31 Days of Awareness: Trigeminal Neuralgia

Trigeminal Neuralgia

Trigeminal neuralgia (TN), (also known as tic douloureux, the Suicide Disease, or Fothergill's disease) is aneuropathic disorder characterized by episodes of intense pain in the face, originating from the trigeminal nerve. It has been described as among the most painful conditions known to mankind. It is estimated that 1 in 15,000 people suffer from TN, although the actual figure may be significantly higher due to frequent misdiagnosis. In a majority of cases, TN symptoms begin appearing after the age of 50, although there have been cases with patients being as young as three years of age. It is more common in females than males.

The trigeminal nerve is a paired cranial nerve that has three major branches: the ophthalmic nerve (V₁), the maxillary nerve (V₂), and the mandibular nerve (V₃). One, two, or all three branches of the nerve may be affected. 10-12% of cases are bilateral (occurring on both the left and right sides of the face). Trigeminal neuralgia most commonly involves the middle branch (the maxillary nerve or V₂) and lower branch (mandibular nerve or V₃) of the trigeminal nerve, but the pain may be felt in the ear, eye, lips, nose, scalp, forehead, cheeks, teeth, or jaw and side of the face.

TN is not easily controlled but can be managed with a variety of treatment options.

Symptoms

Trigeminal neuralgia symptoms may include one or more of these patterns:

• Occasional twinges of mild pain
• Episodes of severe, shooting or jabbing pain that may feel like an electric shock
• Spontaneous attacks of pain or attacks triggered by things such as touching the face, chewing, speaking and brushing teeth
• Bouts of pain lasting from a few seconds to several seconds
• Episodes of several attacks lasting days, weeks, months or longer — some people have periods when they experience no pain
• Pain in areas supplied by the trigeminal nerve, including the cheek, jaw, teeth, gums, lips, or less often the eye and forehead
• Pain affecting one side of your face at a time
• Pain focused in one spot or spread in a wider pattern
• Attacks becoming more frequent and intense over time

Treatment

Treatment options include medicines, surgery, and complementary approaches.

• Anticonvulsant medicines—used to block nerve firing—are generally effective in treating TN.  These drugs include carbamazepine, oxcarbazepine, topiramate, clonazepam, phenytoin, lamotrigin, and valproic acid.  Gabapentin or baclofen can be used as a second drug to treat TN and may be given in combination with other anticonvulsants.
• Tricyclic antidepressants such as amitriptyline or nortriptyline are used to treat pain described as constant, burning, or aching.  Typical analgesics and opioids are not usually helpful in treating the sharp, recurring pain caused by TN.  If medication fails to relieve pain or produces intolerable side effects such as excess fatigue, surgical treatment may be recommended.
• Several neurosurgical procedures are available to treat TN.  The choice among the various types depends on the patient's preference, physical well-being, previous surgeries, presence of multiple sclerosis, and area of trigeminal nerve involvement (particularly when the upper/ophthalmic branch is involved).  Some procedures are done on an outpatient basis, while others may involve a more complex operation that is performed under general anesthesia.  Some degree of facial numbness is expected after most of these procedures, and TN might return despite the procedure’s initial success.  Depending on the procedure, other surgical risks include hearing loss, balance problems, infection, and stroke.

A rhizotomy is a procedure in which select nerve fibers are destroyed to block pain.  A rhizotomy for TN causes some degree of permanent sensory loss and facial numbness.  Several forms of rhizotomy are available to treat TN:

• Balloon compression works by injuring the insulation on nerves that are involved with the sensation of light touch on the face.  The procedure is performed in an operating room under general anesthesia.  A tube called a cannula is inserted through the cheek and guided to where one branch of the trigeminal nerve passes through the base of the skull.  A soft catheter with a balloon tip is threaded through the cannula and the balloon is inflated to squeeze part of the nerve against the hard edge of the brain covering (the dura) and the skull.  After 1 minute the balloon is deflated and removed, along with the catheter and cannula.  Balloon compression is generally an outpatient procedure, although sometimes the patient may be kept in the hospital overnight.
• Glycerol injection is generally an outpatient procedure in which the patient is sedated intravenously.  A thin needle is passed through the cheek, next to the mouth, and guided through the opening in the base of the skull to where all three branches of the trigeminal nerve come together.  The glycerol injection bathes the ganglion (the central part of the nerve from which the nerve impulses are transmitted) and damages the insulation of trigeminal nerve fibers.
• Radiofrequency thermal lesioning is usually performed on an outpatient basis.  The patient is anesthetized and a hollow needle is passed through the cheek to where the trigeminal nerve exits through a hole at the base of the skull.  The patient is awakened and a small electrical current is passed through the needle, causing tingling.  When the needle is positioned so that the tingling occurs in the area of TN pain, the patient is then sedated and that part of the nerve is gradually heated with an electrode, injuring the nerve fibers.  The electrode and needle are then removed and the patient is awakened.
• Stereotactic radiosurgery uses computer imaging to direct highly focused beams of radiation at the site where the trigeminal nerve exits the brainstem.  This causes the slow formation of a lesion on the nerve that disrupts the transmission of pain signals to the brain.  Pain relief from this procedure may take several months.  Patients usually leave the hospital the same day or the next day following treatment.

Microvascular decompression is the most invasive of all surgeries for TN, but it also offers the lowest probability that pain will return.  This inpatient procedure, which is performed under general anesthesia, requires that a small opening be made behind the ear.  While viewing the trigeminal nerve through a microscope, the surgeon moves away the vessels that are compressing the nerve and places a soft cushion between the nerve and the vessels.  Unlike rhizotomies, there is usually no numbness in the face after this surgery.  Patients generally recuperate for several days in the hospital following the procedure.  A neurectomy, which involves cutting part of the nerve, may be performed during microvascular decompression if no vessel is found to be pressing on the trigeminal nerve.  Neurectomies may also be performed by cutting branches of the trigeminal nerve in the face.  When done during microvascular decompression, a neurectomy will cause permanent numbness in the area of the face that is supplied by the nerve or nerve branch that is cut.  However, when the operation is performed in the face, the nerve may grow back and in time sensation may return.

Some patients choose to manage TN using complementary techniques, usually in combination with drug treatment.  These therapies offer varying degrees of success.  Options include acupuncture, biofeedback, vitamin therapy, nutritional therapy, and electrical stimulation of the nerves.

Prognosis

After an initial attack, trigeminal neuralgia (TN) may remit for months or even years. Thereafter the attacks may become more frequent, more easily triggered, disabling, and may require long-term medication. Thus, the disease course is typically one of clusters of attacks that wax and wane in frequency. Exacerbations most commonly occur in the fall and spring.

Among the best clinical predictors of a symptomatic form are sensory deficits upon examination and a bilateral distribution of symptoms (but the absence thereof is not a negative predictor). Young age is a moderate predictor, but a fair degree of overlap exists. Lack of therapeutic response and V1 distribution are poor predictors.

Although trigeminal neuralgia is not associated with a shortened life, the morbidity associated with the chronic and recurrent facial pain can be considerable if the condition is not controlled adequately. This condition may evolve into a chronic pain syndrome, and patients may suffer from depression and related loss of daily functioning. Individuals may choose to limit activities that precipitate pain, such as chewing, possibly losing weight in extreme circumstances. In addition, the severity of the pain may lead to suicide.

To learn more, please visit:

Wikipedia
Mayo Clinic
National Institute of Neurological Disorders and Stroke
Medscape

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