Onset usually occurs in childhood, however some adult cases have been found. Generally, physicians look for the symptoms in children. Symptoms include cerebellar ataxia, spasticity, optic atrophy, epilepsy, loss of motor functions, irritability, vomiting, coma, and even fever has been tied to VWM. The neurological disorders and symptoms which occur with VWM are not specific to countries; they are the same all over the world. Neurological abnormalities may not always be present in those who experience onset as adults. Symptoms generally appear in young children or infants who were previously developing fairly normally.

Most diagnosis occurs in the early years of life around 2 to 6 years old. There have been cases in which onset and diagnosis have occurred late into adulthood. Those with onset at this time have different signs, particularly the lack of cognitive deterioration. Overall, detection of adult forms of VWM is difficult as MRI was not a common tool when they were diagnosed. Common signs to look for include chronic progressive neurological deterioration with cerebellar ataxia, spasticity, mental decline, decline of vision, mild epilepsy, hand tremor, the ability to chew and swallow food becomes difficult, rapid deterioration and fibrile infections following head trauma or fright, loss of motor functions, irritability, behavioural changes, vomiting, and even coma. Those who go into coma, if they do come out usually die within a few years. The diagnosis can be difficult if the physician does not take an MRI.