Dysequilibrium syndrome

Dysequilibrium syndrome (DES) is a group of disorders that are characterized by abnormal brain development, which causes intellectual disabilities and problems with balance and coordination (ataxia). The specific signs and symptoms and the severity of the condition can vary among affected individuals.

In people with DES, the part of the brain that coordinates movement (cerebellum) may be unusually small and underdeveloped (cerebellar hypoplasia). This can lead to ataxia that is present from birth and typically does not worsen over time. Additional brain abnormalities may include further loss of tissue (atrophy) in the cerebellum; fewer folds and grooves (gyri) on the surface of the brain; and a small brainstem, which is the area of the brain that connects the brain to the spinal cord.

Children with DES may have low muscle tone (hypotonia) and delayed development of motor skills such as walking. Some affected individuals learn to walk later in childhood, while others are never able to walk independently. 

Additional features of DES may include intellectual disabilities that can vary from mild to profound; rapid, involuntary eye movements (nystagmus); and eyes that do not look in the same direction (strabismus). People with DES may also have difficulty speaking (dysarthria) or be unable to speak. Flat feet (pes planus), seizures, and short stature have been reported in some people with DES.