To Do or Not to Do – Delving into Profound Decision Making in Neurosurgical Care of Chiari Malformation Type I

Introduction: The goal of this study is to assess the outcome according to objectifiable parameters to decide when surgical intervention in Chiari malformation type I is beneficial in children and adults.

Methods: We evaluated 111 patients from 0 to 63 years [73 female (65.7 %), 38 male (34.3 %)] who underwent surgical decompression of the posterior fossa due to Chiari malformation type I in a single neurosurgical center over a period of 18 years from 2004 till 2022. 46 presurgical clinical and radiographic factors were selected. The outcome was investigated using the Chicago Chiari Outcome Score (CCOS) and Clinical Outcome Scale. The mean postoperative follow-up period was 3.5 years. All factors regarding the outcome were tested individually and in small subgroups to reflect the diversity of clinical presentation.

Results: A favorable outcome, defined as CCOS ≥11, was achieved in 93.1 % (n=95) of all patients who underwent the follow-up examination. Specific pathways for certain symptom constellations were developed, e.g. early onset Chiari in young children (ages 0-5), or elderly patients (≥ 50 years) presenting with Chiari. The most frequent surgical intervention was decompression of the posterior fossa with laminectomy of C1 and duroplasty (n=83, 74.8 %). Headaches were observed preoperatively in 48 patients (43.2 %). Numbness in extremities showed a notable disproportion in children (n=6, 18.2 %) compared to adults (n=8, 10.3 %) with an OR (95% CI): 1.94 (0.62;6.13). Radiographically, we found the highest correlation with a good outcome in patients with a tonsillar herniation distance of more than 10 mm [OR (95% CI): 4.15 (1.34;12.87)].

Conclusion : Our analysis of children and adults enlightens the diverse manifestations of Chiari malformation type I faced in daily neurosurgical practice. It offers the neurosurgeon a tool to help in further understanding the indication for neurosurgical intervention in patients with Chiari malformation.