Diagnostic Considerations
Other causes of facial pain than trigeminal neuralgia (TN) are excluded by history, physical examination, and special investigations (when necessary). In symptomatic cases, a persistence of aching can occur between paroxysms, as well as signs of sensory impairment in the trigeminal division. Then, a cause is demonstrated by appropriate investigation.
Migraine, cluster headaches, and atypical face pain
Migraine and cluster headaches may produce severe unilateral pain, but unlike trigeminal neuralgia, these conditions are not triggered by movement or contact with the face nor do they respond promptly to carbamazepine. See Table 1, below.
Table 1. Characteristic Features of 3 Common Craniofacial Pains (Open Table in a new window)
Condition |
Male:Female Ratio |
Age of onset, y |
Localization |
Accompanying Symptoms |
Attack Duration |
Cycles |
Provocation |
Trigeminal neuralgia |
1:2 |
>50 |
Unilateral |
None |
Seconds |
Month intervals |
Trigger zones |
Cluster headache |
1:6-9 |
30-40 |
Always unilateral |
Horner syndrome, conjunctival injection, epiphora |
15-180 minutes |
Clusters with weeks to months intervals |
Nocturnal attacks |
Migraine |
1:1 |
10-20 |
Variable |
Photophobia, phonophobia, gastrointestinal symptoms |
4-72 hours |
Days to weeks intervals |
Variable |
According to Turp and Gobetti, atypical face pain usually extends beyond the distribution of the fifth cranial nerve, is rarely triggered, and presents with a steady unrelenting discomfort lasting hours to days. [19] See Table 2, below.
In persistent idiopathic facial pain, psychiatric disturbances are associated with pain that is of vague localization and long duration (usually chronic and daily). In Raeder syndrome (paratrigeminal neuralgia), ophthalmoparesis is present. In current practice, Raeder syndrome is believed to essentially be carotid dissection. Tolosa-Hunt syndrome (ophthalmoplegia) presents with pain of longer duration but that is not triggerable; cranial nerve deficits are observed. Short-lasting, unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) present with pain of longer duration (2-3 min) and associated prominent autonomic symptoms (eg, lacrimation, rhinorrhea). [20]
Temporomandibular joint pain and dental problems in the evaluation of trigeminal neuralgia.
Table 2. Distinguishing Features Between Trigeminal Neuralgia and Atypical Facial Pain (Open Table in a new window)
Feature |
Trigeminal Neuralgia |
Atypical Facial Pain |
Prevalence |
Rare |
Common |
Main location |
Trigeminal area |
Face, neck, ear |
Pain duration |
Seconds to 2 minutes |
Hours to days |
Character |
Electric jerks, stabbing |
Throbbing, dull |
Pain intensity |
Severe |
Mild to moderate |
Provoking factors |
Light touch, washing, shaving, eating, talking |
Stress, cold |
Associated symptoms |
None |
Sensory abnormalities |
Glossopharyngeal neuralgia and occipital neuralgia syndromes
Other syndromes with paroxysmal lancinating head pain include the less common glossopharyngeal neuralgia and occipital neuralgia syndromes.
Glossopharyngeal neuralgia causes pain in the tonsillar fossa, posterior pharynx, and ear and may be initiated by coughing, yawning, or swallowing cold liquids. During acute attacks of this condition, which is frequently associated with an underlying pathology, the patient may be unable to speak and tries to avoid moving the lips or tongue. An involuntary startle during an attempt to touch the affected side of the face is diagnostic.
Occipital neuralgia causes pain in the posterior head region. Thus, the distribution easily distinguishes it from trigeminal neuralgia. Confusion arises only if the patient cannot provide a clear history.
Paroxysmal hemicrania syndromes
According to Goadsby and Lipton, similar to trigeminal neuralgia, paroxysmal hemicrania syndromes typically last only seconds, however, the latter syndromes occur in and around 1 eye. [21] Intense unilateral conjunctival injection and lacrimation signal an autonomic component, which further distinguishes paroxysmal hemicrania syndromes. Another feature is that paroxysmal hemicrania syndromes do not respond to carbamazepine.
Secondary vs idiopathic trigeminal neuralgia
Symptomatic or secondary trigeminal neuralgia is a more likely consideration than the idiopathic form when pain is associated with hyperesthesia along the course of the fifth nerve or is observed with other cranial neuropathies. Further, consider secondary trigeminal neuralgia in patients with bilateral sensory loss or weakness of the facial muscles or jaw.
Additional investigation may reveal multiple sclerosis (MS), a tumor in the posterior fossa, or a tumor on the trigeminal nerve.
Acoustic neuromas, cerebral aneurysms, trigeminal neuromas, and meningiomas can produce syndromes similar to idiopathic trigeminal neuralgia. Consider these conditions in patients with onset of pain when younger than 40 years, those with predominant forehead and/or orbit pain (ie, first division of the trigeminal nerve), or those with bilateral facial pain. Also consider granulomatous inflammation (eg, tuberculosis, sarcoidosis, Behçet syndrome, collagen vascular diseases) and other vasculitides, as these may affect the trigeminal nerve and simulate trigeminal neuralgia.
