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TRIGEMINAL NEURALGIA (TN)
•Otherwise known as:
–The Suicide Disease
•Listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institute of Health (NIH). TN, or a subtype of TN, affects less than 200,000 people in the US population.
•1 in 15,000 people suffer from TN, although numbers may be significantly higher due to frequent misdiagnosis.
•The trigeminal nerve is one of 12 pairs of cranial nerves that originate at the base of the brain.
•Trigeminal Neuralgia is a chronic pain condition that affects the trigeminal or 5th cranial nerve, one of the largest nerves in the head.
•It is "one of the most painful conditions known to humans, yet remains an enigma to many health professionals."
•The trigeminal nerve has 3 branches that conduct sensations from the upper, middle, and lower portions of the face, as well as the oral cavity, to the brain.
–Ophthalmic, or upper, branch supplies sensation to most of the scalp, forehead, and front of the head.
–Maxillary, or middle, branch passes through the cheek, upper jaw, top lip, teeth and gums, and to the side of the nose.
–Mandibular, or lower, branch passes through the lower jaw, teeth, gums, and bottom lip.
•More than one branch can be affected by the disorder.
HISTORY OF TRIGEMINAL NEURALGIA
•John Fothergill gave the first full and accurate description of TN in 1773, but early descriptions can be inferred from the writings of Galen, Aretaeus of Cappadocia (born circa AD 81), and in the 11th century by Avicenna (tortura oris).
•The most convincing early description in 1671 was of a German physician, Johannes Laurentius Bausch, who suffered from a lightning like pain in the right face. He became unable to eat properly and apparently succumbed to malnutrition.
•Nicholas André invented the term "tic douloureux" in 1756 and this term remained though not all patients showed the facial tics.
•John Fothergill’s description of "a painful affection of the face" was presented to the Medical Society in London in 1773.
•In 1891, Sir Victor Horsley proposed the first open surgical procedure for the disorder involving the sectioning of preganglionic rootlets of the trigeminal nerve.
•Walter Dandy in 1925 was an advocate of partial sectioning of the nerve in the posterior cranial fossa.
–During this procedure he noted compression of the nerve by vascular loops, and in 1932 proposed the theory that trigeminal neuralgia was caused by compression of the nerve by a blood vessel.
•With the advent of the operative microscope, Peter Jannetta was able to further confirm this theory in 1967 and advocated moving the offending vessel and placing a sponge to prevent the vessel from returning to its native position.
•The presumed cause of TN is a blood vessel pressing on the trigeminal nerve as it exits the brainstem.
•It can also be part of the normal aging process (as blood vessels lengthen they can come to rest and pulsate against a nerve).
•It can occur in people with multiple sclerosis, a disease caused by the deterioration of myelin throughout the body, or may be caused by damage to the myelin sheath by compression from a tumor.
•In some instances, deterioration causes the nerve to send abnormal signals to the brain.
•And, in some cases the cause is unknown.
•Sudden, severe, electric shock-like, stabbing pain that is typically felt on one side of the jaw or cheek.
•Pain may occur on both sides of the face, although not at the same time.
•Attacks of pain, which generally last several seconds and may repeat in quick succession, come and go throughout the day (as often as hundreds of times a day).
•Episodes can last for days, weeks, or months at a time and then disappear for months or years.
•In the days before an episode begins, some patients may experience a tingling or numbing sensation or a somewhat constant and aching pain.
•Intense flashes of pain can be triggered by vibration or contact with the cheek:
–Shaving, washing the face, applying makeup, brushing teeth, eating, drinking, talking, or being exposed to the wind.
•Pain may affect a small area of the face or may spread.
•Bouts of pain rarely occur at night, when the patient is sleeping.
•Patients are considered to have Type 1 TN if more than 50% of the pain they experience is sudden, intermittent, sharp and stabbing, or shock-like. (These patients may also have some burning sensation.)
•Type 2 TN involves pain that is constant, aching, or burning more than 50% of the time.
•Onset of symptoms occurs most often after age 50, but cases are known in children and even infants.
•Disorder is not fatal but can be debilitating.
–Called the Suicide Disease because it’s the most painful affliction know to medical practice.
•Disorder is more common in women than in men.
•Some evidence shows that the disorder runs in families, perhaps because of an inherited pattern of blood vessel formation.
•There is no single test to diagnose TN.
•Generally based on the patient’s medical history and description of symptoms, a physical exam, and a thorough neurological exam by a physician.
•Magnetic Resonance Imaging (MRI) scan to rule out a tumor or multiple sclerosis.
•Magnetic Resonance Angiography (MRA) can more clearly show blood vessel problems and any compression of the trigeminal nerve close to the brainstem.
•Because of overlapping symptoms, obtaining a correct diagnosis is difficult.
•Treatment Options include:
TREATMENTS - MEDICINES
•Anticonvulsant medicines – used to block nerve firing – are generally effective in treatment of TN.
•Tricyclic antidepressants 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.
