Numb Chin Syndrome

What is Numb Chin Syndrome (NCS) / Mental Nerve Neuropathy?

Numb Chin Syndrome (NCS), also known as mental nerve neuropathy, is characterised by facial and oral numbness, rarely pain, restricted to the distribution of the mental nerve of the inferior alveolar nerve.

Although NCS is most commonly associated with non-malignant disease states, it may be the presenting symptom of a systemic malignancy and its prompt recognition is essential for proper management. NCS is most commonly seen as a manifestation of local dental disease but it becomes clinically more significant when it is associated with neoplastic processes, particularly with breast cancer and malignant lymphomata, as any malignant metastasis to the head & neck region shows poor prognosis.

Dental causes, especially odont-iatrogenic ones (such as oral surgery), are by far the most common; if not related to those, this complaint is considered a “red flag” symptom of a distant malignant neoplasm.

When confronted with a possible diagnosis of NCS, clinical evaluation should include evaluation for occult malignancy or relapse of any known previous cancer.

Careful medical history is required to alert the clinician to appropriate diagnostic procedures and ensure correct management.

Distribution of Mental Nerve & Numbness associated with the Mental Nerve Neuropathy

The association of NCS with metastatic malignant disease has been called Roger’s sign.

Dentists need to be aware of the relationship between malignancies and paræsthesia or complete loss of sensation in a jaw segment.

In particular, dentists should be aware of NCS and its clinical manifestations, as well as the limitations of using panoramic radiographs to detect the causative malignancy.