What is the differential diagnosis for trigeminal nerve (TN) neuralgia?

Differential Diagnosis of Trigeminal Neuralgia

When evaluating a patient with suspected trigeminal neuralgia, systematically distinguish it from other neuropathic facial pain conditions, trigeminal autonomic cephalgias, vascular disorders, and post-traumatic pain syndromes using specific clinical features, timing patterns, and associated symptoms. 1

Primary Neuralgic Conditions

Glossopharyngeal Neuralgia

• Location: Unilateral deep in the ear and/or back of tongue, tonsils, neck—not the typical V2/V3 distribution of TN 1
• Pain quality: Sharp, shooting, electric shock-like, identical to TN but different location 1
• Key distinguishing triggers: Swallowing, coughing, touching the ear (versus light facial touch in TN) 1
• Unique feature: Syncope may be provoked during attacks, which never occurs in TN 1
• Timing: Paroxysmal attacks lasting 2 seconds to minutes with refractory periods, identical pattern to TN 1

Trigeminal Autonomic Cephalgias (SUNCT/SUNA)

• Critical distinguishing feature: Prominent autonomic symptoms including tearing, conjunctival injection, rhinorrhea, nasal blockage, facial redness, and ear fullness 1, 2
• Attack frequency: Up to 200 attacks daily with no refractory period between attacks (versus mandatory refractory periods in TN) 1, 2
• Duration: Rapid attacks lasting seconds to several minutes 1
• Distribution: Mainly first and second trigeminal divisions 1
• Triggers: Mostly spontaneous, some light touch evoked 1
• Imaging: Requires MRI including pituitary fossa evaluation 1

Post-Infectious and Post-Traumatic Conditions

Post-Herpetic Neuralgia

• Timing: Continuous pain (not paroxysmal) at the site of previous herpes zoster eruption 1
• Pain quality: Burning, tingling, itchy, tender—can be sharp at times but lacks the pure electric shock quality of TN 1
• Key features: Allodynia and hyperalgesia in the affected dermatome 1
• History: Clear preceding herpes zoster rash 1

Post-Traumatic Trigeminal Neuropathic Pain

• Timing: Continuous pain developing within 3-6 months of trauma or dental procedure 1
• Pain quality: Burning, tingling, can be sharp—but continuous rather than paroxysmal 1
• History: Clear history of dental procedure (root canal, extraction, implant) or facial trauma, often with poor analgesia at the time 1
• Examination: Allodynia or other sensory changes, qualitative sensory testing abnormalities 1

Dental-Related Pain Syndromes

Atypical Odontalgia (Persistent Dentoalveolar Pain)

• Location: Localized to tooth or tooth-bearing area 1
• Timing: Continuous pain (not paroxysmal attacks) 1
• Pain quality: Aching, dull, throbbing, sometimes sharp—lacks the lancinating quality of TN 1
• Severity: Mild to moderate (versus moderate to very severe in TN) 1
• Examination: May show hyperesthesia in the area 1
• Critical diagnostic step: Intraoral X-rays must show no dental pathology 1

Burning Mouth Syndrome

• Location: Tongue (especially tip), lips, palate, buccal mucosa—typically bilateral 1
• Timing: Continuous in most instances 1
• Pain quality: Burning, stinging, itchy, sore—completely different from TN's electric shock quality 1
• Associated features: Dry mouth, abnormal taste, depression, poor quality of life 1
• Demographics: Predominantly peri- and post-menopausal women 1
• Examination: Oral mucosa appears completely normal 1

Vascular and Inflammatory Conditions

Giant Cell Arteritis (Temporal Arteritis)

• Age: Consider urgently in patients over 50 years 3, 4
• Pain quality: Continuous, dull, aching in temporal region and jaw—not paroxysmal 1, 3
• Key trigger: Jaw claudication with chewing 1, 3
• Associated features: Visual disturbances, malaise, fever, myalgia, scalp tenderness, absent temporal pulse 1, 3
• Laboratory: Markedly elevated ESR and CRP 1, 3
• Critical action: Requires immediate high-dose corticosteroids (minimum 40 mg daily) to prevent blindness, with temporal artery biopsy within 2 weeks 1, 3

Central Pain Syndromes

Post-Stroke Pain

• Location: Ipsilateral to stroke 1, 2
• Timing: Continuous pain with sudden onset 1
• Pain quality: Aching, burning with dysesthesia—not lancinating 1, 2
• Examination: Sensory disturbances present 1
• Imaging: CT or MRI shows stroke 1

Persistent Idiopathic Facial Pain (Atypical Facial Pain)

• Location: Non-anatomical distribution, can be extraoral and intraoral 1, 2, 4
• Timing: Continuous but may have days without pain 1
• Pain quality: Dull, aching—lacks the characteristic sharp quality of TN 1
• Triggers: Fatigue, stress, significant life events 1
• Key distinguishing feature: No paroxysmal attacks, no characteristic triggers, widespread pain distribution 1, 2

Secondary Causes Requiring Imaging

Multiple Sclerosis

• Presentation: Can cause secondary TN with identical pain characteristics 2, 5, 6
• Key difference: May have continuous pain between attacks (Type 2 TN) 2
• Imaging: MRI shows demyelinating plaques 2, 5
• Demographics: Younger age of onset than classical TN 5

Space-Occupying Lesions

• Presentation: Tumors affecting the trigeminal nerve can mimic TN 5, 6
• Red flags: Sensory changes on examination, continuous pain component, progressive symptoms 1, 2
• Imaging: MRI with and without contrast is mandatory for all suspected TN patients to rule out tumors 2, 6

Diagnostic Algorithm

Step 1: Characterize pain timing

• Paroxysmal (seconds to minutes) with refractory periods → Consider TN, glossopharyngeal neuralgia 1
• Paroxysmal without refractory periods → Consider SUNCT/SUNA 1, 2
• Continuous → Consider post-herpetic neuralgia, post-traumatic pain, atypical odontalgia, persistent idiopathic facial pain, post-stroke pain 1

Step 2: Assess for autonomic features

• Present (tearing, eye redness, rhinorrhea) → SUNCT/SUNA, not TN 1, 2
• Absent → Proceed to Step 3 1

Step 3: Identify pain distribution

• V2/V3 trigeminal divisions → TN most likely 1
• Deep ear/throat/tonsil → Glossopharyngeal neuralgia 1
• Tooth-bearing area only → Atypical odontalgia 1
• Bilateral oral mucosa → Burning mouth syndrome 1
• Temporal region → Giant cell arteritis if age >50 1, 3

Step 4: Evaluate triggers

• Light touch, washing, cold wind, eating, brushing → TN 1
• Swallowing, coughing → Glossopharyngeal neuralgia 1
• Chewing with jaw claudication → Giant cell arteritis 1, 3

Step 5: Check for red flags requiring urgent action

• Age >50 with temporal pain, visual symptoms, elevated ESR → Start corticosteroids immediately for suspected giant cell arteritis 1, 3
• Sensory changes on examination → Order MRI to rule out secondary causes 1, 2, 6
• History of stroke → Consider post-stroke pain 1
• History of herpes zoster → Post-herpetic neuralgia 1

Step 6: Obtain MRI for all suspected TN cases

• MRI with and without contrast is mandatory to distinguish classical TN (neurovascular compression), secondary TN (MS, tumor), and idiopathic TN 2, 6, 7
• Include pituitary fossa views if SUNCT/SUNA suspected 1