Clinical and electrophysiological assessment of inferior alveolar nerve function after lateral nerve transposition

Inferior alveolar nerve (IAN) transposition surgery may cause some degree o f sensory impairment. Accurate and reproducible tests are mandatory to asse ss IAN conduction capacity following nerve transposition. In this study sub jective (heat, pain and tactile-discriminative tests) and objective (electr ophysiological) assessments were performed in 10 patients receiving IAN tra nsposition (bilaterally in 8 cases) in order to evaluate any impairment of the involved nerves one year post-operatively. All patients reported a ting ling, well-tolerated sensation in the areas supplied by the mental nerve wi th no anaesthesia or burning paresthesia. Tactile discrimination was affect ed the most (all but 1 patient). No action potential was recorded in 4 pati ents' sides (23.5%); 12 sides showed a decreased nerve conduction velocity (NCV) (70.5%) and 1 side normal NCV values (6%). There was no significant d ifference in NCV decrease between partial and total transposition sides, if examined separately. Nerve conduction findings were related 2-point discri mination scores, but not to changes in pain and heat sensitivity. These fin dings show that lateral nerve transposition, though resulting in a high per centage of minor LAN injuries, as determined by electrophysiological testin g, provides a viable surgical procedure to allow implant placement in the p osterior mandible without causing severe sensory complaints. Considering et hical and forensic implications, patients should be fully informed that a c ertain degree of nerve injury might be expected to occur from the procedure . Electrophysiological evaluation is a reliable way to assess the degree of IAN dysfunction, especially if combined with a clinical examination. Intra operative monitoring of IAN conduction might help identify the pathogenetic mechanisms of nerve injury and the surgical steps that are most likely to harm nerve integrity.