TOC  | ID |  Neurology

Trigeminal Neuralgia    REF:  ACP- PIER    http://pier.acponline.org/physicians/diseases/d625/d625.html?hp

H & P  |  Diff-Dx  |  Rx   

Diagnosis

Consider the diagnosis of trigeminal neuralgia (tic douloureux) in patients with unilateral face pain of an electric shock-like or shooting quality that lasts less than one minute, is paroxysmal with pain-free intervals, and is triggered by light touch.
Trigeminal neuralgia is the most common craniofacial pain syndrome of neuropathic origin.  The diagnosis remains based exclusively on history and symptomatology.  

History

1. Duration of pain
   • Seconds to minutes (trigeminal neuralgia)
   • 20 minutes to a few hours (migraine variants)
   • Continuous (atypical facial pain)
2. Quality of pain
   • Electric-like (trigeminal neuralgia)
   • Throbbing (migraine variants)
   • Gnawing, aching (atypical facial pain)
   • Crawling, itching, burning (dysesthetic pain)
3. Triggers of pain
   • Light touch, talking, or eating (trigeminal neuralgia)
   • Spontaneous (trigeminal neuralgia)
   • Coughing or swallowing (vagoglossopharyngeal neuralgia)
   • Light or sound (migraine variants)
   • Worsened by emotional stress (atypical facial pain)
   • Heat, coldness, or pressure on the teeth (dental pain)
4. Location of pain
   • Distributed trigeminally (usually second or third divisions), either alone or in combination (trigeminal neuralgia)
   • First division pain around the eye or forehead occurs in 10%-20% of patients (12015844), often with pain in other parts of the face, usually mid-cheek and upper lip or teeth (trigeminal neuralgia)
   • Usually unilateral (trigeminal neuralgia)
   • In 5%-10% of patients with trigeminal neuralgia only (3598670), and in 11%-20% of patients with trigeminal neuralgia and MS, pain sometimes is on the other side of the face but it is almost never simultaneously bilateral (trigeminal neuralgia)
   • Simultaneous bilateral face pain (atypical facial pain)
   • Distribution of the first division of the trigeminal nerve (postherpetic neuralgia)
   • Back of throat, front of neck, or deep in the ear (vagoglossopharyngeal neuralgia)
5. Frequency of pain
   • Often episodic; weeks or months of remission may be followed by similar periods of pain (trigeminal neuralgia)
6. Severity of pain
   • Varies from mild to severe (trigeminal neuralgia)
7. Refractory period of pain after stimulation of the trigger area (cannot elicit pain again by touching or pushing immediately after a painful attack)
   • Likelihood ratio: positive, 9.5%; negative, 0.05%
   • Highly predictive of trigeminal neuralgia; a person with this refractory period of pain is ~9 times more likely to have trigeminal neuralgia than irreversible plupitis
8. Rash
   • Skin vesicles suggest herpetic infection, which may result in postherpetic neuralgia
9. Nasal discharge
   • Foul odor may indicate sinus disease
10. Other neurologic symptoms
    • Numbness or weakness of arms or legs may be present with MS
    • Brief loss of vision in one eye may occur with optic neuritis and MS
    • Impaired balance may suggest MS or possibly a brain tumor
    • Decreased hearing or facial weakness on the side of face, pain may occur with a brain tumor, such as acoustic neurinoma

Physical Exam

1. Neurologic exam  
   • Usually normal (trigeminal neuralgia)
   • Noninvasive, quantitative somatosensory tests showed abnormalities in 15 of 26 patients with idiopathic trigeminal neuralgia
   • May have impaired sensation if previous surgery, MS (multiple sclerosis), viral (herpes zoster), or brain tumor
   • Weakness of arms or legs, imbalance, or incoordination may reflect MS, especially in a younger patient
2. Dental exam
   • May reveal dental pathology
   • Pain with opening and closing the mouth may suggest temporomandibular joint disease
3. ENT exam
   • Tenderness to firm pressure over the mid-cheek or forehead may be present with sinus disease

Laboratory Tests

• Consider administering carbamazepine or oxcarbazepine as a diagnostic maneuver.
• Consider obtaining an MRI head scan to identify another condition causing trigeminal neuralgia, such as a brain tumor, MS, or vascular compression.

