Trigeminal Neuralgia

1. See Also
   1. Trigeminal Nerve
2. Epidemiology
   1. Incidence: 15,000 new cases per year in U.S. (4.3 cases per 100,000 per year)
      1. Primary care physicians may see a few cases during their entire practice career
      2. Incidence in Multiple Sclerosis patients: 1-2%
   2. Onset after age 40 years (peaks at age 60 to 70 years)
   3. More common in women by ratio of 2:1
3. Pathophysiology
   1. Related to Trigeminal Nerve demyelination
      1. Demyelination due to compression from local structures (esp. Superior Cerebellar Artery)
      2. Demyelinated fibers are more prone to ephaptic conduction
         1. Light touch impulses transmit to nearby pain fibers
   2. Most common site at cerebellopontine nerve root area
   3. Effects all branches of the Trigeminal Nerve (Right side is more commonly involved)
      1. Maxillary branch is most commonly involved
      2. Ophthalmic branch is least commonly involved
4. Symptoms
   1. Facial pain in Trigeminal Nerve distribution
      1. Recurrent paroxysms of sharp, lancinating pain
   2. Distribution
      1. Maxillary and mandibular branches of the Trigeminal Nerve are most commonly affected
      2. Each attack is unilateral (may alternate sides in up to 3-5% of cases)
   3. Characteristics
      1. Lancinating or stabbing pain
      2. Electric shock type pain
      3. Facial spasms related to paroxysms of pain (Tic Douloureux)
   4. Timing
      1. Attacks may occur as often as multiple times daily or as infrequently as monthly
      2. Attacks become more frequent and severe over time
      3. Attacks are rare during sleep
   5. Triggers
      1. Washing face
      2. Tooth brushing
      3. Cold exposure
      4. Chewing
      5. Trigger Zones (pathognomonic for Trigeminal Neuralgia)
         1. Small areas in the region of the nose and mouth
         2. Light touch or other minimal stimulation in these zones triggers an attack
5. History: Red Flags suggesting secondary cause or alternative diagnosis
   1. Abnormal findings on Neurologic Examination or on examination of head and neck
   2. Age under 40 years old
   3. Pain lasts longer than 2 minutes
   4. Bilateral pain during a single attack
   5. Vision change, hearing change or Vertigo
   6. Findings suggestive of Multiple Sclerosis (e.g. ataxia, unilateral vision change)
      1. Multiple Sclerosis is often comorbid with Trigeminal Neuralgia
6. Examination
   1. Evaluate for focal findings suggestive of a secondary cause or alternative diagnosis
   2. Specific focal areas of examination (abnormalities suggest alternative diagnosis)
      1. Temporomandibular Joint
      2. Facial muscle strength and symmetry
      3. Corneal reflex
      4. Trigeminal Nerve sensation (normal in Trigeminal Neuralgia)
         1. Trigger zone presence is pathognomonic for Trigeminal Neuralgia (see above)
7. Diagnosis: Classical Trigeminal Neuralgia (Primary Trigeminal Neuralgia)
   1. Paroxysmal attacks localized to the Trigeminal Nerve
   2. Duration less than 2 minutes
   3. Characteristics (at least one must be present)
      1. Precipitated by triggers (e.g. trigger zones)
      2. Sharp, stabbing, intense pain
   4. Attacks are stereotypical for individual patients
   5. No neurologic clinical findings or other findings suggesting as secondary condition
8. Diagnosis: Symptomatic Trigeminal Neuralgia (Secondary to other conditions)
   1. Similar to classical Trigeminal Neuralgia with the following EXCEPTIONS
      1. Aching pain may persist between episodes
      2. Secondary cause is identified (other than vascular compression)
9. Differential Diagnosis
   1. Cluster Headache or other Migraine Headache
   2. Postherpetic Neuralgia
   3. Glossopharyngeal Neuralgia
   4. Dental infection or Dental Caries
   5. Temporomandibular Joint Syndrome
   6. Acoustic Neuroma
   7. Multiple Sclerosis (may be comorbid)
   8. Vascular malformation
10. Imaging
    1. Head MRI Indications
       1. Indicated in most cases of Trigeminal Neuralgia at onset
11. Diagnostics
    1. Trigeminal reflex testing (via EMG testing)
       1. Differentiates classic from symptomatic Trigeminal Neuralgia with high efficacy
       2. Cruccu (2006) Neurology 66:139-41
12. Management: Seizure medications (examples)
    1. Carbamazepine (Most studied)
       1. Typical effective dosage: 200-800 mg/day divided bid to tid
    2. Baclofen (Lioresal)
       1. Typical effective doses: 10-80 mg/day
    3. Phenytoin (Dilantin)
    4. Gabapentin (Neurontin)
    5. Topiramate (Topamax)
    6. Delzell (1999) Arch Fam Med 8(3): 264-8
13. Management: Symptomatic therapies
    1. Topical Capsaicin
    2. Intranasal Lidocaine (for second Trigeminal Nerve branch)
    3. Acupuncture is ineffective in Trigeminal Neuralgia
       1. Millan-Guerrero (2006) Headache 46(3): 532
14. Management: Surgical
    1. Percutaneous Methods (non-invasive but short lasting)
       1. Glycerol injection
       2. Radiofrequency thermocoagulation
       3. Gamma Knife
       4. Oturai (1996) Clin J Pain 12(4):311-5
    2. Invasive Surgical Techniques (posterior fossa exploration)
       1. Microvascular decompression (Most effective, duration of 10 years in 70% of cases)
       2. Hai (2006) Neurol India 54(1):53-6
       3. Tronnier (2001) Neurosurgery 48(6): 1261-8
15. References
    1. Krafft (2008) Am Fam Physician 77(9):1291-6
    2. Kumar (1998) Postgrad Med 104(4):149-56
    3. Scrivani (2005) Oral Surg Oral Med Oral Pathol Oral Radiol Endod 100(5):527-38