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patients with c1 nerve root schwannomas usually present with signs relating to nerve root compression . however , asymptomatic presentations have never been reported .
a healthy , 37-year - old female was referred in view of a slow - growing lump in the left posterosuperior aspect of the neck .
magnetic resonance imaging revealed a left c1 nerve root tumour , extending around the c1 vertebra and compressing the thecal sac .
the tumour had invaded the basiocciput and was impinging on the left cerebellar hemispheric dura .
stereotactic biopsies of the lesion showed a spindle - cell tumour exhibiting an immunoprofile consistent with a schwannoma .
the case report adds to the diverse modes of presentation of c1 nerve root schwannomas , in that such lesions must be included in the differential diagnosis of asymptomatic posterior neck lumps .
schwannomas of the c1 nerve root are rare neoplasms . cases typically present with signs and symptoms relating either directly to c1 nerve dysfunction or compression of adjacent structures , including the spinal cord and vertebrobasilar arterial system .
we present the case of a young female , who presented in view of a slow - growing posterior neck lump , which was confirmed to be a c1 nerve root schwannoma following imaging and histopathological studies .
the case is unique in that , despite the extent of disease , the patient was completely asymptomatic and neurological examination was normal .
a 37-year - old caucasian housewife , with no previous medical history , was referred to the surgical outpatient department in view of a slow - growing lump on the left posterosuperior aspect of the neck .
she had first noted the lump 7 years previously . since it was above the hairline , it was not cosmetically obvious , however , it had been growing slowly over the past years
examination revealed the presence of a smooth , hard 5 cm mass in the left posterosuperior aspect of the neck .
magnetic resonance imaging ( mri ) of the neck was performed for full characterization of the lesion .
this showed a soft tissue mass in the left occipital region , centred about the left c1 nerve , extending circumferentially around the first cervical vertebra and displacing the posterolateral thecal sac ( fig .
the lesion had eroded through the left basioccipital skull and was impinging on the dura overlying the cerebellum ( fig .
2 ) . computed tomographic ( ct ) angiography was performed and tumour vasculature was ascertained to arise from the cervical and muscular branches of the left vertebral artery ( fig .
figure 1:t1-weighted mri showing the lesion in the posterosuperior aspect of the left neck arising at the level of c1 , eroding through the c1 vertebra and displacing the thecal sac . 
 figure 2:t1-weighted mri showing the lesion eroding through the left basioccipital skull , impinging the dura overlying the left cerebellum . 

figure 3:computed tomographic angiography of the left vertebral artery showing the tumour deriving its vascular supply from the cervical and muscular branches of the artery .
t1-weighted mri showing the lesion in the posterosuperior aspect of the left neck arising at the level of c1 , eroding through the c1 vertebra and displacing the thecal sac .
t1-weighted mri showing the lesion eroding through the left basioccipital skull , impinging the dura overlying the left cerebellum .
computed tomographic angiography of the left vertebral artery showing the tumour deriving its vascular supply from the cervical and muscular branches of the artery .
histological assessment of ct - guided core biopsies taken from the lesion showed a spindle - cell proliferation set in a myxoid stroma .
the tumour was organized in fascicles , with tumour cells exhibiting focal palisading but no mitotic activity or necrosis .
immunostaining showed positivity for s100 , glial fibrillary acidic protein ( gfap ) and vimentin .
figure 4:haematoxylin and eosin ( h&e ) staining showing spindle - shaped cells organized in whorls and fascicles is shown , together with the tumour immunoprofile for s100 , gfap , epithelial membrane antigen ( ema ) , cd34 and ki-67 .
haematoxylin and eosin ( h&e ) staining showing spindle - shaped cells organized in whorls and fascicles is shown , together with the tumour immunoprofile for s100 , gfap , epithelial membrane antigen ( ema ) , cd34 and ki-67 .
the procedure was performed under general anaesthesia , with the patient prone , her head fixed in a mayfield frame and her shoulders strapped caudally .
she was given 300 mg of clindamycin preoperatively and , following serial skin disinfection , a midline incision was made extending from the external occipital protruberance to the level of the third cervical vertebra .
monopolar dissection was carried out down to the occiput and spinous vertebral processes , hence exposing the tumour , which was subsequently enucleated by blunt dissection .
the point of abutment of the tumour with the intracranial subcerebellar dura , which corresponded to a small opening in the tentorial membrane , was diathermied .
