in the ATP1A3 gene. This gene provides instructions for creating a protein essential for the proper function of sodium-potassium pumps in brain cells. When these pumps fail to regulate ion balance correctly, it leads to the neurological instability seen in patients. While it is a genetic condition, it is typically a de novo mutation, meaning it is not inherited from the parents.

How rare is Alternating Hemiplegia of Childhood?

Alternating Hemiplegia of Childhood is an extremely rare condition with an estimated prevalence of approximately 1 in 1,000,000 people. Due to its rarity and complex presentation, it is often misdiagnosed as epilepsy or cerebral palsy in early stages. Currently, 72 people with Alternating Hemiplegia of Childhood have joined the DiseaseMaps community to share their experiences and support one another.

What differentiates this condition from other disorders?

Unlike standard epilepsy, the paralysis in Alternating Hemiplegia of Childhood usually resolves completely during sleep, though symptoms often return shortly after waking. The combination of paroxysmal hemiplegia and specific ocular signs is the clinical diagnostic gold standard for Alternating Hemiplegia of Childhood.

Next steps

• Consult a pediatric neurologist specializing in movement disorders to discuss genetic testing.


• Connect with the Alternating Hemiplegia of Childhood community at DiseaseMaps.org to find peer support.


• Maintain a detailed symptom diary to help your medical team identify specific triggers.


• Explore clinical trial opportunities through the NIH GARD or patient advocacy groups.

Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Alternating hemiplegia of childhood.


• Orphanet: Rare disease database entry for AHC.


• OMIM (Online Mendelian Inheritance in Man): ATP1A3-related disorders.


• Alternating Hemiplegia of Childhood Foundation (AHCF).