What is Rasmussen Syndrome, the rare disease that primarily affects children?

Rare diseases (RD) or infrequent diseases are those with a low prevalence in the population. To be classified as rare, each specific pathology can only affect a specific number of people. A disease is classified as 'rare' when it affects fewer than 5 percent of every 10,000 inhabitants. According to the Spanish Federation of Rare Diseases (FRD), the number of people living with this type of condition in Spain (there are 7,000 rare diseases recorded) reaches three million.

Rare diseases are, for the most part, chronic and degenerative. In fact, 65 percent of these pathologies are serious and disabling and are characterized by early onset (two out of three appear before the age of two) ; chronic pain; and/or the development of motor, sensory, or intellectual deficits in half of cases, which result in impaired autonomy.

What is Rasmussen Syndrome?

Rasmussen's disease is a chronic, progressive, inflammatory brain disorder that manifests as treatment-resistant focal neocortical motor seizures and culminates in severe impairment with hemiparesis, cognitive delay, and aphasia. It typically causes epilepsia partialis continua, and there is no differential prevalence between girls and boys.

This syndrome, which can also occur in adulthood (in 10 percent of cases) but primarily affects young children, is a rare disease that, as experts explain, progresses in three phases: prodromal with focal seizures; acute with increased seizures and loss of brain volume; and residual with hemispheric atrophy and neurological deficits. Diagnosis is based on clinical criteria and studies such as magnetic resonance imaging and electroencephalography.

Among the most visible symptoms are frequent and severe seizures, loss of motor and speech skills, and mental decline. As it is also an autoimmune disease, the immune system mistakenly attacks the brain, causing inflammation in one of its hemispheres. Children with Rasmussen syndrome generally begin experiencing seizures before the age of 10 , although experts currently do not know the cause of this "rare" syndrome. Regarding treatment, there is a type of brain surgery, hemispherectomy, which can prevent seizures and improve some of the problems that can occur with epilepsy.

The main problems they face

As explained by Feder, one of the main problems faced by people with rare diseases is diagnosis. The main causes of this lack of diagnosis are multiple; the main ones are the lack of knowledge surrounding these pathologies, the difficulty in accessing necessary information, and finding specialized professionals or centers.

All of this causes a series of "consequences that affect both the patient and their family. In fact, this diagnostic delay influences access to therapeutic interventions, leading, in 31 percent of cases, to a worsening of the disease that could have been previously avoided or alleviated. These difficulties are key to the healthcare treatment and the development of the disease." Not surprisingly, 42.68 percent of people with these pathologies do not have access to treatment . In many cases, if it exists, it turns out to be inadequate.

Rare diseases are characterized by a wide variety of symptoms that vary not only from disease to disease, but also within the same pathology. The same condition can have very different clinical manifestations from one person to another . For many disorders, there is a wide variety of subtypes of the same disease.