Trigeminal neuralgia is a severe form of facial pain that is usually caused by blood vessels compressing the trigeminal nerve. In some cases, however, the cause of the condition cannot be identified.

Also called the fifth cranial nerve, the trigeminal nerve is one of the largest nerves in the skull and is responsible for most of the sensations felt across the face. One trigeminal nerve supplies each side of the face and each nerve is divided into the following three branches:

• The ophthalmic or upper branch is responsible for the sensation felt above the eyes, in the forehead and at the front of the head.
• The maxillary or middle branch supplies the cheek, upper jaw and side of the nose.
• The mandibular or lower branch supplies the lower jaw, teeth and gums.

These three branches all transmit nervous impulses to the brain from the facial skin, teeth and jaws. In trigeminal neuralgia, it is usually the maxillary branch that is affected, although more than one branch may be involved. The ophthalmic branch is the least frequently affected.

Causes

Pressure over the trigeminal nerve
Around 80-90% cases of trigeminal neuralgia are caused by pressure on the trigeminal nerve, near to the site where the nerve enters the brain stem. The pressure is thought to lead to uncontrollable pain signals being sent to the face, causing the stabbing sensations.

Underlying disorders
Several underlying disorders may present with trigeminal neuralgia as a symptom. Examples include a benign tumour in the trigeminal nerve and multiple sclerosis, a chronic degenerative condition of the brain and spinal cord.

Triggers