Outcome of Immediate Allograft Reconstruction of Long Span Defects of the Inferior Alveolar Nerve

Statement of the Problem: Contemporary management of ablative jaw defects includes not only bony and soft tissue reconstruction, but also addresses restoration of neurosensory function. The goal of this study is to determine the outcome of immediate reconstruction of long span defects (≥5 cm) of the inferior alveolar nerve (IAN) following ablative mandibular resection using allogenic nerve grafts.

Materials and Methods: A retrospective cohort study of patients who underwent immediate reconstruction of an IAN gap of ≥50 mm with allogenic nerve graft (AxoGen Avance, Alachua, FL) at a single academic medical center by a single surgeon from September 2013 to March 2015 was completed. The demographic and clinical data was collected for each patient and analyzed using clinical neurosensory testing, and the outcomes were reported according to the Medical Research Council Scale (MRCS) classification for functional sensory recovery. Additionally, patient perceived sensory recovery using Visual Analog Scale (VAS) was recorded (0 to 10 with 0 being normal sensation and 10 being totally anesthetic).

Methods of Data Analysis: The subjective (VAS) and objective (MRCS) measurements of functional sensory recovery were recorded and compared across the study population. Additionally, demographic and clinical data including patient age, gender, pathology, length of nerve allograft used, and follow up length was recorded and compared. 

Results: Of 12 nerve repairs, a total of 6 subjects met the inclusion criteria. The average age was 37.5 years (range: 20 to 61) and 66.7% were male subjects. All IAN defects resulted from resection of mandibular pathology (5 benign, 1 malignant). 5 out of the 6 IAN defects were reconstructed with a 70 mm nerve allograft, while the remaining defect was reconstructed with a 50 mm graft. Mean follow up time was 17.1 months (range: 10 to 27.5 months). Mean VAS reported was 6.1 (range: 3 to 10). 83.3% of subjects displayed return of some superficial pain and tactile sensation without overresponse (S3) with 16.7% displaying good stimulation localization (S3+) using the MRCS classification. The subject that displayed S3+ functional recovery was the one that was reconstructed with the 50 mm graft. Only one of the six subjects had no neurosensory recovery (S0).

Outcome Data: The results of the MRCS exam were the primary outcome variable from which functional sensory recovery was determined. Additionally, the VAS of patient perceived neurosensory recovery was used. 

Conclusions: Immediate reconstruction of the IAN using allogenic nerve graft of long span defects (≥5 cm) is a viable option to achieve useful functional sensory recovery. This pilot study will continue to recruit subjects to determine the validity and reliability of these findings.

 References:

1. 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: 734-44, 2015.
2. Miloro M, Ruckman P, Kolokythas A: Lingual nerve repair: To graft or not to graft? J Oral Maxillofac Surg 73: 1844-50, 2015.