Traumatic Facial Nerve Palsy: CT Patterns of Facial Nerve Canal Fracture and Correlation with Clinical Severity

Abstract

Purpose: To analyse the patterns of facial nerve canal injury seen at temporal bone computed tomography (CT) in patients with traumatic facial nerve palsy and to correlate these with clinical manifestations and outcome. Materials and Methods: Thirty cases of temporal bone CT in 29 patients with traumatic facial nerve palsy were analyzed with regard to the patterns of facial nerve canal involvement. The patterns were correlated with clinical grade, the electroneurographic (ENoG) findings, and clinical outcome. For clinical grading, the House-Brackmann scale was used, as follows: grade I-IV, partial palsy group; grade V-VI, complete palsy group. The electroneuronographic findings were categorized as mild to moderate (below 90%) or severe (90% and over) degeneration. Results: In 25 cases, the bony wall of the facial nerve canals was involved directly (direct finding): discontinuity of the bony wall was onted in 22 cases, bony spicules in ten, and bony wall displacement in five. Indirect findings were canal widening in nine cases and adjacent bone fracture in two. In one case, there were no direct or indirect findings. All cases in which there was complete palsy (n=8) showed one or more direct findings including spicules in six, while in the incomplete palsy group (n=22), 17 cases showed direct findings. In the severe degeneration group (n=13), on ENog, 12 cases demonstrated direct findings, including spicules in nine cases. In 24 patients, symptoms of facial palsy showed improvement at follow up evaluation. Four of the five patients in whom symptoms did not improve had spicules. Among ten patients with spicules, five underwent surgery and symptoms improved in four of these; among the five patients not operated on, symptoms did not improve in three. Conclusion: In most patients with facial palsy after temporal bone injury, temporal bone CT revealed direct or indirect facial nerve canal involvement, and in complete palsy or severe degeneration groups, there were direct findings in most cases. We believe that meticulous analysis and symptom correlation of the fracture patterns seen in facial nerve canal injury in patients with traumatic facial nerve palsy is helpful for treatment planning and prognosis.