Differential Diagnosis of Trigeminal Neuralgia         

• Consider the diagnosis of vagoglossopharyngeal neuralgia when unilateral paroxysmal pain involves the throat, back of the tongue, ear, or anterior aspect of the neck.
• Consider the diagnosis of MS (Multiple Sclerosis)  if the patient is under age 45 and has bilateral trigeminal neuralgia or other neurologic abnormalities.
• Consider the possibility of a brain tumor in a patient with trigeminal neuralgia if there are abnormalities in function of the fifth, seventh, or eighth cranial nerves.
• Consider atypical trigeminal neuralgia in a patient with paroxysmal triggered face pain and constant, nontriggered face pain.
• Consider atypical facial pain when pain is constant, not triggered, often bilateral, and is not trigeminally distributed in a patient who claims to have severe pain but does not appear to be in severe pain.

Differential Diagnosis of Trigeminal Neuralgia

1. Dental pain
   • Often provoked by hot, cold, or pressure stimuli
     Requires direct exam of dental structures
   • Common
2. Sinus disease
   • Tenderness over the sinus (mid cheek, maxillary), supraorbital (frontal)
   • Often with purulent secretion in the nasal cavity
3. Temporomandibular joint disease
   • Increased discomfort with use of chewing muscles
     Tenderness of these muscles and of the temporomandibular joint
   • Often associated with a psychological disorder
     Abnormal mandibular range of motion (<35 mm males, <30 mm females) (Drangsholt M, J Evid Base Dent Pract, 2001)
4. Postherpetic neuralgia
   • Eye and forehead usually involved, often with skin rash and vesicles during the acute onset
   • Usually analgesic or hypoalgesic on exam  
     Tricyclic antidepressants may be the most effective drugs
5. Vascular dysfunction (migraine variants)
   • Pain lasts longer than trigeminal neuralgia, usually from 20 minutes to a few hours
     Lower half face pains may be throbbing and associated with nausea and photophobia
     Upper face pain, usually in men, in the orbit and cheek may be associated with conjunctival congestion, lacrimation, ptosis or myosis, facial sweating and erythema (cluster headache)
   • Often respond to antimigraine medicines.  See module Migraine
6. Inflammatory vascular disease (temporal arteritis)
   • Throbbing, aching along the scalp arteries
     Sometimes with visual impairment
     Elevated sedimentation rate
   • Responds to steroids
7. Deafferentation pain
   • Usually a constant, tightness, itching, crawling, or burning pain in someone who has had damage to the trigeminal nerve
   • May respond to antidepressants and/or gabapentin
8. Atypical trigeminal neuralgia
   • Paroxysmal, triggered face pain (trigeminal neuralgia) and constant, nontriggered face pain
   • The trigeminal neuralgia component often responds to trigeminal neuralgia drugs and surgeries; the constant pain component does not
     Results of neurosurgical treatment for atypical trigeminal neuralgia are less good than for trigeminal neuralgia
     The constant pain may be caused by deafferentation or may be without a clearly defined cause, as is usually the case with atypical facial pain
9. Vagoglossopharyngeal neuralgia
   • Pain in the ear, throat, back of the tongue or front of the neck
   • Much less common than trigeminal neuralgia
     May coexist with trigeminal neuralgia
     Responds to carbamazepine, oxcarbazepine, or surgery
10. Atypical facial pains
    • Usually continuous pain, often bilaterally, not trigeminally distributed, not triggered by light touch
    • Responds to antidepressants and not carbamazepine
      Low-dose amitriptyline (30 mg qhs) was more effective than placebo after 4 weeks of treatment in patients with chronic oral-facial pain (not trigeminal neuralgia). The pain reduction was independent of its effects on depression
      70% of patients were women; average age of onset was 44.5 years, which was 10.5 years younger than patients with trigeminal neuralgia

Non-drug Therapy        
Although there are no known nonsurgical therapies that influence the course of trigeminal neuralgia, suggest certain maneuvers that may make the condition more tolerable.

