Trigeminal Neuralgia

Trigeminal Neuralgia is also called Tic Douloureux, trifacial neuralgia or Fothergill's disease. Trigeminal neuralgia is an extremely painful condition as it is unique to humans. It is a syndrome in which symptoms are sufficientntly distinctive to permit a reliable diagnosis solely on the basis of history.
Etiology
It can be Idiopathic or secondary
Idiopathic trigeminal neuralgia

• Dental pathosis is believed by some investigators to be involved with the onset of trigeminal neuralgia.
• Secondary to excessive traction on the various divisions of the fifth nerve, being influenced by maxillo-mandibular relationship.
• It can be secondary to  an allergic & hypersensitivity reaction causing edema of the trigeminal nerve root.
• Wolf thought that ischemia at various portions of the trigeminal pathway might be responsible for the paroxysms of pain.
• Jannetta & others have shown subtle changes of a compression-distortion phenomenon which is  usually caused by arterial loops of atherosclerotic vessels.Vessels become elongated with advancing age & with atherosclerotic involvement  gain abnormal positions by wedging in to the space between the pons & trigeminal nerve. It is postulated taht with progressive material nerve. It is postulated that with progressive material elongation, fascicles of adjacent nerves later myelin injury & pain result.

Secondary trigeminal neuralgia

• Conditions such as carcinoma of the maxillary antrum,nasopharyngeal carcinoma & tumors of peripheral nerves root can cause secondary trigeminal neuralgia
• Benign tumors ,as well as intracranial vascuar anomalies may present trigeminal pain.
• Multiple sclerosis is usually associated with trigeminal neuralgia.

Trigeminal neuralgia

Clinical features

• Age- middle & old age, the didease seldom occurs before 35 years of age.Incidence increases with age due to degenerative changes of the nerve fibers.
• Sex-more common in women
• Site-more common on right side & the lower portions of the face.
• Nature of pain-the pain is paroxysmal, lasting only a few seconds to a few minutes & is usualy of extreme intensity.It may be described by the patient as resembling "knife like stabs" lightening, electric shock, stabbing or lancinating type of pain.During the intervals between these violent experiences, there is usually no pain or a mild or dull ache.
• Aggravating factor-the pain is provoked by obvious stimuli to the face. A touch, a draft of air, any movement of the face as in talking, chewing, yaning or swallowing may evoke a lancinating attack.Later the pain may be so severe that the patient lives in constant fear of ant attack. As the attack  occurs , the patient may clutch his face as if in terror of the dreaded pain.
• Trigger zone- 'trigger zone' which precipitate an attack when touched, are common on vermillion border of lips,the ala of the nose, the cheeks, & around the eyes.The patient learns to avoid touching the skin over the trigger zone which frequently makes him go unwashed or unshaven for days.
• The pain is confined to the trigeminal zone, nearly always unilateral & if bilateral ,is successive rather than concomitant.The mandibular & maxillary divisons are more commonly involved than the opthalmic, in some instances these two divisions may be simultaneously affected. the pain never crosses the midline.
• There may be hyperkeratinization of the skin in the affected region of the face due to the vigorous rubbing by the patient during the attack.
• It had been odserved that as the disease progresses, the frequency of attack is increased & the constant rubbing of the face with a rough cloth may even cause small haemorrhages on the face.
• The neurological examination findings are normal.
• It is also called Tic Douloureux which is only applied when the patient suffers from spasmodic contractions of the facial muscles.

Diagnosis

Mainly based on the history & clinical features of the disease. The trigger zone can be identified. The diagnosis of Idiopathic trigeminal neuralgia should only be established when no other organic cause is traceable.Diagnosis is confirmed bi injecting 0.5 ml of 2 % lignocaine hydrochloride solution in the vicitity of the nerve. If the pain is relieved & does not develop by usual methods of stimulating the trigger zone, it can be labelled as idiopathic trigeminal neuralgia.

Treatment 

The treatment instituted consists of both medicinal & surgical management

1. Medicinal therapy

• Anti convulsant agents such as dilantin or phenytoin sodium is reported to decrease the pain considerably.
• Carbamazepine( tegretal) 100-200 mg TDS is newer drug of choice . total pain relief is possible.
• Trichloro ethylene
• IM  morphine

    2. Injection therapy

• Injection of anaesthetic agent.( 2% xylocaine hydrochlodide) can be given extracranially in peripheral nerves as well as intracranially at gasserian ganglion
• Injection of boiling water
• Injection of absolute alcohol

     3. Surgical therapy

• Nerve section & avulsion
• RFTC at gasserian gaglion
• Retrogasserian rhizotomy-In this operation, preganglionic  trigeminal sensory roots are sectioned between the gasserian ganglion & point of entry in to the pons. This procedure yields better & long lasting results but should be reserved when all other measures have failed.
• medullary trectotomy-Relapse rate & mortality rate is high in this procedure.
• electrosurgery
• cryosurgery-cryotherapy of the concerned branch of the trigeminal nerve eliminates the peripheral trigger effects & hence pain.The nerve is frozen with a cryoprobe that is thermostatically controlled at approximately -100 degree celcius ( nitrous oxide probe) for a period of 1-2 mins. followed by 3 mins. thaw, to be repeated 3 times. The procedure is simple & advantageous that the anatomy of the area is not disturbed & subsequent operations are easier.
• selective radiofrequency thermogangliolysis-The trigeminal gaglion is approached with insulated 22 gauge needle with slightly exposed tip through the intraoral route & foramen ovale.The final position is confirmed by giving mild electrical stimulus & patient is given one or more thermal lesions of 60-70 degree Celsius for a period of 30 sec. each

     4. Peripheral neurectomy

     5. Newer approaches

• TENS
• Acupuncture for trigeminal neuralgia

     6. Psycological approach for trigeminal neuralgia

• Bio feedback
• Psychiatric councelling
• Hypnosis