Disease Information
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Chiari [Kee-AR-ee]: is a malformation of the back of
the cerebellum, thought to be caused by a small posterior fossa. The
crowded cerebellum pushes against the brainstem and/or the foramen
magnum, blocking off CSF to the
brain and/or spinal canal, causing all manner of neurological problems.
The most common symptom is the pounding, sub-occipital headache, which
does not respond to regular successful therapies. Chiari is most often
congenital, but it can be acquired by traumatic accidents, lumbar puncture,
etc. Chiari is associated with many other disease processes including:
Syringomyelia, Scoliosis, Tethered Spinal Cord, Ehlers-Danlos Syndrome
and other connective tissue disorders, and Pseudo-tumor Cerebri, etc.
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What is the prevalence of Chiari malformation?
Until recent years, CM1 was regarded as a rare condition. With the increased availability of magnetic resonance imaging (MRI), the number of cases has risen sharply. Current estimates range from 200,000 to 2 million Americans with the condition. Genetic studies spearheaded by Thomas Milhorat, M.D., Chairman of the Departments of Neurosurgery at North Shore Univ. Hospital in Manhasset, N.Y., and the late Marcy Speer, PhD., the Director of the Center for Human Genetics at Duke University Medical Center, support a hereditary tendency with a transmissibility rate of 12 percent. Women are affected three times more often than men. Approximately 3,500 Chiari operations are performed each year in the United States.
How are patients diagnosed?
The evaluation of patients begins with a detailed clinical
questionnaire. A team of nurse practitioners supervises the data entry,
the scheduling of tests and physician consultations, travel arrangements
and housing. The workup is exhaustive and usually completed over a
two-day period. The goal of the diagnostic workup is to: (1) establish
the correct diagnosis; (2) educate the patient and answer questions; (3)
provide a list of management options; and (4) discuss the preferred
operative technique if surgery is required.
How is surgery performed?
According to Paolo Bolognese, MD of the Chiari Institute, the decision to treat patients surgically requires a detailed consultation between the patient and physician. Generally, surgery is not recommended unless one or more of the following conditions is met: (1) evidence of neurological deterioration; (2) progression of symptoms which have become unbearable or disabling; and (3) MRI evidence of syrinx enlargement. Surgery is not recommended to prevent problems from occurring in the future because the natural history of CM and SM is incompletely understood.
For the past 10 years or so, physicians studying Chiari and the diseases related to it have begun to develop very patient-specific surgical procedures, taking into account that each patient can have unique structural differences. For instance, Dr. Milhorat and Dr. Bolognese, of The Chiari Institute in Great Neck, NY routinely use real-time intraoperative color Doppler ultrasound monitoring in their Chiari neurosurgery to confirm their goals of surgery.
To achieve a successful Chiari surgery, the neurosurgeon must reconstruct normal sized CSF spaces behind the cerebellum, decompressing the patient’s nervous tissue; thus restoring normal CSF flow between the cranial and spinal compartments. All other possible complications and/or root causes of the Chiari malformation must also be ruled out before a decompression surgery is even considered.