Large myelinated nerve fiber hypersensitivity in oral malignancy

Objectives. The purpose of this study was to assess the sensory function of trigeminal nerve A-β fibers in suspected soft tissue oral malignancies. Study design. Twenty-three patients referred for the evaluation of an oral lesion suspected of malignancy were included in the study. All lesions were classified as in, near, or out of the nerve territory containing the lesion. Within these subgroups we assessed the sensitivity of A-β primary afferents to weak electrical currents applied bilaterally to regions innervated by 3 peripheral branches of the trigeminal nerve. The ratio of electrical detection thresholds from the affected and the unaffected side was calculated. Electrical detection threshold ratios were contrasted with the results of physical examination, radiographic imaging, and biopsy. Results. For dermatomes containing the lesions, ratios were lower than 0.8 in 12 patients. Biopsy showed that the lesions in 10 of these 12 patients were malignant. No malignancy was found in the remaining 11 patients. Conclusions. A-β primary afferent hypersensitivity is observed to occur in nerves exposed to soft tissue oral malignancy.