Factors Associated with the Recurrence or Resolution of Neuropathic Pain Following Trigeminal Nerve Repair for Neuropathic Pain
Neuropathic pain is best identified by its symptomology including: hyperalgesia, allodynia, radiating pain, burning or sharp pain, and is often associated with some degree of numbness and tingling (1).
Neuropathic pain appears to not be caused by surgical nerve repair when neuropathic pain is not present before surgery (2). However, nerve repair surgery is effective in resolving neuropathic pain in only a small minority of patients when neuropathic pain is present before surgery. The objective of this study was to determine which factors might be associated with the resolution or recurrence of neuropathic pain following trigeminal nerve surgery in those patients who had neuropathic pain before surgery.
Materials
This study performed a retrospective review of 17 patient records who underwent trigeminal nerve repair for neuropathic pain, including both the inferior alveolar nerve and lingual nerve. Each record was reviewed to account for age, gender, presence of neuropathic pain, etiology, class of injury, type of repair, and duration of injury. The primary end point was the presence or absence of neuropathic pain at 3, 6, and 12 months after surgery.
Results
A four-fold table was used to obtain sensitivity, specificity, positive predictive values, and negative predictive values for neuropathic pain after surgery. A chi square was used to determine the level of statistical significance, and a logistic regression analysis was used to evaluate the association between neuropathic pain and secondary endpoints for the 17 patient records reviewed. There was no difference in the average age at time of injury for those with recurrent pain (44.4 years) vs resolved pain (43.3 years). There was no difference in the branch of the trigeminal nerve injured in the recurrent pain (Lingual 33%, Inferior Alveolar 66%) vs resolved pain (Lingual 25%, Inferior Alveolar 75%) groups. There was no difference in the gender ratio (male/female) in recurrent pain (20%) vs resolved pain (33%); the mean duration of injury before repair for recurrent pain (16.1 mos) versus resolved pain (4 mos) was significant. The class of injury distribution for recurrent pain was: 33% for each Class III, IV and V versus resolved pain was Class III – 66%, Class IV 33 %, Class V – 0%; etiology of nerve injury: 3rd molar surgery (56%) was the predominant cause of injury in those with recurrent pain and implants (22%). In those patient with resolved pain the etiology of injury was equally split between Implants, 3rdMolar Surgery, and Endodontic injuries. Significant variation exists regarding the type of repair performed: recurrent pain group: Neurolysis 12%, Direct Repair 44%, Auto or Allografts 44%; resolved pain group: Neurolysis 33%, Direct Repair 66%.
Discussion/Conclusion
The recurrence of neuropathic pain following trigeminal nerve repair for neuropathic pain is likely multifactorial. Our findings suggest that patients who undergo repair immediately after their injury that caused the onset of neuropathic pain are more likely to experience complete resolution of their neuropathic pain after nerve repair surgery. Our preliminary findings also suggest that the type of repair, injury class, and etiology of injury may influence the outcome. It does not appear that age and gender are significant factors affecting the resolution or recurrence of neuropathic pain following repair.
References:
1) Gregg JM. Medical Management of Traumatic Neuropathies. Oral and Maxillofacial Surgery Clinics of North America. 13:343-363 2001.
2) Yates D, Zuniga JR: Risk Factors Associated with Neuropathic Pain Following Trigeminal Nerve Repair. J Oral Maxillofacial Surg, (Suppl 2) 67: 52-53, 2009.