oblique basal skull fractures involving both clivus and occipital condyle are uncommon and typically result from high impact lateral crushing injuries . in addition , basal skull fractures may cause multiple cranial nerve deficits and vascular complications due to the tight neural and vascular entry and exit routes present in this region6,8 ) . however , the diagnosis of basal skull fracture is difficult by routine cranial radiography due to the presence of radiographically dense petrous temporal bones , and presumably , this explains the small number of cases described in the literature . nonetheless , modern imaging modalities are capable of providing a diagnosis of basal skull fractures and potential cranial injuries . here , we report a unique case of basal skull fracture , involving both the clivus and occipital condyle that presented with sixth and contralateral twelfth cranial nerve palsies . we discuss the ct characteristics and clinical findings of this case , and the courses of cranial nerve deficits . a 45-year - old male patient who sustained major cranial injuries following a high - speed motorcycle accident was referred to our emergency room . on initial examination , he was alert and fully oriented , and there was no evidence of otorrhea , rhinorrhea , or hematorrhea . however , a detailed neurological examination revealed right vi and left xii cranial nerve deficits ( fig . 1 ) , and a ct scan revealed a fracture line extending obliquely through the clivus and an avulsion fracture of the occipital condyle ( fig . 2 ) . ct also showed massive pneumocephalus with air ventricles , but no shift of the midline structure was evident . clinically , the patient remained awake , alert , and oriented without hemiparesis , and non - operative supportive treatment was administered . a repeat ct scan 10 days after presentation demonstrated complete resolution of the pneumocephalus , and a neurological examination performed at three months after presentation revealed partial improvement of right vi cranial nerve function but an unchanged xii cranial nerve deficit . basal skull fractures account for 21% of all skull fractures and occur in 4% of all head injury cases4 ) . historically , fractures of the skull base have most often been identified based on clinical findings , such as , cranial nerve palsies and cerebrospinal fluid leaks . these fractures are difficult to diagnose by simple radiography , and reportedly are only identified in 20% of cases5,7 ) . however , due to the ever - increasing sophistication of ct imaging , including three - dimensional reconstruction , trauma surgeons can now rapidly diagnose basal skull fractures and related cranial injuries . the skull base contains a number of areas where bones are weak and through which fractures tend to extend . these areas include the internal and external auditory canal , middle ear , carotid canal and foramen lacerum , jugular foramen , hyoglossal canal , occipital condyle , and foramen magnum9 ) . pneumocephalus is an important condition to be vigilant of , along with symptoms of increased intracranial pressure , such as , anisocoria , hemiparesis , and signs of meningeal irritation2 ) . frontobasal fractures generally injure olfactory or optic nerves , whereas cranial nerve palsy of nerves iii , iv , v , and vi have been reported for fractures involving the cavernous sinus and superior orbital fissure , because these nerves exit the skull base through the superior orbital fissure . in particular , for fractures of the skull base , the long intracranial course of the sixth nerve renders it particularly susceptible to injury . as mentioned above , cn vi may be damaged in the superior orbital fissure and is classically accompanied by cn iii and cn iv palsies . however , in the described case , right vi nerve palsy was associated with a clivus fracture without fracture of the right side of the superior orbital fissure . furthermore , vertical movement of the brain stem during trauma may stretch or avulse the nerve on leaving the pons in the absence of a fracture of the superior orbital fissure . treatment is conservative and in most cases , abducens nerve injury recovers spontaneously after approximately 4 weeks . the glossopharyngeal , vagus , and spinal accessory nerves exit the skull base in the jugular foramen , whereas the hypoglossal nerve passes though the hypoglossal foramen just medial to the jugular foramen . palsies of nerves ix , x , xi , and xii have been reported in patients with basal skull fractures , especially in patients with occipital condyle fractures . three types of occipital condyle fractures have been described by anderson and montesano1 ) . in the described case , the fracture was believed to be an avulsion fracture of the occipital condyle by the alar ligament injury , which corresponded to a type iii occipital condyle fracture , and caused depression into the foramen magnum resulting in xii nerve palsy . because of the proximity of cranial nerves in the craniofacial and skull base regions , localized trauma can result in cranial nerve injuries . the early recognition of injury patterns of the skull base can lead to rapid diagnosis and prompt appropriate management .
oblique basal skull fractures resulting from lateral crushing injuries involving both clivus and occipital condyle are rare due to their deep locations . 
 furthermore , these fractures may present clinically with multiple cranial nerve injuries because neural exit routes are restricted in this intricate region . 
 the authors present an interesting case of basal skull fractures involving the clivus and occipital condyle and presenting with sixth and contralateral twelfth cranial nerve deficits . 
 clinico - anatomic correlations and the courses of cranial nerve deficits are reiterated . to the authors ' knowledge , 
 no other report has been previously issued on concomitant sixth and contralateral twelfth cranial nerve palsies following closed head injury .