TRIGEMINAL NEURALGIA (TIC DOULOUREUX)
Trigeminal neuralgia is a condition of the 5th cranial nerve characterized paroxysms of pain similar to an electric shock or a lancinating burning sensation in area innervated by one or more branches of the trigeminal nerve.
Causes
Not certain, but chronic compression or irritation of the trigeminal nerve degenerative changes in the gasserian ganglion are suggested causes. Some believe t it may be due to vascular pressure from structural abnormalities (loop of an artery encroaching on the trigeminal nerve, gasserian ganglion or root entry zone).
Clinical Manifestations
Pain is felt in the skin, not in the deeper structures (but i more severe at the peripheral areas of distribution of the affected nerve) notably over lip, the chin, the nostrils and in the teeth.
Paroxysms are aroused by (any stimulation of the terminals of the affected branches) such as washing the face, shaving, brushing, the teeth, eating and drinking.
Early attacks are usually mild and brief. Pain-free intervals may be measured in terms, minutes, hours, days, or longer. With advancing years, the painful episodes tend become more and more frequent and agonizing. The patient lives in constant fear attacks.
Diagnosis: Patients avoid stimulating trigger points. They try not to touch or wash the frees, shave, chew or do anything else that might cause an attack. This behaviour is clue to diagnosis.
Management
Antiepileptic agents Carbamazepine (Tegretol) and phenytoin (Dilanti) reducing the transmission of impulses at certain nerve terminals, relieve pain most patients. (Carbamazepine is taken with meals, in dosages gradual increased until relief is obtained. Side Effects: nausea, dizziness, drowsiness and hepatic dysfunction. The patient is monitored for bone marrow depression during long-term drug therapy. Phenytoin somnolence, ataxia and skin allergies. Side Effects: nausea, dizziness.
Alcohol injection of the gasserian ganglion and peripheral branches of the trigeminal nerve relieves pain for several months. However, the pain returns after the nerve regenerates.
Percutaneous Radio frequency Trigeminal Gangliolysis Percutaneous radio frequency interruption of the Gasserian ganglion, whereby the small unmyelinated and thinly myelinated fibres that conduct the pain are thermally destroyed, is becoming the surgical procedure of choice for trigeminal neuralgia.
(Under LA, the needle is introduced through the cheek on the affected side. Under fluoroscopic control, the needle electrode is guided through the foramen ovale into the Gasserian ganglion. The division of the Gasserian ganglion (mandibular, maxillary and ophthalmic) are encountered sequentially. The nerve is stimulated with a small current, while the patient is awake. The patient then reports when a tingling sensation is felt. When the electrode needle is in the desired position, the patient anesthetized briefly and a radio frequency current (heating current to destroy the nerve) is passed in a controlled manner to thermally injure the trigeminal ganglion and rootlets.
The patient is then awakened from the anesthetic and examined for sensory deficits. Repeat lesions may be produced until the desired effect is achieved. The operative procedure taken more than 1 hour and gives permanent pain relief in most patients. Touch and proprioceptive functions are left intact).
Microvascular decompression of the Trigeminal nerve decompresses the trigeminal nerve, since tic douloureux may be caused by vascular compression of the entry zone of the trigeminal root by an arterial loop and occasionally by a vein. (With aid of an operating microscope, the artery loop is lifted from the nerve in order to relieve the pressure and a small prosthetic device is inserted to prevent recurrence of impingement on the nerve. This relieves facial pain while preserving normal sensation. It is a major procedure, involving a craniotomy).
Nursing Interventions
1. Recognize certain factors that may aggravate excruciating facial pain food that is too hot or too cold or jarring the bed, washing the face, combing the hair, brushing the teeth etc.
2. Nurse can lessen these discomforts by using cotton pads and room temperature H₂O to wash the patients face, instructing the patient to rinse the mouth after eating (When tooth brushing causes pain) and doing personal hygiene during pain-free intervals.
3. Advise to take food and fluids at room temperature, chew on the unaffected side and ingest soft foods.
4. Be aware of the anxiety, depression and insomnia that often accompany chronic painful conditions and use appropriate interventions.
