How do you differentiate and treat trigeminal neuralgia vs temporal arteritis?

Differentiating and Treating Trigeminal Neuralgia vs Temporal Arteritis

Trigeminal neuralgia and temporal arteritis (giant cell arteritis) present with distinct clinical features that allow for differentiation, with trigeminal neuralgia requiring anticonvulsants like carbamazepine or oxcarbazepine as first-line treatment, while temporal arteritis demands urgent high-dose corticosteroid therapy to prevent vision loss. 1, 2

Key Differentiating Features

Trigeminal Neuralgia

• Pain Characteristics: Unilateral, paroxysmal attacks lasting seconds to minutes with refractory periods between attacks; sharp, shooting, electric shock-like pain 1, 2
• Location: Follows distribution of trigeminal nerve (most commonly second and third divisions) 1
• Triggers: Light touch, washing, cold wind, eating, brushing teeth 1, 3
• Associated Features: Rarely has sensory changes; no systemic symptoms; fear and depression may develop if severe 1
• Age: Can occur at any age but more common after 50 4

Temporal Arteritis (Giant Cell Arteritis)

• Pain Characteristics: Continuous, dull, aching pain in temporal region and jaw 1
• Location: Temporal region, scalp, jaw 1, 5
• Triggers: Often aggravated by chewing (jaw claudication) 1
• Associated Features: Scalp tenderness, visual disturbances, malaise, fever, myalgia, elevated ESR/CRP, absent temporal pulse 1
• Age: Almost exclusively affects patients over 50 years 5
• Critical Feature: Risk of permanent vision loss if untreated 1, 5

Diagnostic Approach

For Suspected Trigeminal Neuralgia

• Clinical Diagnosis: Based on characteristic paroxysmal pain pattern and triggers 1, 2
• Imaging: MRI recommended to evaluate the trigeminal nerve course and rule out secondary causes (tumors, multiple sclerosis) 1, 2
• Examination: Light touch may trigger pain; rarely shows sensory changes 1

For Suspected Temporal Arteritis

• Laboratory Tests: Obtain ESR and CRP (typically markedly elevated) 1, 5
• Biopsy: Temporal artery biopsy is recommended within 2 weeks of starting treatment 1
• Imaging: Consider temporal artery ultrasound if expertise available 1
• Physical Examination: Check for scalp tenderness, diminished temporal pulse, and visual acuity 1

Treatment Approaches

Trigeminal Neuralgia Treatment

1. First-Line Pharmacological Treatment:

   • Carbamazepine (gold standard) or oxcarbazepine (better side effect profile) 2, 3, 6
   • Start with low dose and titrate gradually to effective dose 3
   • Initial pain relief may occur within 24 hours in responders 3

2. Second-Line Pharmacological Options:

   • Gabapentin (often combined with ropivacaine) 3
   • Pregabalin 3
   • Lamotrigine 1, 3
   • Baclofen 3, 6

3. Surgical Interventions (when medications fail):

   • Microvascular decompression (MVD) - non-ablative procedure with 70% chance of being pain-free at 10 years 3
   • Ablative procedures: glycerol rhizotomy, balloon compression, Gamma Knife radiosurgery 3

Temporal Arteritis Treatment

1. Immediate Intervention:

   • High-dose corticosteroids (prednisone 1 mg/kg/day up to 80 mg) started immediately upon suspicion 1
   • Do not wait for biopsy results before starting treatment if clinical suspicion is high 1

2. Diagnostic Confirmation:

   • Temporal artery biopsy within 2 weeks of starting steroids 1
   • Long-segment biopsy specimen (>1 cm) preferred 1

3. Maintenance Therapy:

   • Gradual tapering of corticosteroids based on clinical response and normalization of inflammatory markers 1
   • Consider steroid-sparing agents in refractory cases 1

Common Pitfalls and Caveats

• Misdiagnosis: Trigeminal neuralgia can be confused with dental pain, leading to unnecessary dental procedures 1
• Overlap Syndrome: Rare cases of temporal arteritis and trigeminal neuralgia occurring simultaneously have been reported 7, 8
• Delayed Treatment: Delayed treatment of temporal arteritis can lead to permanent vision loss 1, 5
• Medication Failure: The antineuralgic effect of medications for trigeminal neuralgia may wear off over time, requiring combination therapy or surgical intervention 3, 6
• Age Consideration: In patients over 50 with new-onset facial pain in the temporal region, always consider temporal arteritis and check inflammatory markers 5

Treatment Algorithm

1. Assess pain characteristics and associated features

2. If paroxysmal, shock-like pain triggered by light touch: Suspect trigeminal neuralgia

   • Start carbamazepine or oxcarbazepine 2, 3
   • Obtain MRI to rule out secondary causes 1, 2
   • Consider surgical options if medical therapy fails 3

3. If continuous pain with systemic symptoms in patient >50 years: Suspect temporal arteritis

   • Check ESR and CRP immediately 1
   • Start high-dose corticosteroids without delay 1
   • Arrange temporal artery biopsy within 2 weeks 1
   • Monitor visual symptoms closely 1, 5