The Symptom Spectrum: Preoperative Indicators and Their Influence on Surgical Outcomes for Type 1 Chiari Malformation in Adults

Introduction: Chiari I malformation (C1M) may remain asymptomatic during childhood, necessitating surgical decompression (SD) later in life due to the emergence of debilitating neurological symptoms. The outcomes of surgical management for C1M in the adult population are variable and have been less extensively studied.

Methods: A retrospective cohort was conducted on adult patients who underwent primary SD for C1M at our center from 2004 to 2023. Patients with concurrent tumors or congenital malformations affecting the central nervous system were excluded from the study. The primary outcomes assessed were symptom improvement and pain medication use at the final follow-up visit.

Results: This study included a total of 221 adult patients with primary SD for C1M, with a median age of 36 years at the time of surgery and a male-to-female ratio of 1:4.4. The median duration of symptoms prior to SD was 12 months (0-480 months) and the median follow-up period was 29 months (1-254 months). Syringomyelia was present in 75 (33.9%) cases with a median syrinx length of 40.5 mm (1-420 mm). Headache was the most common presenting symptom (89.1%) with 62.4% aggravated with Valsalva maneuvers. In multivariate regression analysis, cauterization of the cerebellar tonsils at the time of surgery was associated with higher odds of complete symptom resolution (OR=0.23, 95% CI:0.09-0.59) and being free from pain medications (OR=0.26, 95% CI:0.13-0.50) at the last follow-up visit. Patients reporting preoperative symptoms of hand numbness (OR=3.17, 95% CI:1.33-7.55) or dizziness (OR=3.03, 95% CI:1.15-8.00) were more likely to remain symptomatic at the last follow-up visit.

Conclusion : In adult patients undergoing SD for C1M, preoperative hand numbness or dizziness significantly reduced the odds of achieving complete symptom relief at the final follow-up. In contrast, cauterization of the cerebellar tonsils during surgery was associated with higher odds of complete symptom relief and freedom from pain medication.