The signs and symptoms of cerebellar agenesis can vary greatly from one individual to another. According to the medical literature, some individuals with cerebellar agenesis have had only mild symptoms. In fact, in some reported cases, it has been claimed that motor function may be almost normal, perhaps due to partial compensation from other areas of the brain. Reports in the medical literature discuss individuals with cerebellar agenesis who had a normal lifespan, attended regular schools and found employment and lived productive though often “simple” lives.
Additional reports have noted individuals with cerebellar agenesis whose mental capacities were unaffected and who did not exhibit any symptoms of cerebellar agenesis (asymptomatic cases). However, other researchers have disputed these claims, stating that in virtually all of cases of cerebellar agenesis there have been observable symptoms including profound abnormalities in motor skills. Most likely, cerebellar agenesis represents a spectrum of disease that may range from those with severe disability to those with milder expressions of the disorder.
It is important to note that the symptoms of cerebellar agenesis are extremely variable and that affected individuals may not have all of the symptoms discussed below. Affected individuals or parents of affected children should talk to their physician and medical team about their specific case, associated symptoms and overall prognosis.
Cerebellar agenesis is most often associated with impairment of motor function, especially an inability to coordinate of voluntary movements (ataxia). Affected individuals may be clumsy and there may be delays in the acquisition of motor activities (psychomotor delays). Walking may be delayed until 4-7 years of age. Cerebellar agenesis may also be associated with Low muscle tone (hypotonia).
Some affected individuals may have difficulty speaking usually due to problems with the muscles that enable speech (dysarthria). The ability to speak is usually delayed, sometimes significantly. Some individuals may exhibit rapid, involuntary movements of the eyes (nystagmus).
Intelligence may be unaffected. However, some affected individuals may display mild to moderate cognitive impairment. Some individuals with cerebellar agenesis have exhibited intellectual disability, but normal or near-normal motor skills.
In addition to affecting motor skills, damage to the cerebellum has also been associated with abnormalities of non-motor functions. Cerebellar dysfunction may also be associated with abnormalities of visuospatial abilities, expressive language, working memory and affective behavior.