Mental nerve neuropathy: patient characteristics and neurosensory changes

The objective of this study was to analyze the etiological factors and neurosensory signatures of patients attending with a primary complaint of numb chin.

Charts of 27 patients referred to Hadassah School of Dental Medicine, Jerusalem, Israel, with a complaint of unilateral numbness or paresthesias of the chin were reviewed. Demographic and etiologic data and special tests, including imaging, that were prescribed as necessary for the treatment protocol were evaluated. The neurosensory evaluation protocol included assessment of detection thresholds to electrical stimulation (assessing large myelinated nerve fibers) and heat (assessing thin unmyelinated nerve fibers) in the mental and infraorbital nerves regions bilaterally. Data from 8 healthy, age and sex-matched subjects who underwent similar sensory testing served as the control group.

Invasive dental procedures (eg, extractions, implants) were the etiologic factor in 63% of the cases. Inflammatory pathoses (15%) (eg, periapical periodontitis or infection), and malignant lesions (22%) were identified as causative in the remaining patients. Frank nerve injury due to advanced malignant processes was characterized by significantly elevated heat and electrical thresholds (hyposensitivity). Inflammatory process was accompanied by reduced electrical detection thresholds (hypersensitivity).

This study concurs with previous studies that sensory hyposensitivity accompanies nerve damage. Accordingly, quantitative sensory testing may contribute to the diagnostic process of patients with mental nerve neuropathy. In this sample of patients, the most common cause for mental nerve neuropathy was dental treatment followed by malignant metastasis.