Spontaneous Osteonecrosis of the Jaw During Bisphosphonate Therapy: An Unusual Etiology of the Numb Chin Syndrome.

The numb chin syndrome is a rare manifestation of intractable pain in the palliative care setting and represents a major therapeutic challenge. The reported etiologies of the numb chin syndrome include trauma, infections, immune-mediated systemic conditions, and malignancy, both through local infiltration or compression of the inferior alveolar nerve sheath. The authors present the case of a patient with long-standing multiple myeloma, suffering from numb chin syndrome caused by a spontaneous osteonecrosis of the jaw after bisphosphonate therapy. Intractable unilateral orofacial pain over the right chin and lower lip with associated numbness and paresthesia in the distribution area of the mental nerve were the clinical features. A complex pharmacological therapy, including methadone, carbamazepine, and dexamethasone was started, with insufficient pain control. In consideration of the prevalent neuropathic etiology, the authors opted for a locoregional nerve block of the mandibular nerve with bupivacaine and clonidine. The interdisciplinary approach was successful, and the patient was discharged with satisfactory pain control. The purpose of this report is to demonstrate the complexity of the therapeutic approach, which may include pharmacological measures and interventional procedures to improve symptom management in this challenging clinical condition.