Paresthesia of the Lower Lip:Delayed Complication of Radiotherapy to Nasopharynx

Paresthesia of the lower lip may develop following injury to the inferior alveolar nerve or mental nerve. The most common cause of lip paresthesia is iatrogenic where inadvertent injury takes place during surgery. Paresthesia may also develop as a result of pathology interfering with the integrity of nerve. While expanding benign lesions cause paresthesia by compression of the nerve, malignant lesions do so by invading the nerve tissue. Ionizing radiation may also cause damage to the nerves. The adverse effects of radiation therapy on oral health are well known with the most emphasis given to osteoradionecrosis. Our case is the first report that the inferior alveolar nerve or mental nerve is at risk of long term side effects of radiotherapy to the nasopharyngeal region.