Prognosis

Great care must be taken in accessing the results of any given treatment for symptoms referable to a Chiari Malformation. Since many will show evidence of symptom recurrence within two years of surgery, follow-up must be for at least this duration.

Symptoms directly referable to the hind brain malformation seem to be more amenable to treatment. Cough headache and symptoms due to cerebellar dysfunction (dizziness, difficulty with coordination, unsteadiness in gait) resolves over 80% of the time by report. Symptoms due to an associated syrinx are somewhat more problematic. Scoliosis will stabilize or improve in 50 to 100% of children. Younger age, the absence of extreme angulation, and MRI confirmed resolution of hydromyelia are associated with a better chance for improvement. Central cord syndrome (a characteristic pattern of weakness effecting the arms more than the legs due to a injury to the central portion of the spinal cord) in association with a syrinx has generally been associated with a poor response to treatment with only one third experiencing a sustained improvement.

A review of all the reported cases of hydromyelia and the Chiari I malformation operated on prior to the advent of MRI found that 46% improved, 32% remained stable and 20% progressed postoperatively. Thus 78% of those operated on, regardless of the surgical technique used, experienced an outcome better than that seen if no treatment is offered. The authors of the paper concluded that surgery was preferred to conservative management. However, while patients reported improvement of their complaints and functional capabilities, not infrequently there were persisting neurologic deficits and symptomatic complaints.

Infants with myelomeningocele (spina bifida) and symptomatic Chiari Type ll malformations continue to have significant morbidity and mortality. Most report up to a 50% long term mortality, regardless of the treatment strategy. Tracheotomy (creation of a new airway outlet through the neck) and gastrostomy (creation of a new food inlet through the abdominal wall) or nasogastric (a tube through the nose, down the throat to the stomach) feedings are often required for months after surgically dealing with the malformation. Intervention prior to the onset of bilateral vocal cord paralysis is associated with a better outcome.

Tania Shiminski-Maher, MS, CPNP