Oculogyric Crises in AADC Deficiency
One of the symptoms of aromatic L‐amino acid decarboxylase (AADC) deficiency are oculogyric crises, which can be frightening for patients and their parents and caregivers.
What happens in an oculogyric crisis?
An oculogyric crisis occurs when the muscles of the eye spasm, sometimes during seizures. Patients are unable to control their eyes or focus their vision. During these episodes, patients also may be unable to close their mouths. Their tongues may protrude, and their neck movement may be restricted.
What causes oculogyric crises?
The precise cause or trigger of these episodes is unknown. Researchers think they may be the result of a dopamine imbalance in the brain. Dopamine is a key neurotransmitter, which is a signaling molecule that allows nerve cells to communicate.
Patients with AADC deficiency are unable to make enough dopamine due to a mutation in the DDC gene, which contains the information necessary to produce the enzyme that makes dopamine. Researchers think this leads to uncontrolled signaling in the brain, which results in seizures and oculogyric crises.
Other conditions, as well as some medications, also may cause oculogyric crises in people without AADC deficiency.
How do doctors treat oculogyric crises?
The treatment for oculogyric crises is very specific to the patient. Some patients respond well to medications that help balance dopamine levels in the brain, reducing seizure activity. Anticholinergic agents sometimes can be useful in treating these episodes.
If your child is having a prolonged episode (longer than three to five minutes) you should seek medical assistance.
Can gene therapy help?
Oculogyric crises seem to be markedly decreased in frequency and severity in AADC deficiency patients who have been treated with gene therapy.
A small study described the cases of six patients ages 4 to 19 who received a single dose of gene therapy, which is a treatment that supplies the patients’ cells with a healthy copy of the DDC gene. At up to two years following treatment, patients showed significant improvements in motor function and a marked decrease in seizure activity and oculogyric crises.
Last updated: Aug. 5, 2020
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