Patients with prominent hemifacial spasm, especially if it is continuous, may have tic convulsif, a condition associated with a dilated and ectatic basilar artery or other vascular malformation compressing the trigeminal nerve.
Brain magnetic resonance imaging (MRI) with and without contrast is critical in diagnosing the secondary causes of trigeminal neuralgia.
Failure to properly assess for secondary trigeminal neuralgia is a major potential pitfall. A careful examination of the cranial nerves and an MRI of the brain, especially in an individual who develops the disorder when younger than 60 years, should protect against missing structural lesions (eg, tumor, cerebral aneurysm, acoustic neuroma).
Trigeminal neuropathy and atypical trigeminal neuralgia
Trigeminal neuropathy is also a consideration in the evaluation of trigeminal neuralgia. This condition presents as a constant, unilateral, often mild facial pain with prominent sensory loss. It is nontriggerable and unremitting, and it may be either symptomatic or idiopathic. By contrast, as previously discussed, idiopathic trigeminal neuralgia presents as episodic, unilateral, lancinating, triggerable, often shocklike facial pain with pain-free intervals.
To further complicate diagnostic matters, the clinician may encounter atypical trigeminal neuralgia, a syndrome that overlaps trigeminal neuralgia and trigeminal neuropathy. This syndrome consists of constant pain that episodically intensifies. According to Burcheil, these patients experience both lancinating triggered pain and a baseline, constant, dull, and throbbing discomfort. [2] The atypical form may occur in up to 5% of people after facial surgery or significant trauma and in 1-5% after the removal of impacted teeth. In the experience of many neurosurgeons, atypical trigeminal neuralgic pain results from lesions or injuries of the trigeminal nerve root distal to the route entry zone but with even greater compression than found in the idiopathic form of trigeminal neuralgia.
In contrast to trigeminal neuropathy, whether typical or atypical, atypical facial pain is distinguished by the extension of discomfort beyond the distribution of the fifth cranial nerve and by the frequent lack of lancinating pain and triggers.
Multiple sclerosis
As discussed in the Clinical section, rarely, multiple sclerosis (MS) presents with trigeminal neuralgia. Consider multiple sclerosis in the diagnostic evaluation of individuals who display other features of this demyelinating disorder.
Herpetic and postherpetic neuralgia
Herpetic and postherpetic neuralgia (PHN) usually affects the first branch of the trigeminal nerve. The diagnosis of postherpetic neuralgia usually requires the outbreak of shingles (herpes zoster) in the forehead or eye. Acute herpetic neuralgia is the norm in shingles, but pain that persists after the lesions have healed is postherpetic neuralgia. The risk of development of postherpetic neuralgia is directly related to patient age.
Differential Diagnoses
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Illustration depicting the trigeminal nerve with its 3 main branches
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Microscopic demonstration of demyelination in primary trigeminal neuralgia. A tortuous axon is surrounded by abnormally discontinuous myelin. (Electron microscope; 3300×).
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Magnetic resonance image (MRI) with high resolution on the pons demonstrating the trigeminal nerve root. In this case, the patient with trigeminal neuralgia has undergone gamma-knife therapy, and the left-sided treated nerve (arrow) is enhanced by gadolinium.
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Microvascular decompression (Jannetta procedure) used to treat trigeminal neuralgia. The anteroinferior cerebellar artery and the trigeminal nerve are in direct contact. Courtesy of PT Dang, CH Luxembourg
Tables
Condition |
Male:Female Ratio |
Age of onset, y |
Localization |
Accompanying Symptoms |
Attack Duration |
Cycles |
Provocation |
Trigeminal neuralgia |
1:2 |
>50 |
Unilateral |
None |
Seconds |
Month intervals |
Trigger zones |
Cluster headache |
1:6-9 |
30-40 |
Always unilateral |
Horner syndrome, conjunctival injection, epiphora |
15-180 minutes |
Clusters with weeks to months intervals |
Nocturnal attacks |
Migraine |
1:1 |
10-20 |
Variable |
Photophobia, phonophobia, gastrointestinal symptoms |
4-72 hours |
Days to weeks intervals |
Variable |
Feature |
Trigeminal Neuralgia |
Atypical Facial Pain |
Prevalence |
Rare |
Common |
Main location |
Trigeminal area |
Face, neck, ear |
Pain duration |
Seconds to 2 minutes |
Hours to days |
Character |
Electric jerks, stabbing |
Throbbing, dull |
Pain intensity |
Severe |
Mild to moderate |
Provoking factors |
Light touch, washing, shaving, eating, talking |
Stress, cold |
Associated symptoms |
None |
Sensory abnormalities |
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