How Can Paresthesia After Zygomaticomaxillary Complex Fracture Be Determined After Long-Term Follow-Up? A New and Quantitative Evaluation Method Using Current Perception Threshold Testing

Purpose The aims of the present study were to analyze the effectiveness of current perception threshold (CPT) testing to determine patients' minor paresthesia of the infraorbital region after open reduction and internal fixation (ORIF) for unilateral zygomaticomaxillary bone fracture (UZF) and to clarify which nerve fiber was related to the paresthesia. Materials and Methods We conducted a retrospective cohort study of patients who had undergone ORIF after UZF. We also performed neurosensory testing for healthy volunteers who served as the control group. The predictor variables were the period of measurement of Semmes-Weinstein monofilament (S-W) testing and CPT testing (preoperatively and 1 and 5 years postoperatively), measurement side, and disease status (UZF or control). The outcome variables were paresthesia status of the infraorbital nerve region and the results of S-W and CPT testing in both UZF and control groups. The differences in the S-W and CPT values between the affected and unaffected sides in the UZF group and between the UZF and control groups were analyzed by t test ( P < .05 was considered significant). Results The present study included 10 patients (6 males and 4 females), with an average age of 25.0 ± 12.7 years, and 21 controls (10 males and 11 females), with an average age of 24.3 ± 1.7 years. In the control group, the CPT and S-W test results did not show any significant differences between the left and right sides. All 10 patients had paresthesia at 1 and 5 years postoperatively. At 5 years postoperatively, the S-W values in all patients showed normalization. From the results of CPT testing, only the A-β fiber function showed significant improvement at 5 years postoperatively. Conclusion The CPT test was an effective sensory test for determining minor paresthesia that could not be detected using S-W testing. Paresthesia of the infraorbital nerve region was caused by the damaged A-δ and C fibers.