Outcome of Therapies for Chiari Malformations in Children

Outcome After Surgery

Chiari I malformations

• Headaches, scoliosis, and apnea most responsive: Symptoms most likely to improve with surgery are scoliosis of less than 30 degrees, occipital headache, cervical pain, and sleep apnea (24). Patients with more brainstem and spinal cord symptoms are less likely to improve than patients with headaches alone (7).
• Symptom recurrence in 22%: A review of 256 pediatric patients undergoing suboccipital craniectomy and Chiari malformation decompression showed that 22% of patients had mild to moderate symptom recurrence and 7% required revision for severe symptom recurrence. Headache was 70% more likely to recur than brainstem symptoms. Increasing duration of headache, frontal headache, and vertigo were independent predictors of symptom persistence or recurrence (12). Patients with more brainstem and spinal cord symptoms are less likely to improve than patients with headaches alone (16).
• Patients with foramen magnum or central cord syndromes more likely to relapse: In a series of 71 adult patients, 80–90% of patients presenting with any symptomatology improved initially, but patients with foramen magnum syndromes and patients with central cord syndrome were more likely to relapse later (33% and 25%, respectively) (32).
• Syringomyelia should resolve: Syringomyelia should resolve after decompression for Chiari I malformation; if not, re-exploration of the posterior fossa is preferred before consideration is made to shunt the syrinx directly to the subarachnoid space, pleura, or peritoneum.

Chiari II malformations

• Early recognition key to good prognosis: Early recognition of symptoms and early treatment are key to a good prognosis.
• Improvement lessens as symptoms worsen: Based on a classification system proposed by Charney et al. (6), patients with less severe symptoms at diagnosis are much more likely to improve with surgical intervention. Nearly all patients with stridor alone (grade I) have a reasonable chance of full recovery with shunt revision and/or decompression. Patients with stridor and apnea spells (grade II) had a 50% chance of recovery and a 75% chance of survival. Patients with stridor, apnea spells, cyanotic spells, and dysphagia had very little chance of resolution of symptoms and only a 40% chance of survival.
• Better outcomes once importance of shunt function realized: The results described by Charney et al. (6) were reported prior to the recognition of shunt malfunction without ventricular dilatation. Most recent series report better outcomes. Regardless, it is worth stating again that the most important intervention in patients with spina bifida who present with symptoms and signs of Chiari II malformation, namely lower brainstem symptoms and signs and apnea, is to ensure adequate shunt function (17).