Hypereplexy is a movement disorder which, despite being serious, is poorly studied, perhaps because of its low incidence compared to other existing ones. It manifests itself by virtue of a mutation in glycine receptors of the individual.
Its name, of Greek origin, means “exaggerated spasm”. Thus, consisting of involuntary startle reactions in response to visual, tactile, or auditory stimuli, such as loud noises. Such behavior is one of the fastest movements that our species can generate, from sensory stimuli.
An exaggerated blink, grimaces, head bends, shoulder lifts and elbows, trunk and knees bending are its main features. In these sudden attacks, there may be an increase or loss of muscle tone, the former being the most common. The more tense or tired they are, the stronger the reaction.
Due to the loss of postural control, the individual may fall after the spasms, which may generate consequences more serious. Hip dislocation and hernias can occur over time as a consequence of muscle tension.
É usually hereditary, but there are cases in the literature of incidence without this type of relationship. Affected people, in most cases, are born with typical characteristics, such as the stiffening of the muscles, especially around the shoulder, and accentuated startle in situations like the ones mentioned previously. In these cases, the doctor may tap the tip of the baby's nose in order to check whether or not there is a specific reaction for this condition. In infants, movements may be followed by apnea and, at this stage of life, children may have difficulty swallowing and choke more easily.
During sleep, spasms may disappear. However, there are cases in which the patient has sudden, repetitive and involuntary movements of the limbs, usually during peaceful sleep.
Electroencephalograms are capable of to detect this disease.
As for the drugs, conazepam, benzodiazepines, valproic acid, 5-hydroxytryptophan, piracetam and vigabatrin are used for treatment, according to the characteristics and manifestations of the individual.
By Mariana Araguaia
Graduated in Biology
