For information about neurosurgical services, contact the UC Neuroscience Institute at 513-584-2214 or 866-941-8264. You can visit the Mayfield Chiari Center at http://www.mayfieldchiaricenter.com.
UC HEALTH LINE: Years of Frustration Often Precede Cure for Chiari
CINCINNATI—A spinal malformation that blocks the normal flow of cerebrospinal fluid can produce such an array of symptoms that it is frequently undiagnosed or misdiagnosed, according to a University of Cincinnati (UC) neurosurgeon.
Chiari malformation, a condition in which a portion of the brain pushes through the opening at the base of the skull, can cause headaches, fatigue, dizziness, difficulty swallowing, muscle weakness and balance problems. It can also produce hoarseness, sleep apnea, weakness or numbness in an extremity, neck pain, pain across shoulder blades, general body pain, ringing in the ear, trouble walking, blurred vision, mood changes, anxiety and problems with memory or concentration.
"There are more than two pages of symptoms produced by Chiari malformation,” says Mario Zuccarello, MD, Frank H. Mayfield Professor and Chairman of the UC Department of Neurosurgery and a neurosurgeon at the Mayfield Clinic and the Mayfield Chiari Center. "It is very difficult to make a diagnosis only by reviewing the symptoms. A patient who says, ‘I have neck pain, numbness and dizziness’ may go underdiagnosed.”
The fact that a typical patient will go three to seven years before getting an accurate diagnosis, Zuccarello says, reflects an educational shortcoming in U.S. medical schools. "It is not an obvious diagnosis,” Zuccarello says. "How many patients have headaches? Every one.”
A frequent "scapegoat diagnosis” is multiple sclerosis. Patients with undiagnosed Chiari also may be told they have fibromyalgia or a mood disorder, leading to years of frustration and distress. "There is a lot of emotion associated with this condition,” Zuccarello says. "Many patients go through dramatic diagnostic procedures for diseases they do not have. A tearful patient is not unique.”
Chiari (pronounced key-AR-ee) is named after Hans Chiari, an Austrian pathologist who first described it in the late 19th century. There is no data to support the exact incidence of the condition, according to the World Arnold Chiari Malformation Association. Zuccarello says physicians estimate that the condition affects one in every 1,300 to 18,000 individuals, with familial clustering occurring in 3 to 12 percent of cases.
Chiari I malformation, the least severe and most common form, is a disorder in which the bony space enclosing the lower part of the brain (the cerebellum) is smaller than normal, causing two small portions of the cerebellum (the cerebellar tonsils) to migrate into the spinal canal. If the cerebellar tonsils obstruct the opening of the skull (the foramen magnum) that connects the brain to the spinal cord, the flow of cerebrospinal fluid can be blocked. Instead of moving in an easy, pulsating movement through this opening, the fluid can begin to force its way through, pushing the cerebellar tonsils down even farther and exerting pressure on the lower stem of the brain.
Diagnostic tests used to confirm the presence of Chiari include: (1) a CT scan, which can detect thickened bone or previous trauma; (2) an MRI, which can reveal how far the cerebellar tonsils have herniated; and (3) a CINE MRI, or "movie” MRI, which can show whether the cerebrospinal fluid is flowing normally through the foramen or is being blocked.
The first symptom, which is often headache, emerges once the blockage is sufficiently severe. "Patients often will tell you they have pain in the back of the head that increases when they strain, cough or do anything demanding,” Zuccarello says.
Some patients require monitoring only, Zuccarello says. Those patients are typically treated with pain medication. They also may be referred to a sleep specialist if they are struggling with sleep apnea. And if they are overweight, they may be encouraged to lose weight to reduce strain on the arms and legs and to alleviate numbness or tingling.
Most patients will need decompression surgery to enlarge the bony opening, to restore normal fluid circulation around the brain, and to prevent a syrinx, a cyst that results from the accumulation of cerebrospinal fluid in the spinal canal. This condition, called syringomyelia, can damage the spinal cord, thereby causing its own cascade of neurological problems.
Zuccarello compares enlargement of the bony opening to "a situation where you have two children and two small rooms and you take down the wall to make the room larger.”
During surgery, surgeons cut through the bone at the back of the head and then open the protective covering of the brain and spinal cord (the dura). Some bone is removed permanently, and surgeons sometimes—but not always—use electrocautery to shrink the cerebellar tonsils. The tonsils cannot simply be removed, because they are an extension of the individual’s brain, and complete removal could result in neurological impairment.
A patch of synthetic material is placed inside the dural opening and then covered with a dural sealant to prevent cerebrospinal fluid from leaking. Placing the dural patch, Zuccarello says, "is like fixing a tire from the inside.”
Recovery is gradual and can take weeks, months or even years. But Zuccarello says the vast majority of patients experience improvement of symptoms after the blockage of cerebrospinal fluid flow is corrected.