5th Cranial nerve – Trigeminal nerve lesions

Definition:

A trigeminal nerve lesion describes any pathological process, with the potential to negatively affect the nerve’s function. This definition encompasses: trigeminal neuralgia, tic douloureux (prospalgia, suicide disease, Fothergill’s disease).

The 5th nerve has three divisions. They consist of the ophthalmic, maxillary, and mandibular nerves. The sensory aspect of the trigeminal supplies; sense of touch,pain and temperature to the face. While the proprioceptive impulses from the temporomandibular joint and mastication muscle nerve supply are regulated by the motor portion.

Causes:

Recent research suggests that a common cause for trigeminal neuralgia is compression of the nerve within the skull from an enlarged artery. This type of lesion may be caused by an aneurysm, a space occupying lesion, an arachnoid cyst in the cerebello-pontine angle or by trauma, and even a tongue piercing. Trigeminal neuralgia is also associated with a progressive demyelination of axons in the gasserion ganglion, thereby linking it with multiple sclerosis. Post-herpetic neuralgia, is also of consideration.

Examination:

Trigeminal neuralgia is more common in females and occurs more frequently after the age of fifty.

Trigeminal neuralgia most commonly involves the middle branch (the maxillary nerve or V2) and lower branch (mandibular nerve or V3) of the trigeminal nerve, but the pain may be felt in the ear, eye, lips, nose, scalp, forehead, cheeks, teeth, or jaw and side of the face.

This condition is characterised by periods of intense facial pain that last from a few seconds to several minutes or hours, which may be trigger by something as innocuous as wind blowing on the face, or hair brushing. The symptoms are described as electric shocks, and agonising shooting pains.

The integrity of the trigeminal nerve can be assessed by testing the resistance of the muscles of mastication, assessing the glabella reflex, and jaw jerk. Sensory testing along the three divisions of the trigeminal nerve should also be performed, looking for any decreased sensation or left/right asymmetry.

Because of the potentially dangerous causes of trigeminal nerve lesions, referral for MRI and brain scan is also warranted if no benign cause is found.