2025 Poster Presentations
P075: EVALUATION OF PATIENTS WITH PLATYBASIA AND CONCOMITANT CHIARI MALFORMATION AND THE NEED FOR UPFRONT SUB-OCCIPITAL CRANIECTOMY AT THE TIME OF INITIAL ANTERIOR DECOMPRESSION
Jeffery R Head, MD1; Kelly E Daniels, MD2; Hussam Abou-Al-Shaar, MD1; Hanna N Algattas, MD3; David O Okonkwo, MD1; David K Hamilton, MD1; Eric W Wang, MD2; Garret W Choby, MD2; Carl H Snyderman, MD, MBA2; Robert M Friedlander, MD, MA1; Georgios A Zenonos, MD1; Paul A Gardner, MD1; 1University of Pittsburgh Medical Center, Department of Neurosurgery; 2University of Pittsburgh Medical Center, Department of Otolaryngology; 3University of Buffalo, Department of Neurosurgery
Objective: Disorders of the craniocervical junction (CCJ) are associated with high morbidity and reduced quality of life. For anterior vectors of compression the endoscopic endonasasl approach (EEA) has become increasingly utilized for achieving ventral decompression. However, a certain subset of patients with CCJ dysfunction (CCJD) present with a concomitant Chiari Malformation (CM) and posterior vector of compression. This study aims to characterize this subset of patients and to determine the need for upfront suboccipital craniectomy (SOC).
Methods: A retrospective review was performed of all patients with CCJ pathologies treated with EEA decompression from 2008 to 2023 at a single center. Radiographic data, outcomes, and surgical approach were obtained.
Results: A total of 52 patients who underwent an EEA for various CCJ abnormalities were included in this study. Of these, 14 patients had CCJD plus concomitant CM and these patients were significantly younger (39.7 ± 21.22) than other CCJD patients (60.9 ± 23.9, p=.01). A total of 71.4% (n=10) of these patients had a retroflexed dens and additionally patients with a retroflexed dens were significantly more likely to have a CM (p<.001). Patients with CM were also significantly more likely to have O-C1 assimilation (n=7; 50% v. 21.6%, p=.015). The most common presenting symptoms for patients with CCJD plus CM were dysphagia (n=10; 71.4%), myelopathy (64.3%; n=9), and chiari-like symptoms (headaches and paresthesias; n=6, 42.9%). Two patients (14.3%) had undergone an SOC prior to presentation and 5 patients (35.7%) had an SOC at the time of their index EEA surgery. All CCJ plus CM patients with an SOC at the time of surgery had the occiput included in their fusion compared to only three patients with CCJD plus CM without an SOC (33.3%; p=.015). Patients with CCJD plus CM and O-C1 assimilation were not more likely to have the occiput included in their fusion (n=6, 75%) compared to those without O-C1 assimilation (n=2, 33.3%; p=0.12)
When compared to those patients with CCJD plus CM who underwent SOC at the time of surgery patients who did not receive a SOC had non-significantly higher rates of persistent radiographic tonsillar descent (n= 7, 77.8% v. n=2, 40%; p=.15), tonsillar crowding (n=5, 55.6% v. n=1, 20%; p=.19), and chiari-like symptoms at last follow-up (n=7, 77.8% v. n=1, 20%; p=.19). No patient with CCJD plus CM who only underwent EEA has required additional surgery, though one patient who did not have an SOC is considering additional decompression for persistent chiari-like symptoms.
Conclusions: Platybasia with a retroflexed dens appears to be linked to Chiari malformation. In treating these patients, SOC either before, during, or after anterior decompression may necessitate fusion including the occiput. While more patients with CCJD plus CM who did not have an SOC at the time of index surgery had persistent radiographic and symptomatic features of CM, this did not reach statistical significance. Further studies are needed to determine whether primary posterior decompression is needed at the time of index ventral surgery for a circumferential decompression in patients presenting with CCJD plus CM.