Chiari malformations (CMs) are structural defects in the cerebellum, the part of the brain that controls balance. Normally the cerebellum and parts of the brain stem sit in an indented space at the lower rear of the skull, above the foramen magnum (a funnel-like opening to the spinal canal). When part of the cerebellum is located below the foramen magnum, it is called a Chiari malformation.
CMs may develop when the bony space is smaller than normal, causing the cerebellum and brain stem to be pushed downward into the foramen magnum and into the upper spinal canal. The resulting pressure on the cerebellum and brain stem may affect functions controlled by these areas and block the flow of cerebrospinal fluid (CSF)— the clear liquid that surrounds and cushions the brain and spinal cord—to and from the brain.
CM has several different causes. It can be caused by structural defects in the brain and spinal cord that occur during fetal development, whether caused by genetic mutations or lack of proper vitamins or nutrients in the maternal diet. This is called primary or congenital CM. It can also be caused later in life if spinal fluid is drained excessively from the lumbar or thoracic areas of the spine either due to injury, exposure to harmful substances, or infection. This is called acquired or secondary CM. Primary CM is much more common than secondary CM.
Individuals with CM may complain of neck pain, balance problems, muscle weakness, numbness or other abnormal feelings in the arms or legs, dizziness, vision problems, difficulty swallowing, ringing or buzzing in the ears, hearing loss, vomiting, insomnia, depression, or headache made worse by coughing or straining. Hand coordination and fine motor skills may be affected. Symptoms may change for some individuals, depending on the buildup of CSF and resulting pressure on the tissues and nerves. Persons with a Type I CM may not have symptoms. Adolescents and adults who have CM but no symptoms initially may, later in life, develop signs of the disorder. Infants may have symptoms from any type of CM and may have difficulty swallowing, irritability when being fed, excessive drooling, a weak cry, gagging or vomiting, arm weakness, a stiff neck, breathing problems, developmental delays, and an inability to gain weight.
Questions to ask when consulting a surgeon that specializes in Chiari Malformation:
Do you have experience with Chiari?
Not all neurosurgeons frequently treat patients with Chiari malformation.
How many cases of Chiari have you treated?
What were the outcomes in those cases?
What complications have you seen?
Should I expect a second surgery?
What does recovery look like?
What does follow-up look like?
Do you typically need to cut the dura?
What do you use to replace any bone deficits?
When can we expect to see symptoms subside?
How long do you predict surgery will be?
Do you use subcutaneous sutures for the incision?
Like a craniofacial patient, patients with Chiari malformation benefit from a team approach, in which neurosurgeons collaborate with other specialists – including otolaryngologists (ENTs), cardiologists, gastroenterologists, and specialists in a variety of brain and spine conditions — before making a recommendation on how to proceed.
