Radiation exposure alters airway deformability and bony structure displacement during laryngoscopy.

BACKGROUND: Prior therapeutic radiation exposure in the setting of head and neck malignancies is associated with difficult airway instrumentation. We sought to characterize the anatomic changes that produce this phenotype. STUDY DESIGN: Retrospective review. METHODS: Five individuals with prior radiation therapy to the upper aerodigestive tract (previously irradiated) and 10 with no prior history of therapeutic radiation exposure (nonirradiated) were enrolled. Computed tomography images obtained before and during laryngoscope insertion ("uninstrumented" and "instrumented", respectively) were used to reconstruct three-dimensional representations of the pharyngeal airway, hyoid, and mandible. RESULTS: In the instrumented state, pharyngeal airway volumes were significantly greater in nonirradiated subjects relative to previously irradiated subjects (P = .01), and overall translation of both the hyoid and mandible was also greater in nonirradiated subjects (P = .01 and .04, respectively). CONCLUSION: Individuals with prior therapeutic radiation exposure to the upper aerodigestive tract differ from nonirradiated subjects with respect to airway deformation and bony structure translation during laryngoscopy. LEVEL OF EVIDENCE: 4.

Improving target localization during trans-oral surgery with use of intraoperative imaging.

PURPOSE: Trans-oral surgery provides a less invasive means for the surgical management of upper aerodigestive tract malignancies but is limited in its ability to readily assess submucosal tumor extent and location of critical structures intraoperatively. We sought to determine surgeons' baseline target localization accuracy during operative laryngoscopy with preoperative imaging alone and then assess for improvement in localization accuracy when presented with intraoperative CT imaging capturing soft tissue deformation. METHODS: Fiducial beads were placed submucosally in four cadaver heads. "Preoperative" (PO) and "intraoperative" (IO) neck CTs were acquired before and during suspension laryngoscopy using a CT-compatible laryngoscopy system. Surgeons attempted to localize submucosal fiducials beads using pins based on sequential review of PO and IO images. RESULTS: Mean total error (TE) decreased from 12.8 ± 9.9 to 10 ± 7.5 mm from PO to IO (P < 0.001), respectively. TE for base of tongue and vallecula decreased by 1.7 ± 6.7 mm (P = 0.015). Right-sided structures were most exposed by scope positioning and experienced a TE reduction of 4.8 ± 9.3 mm (P < 0.001). Task completion time decreased from PO to IO by 26% (P < 0.001). CONCLUSIONS: Intraoperative imaging significantly improves localization accuracy and task efficiency when targeting submucosal beads in cadaver heads during operative laryngoscopy.

Multi-modal Framework for Image-guided Trans-oral Surgery with Intraoperative Imaging and Deformation Modeling.

Treatment of throat cancers have improved due to minimally-invasive trans-oral approaches. Surgeons rely on preoperative imaging to guide their resection; however, large tissue deformations occur during trans-oral procedures due to placement of necessary retractors and laryngoscopes which hinders the surgeon's ability to accurately assess tumor extent and location of critical structures. We propose an image-guided framework utilizing intraoperative imaging and deformation modeling to improve surgeon accuracy and confidence. A CT-compatible laryngoscopy system previously developed was evaluated in this framework. Intraoperative images were acquired during laryngoscopy; force-sensing capabilities were enabled in the laryngoscope; and tracking of the scope and anatomic features was trialed. Tissue deformation and displacement were quantified and determined to be extensive, with values <; 4.6 cm in the tongue, <; 1.8 cm in bony structures, and <; 108.9 cm3 in airway volume change. Surgical navigation using intraoperative imaging and tracking was evaluated. Preliminary assessment of deformation modeling showed potential to supplement intraoperative imaging. Future work will involve streamlined integration of the components of this framework.

A Cohort Study of the Natural History of Odontoid Pseudoarthrosis Managed Nonoperatively in Elderly Patients.

OBJECTIVE: Although the primary goal of treatment of type II odontoid fracture is bony union, some advocate continued nonsurgical management of minimally symptomatic older patients who have fibrous union or minimal fracture motion. The risk of this strategy is unknown. We reviewed our long-term outcomes after dens nonunion to define the natural history of Type II odontoid fractures in elderly patients managed nonoperatively. METHODS: A retrospective chart review of 50 consecutive adults aged 65 or older with Type II odontoid fracture initially managed nonsurgically from 1998 to 2012 at a single tertiary care institution was conducted. Particular attention was paid to patients who had orthosis removal despite absent bony fusion. Patients were contacted prospectively by telephone and followed until death, surgical intervention, or last known contact. RESULTS: Fifty patients initially were managed nonsurgically; of these, 21 (42.0%) proceeded to bony fusion, 3 (6%) underwent delayed surgery for persistent instability, and 26 (52%) had orthosis removal despite the lack of solid arthrodesis on imaging. The last group had a median follow-up of 25 months (range 4-158 months), with 20 of 26 (76.9%) followed until death. Of these patients, 1 patient developed progressive quadriplegia and dysphagia 11 months after initial injury. Compared with patients with spontaneous union, patients with nonunion had shorter life expectancy, despite no significant differences between the groups with respect to age, sex, injury mechanism, radiographic variables, or follow-up duration. CONCLUSIONS: Orthosis removal despite fracture nonunion may be reasonable in elderly patients with Type II dens fractures.