Cranial nerve injury after minor head trauma

Clinical article

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There are no specific studies about cranial nerve (CN) injury following mild head trauma (Glasgow Coma Scale Score 14–15) in the literature. The aim of this analysis was to document the incidence of CN injury after mild head trauma and to correlate the initial CT findings with the final outcome 1 year after injury.


The authors studied 49 consecutive patients affected by minor head trauma and CN lesions between January 2000 and January 2006. Detailed clinical and neurological examinations as well as CT studies using brain and bone windows were performed in all patients. Based on the CT findings the authors distinguished 3 types of traumatic injury: no lesion, skull base fracture, and other CT abnormalities. Patients were followed up for 1 year after head injury. The authors distinguished 3 grades of clinical recovery from CN palsy: no recovery, partial recovery, and complete recovery.


Posttraumatic single nerve palsy was observed in 38 patients (77.6%), and multiple nerve injuries were observed in 11 (22.4%). Cranial nerves were affected in 62 cases. The most affected CN was the olfactory nerve (CN I), followed by the facial nerve (CN VII) and the oculomotor nerves (CNs III, IV, and VI). When more than 1 CN was involved, the most frequent association was between CNs VII and VIII. One year after head trauma, a CN deficit was present in 26 (81.2%) of the 32 cases with a skull base fracture, 12 (60%) of 20 cases with other CT abnormalities, and 3 (30%) of 10 cases without CT abnormalities.


Trivial head trauma that causes a minor head injury (Glasgow Coma Scale Score 14–15) can result in CN palsies with a similar distribution to moderate or severe head injuries. The CNs associated with the highest incidence of palsy in this study were the olfactory, facial, and oculomotor nerves. The trigeminal and lower CNs were rarely damaged. Oculomotor nerve injury can have a good prognosis, with a greater chance of recovery if no lesion is demonstrated on the initial CT scan.

Abbreviations used in this paper: CN = cranial nerve; GCS = Glasgow Coma Scale; SAH = subarachnoid hemorrhage.

Article Information

Address correspondence to: Alejandro Fernández Coello, M.D., Comerç n10bis 2°, 08003, Barcelona, Spain. email:

Please include this information when citing this paper: published online July 16, 2010; DOI: 10.3171/2010.6.JNS091620.

© AANS, except where prohibited by US copyright law.



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    Bar chart relating CT findings with the final outcome after 1 year of follow-up. Dark gray bars, no deficit; light gray bars, deficit.

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    Coronal CT scan, bone window setting, demonstrating a fracture through the cribriform plate in a 58-year-old man with associated bifrontal contusions. This kind of fracture causes disruption of the olfactory rootlets and subsequent impairment of smell. This patient showed partial clinical improvement by the end of the follow-up period.

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    Axial CT scan showing multiple fractures and bone fragments affecting both orbits in a 57-year-old man with associated LeFort I fracture, frontal contusions, and a burst eye that required surgical extraction of the ocular globe.

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    Left: Axial CT scan showing an anterior perimesencephalic SAH in a 21-year-old woman with CN III palsy that became completely asymptomatic. Right: Axial CT scan demonstrating a tentorial subdural hematoma affecting the CN IV in a 53-year-old man who partially recovered from a vertical diplopia in the 3rd month of follow-up.

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    Temporal bone CT scan showing a longitudinal left temporal bone fracture in a 60-year-old man with facial and vestibulocochlear nerve palsy. Otorrhagia and impairment of audition were associated with the facial palsy, which had not improved by the end of the follow-up period.


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