The "numb chin syndrome": A case report

Numb chin syndrome: What all oral health care professionals should know

BACKGROUND

Numb chin syndrome (NCS) is a rare sensory neuropathy involving the mental nerve. Symptoms of NCS are often overlooked because of their apparent innocent nature; however, owing to the frequent association of NCS with malignancies, the opposite should be the rule. Oral health care professionals may be the first to encounter patients with NCS and should be aware of its clinical characteristics in an effort to decrease patient morbidity and mortality.

TYPES OF STUDIES REVIEWED

A search in PubMed (MEDLINE) and the Cochrane Library was performed using the terms numb chin syndrome, numb chin, mental neuropathy, mental nerve neuropathy, and malignant mental nerve neuropathy, yielding 2,374 studies. After inclusion and exclusion criteria were applied, 102 studies remained. Descriptive statistics were performed, analyzing the etiology responsible for NCS, characteristics of NCS including associated symptoms, unilateral or bilateral nature, and information on professionals visited and examinations requested to make a diagnosis.

RESULTS

NCS was associated with malignancy in 29% through 53% of the published cases. Twenty-eight percent of patients initially consulted an oral health care professional with the symptom of a numb chin. Patients more likely to have NCS were those from the ages of 61 through 70 years; 74% were unilateral; and the most common symptoms reported were numbness (100%), paresthesia (18%), and pain (17%). Forty-seven percent of the NCS cases were associated with a recurrent malignancy, and the most prevalent associated diagnoses were breast cancer (32%) and lymphoma and leukemia (24%).

CONCLUSIONS

Oral health care professionals should be aware of the characteristics of NCS as they may be the first health care providers consulted for these symptoms.

PRACTICAL IMPLICATIONS

A thorough medical and dental history as well as a complete cranial nerve screening should be performed on all patients, especially those with numbness, as this may prevent misdiagnosis and allow a timely referral and a substantial improvement of treatment course and prognosis.

A Case of Secondary Trigeminal Neuropathy Due to Local Malignant Invasion of the Maxillary and Mandibular Nerves at the Skull Base: A Case Report With Review of Differential Diagnosis

Trigeminal neuropathies (TNp) are a group of well-characterized disorders that involve damage to or infiltration of the trigeminal nerve. The underlying etiology of trigeminal neuropathy can be traumatic, inflammatory, autoimmune, paraneoplastic, malignant, and very rarely infectious. We present a case of trigeminal neuropathy due to local malignant invasion of the mandibular nerve with mandibular nerve enhancement at the foramen ovale and foramen rotundum. In the process, we review various etiologies of trigeminal neuropathy associated with trigeminal nerve involvement at the foramina. We emphasize the importance of a comprehensive evaluation in patients with trigeminal neuropathy, which includes searching for perineural spread or invasion by a local head and neck malignancy, as well as ruling out an inflammatory or autoimmune etiology. Our case also demonstrates that a higher field strength magnet can reveal pathology unseen with a lower field strength magnet.