Comparison of operative and non-operative outcomes based on surgical selection criteria for patients with Chiari I malformations

Few studies have directly compared operative and non-operative outcomes in Chiari I patients. We evaluated risk factors for clinical improvement in 177 patients in order to help determine the optimal treatment of these often difficult to treat patients. The mean age at surgery for the operative treatment group was 29.9 years. The most common presenting signs and symptoms included cough headache (63.0%), migraine and non-cough type headaches (23.9%), paresthesias (32.1%), and abnormal reflexes or clonus (27.5%). The mean age of diagnosis for the non-operative treatment group was 30.2 years. The most common presenting signs or symptoms included migraine and other types of non-cough-associated headache (57.4%), paresthesias (45.6%), cough headache (44.1%), cerebellar signs or symptoms (41.2%), and dysphagia or apnea (15.7%). A propensity score was generated using cough headache, any headache, other headache, syrinx, abnormal reflexes or clonus, cerebellar symptoms, and miscellaneous symptoms as independent predictors of selection for surgery. The propensity score-adjusted odds of overall improvement for patients treated with surgery were 16.5 times the odds of overall improvement for patients treated conservatively (95% confidence interval 5.5–57.1, p < 0.0001). Overall 94.5% and 47.1% of operative and conservatively treated patients reported improvement, respectively. Only 26.5% of conservatively treated patients reported worsening of any of their symptoms. In conclusion, we provided further evidence for the use of cough headache as surgical indication for suboccipital decompression in patients with Chiari I malformation.