Cranial Nerve Injury

The cranial nerves are nerves that run from the base of the brain into different parts of the head. They can commonly be involved in traumatic injury which also includes injury to the brain itself. Unlike injuries to nerves and other parts of the body, injuries to the cranial nerves can also involve alteration or destruction of some of our senses themselves.

One of the most commonly injured cranial nerves is cranial nerve Injury the olfactory nerve, which controls the sense of smell. Because our sense of taste depends primarily on smell, our sense of taste might be altered as well. Terms used to describe problems in this include:

Dysnosmia - impaired sense of smell
Ansomia - Complete lost of smell
Prosmia - Sensation of smell without cause
Cosmia - Smelling an offensive odor that does not exist

Generally cranial nerves are not injured in cases of mild TBI. However, it is well document that cranial nerve 1 can be disrupted in the context of a mild TBI. The optic (cranial nerve II) plays a critical role in human sight. Approximately 5 % of patients with TBI receive optic nerve injury. Injury to the optic nerve can cause the pupil to lose its reactivity to light, visual acuity, or visual fields. Examination must be done to differentiate between effects of optic nerve damage versus damage to non-nerve related areas to the visual system.

Remembered that, like the brain, the cranial nerve can recover from a traumatic injury (when the cranial nerve is stretched or bruised). Function can recover for up to a year post-trauma. During that time there may be tingling or sporadic enervation, both of which are uncomfortable, but also show signs of recovery of that nerve.

Treating physicians also refer to cranial nerves by their number. There are twelve below which are described and represented by roman numerals.

Cranial Nerves by Number (1-12)