Herald facial numbness

Numbness matters: a clinical review of trigeminal neuropathy

AIM

Trigeminal neuropathies are a group of clinical disorders that involve injury to primary first-order neurons within the trigeminal nerve. We review the spectrum of etiologies underlying both painful and non-painful trigeminal neuropathies, with attention to particularly dangerous processes that may elude the clinician in the absence of a meticulous evaluation. Complications and management issues specific to patients with trigeminal neuropathy are discussed.

METHODS

Retrospective literature review.

RESULTS

Facial or intraoral numbness, the hallmark of trigeminal neuropathy, may represent the earliest symptomology of malignancy or autoimmune connective tissue disease as sensory neurons are destroyed. Such numbness, especially if progressive, necessitates periodic evaluation and vigilance even years after presentation if no diagnosis can be made.

CONCLUSIONS

In the routine evaluation of patients with facial pain, the clinician will inevitably be confronted with secondary pathology of the trigeminal nerves and nuclei. The appearance of numbness, even when pain continues to be the most pressing complaint, necessitates clinical assessment of the integrity of all aspects of the trigeminal pathways, which may also include neurophysiologic, radiographic, and laboratory evaluation.

Numb chin syndrome: an ominous clinical sign

Numb chin syndrome (NCS) is a rare but important clinical symptom and sign. It describes a condition presenting as anaesthesia or paraesthesia over the chin, which is usually unilateral. The condition manifests spontaneously with no history of trauma, infection or obvious odontogenic cause. NCS is a clinically important finding as it may be the primary manifestation of Multiple Sclerosis (MS) or sign of systemic malignancy. We present a case of a 58-year-old gentleman who was referred to a regional oral and maxillofacial unit with a three-month history of sudden onset unilateral numbness of the chin. No odontogenic cause could be found and subsequent CT/PET scan from the cerebellum to the upper thighs revealed evidence of widespread metastatic disease. The patient died five weeks after his initial presentation. We discuss the importance of this clinical symptom, the likely mechanism of disease and offer differential diagnoses. Additionally, we recommend that patients presenting to their general dental practitioner with a numb chin be urgently investigated for a potentially undiagnosed malignancy or MS and be referred to their local oral and maxillofacial unit as an urgent 'target' referral.

Trigeminal neuropathy

Trigeminal neuropathies (TNs) are well recognized disorders characterized and manifesting as skin and mucosal numbness in the region innervated by the trigeminal nerve. Facial numbness indicates trigeminal sensory alteration affecting the trigeminal system. TNs always pose differential location difficulties as multiple diseases are capable of producing them: they can be the result of traumatism, tumors, or diseases of the connective tissue, infectious or demyelinating diseases, or may be of idiopathic origin. Their importance is explained by the fact that TN may represent the first manifestation of tumor disease, or of relapse in patients with prior neoplastic processes. As such, these manifestations are ominous, and patient life expectancy is often short. The clinical exploration reveals a loss of sensitivity in the cutaneous territory corresponding to the affected nerve, which can be partial (hypoesthesia) or complete (anesthesia). The sensory defect is occasionally associated with hyperesthesia (i.e., the patient suffers a decrease in sensory perception, but when sensation is perceived, it may cause considerable discomfort). Complementary studies are needed to establish the etiologic diagnosis, with laboratory tests to discard the possible causative diseases underlying the trigeminal neuropathy, and the opportune radiographic examinations in the form of plain X-rays or a routine cranial computed tomography scan.

The trigeminal nerve

The trigeminal nerve is the largest of the cranial nerves, serving as a major conduit for sensory information from the head and neck and primarily providing motor innervation to the muscles of mastication. An understanding of the pathologic processes that may involve this nerve requires a detailed knowledge of its origin within the brain stem as well as its course intracranially. This article describes the neuroanatomy of the nerve and divides it into its various segments to provide a differential diagnosis of common and some uncommon pathologic processes.

Mental neuropathy: report of five cases and review of the literature

Mental nerve neuropathy, also referred to as numb chin syndrome, is a rare, seemingly harmless symptom. It is more often associated with cancer, either as first symptom or during the outcome, than with benign diseases. In this review, we will focus on the numb chin syndrome presenting as an isolated neurological symptom. We report five patients with mental nerve neuropathy associated with metastatic disease (small cell lung cancer, prostatic cancer and breast cancer). In one patient, numb chin syndrome preceded the discovery of the disease, while, in the four others, it occurred as a sign of relapse or progression. Isolated mental nerve neuropathy, frequently associated with breast cancer and lymphoproliferative diseases, is generally thought to be the consequence of bone metastases or leptomeningeal seeding, but may also present without an obvious cause, most often secondary to the involvement of the mental nerve itself. Although various therapies may lead to the resolution of this symptom, median survival after diagnosis is generally less than 1 year. The appearance of a mental nerve neuropathy should never be considered as a 'banal' symptom and investigations to detect a possible cancer should be mandatory.