CHIARI MALFORMATION

DEFINITION

The Chiari malformations (CM) , divided into Chiari type 1 (which usually presents in adulthood) and Chiari type 2 (which usually presents in infancy), are thought to be congenital malformations of the brain. CM type 2 is usually associated with myelomeningocele and hydrocephalus. The blockage of csf flow at the skull base may also cause a syrinx to form in the spinal cord (syringomyelia).

In infants, the most common symptoms are stridor and swallowing difficulties. In older children, upper (and lower as age marches on) limb weakness and breathing difficulties may occur. Patients may experience no symptoms or remain asymptomatic until early adulthood, at which point they will often experience quick onset severe headaches and neck pain. Fatigue, dizziness, vertigo, neuropathic pain, visual disturbances, difficulty swallowing, ringing in the ears, sleep apnea, impaired fine motor skills, muscle weakness, and palpitations and excessive clearing of the throat with no obstructions are other common symptoms. Because of the complex combination fo symptoms, patients are frequently misdiagnosed.

Some patients may go an entire lifetime without having noticeable symptoms. Or, symptoms can be minimal, then turn severe suddenly due to head trauma which alters the condition of the spine, brain, or cerebellar tonsils and begins to cause more difficulties. A Chiari malformation may be congenital or acquired. Research is still being done to determine its causes. In some cases it can be hereditary, and numerous cases exist of multiple members of one family having the condition.
It is common for adults to start showing noticeable symptoms when they are in the mid to late 30's. It is more common in women than in men.

Once symptomatic onset occurs, the most frequent treatment is decompression surgery, in which a neurosurgeon seeks to open the base of the skull and through various methods unrestrict CSF flow to the spine. This treatment is well recognized and accepted with many studies published (involving a total of hundreds of patients) in well respected peer reviewed medical journals showing that about 80% of patients obtain improvement.