TREATMENTS – NERVE BLOCKS
A nerve block is a technique used for the relief of TN during which a drug is injected into an area of the body to temporarily stop the ability of a nerve to transmit pain signals.
•Local anesthetics – A local anesthetic is injected into the trigger area and stops the pain for approximately the time period that the drug is active (not a long-term relief).
•Alcohol block – Alcohol is injected into the peripheral branches of the trigeminal nerve resulting in pain relief that lasts approximately one year. Repeated blocks tend to be less effective.
TREATMENT – COMPLEMENTARY TECHNIQUES
•Some patients choose to manage TN using complementary techniques, usually in combination with drug treatment.
–Electrical stimulation of the nerves
•These therapies offer varying degrees of success.
TREATMENTS – SURGERY
Surgical procedures can be classified as either destructive or non-destructive.
•Destructive – Treatments intended to control the pain by destroying or damaging sections of the trigeminal nerve, such as:
–Gamma knife radiosurgery
–Percutaious rhizotomy (gangliolysis)
–Stereotactic radiosurgery (Gamma Knife)
•Non-destructive – Treatments that are intended to eliminate the underlying cause of the trigeminal neuralgia without causing injury or damage to the trigeminal nerve, such as:
•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 or rhizotomy are available to treat TN:
–Balloon compression (destructive)
–Glycerol injection (destructive)
–Radiofrequency thermal lesioning (destructive)
–Stereotactic radiosurgery (destructive)
–Microvascular decompression (non-destructive)
TREATMENT – SURGERY BALLOON COMPRESSION
•Works by injuring the insulation on nerves that are involved with the sensation of light touch on the face.
•A tube called a cannula is inserted through the cheek and guided to where one branch of the trigeminal nerves 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.
TREATMENT – SURGERY GLYCEROL INJECTION
•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.
TREATMENT – SURGERY RADIOFREQUENCY THERMAL LESIONING
•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 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.
•Electrode and needle removed, patient awakened.
Treatment – Surgery 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.
TREATMENT – SURGERY MICROVASCULAR DECOMPRESSION (MVD)
•Most invasive of all surgeries for TN, but it also offers the lowest probability that pain will return.
•Inpatient procedure 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.
•Patients recuperate in the hospital for several days.
–Involves cutting part of the nerve, may be performed during microvascular decompression if no vessel is found to be pressing on the trigeminal nerve.
–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.
–When the operation is performed in the face, the nerve may grow back, and in time, sensation may return.
RISKS OF MVD
•No surgery is without risks.
•General complications of any surgery include:
–Bleeding, Infection, Blood Clots, and Reactions to Anesthesia.
•Specific complications related to a craniotomy may include:
–Stroke, Seizures, Venous Sinus Occlusion, Swelling of the Brain, and CSF Leak.
•Most common complication is nerve damage that may include:
–Hearing loss, double vision, facial numbness or paralysis, hoarseness, difficulty swallowing (dysphagia), and unsteady gait.
Results of MVD
•Highly successful in treating trigeminal neuralgia:
–95% effective with a relatively low risk of pain recurrent (20% within 10 years).
–Major benefit is that it causes little or no facial numbness compared to percutaneous stereotactic rhizotomy (PSR).
TN PAIN RECURRENCE
•MVD is highly successful in treating pain of TN with a relatively low risk of pain recurrence. However, one should not overlook the perioperative risks associated with this surgery, especially in the elderly. MVD is best suited for healthy patients.
•PSR rhizotomy generally seems to be the most appropriate procedure for the elderly and for those in poor medical health. This procedure may not be the best choice for patients with V-1 pain or with pain distributed over the three trigeminal divisions.
•Glycerol rhizotomy is associated with a high recurrence rate, the procedure likely requires repetition. Multiple glycerol injections are associated with a higher risk of failure and adverse effects. This procedure is advantageous for patients with contralateral pain, trigeminal motor weakness, and temporo-mandibular joint dysfunction. And, is appropriate for patients who have pain over V-1 or the entire face and are not candidates for a posterior fossa procedure.
•Balloon compression seems particularly advantageous for patients who have V-1 pain and are not good candidates for microvascular decompression. Alternative procedures for these patients include glycerol rhizotomy, peripheral nerve section, and radiosurgery.
•Other surgical procedures have a role also. Peripheral nerve section is appropriate for elderly patients with V-1 pain or with bilateral facial pain. Radiosurgery is for patients who cannot safely undergo surgical procedures.
•Depending on the stage of TN, many sufferers may not present with any outwardly noticeable symptoms or will exhibit brief facial spasms during an attack.
•Some physicians will seek a psychological root cause rather than a physiological abnormality especially if there is no compression of the TN.
•Sometimes the nerve is damaged during a dental procedure such as root canals, extractions, gum surgeries or it may be a condition secondary to multiple sclerosis.
•Many TN sufferers are confined to their homes or are unable to work because of the frequency of their attacks and side effects from medications.
•Clinical depression has the potential to set in, especially in younger patients who often are under-treated for chronic pain.
•It is important for family and friends to educate themselves on the intense severity of TN pain and to be understanding of its limitations.