Patients with head injuries may have associated injuries in other parts of the body. In particular it is essential to examine for life-threatening cervical spine, chest, abdominal-viscera, pelvic and long-bone injuries. This post reviews cranial nerve injuries that may occur with head injury. enjoy it!

Cranial Nerves Injury

The cranial nerves may be injured as a result of either direct trauma by the skull fracture, movement of the brain, or cerebral swelling.

The 1^st (olfactory) nerves. These are the most commonly affected and this may be as a result of either a fracture through the anterior cranial fossa, directly affecting the tracts, or tearing of the delicate nerve rootlets passing through the cribriform plate caused by the sudden brain movement, particularly from a blow to the back of the head. The features are parosmia or anosmia.

The 8th (vestibullocochlear)nerve. Damage to this nerve is often associated with a fracture of the petrous temporal bone. Deafness may be conductive, due to a haemotympanum, or sensorineural as a result of injury to the inner ear or to the nerve itself. Vertigo and nystagmus are due to vestibular nerve or end-organ damage and usually resolve within a few months of the injury.

Facial(7^th nerve) paralysis. This is usually associated with a fracture through the petrous temporal bone, although this may only be evident on a high-resolution CT scan using the bone ‘window’. It may be either immediate, as a result of direct compression of the nerve, or delayed, due to bleeding and/or swelling around the nerve. The features include deviation of the mouth to the normal side, flattening of the nasolabial fold, drooling of the eyelids, loss of eyebrows, etc.

The 6th (abduscens) cranial nerve. This has a long course from the brainstem to its entry into Dorello’s canal and the nerve is easily damaged by torsion or herniation of the brain. Affected individuals present with lateral gaze palsy.

The 3^rd (occulomotor) nerve. This may also be damaged by direct trauma or by brain herniation, the herniated uncus of the temporal lobe either impinging on the midbrain or directly stretching the nerve. Occulomotor nerve palsy causes ptosis with the eye deviated “down and out”.

The 2^nd (optic) nerve. This is infrequently injured by direct trauma.

Skull fractures

Trauma may result in skull fractures which may be open/closed or linear/depressed. See skull fractures for further details.

Scalp lacerations

The extent of the scalp laceration does not necessarily indicate the degree of trauma to the underlying brain.

Other injuries

The most common associated injuries are to the chest, cervical spine, skeletal and cardiovascular systems. Many individuals with associated high cervical cord injuries do not survive long enough as to reach hospitals.

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