Numb Chin Syndrome

• Numbness/decreased sensation of the chin and lower lip
• Easily underemphasised by clinicians and patients
• Caused by a wide range of differentials - some associated with significant morbidity and mortality

Epidemiology

• Epidemiology
• ♀ > < = ♂

Clinical Features

• Clinical features

Differential Diagnosis

• Differential Diagnosis

Aetiology and Pathogenesis

Pathophysiology

• Can occur from a lesion anywhere along the course of the trigeminal nerve (including as proximal as trigeminal ganglion and pons)
• Lesions can be divided into:
  1. Peripheral lesions - involving mandible, direct nerve infiltration , inflammation or compression
  2. Central lesions - involving the base of skull, leptomeninges, or brainstem
• Malignancy associated cases can occur through the following mechanisms:
  1. Direct infiltration of the nerve (head and neck primary or metastasis from distant site to mandible)
  2. Leptomeningeal seeding
     • May have no obvious mass in the mandible or skull base
     • These cases are thought to be due to leptomeningeal seeding
  3. Cervical lymphadenopathy
     • Cervical lymphadenopathy in the deeper upper cervical region - can exert pressure on the inferior alveolar nerve just before it enters the mandibular foramen

There have In addition, some cases of NCS may be a paraneoplastic process, with antibodies directed against a yet-unknown antigen in the nervous system. In support of this, a case of buccal neuropathy ("numb cheek" syndrome) was associated with the anti-Hu antibody [11]. Pathogenesis remains uncertain, however, as the patient went on to be diagnosed with small cell lung cancer four months later.

• Aetiology and pathogenesis

Management

• Management

Prognosis and Complications

• Prognosis and Complications

Follow-up

• Follow-up

References

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