Fracture of bony lamellae within the frontal recess after balloon catheter dilatation

Background: The precise manner in which balloon catheter dilatation (BCD) alters the dimensions of the frontal recess and frontal sinus outflow tract is not well characterized. The purpose of this investigation was to determine whether BCD within the frontal recess is associated with reproducible patterns of fracture in bony lamellae, to characterize changes between pre- and postintervention measurements of the frontal sinus outflow tract, and to compare the degree of change seen with endoscopic Draf I dissection. Methods: Eight cadaver heads underwent pre- and postintervention endoscopic visualization and computed tomography (CT) of the frontal recess and frontal sinus outflow tract. Frontal recesses were assigned for either BCD or Draf I dissection. CT scans were evaluated by two reviewers (principal investigator and neuroradiologist). Results: Inter-rater reliability was strong for all measures (r > 0.77; p < 0.001). The sagittal and coronal dimensions of the frontal sinus outflow tract increased significantly after BCD and Draf I dissection (p < 0.028). Significantly less change was noted in average coronal dimensions of the frontal sinus outflow tract after BCD compared with Draf I dissection (0.9 ± 0.5 mm versus 2.6 ± 0.6 mm; p < 0.018). Mean change in the sagittal dimension was significantly less after BCD compared with Draf I dissection (1.0 ± 0.8 mm versus 4.0 ± 1.2 mm; p < 0.018). The anterior face of the ethmoid bulla was the most frequently fractured lamella after BCD (56%). Conclusion: The sagittal and coronal dimensions of the frontal sinus outflow tract increased significantly after BCD and Draf I dissection. A significantly greater change in dimensions of the frontal sinus outflow tract is observed after Draf I dissection compared with BCD. No orbital or skull base injury was noted with either technique.