Case of the Month #36: Facial pain by Dr Ameana Khan & Dr Shefali Kadambande

• What are the potential differentials for unilateral facial pain?

Differential diagnoses include cluster headache, trigeminal autonomic cephalalgia¹, trigeminal neuralgia,  temporomandibular joint disorders, persistent idiopathic facial pain, painful trigeminal neuropathy, short-lasting unilateral neuralgia headache with conjunctival injection and tearing, giant cell arteritis, glossopharyngeal neuralgia², dental issues like cracked teeth or abscesses, tumours such as acoustic neuromas or meningiomas. Other neuralgias such as, post-herpetic neuralgia, atypical facial pain, sinus or ear infection³.

• What red flag symptoms should be considered when taking a patient's history?

Urgent assessment is required if there are sensory changes, ear problems or deafness, a history of skin or oral lesions with perineural spread potential, pain isolated to the ophthalmic division of the trigeminal nerve (TN), optic neuritis, a family history of multiple sclerosis, and onset before the age of 40².

• How does trigeminal neuralgia (TN) differ from other facial pains in terms of characteristics?

Trigeminal Neuralgia (TN) is characterised by severe intensity, sharp, shooting, electric shock-like pain that is short-lived, recurrent, and episodic, lasting from seconds to minutes. It is generally unilateral (3% bilateral)² and manifests as facial pain in the distribution(s) of one or more divisions of the trigeminal nerve, with no radiation beyond. TN is triggered by innocuous stimuli or specific facial/oral movements, often involving confined trigger zones. Autonomic features such as lacrimation, nasal congestion, conjunctival injection, ptosis, facial sweating, and eyelid oedema may accompany attacks. Importantly, TN lacks clinically evident neurological deficits and is not attributed to another disorder³.

• What are the classifications for Trigeminal Neuralgia (TN) in accordance to International Classification of Headache Disorders International Classification of Headache Disorders (ICHD)?

The ICHD classification system delineates the etiological basis of Trigeminal Neuralgia (TN) into three distinct categories:

1. Classical TN: Characterised by neurovascular compression, discernible through MRI or intraoperative findings, leading to root atrophy or displacement.
2. Idiopathic TN: Manifests without significant compression, allowing for simple contact without inducing changes in the nerve root.
3. Secondary TN: Occurs due to an underlying cause other than vascular compression, as evidenced by conditions such as tumours in the cerebellopontine angle or multiple sclerosis.

It is noteworthy that concurrent continuous pain may be associated with all three types of TN¹.