018. Heritable Connective Tissue Disorders Associated with Complex Comorbidities, Increased Craniocervical Instability, and Worse Perioperative Outcomes in Chiari I Malformation Patients

Authors: Jamie Clarke

Chiari malformation type I (CMI), an inferior herniation of the cerebellar tonsils, may result in severe, debilitating neurologic symptoms. Hypothesized etiologies include congenital anatomic abnormalities, trauma, and connective tissue disorder (CTD)-related herniation. Its treatment is typically posterior fossa decompression. However, treating CMI and craniocervical instability (CCI) patients with heritable CTDs is more challenging; best-practices in identifying and treating these patients have yet to be fully characterized.Methods: Patients with CMI admitted for surgical decompression from 2008-2015 were captured using the National Inpatient Sample (NIS). Information on patient demographics, comorbidities, and perioperative course was collected. Diagnoses and procedures were determined by ICD-9-CM and ICD-9-PCS codes, respectively. Descriptive and regression analyses were performed in SPSS (v26).
38,169 CMI patients, 353 of whom with CTD, were identified. CMI patients with CTD were more likely to be female (p < 0.001) and present during the teenage (p=0.033) or young adult years (p < 0.001). Despite their younger age, they had more chronic issues (p < 0.001): systemic comorbidities include postural orthostatic tachycardia syndrome, cardiac dysrhythmias, and gastroparesis (all p < 0.001). Central nervous system (CNS) comorbidities include migraine, tethered cord, and epilepsy (all p < 0.001). They have increased joint instability, including craniocervical instability (CCI) (all p < 0.001), as evidenced by increased concomitant posterior cervical fusion surgeries and application of cervical halo procedures (both p < 0.001) during the same inpatient stay . Patients with CTD had longer length of stay (6.61 vs. 4.00 days), more procedures during hospitalization, and increased hospitalization charges ($87,967.4 vs. $58,378.3; all p < 0.001).
Patients with concurrent CTD and CMI were more likely to present with complex Chiari and associated CCI. They were also younger, more likely to be female, and had more systemic, CNS, and joint abnormalities with longer, more complicated, and more expensive hospitalizations. As such, preoperative recognition of an underlying CTD is imperative to achieve optimal outcomes in this patient population.