Long-term Outcomes of Trigeminal Nerve Repair
Following a nerve injury, proper documentation with neurosensory testing (NST) is imperative to determine if surgical intervention is warranted. The indications for microneurosurgery are complete anesthesia, observed nerve transection, or less than 50% residual sensation with a Sunderland Grade III-V NST. Nerve repair may be performed with a direct or indirect (graft) neurorrhaphy procedure if there is tension at the repair site. The overall success rates of microneurosurgery of the trigeminal nerve vary considerably in the literature from 50-92%, but no study has evaluated the difference in success of direct vs. indirect repair techniques.
Sensory recovery following nerve repair is evaluated using the Medical Research Council Scale (MRCS) with grades S3, S3+, S4 all constituting a functional sensory repair (FSR). An FSR S3 corresponds to a return of some superficial pain and tactile sensation without over-response and two point discrimination of >15mm.
The goal of this study is to compare the subjective and objective outcomes of trigeminal nerve repair by direct epineurial repair vs. indirect repair using a sural nerve graft, and to assess the impact of other confounding variables.
Following IRB approval (IRB #2013-1098), CPT codes for trigeminal nerve repair were used to search for nerve repair cases completed by one surgeon (MM) between 01/2008 thru 12/2012. Of 72 patients, 14 have been contacted, 10 female, 4 male, mean age: 25.4 years. Once the subject was identified, he/she was called and asked for a valid email address. The subject was emailed a link to complete a 20-question survey (Survey Monkey), and a consent form to access the electronic medical record (EMR) for age, gender, race, type of nerve repair, and information regarding the neurological examination at the time of the initial presentation prior to the nerve repair. The results of the questionnaire along with data from the EMR were analyzed for significance specifically comparing direct vs. indirect repair techniques. A student’s t-test and chi-square was used to determine whether a significant difference exists in the success between the two techniques, and whether there was an influence of age, gender, race, and degree of initial nerve deficit on the success of nerve repair.
Based upon the preliminary data from a small segment of the study group thus far, it appears as if sural nerve graft repair of the trigeminal nerve provides superior long-term (>2 yrs) outcomes compared to direct repair. This may be due to the lack of tension at the repair site, as well as the addition of neurotropic and neurotrophic factors at the site of injury to augment recovery. The other variables were not found to be significant in this group of patients.
The plan is to complete an evaluation of the entire study group and possibly expand the group to include patients who underwent trigeminal nerve repair prior to 2008.
Relevant literature
Pogrel, MA. The results of microneurosurgery of the inferior alveolar and lingual nerve. Journal of Oral and Maxillofacial surgery, 2002. 60: 485-489.
Leung, L. Treatment modalities of neurosensory deficit after third molar surgery. Journal of Oral and Maxillofacial Surgery. 2012, 70: 768-778.
Bagheri, S. Microsurgical repair of the inferior alveolar nerve: Success rate and factors that adversely affect outcome. Journal of Oral and Maxillofacial Surgery. 2012, 70: 1978-1990.