What Is the Main Cause of Trigeminal Neuralgia?

The main symptom of trigeminal neuralgia (tic douloureux) is stabbing facial pain on one side of the face, often on the right side.

Trigeminal neuralgia, also called tic douloureux, is a nerve pain condition of the face that can be recurrent and chronic. The function of the trigeminal nerve which supplies nerve sensations to parts of the face is disrupted, resulting in pain on one side along the cranial nerve V (typically radiating to upper jaw, teeth, and lower jaw in about one-third of affected patients) that is often accompanied by a brief facial spasm or tic. 

The main symptom of trigeminal neuralgia (tic douloureux) is stabbing facial pain on one side of the face, often on the right side. The frequency of pain attacks varies widely from less than once daily to 12 or more per hour and up to hundreds each day. 

The pain is localized and:

• It commonly affects the mandibular and maxillary nerves that provide sensation in the upper jaw, teeth, and lower jaw or the ophthalmic portions of the nerve that feed the eyes
• In about 60% of cases, the pain radiates from the corner of the mouth to the jawline
• In about 30% of patients, the pain shoots from the upper lip or the cuspids (upper “canine teeth”) to the eye and eyebrows
• In fewer than 5% of cases, the pain affects the ophthalmic branch of the facial nerve and the eye is affected

Many causes of trigeminal neuralgia are unknown (idiopathic). Known causes may include:

• Vascular problems
• Aneurysms
• Pontine infarct 
• Arteriovenous malformation
• Stroke
• Tumors
• Chronic meningeal inflammation
• Surgical injuries
• Facial trauma
• Lesions that may irritate trigeminal nerve roots along the pons 
• Inflammatory disorders
• Multiple sclerosis (common)
• Sarcoidosis
• Lyme disease neuropathy
• Adjacent dental fillings of dissimilar metals (uncommon)

Pain attacks due to trigeminal neuralgia are caused by certain triggers, which commonly include:

• Chewing/eating
• Talking
• Smiling
• Drinking 
• Touching your face
• Washing your face
• Shaving
• Brushing your teeth
• Blowing your nose
• Applying makeup
• Encountering a cold breeze from an open window

There are no specific laboratory or imaging tests routinely used to diagnose trigeminal neuralgia (tic douloureux). Diagnosis is usually made based on the patient’s history and a neurological examination. 

When tests are indicated, they are used to help rule out other conditions such as migraines, cluster headaches, and atypical face pain. Tests may include:

• Blood tests 
  • Complete blood count (CBC)
  • Sedimentation rate (ESR)
  • Antinuclear antibody titer (ANA)
  • Double-stranded DNA, anti-Sm antibody
  • Lupus erythematosus cell preparation
• Liver function tests 
• Cerebrospinal fluid analysis 
• CT scans 
• Magnetic resonance imaging (MRI)

Treatment for trigeminal neuralgia (tic douloureux) depends on the patient's age and overall health. Medications are effective in about 75% of patients and include:

Antiepileptic drugs (AEDs) such as carbamazepine (Tegretol XR, Equetro, Epitol), valproate, clonazepam (Klonopin), lamotrigine [Lamictal, Lamictal Starter (Blue) Kit, Lamictal XR], and possibly gabapentin (Neurontin)

• Antispasmodic agents such as baclofen (Gablofen, Lioresal) and tizanidine (Zanaflex)
• Other medications: 
• Pimozide (Orap), a dopamine receptor antagonist, was more effective than carbamazepine in one trial but is seldom used for TN because it has many potentially serious side effects
• Topical lidocaine is given by intraoral application for pain reduction 
• Tocainide (Tonocard) is an antiarrhythmic drug that was found to be as effective as carbamazepine in one trial
• Botulinum toxin injections may be beneficial for patients with medically refractory TN, although data are limited

Patients with trigeminal neuralgia may also have accompanying depression and may require antidepressant therapy.

Patients who do not respond to medical treatments may require surgery to treat trigeminal neuralgia. The types of surgeries include:

• Microvascular decompression for TN caused by compression of the trigeminal nerve root
• Ablative procedures
  • Rhizotomy with radiofrequency thermocoagulation, mechanical balloon compression, or chemical (glycerol) injection
  • Radiosurgery
  • Peripheral neurectomy and nerve block

Transcranial magnetic stimulation has been investigated as a treatment for TN and while results appear promising, more investigation is needed. 

The main complication of trigeminal neuralgia is side effects and toxicity from long-term use of anticonvulsants. In addition, some anticonvulsants lose effectiveness over time and another anticonvulsant may be needed, which increases the risk for drug-related adverse reactions.

There may be complications from surgical procedures used to treat trigeminal neuralgia, such as:

• loss of sensation of a portion of the face or mouth
• jaw weakness
• eye numbness
• corneal ulceration
• reactivation of a herpes simplex infection
• lack of relief from the procedure
• short-term relief (1-2 years) from the procedure, requiring a second operation
• damage to the nerve which results in a permanent numbness of the face accompanied by pain (anesthesia dolorosa)

Trigeminal neuralgia is a chronic nerve pain disorder but it does not directly affect life expectancy and patients with the condition can live a normal life span. 

However, the pain is so intense for some patients, trigeminal neuralgia has been nicknamed “The Suicide Disease” due to higher rates of depression, anxiety, and suicidal ideation seen in patients with the disorder. Modern treatments are more effective and patients now fare better than they have in the past. If you have trigeminal neuralgia, tell your doctor if you have worsening depression or anxiety or thoughts of suicide.