CureGRIN is investigating a new symptom of GRIN disorders, a group of rare genetic conditions that cause a wide variety of physical and intellectual symptoms. Referred to as neurostorms, this new symptom is characterized by large pupils, increased heart rate, sweating, and heavy breathing. Many caregivers have noticed that these episodes are usually preceded by abnormal emotional behavior. In an effort to learn more about this new symptom, CureGRIN released a survey regarding neurostorms and worked with experts in the field.

About the Survey

Before the survey, medical professionals did not know much about neurostorms. According to patients, the episodes can last anywhere from a few minutes to a few hours and cause a rapid heart rate, sweating, heavy breathing, and enlarged pupils. Some patients have reported an external trigger that sets off the neurostorm, while others are unsure why their episodes start. Regardless of triggers, all episodes follow atypical emotional behavior, such as abnormal crying, laughter, or physical harm. In addition, epileptic medication does not work and the events cannot be seen on EEG.

When asked about these episodes in the survey, one-third of the respondents said that they experienced similar episodes that were not related to epilepsy. This means that neurostorms are a common experience for many GRIN disorder patients.

Learning From Experts

CureGRIN also spoke with some of the top medical professionals in their fields. First, they met with Dr. Timothy Benk and Dr. Johannes, who work at the Children’s Hospital of Colorado and the Institute of Human Genetics and the Center for Rare Diseases respectively. The first thing that Dr. Benke pointed out was that neurostorms are not epileptic, they are autonomic. This means that they can produce a wider variety of symptoms and progress differently.

While doctors have discovered that neurostorms are not epileptic, they do not know enough about the underlying causes yet. Dr. Alejandro Rabinstein, a neurologist at Mayo Clinic, believes that neurostorms may be related to paroxysmal sympathetic hyperactivity (PSH) storms. These episodes occur when the sympathetic nervous system, which is in charge of the “fight or flight” response, is too active. Similarities exist between the two storms, such as rapid breathing, increased heart rate, sweating, and high blood pressure. On the other hand, neurostorms have unique effects like screaming, crying, panicking, and acting aggressively.

While these contrasts differentiate between the two forms of episodes, Dr. Rabinstein believes that neurostorms could be a form of PSH. He draws another connection, as PSH has been recorded in adults with anti-NMDA autoimmune encephalitis, where the NMDA receptor plays a large role. As this same receptor is important to GRIN disorders, it could point to neurostorms’ relation to PSH.

Looking Forward

Dr. Rabinstein prescribes gabapentin for his patients with PSH, and he is interested in looking into this treatment for GRIN disorders. More research is needed, but if he is right, then this medication could reduce the frequency and severity of neurostorms.

About GRIN Disorders

GRIN disorders are a group of rare, genetic disorders that occur when one of seven genes are mutated. The most common genetic causes of these conditions are the GRIN1, GRIN2A, GRIN2B, and GRIN2D genes. These mutations are typically sporadic but are passed down in an autosomal dominant pattern if inherited. The similarity between the genes is their role in the production of NMDA receptors, which are necessary for proper memory and learning. They result in symptoms such as:

• Dystonia
• Developmental delay
• Autism
• Intellectual disability
• Seizures
• Limited or non-verbal communication
• Issues with feeding
• Gastrointestinal symptoms
• Low muscle tone
• Cortical visual impairment
• Limited mobility

There is no cure for these disorders; treatment is symptomatic and supportive. Physical, occupational, and speech therapy are often helpful, as are antiepileptic medications.

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