The symptom spectrum: preoperative symptom-related indicators of surgical outcomes for adult type 1 chiari malformation.

Chiari I malformation (C1M) may necessitate surgical decompression in adulthood due to the emergence of debilitating neurological symptoms. The outcomes of surgical management for C1M in the adult population are variable and predictive value of individual symptoms has been less extensively studied. A retrospective cohort study was conducted on adult patients (≥ 18 years) who underwent posterior fossa decompression surgery (PFDS) for C1M at our institution between 2004 and 2024. Univariate and multivariate analyses were performed to evaluate the predictive value of preoperative C1M-related symptoms on postoperative clinician-documented outcomes and complete symptom resolution at 30-, 90-day, and long-term follow-up. A total of 209 adult patients underwent PFDS for C1M, with a median age of 36 years and a male-to-female ratio of 1:4.9. Headache was the most common presenting symptom (91.4%), with tussive headaches present in 62.3% of cases with headache. Multivariate regression analysis identified preoperative sleep apnea (OR = 6.55, 95% CI: 1.16-37.05), imbalance (OR = 2.33, 95% CI: 1.12-4.84), and tinnitus (OR = 2.81, 95% CI: 1.14-6.89) as predictors of symptom improvement at 30-days follow-up, while dysphagia (OR = 5.80, 95% CI: 1.39-24.12) was predictive at 90-days. Patients with preoperative hearing loss were more likely to experience symptom recurrence during long-term follow-up (OR = 4.55, 95% CI: 1.04-19.77). Hand numbness/weakness and visual symptoms were the only two preoperative symptoms predictive of a lower odds of complete symptom resolution at the final follow-up (OR = 0.50 and OR = 0.42, respectively). Several clinical factors were associated with postoperative symptom outcomes after PFDS for C1M. These associations should be considered hypothesis-generating and require prospective validation before clinical application.