Patients who have this type usually also have a myelomeningocele. Types III and IV are extremely rare. Type III patients have portions of the cerebellum and brainstem in the upper spinal canal. With Type IV, the individual has an underdeveloped cerebellum and usually the back portions of the head and spinal canal are open to the outside. Chiari malformations are thought to be congenital.
Symptoms usually surface first in infancy.
In some cases, symptoms do not appear until the teenage years or adulthood. Depending upon the severity and the type of malformation, symptoms vary. Others may experience blurred vision, poorly coordinated movements, episodic pain around the eyes, burning or shooting pain in the head and neck, dizziness, involuntary and rapid downward eye movements, headache, and decreased sensations in the arms, hands and feet with specific decline in pain and temperature sensations in the upper body. Many of the symptoms of the Type I disorder also mimic that of chronic fatigue syndrome and fibromyalgia due to the significant amount of tiredness and fatigue that accompany this problem. If the symptoms do not arise until adolescence or adulthood, the person may present to the family practice doctor with complaints of progressive impairments, such as the involuntary and rapid downward eye movements, vertigo, headache, double vision, loss of hearing, poorly coordinated movements and eye area pain.