• Avoid situations that may trigger face pain, and try certain maneuvers that may provide temporary relief.
• Teach patients who have trigeminal denervation, such as from neurosurgical procedures, to take precautions against accidentally injuring themselves.
• Consider neurosurgical intervention for patients with trigeminal neuralgia for whom medical therapy has failed.

Drug Treatment for Trigeminal Neuralgia   (Agent | Mechanism of Action | Dosage | Benefits | Side Effects | Notes )       
Consider long-term drug treatment for prevention of further attacks of trigeminal neuralgia.

• Consider no treatment for mild and infrequent pain.
• Consider oxcarbazepine or carbamazepine as the drug of choice for treating trigeminal neuralgia.
• Consider alternate drugs, either alone or in combination.

Carbamazepine (Tegretol)

• Sodium-channel modulator - Antiepileptic drug
• 100 mg bid (200 mg/d)
  Add up to 200 mg/d in increments of 100 mg every 12 hr. Maximum dose, 1200 mg per 24 hrs. The long-acting (XR) form is given bid; the regular form is given bid, tid, or qid
• Greatest pain relief.  Most evidence confirming benefit
• Side Effects: Many. Aplastic anemia and agranulocytosis are rare, but can be fatal.  Commonly causes dizziness, drowsiness, unsteadiness, and cognitive impairment; Rash;  Hyponatremia; Many drug interactions
• Monitor for anemia, neutropenia, and/or thrombocytopenia as well as for liver function test abnormalities.
  Monitor carbamazepine blood level
  Available in tablet, chewable, suspension, and long-acting forms
  Effectiveness shown on randomized, controlled trials

Oxcarbazepine (Trileptal)

• Sodium-channel modulator, calcium-channel modulator.  Antiepileptic drug
• 300 mg po bid. Maximum total daily dose of 2400 mg when given as monotherapy
• Pain relief similar to carbamazepine, but has fewer side effects or drug interactions
• Dizziness, diplopia, ataxia, nausea, somnolence, headache, hyponatremia (more often than with carbamazepine); Rash in 25% of patients who develop a rash from carbamazepine
• 300 mg of oxcarbazepine is equivalent to 200 mg of carbamazepine
  Monitor serum sodium, especially in patients receiving other drugs, such as diuretics, that can also cause hyponatremia

Gabapentin (Neurontin)

• Antiepileptic drug
• 300 mg po tid.  Maximum daily dose of 3600 mg
• Few side effects and fewest drug interactions
• Somnolence, dizziness, ataxia, fatigue, nystagmus, tremor
• Good for adjunctive treatment with other antiepileptic drugs

Phenytoin (Dilantin)

• Antiepileptic drug, sodium-channel modulator
• 100 mg po tid, or 300 mg once per day
• Comes in an intravenous form
• Many drug interactions ; Ataxia, slurred speech, rash
• Monitor blood levels

Lamotrigine (Lamictal)

• Antiepileptic drug, sodium-channel modulator
• 25 mg bid for first 2 weeks. 50 mg bid for weeks 3 and 4. Then increase by 100 mg/d every 1-2 weeks. Usual maintenance dose, 300-500 mg/d  
  A dose of 25 mg/d, increasing by 25 mg every third day, to a maximum of 400 mg/d, has been used for patients with trigeminal neuralgia
• Pain relief proportional to daily dosage (400 mg maximum) and to drug plasma levels
• Rash; may be severe;  Many drug interactions ; Dizziness, incoordination, vomiting; Dose escalation must be slow
• Stop at first sign of a rash ;  Slow build-up of dose is a drawback
  Possible added risk of rash when taken with valproic acid
  Pain relief is proportional to dose and drug levels
  Effectiveness shown on randomized, controlled trial  

Baclofen (Lioresal)

• Antispasmodic ; Structurally similar to gabapentin
• 5-10 mg po tid. Increase by 10 mg every other day until 60-80 mg daily
• Few drug interactions
• Ataxia, lethargy
• Possibly synergistic with carbamazepine
  Benefit shown on randomized, controlled trial

Narcotics (none has been shown to be more effective than others)

• Can be given intravenously
• Side effects: Many
• Not usually of value  See module Pain

10262002