Alternating hemiplegia of childhood (AHC) is a rare genetic disease that causes sudden paralysis on one side of the body, along with seizures and unusual eye movements. Doctors tried standard medications on a young patient, but they didn’t work well. When they switched to a ketogenic diet—a high-fat, low-carb eating plan—the patient’s sudden paralysis episodes improved significantly. While the seizures didn’t completely stop, the child’s overall brain development and health got better. This case suggests the ketogenic diet might be a helpful new treatment option for this serious condition, though more research is needed to confirm this finding.

The Quick Take

  • What they studied: Whether a ketogenic diet (high-fat, low-carb eating plan) could help a child with alternating hemiplegia of childhood, a rare genetic disease causing sudden paralysis and seizures.
  • Who participated: One child who had been diagnosed with alternating hemiplegia of childhood through genetic testing. The child had tried two standard medications without success.
  • Key finding: After starting the ketogenic diet, the child’s sudden paralysis episodes improved noticeably over time. The child also showed better overall brain development and neurological health, though seizures continued to occur.
  • What it means for you: If you or a family member has alternating hemiplegia of childhood, this case suggests the ketogenic diet might be worth discussing with your doctor as an additional treatment option. However, this is based on one patient’s experience, so more research is needed before making it a standard recommendation.

The Research Details

This is a case report, which means doctors documented the medical history and treatment of one specific patient with alternating hemiplegia of childhood. The patient initially came to the hospital with unusual eye movements, and later developed seizures and sudden paralysis on alternating sides of the body. Doctors performed genetic testing (whole exome sequencing) and found a mutation in the ATP1A3 gene, confirming the diagnosis of AHC.

The patient was first treated with two medications: flunarizine and oxcarbazepine. When these didn’t work well, the medical team decided to try the ketogenic diet—a special eating plan that is high in fats and very low in carbohydrates. The doctors then carefully watched how the patient responded to this diet over time.

A case report is the simplest type of medical study because it follows just one person rather than comparing large groups. While this means the findings are limited, case reports can still be valuable for identifying new treatment ideas that deserve further investigation.

Case reports are important because they can identify new treatment possibilities that doctors might not have considered before. In this situation, the ketogenic diet is already known to help some patients with seizures, but this is one of the first reports suggesting it might also help with the sudden paralysis episodes that define alternating hemiplegia of childhood. This observation could lead to larger studies testing whether the diet helps other AHC patients.

This is a single case report, which is the lowest level of medical evidence. The findings are based on one patient’s experience, so we cannot be sure the diet would work the same way for other patients. The study lacks a control group (patients not receiving the diet) for comparison. However, the diagnosis was confirmed through genetic testing, which is reliable. The patient was followed over time, which strengthens the observation. More research with multiple patients is needed to confirm these findings.

What the Results Show

The most important finding was that the ketogenic diet appeared to reduce the frequency and severity of the sudden paralysis episodes that are the main feature of alternating hemiplegia of childhood. These episodes gradually improved after the patient started the diet and continued to improve during long-term follow-up.

The patient’s overall neurological development also showed improvement, meaning the child’s brain function and development progressed better than expected for someone with this serious condition. This is significant because AHC typically causes progressive brain damage and developmental delays.

However, the seizures that the patient experienced did not resolve with the ketogenic diet alone. The child continued to have seizures despite the diet, suggesting that the diet may help some symptoms of AHC but not all of them.

Beyond the main findings, the case demonstrates that the ketogenic diet was tolerated reasonably well by the patient, meaning the child could follow the diet without severe side effects that forced them to stop. The improvement in the child’s overall neurological development suggests the diet may have broader protective effects on the brain beyond just reducing paralysis episodes. The fact that standard medications (flunarizine and oxcarbazepine) had failed to help makes the response to the ketogenic diet more noteworthy, as it represents a different type of treatment approach.

The ketogenic diet is already established as a helpful treatment for certain types of seizures, particularly in children whose seizures don’t respond to medications. This case is interesting because it suggests the diet might help with a different symptom of AHC—the sudden paralysis episodes—rather than just the seizures. Previous research on AHC has focused mainly on medications that affect calcium channels or sodium pumps in the brain. The ketogenic diet works through different mechanisms, possibly by changing how the brain uses energy, which may explain why it helped when standard medications did not.

This study has several important limitations. First, it describes only one patient, so we cannot know if the diet would help other children with AHC. Second, there is no control group—we don’t know what would have happened if the patient had not started the diet. Third, the improvement could potentially be due to other factors besides the diet, such as natural disease progression or the passage of time. Fourth, the seizures did not improve, which suggests the diet is not a complete solution. Finally, this is a published case report, which means there may be a bias toward reporting positive outcomes, while cases where the diet didn’t help might not be published.

The Bottom Line

Based on this single case, the ketogenic diet may be worth considering as an additional treatment option for alternating hemiplegia of childhood, particularly for patients whose symptoms don’t respond well to standard medications. However, this recommendation has low confidence because it is based on only one patient. Any decision to try the ketogenic diet should be made in close consultation with a neurologist who specializes in rare childhood neurological conditions. The diet requires careful medical supervision and planning to ensure proper nutrition.

This research is most relevant to families dealing with alternating hemiplegia of childhood, particularly those whose children have not responded well to standard medications. Neurologists and pediatricians treating AHC patients should be aware of this case as a potential treatment option to discuss with families. Researchers studying AHC and rare neurological conditions should take note as a basis for future studies. This research is not directly relevant to people without AHC or other rare genetic neurological conditions.

Based on this case, improvements in the sudden paralysis episodes appeared gradually over weeks to months after starting the ketogenic diet. The patient showed continued improvement during long-term follow-up, suggesting benefits may increase over time. However, realistic expectations should be set: the diet did not eliminate seizures in this patient, and results may vary significantly between individuals. Any trial of the ketogenic diet should involve at least several months of careful monitoring to assess whether it is helping.

Want to Apply This Research?

  • If trying the ketogenic diet for AHC, track the frequency and duration of paralysis episodes weekly (for example: ‘Number of episodes per week’ and ‘Average duration of each episode in minutes’). Also monitor seizure frequency separately, as the diet may affect these symptoms differently.
  • Work with a dietitian to plan and follow a ketogenic diet, tracking daily carbohydrate and fat intake to maintain proper ratios. Log meals and snacks in the app to ensure consistency. Record any side effects or tolerance issues to discuss with your medical team.
  • Create a long-term tracking dashboard showing trends in paralysis episodes, seizure frequency, and overall neurological symptoms over months. Include notes on diet adherence, any medication changes, and observations about development or functioning. Share this data regularly with your neurologist to assess whether the diet is providing benefit and whether adjustments are needed.

This case report describes the experience of one patient and should not be considered definitive medical advice. Alternating hemiplegia of childhood is a serious rare genetic condition that requires specialized medical care from a pediatric neurologist. The ketogenic diet is a significant dietary change that requires medical supervision and should only be attempted under the guidance of qualified healthcare providers, including a neurologist and registered dietitian. Results may vary significantly between individuals. This information is for educational purposes only and does not replace professional medical evaluation, diagnosis, or treatment. Always consult with your healthcare team before making changes to treatment plans or diet.