Immediate Nerve Allograft Reconstruction with Ablation of Mandible for Benign Pathology

Statement of Problem: Ablation of the mandible for benign pathology requires resection of bone, teeth, soft tissue and inferior alveolar nerve (IAN) that results in failure to recover significant sensations to the lip and chin in the majority of patients¹.  This study was designed to determine if the immediate reconstruction of the IAN with AVANCE allograft in conjunction with the simultaneous ablation and reconstruction of the mandible will be effective in restoring sensation of the lip and chin as found in delayed nerve repair².

Materials and Methods: Patients (age 5-70) requiring the ablative resection of the unilateral or bilateral mandible for benign pathology which would include the continuity injury of the IAN were included.   The length of the graft must be between 4.5 and 7.0 cm. Sensory values were recorded before and at least twice with the last recording at 6 months postoperatively. Safety data was recorded during the immediate to 6 month postoperative times.

Results and Outcome Data: Twenty-six subjects with unilateral or bilateral mandibular pathology were consented to this study. There were 2 patients requiring bilateral repairs.  Three patients served as positive control since they were consented to participate in the study but the nerve repair was not performed due to decision to delay reconstruction in two cases and failure to identify the IAN proximal stump in the other. Five patients were lost to follow up and did not complete a 6 month evaluation.  Eighteen patients met the criteria for inclusion in this study, 7 males and 11 females, mean age was 26.4 years, range 10 to 64. The confirmed pathology of the mandible was ameloblastoma (n=12), central ossifying fibroma (n=4), myxoma (n=1), and sclerosing osteomyelitis(n=1).  The mean length of discontinuity nerve defect was 59.75mm, range 45 to 70mm.  The mean length of allograft was 62.7mm, range 45 to 70 x 2 to 4mm.  Seventeen of 18 patients had S4+ (normal) scores preoperatively and the postoperative score was S4+ at 6 months postoperatively in 10 patients and in 14 patients at 12 months.  The positive control patients reached S2 levels only. There were no adverse events or recurrences of pathology at these postoperative times.

Conclusions: Processed nerve allografts were found to be safe and effective in restoring sensation to the lip and chin in dramatic fashion with 94% reaching useful and functional  sensory  recovery and >80% reporting similar sensations to preoperative subjective values.

References:

1.  Chow H-T, Teh L-Y: Sensory impairment after resection of the mandible: a case report of 10 cases. J Oral Maxillofac Surg 58:629-635, 2000
2. Zuniga JR: Sensory Outcomes After Reconstruction of Lingual and Inferior Alveolar Nerve Discontinuities Using Processed Nerve Allograft- A Case Series. J Oral Maxillofac Surg, 73:734-744, 2015