4. Trigeminal neuralgia.

According to the IASP-International Assosiation for the Study of Pain definition, trigeminal neuralgia is defined as a syndrome characterized by sudden, brief, intense, recurring pain in the area of ​​innervation of one or more branches of the trigeminal nerve, usually on one side of the face.

Etiology – trigeminal nerve compression due to extra- and intracranial factors.

Extracranial factors:

• tunnel syndrome (trigeminal nerve root compression in bone canal due to its congenital or acquired (dental caries, sinusitis) narrowness.

Intracranial factors:

• superior cerebellar artery loop in the cerebellopontine angle, vascular aneurysm of basilar artery,

• tumors in the cerebellopontine angle,

• trigeminal nerve compression at meninges pathology (arachnoiditis),

• trigeminal nerve dysfunction at circulation disorder, demyelinating diseases, infection.

Pathogenesis. It is considered that trigeminal neuralgia is caused by the appearance of paroxysmal discharges that resemble the mechanisms of epilepsy, paroxysmal pain is generally thought to be due to aberrant transmission of nerve impulses from somatosensory to nociceptive fibers within the trigeminal nerve at a site of local damage to myelin sheaths.

The myelin lesion is, in turn, attributed to mechanical factors relating to old age, or to the compressive effect of a pulsating vascular loop making contact with the trigeminal nerve near the brainstem at it root entry zone.

Clinic:

• recurrent paroxysms of sharp, lancinating or stabbing pain (electric shock type pain) that may last a few seconds or minutes,

• pain distribution - maxillar and mandibular branches of the trigeminal nerve are most commonly affected,

• each attack is unilateral (may alternate sides in up to 3-5% of cases),

• attacks may occur as often as multiple times daily or as infrequently as monthly, attacks become more frequent and severe over time, attacks are rare during sleep,

• some patients are sensitive in certain areas of the face, called trigger zones (Fig. 2), light touch or other minimal stimulation in these zones triggers an attack. These zones are usually near the nose, lips, eyes, ear, or inside the mouth,

Fig. 2. Facial areas of trigger zones.

• everyday activities can trigger an episode. Triggers of pain: talking, eating, kissing, drinking, shaving, teeth brushing, face washing cold exposure, cewing,

• appearance at the height of the paroxysm twitching of facial muscles - pain teak,

• trismus - spasm of the muscles of mastication and reduced opening of the jaws caused by trigeminal motor fibres irritation,

• the disease has a chronic course, complaints and neurological symptoms at remission period are absent,

• at examination - pain at the exit point of the affected branches, no violations of sensitivity in the area of innervation.

Treatment.

Medication:

1. Antiepileptic drugs: carbamazepine (Tegretol) 600-1600 mg, gabapeptin 300-2400 mg daily for 3 times, pregabalin (Lyrica) 75-600 mg, daily in 3 times.

2. Tricyclic antidepressant amitriptyline 25 mg 3 times daily.