prolene 3/0. postoperative recovery was unremarkable . a review performed 6 weeks after the procedure did not reveal any complications .
an mri performed 6 months after the procedure showed the presence of scar tissue at the previous tumour site , with no evidence of residual tumour or recurrence ( fig .
figure 5:t1-weighted mri scan showing the presence of scar tissue at the previous tumour site 6 months post - operatively .
t1-weighted mri scan showing the presence of scar tissue at the previous tumour site 6 months post - operatively .
they form part of a larger category of tumours referred to as peripheral nerve sheath tumours .
schwannomas are usually solitary lesions , and can arise from any peripheral nerve , often originating from the sensory nerve roots , with motor and autonomic nerves being less frequently involved .
they are most commonly observed in patients between the ages of 20 and 50 years , in a roughly equal gender distribution [ 1 , 2 ] .
the pathogenesis behind schwannomas is incompletely understood and most cases tend to be sporadic in nature .
neurofibromatosis type 2 , which is caused by point mutations in the nf2 gene , is associated with the formation of unilateral or bilateral neuromas of the vestibular nerve , with 70% of patients also suffering from numerous peripheral schwannomas .
conversely , schwannomatosis , which is associated with mutations in the smarcb1 gene , results in the formation of numerous peripheral , often painful , schwannomas , affecting the neck , trunk and extremities .
the carney complex , a condition caused by an autosomal dominant mutation in the prkar1a gene , is associated with the formation of atrial myxomas , lentigines , blue nevi and myxoid schwannomas that often affect the upper gastrointestinal tract and sympathetic chains .
this is because the c1 nerve is unique , in that , unlike the other spinal nerves , it lacks a well - defined sensory root .
however , microscopic clusters of sensory neurons in the c1 nerve root have been illustrated in roughly two - thirds of the population , with half of these cases having a primary dorsal root and the rest deriving the sensory component from the spinal accessory nerve .
multiple case reports for c1 schwannomas exist , as illustrated in table 1 , however , this case is unique in that it is the first c1 cervical schwannoma to be completely asymptomatic . 

table 1:a synopsis of c1 nerve root schwannomas and their respective clinical presentations.authorsyearage ( years)genderpresentationgopalakrishnan et al .
201140malegiant cystic craniovertebral schwannoma with raised intracranial pressure and masquerading as a fourth ventricle massyousefzadeh et al.200960femalec1 ventral root schwannoma presenting with occipitocervical pain , spastic quadriparesis and dissociative sensory losskalavakonda et al .
200052maleleft - sided c1 schwannoma with left vertebral artery compression , causing vertigo on turning the head to the right and extending the neckhan kim et al .
200560femalec1 schwannoma eroding the c1 articular facet and transverse process , causing neck pain but no neurological symptomshelmes et al .
201229femalec1 schwannoma presenting as a mass in the craniocervical region with numbness and weakness of the left arm and leg a synopsis of c1 nerve root schwannomas and their respective clinical presentations .
traditionally , these lesions have been described on the basis of anatomy , with intradural lesions arising from the intrathecal portion of the c1 nerve root , and extradural lesions arising anywhere along the c1 nerve following passage through the theca .
the management of these tumours tends to be complex , varied and case - specific .
overall , a posterior approach is usually favoured for c1 schwannoma resection , owing to the relative low vascularity of the nuchal and paranuchal area , the absence of vital anatomical structures in the posterior dissection plane , all the while achieving optimal exposure of the tumour .
a far lateral approach is only opted for in rare cases of tumours projecting anteriorly .
abstractpatients with c1 nerve root schwannomas usually present with signs relating to nerve root compression . 
 however , asymptomatic presentations have never been reported . 
 a healthy , 37-year - old female was referred in view of a slow - growing lump in the left posterosuperior aspect of the neck . 
 the lump was asymptomatic and neurological examination was normal . 
 magnetic resonance imaging revealed a left c1 nerve root tumour , extending around the c1 vertebra and compressing the thecal sac . 
 the tumour had invaded the basiocciput and was impinging on the left cerebellar hemispheric dura . 
 stereotactic biopsies of the lesion showed a spindle - cell tumour exhibiting an immunoprofile consistent with a schwannoma . 
 the lesion was surgically excised by blunt dissection using a posterior midline approach . 
 the case report adds to the diverse modes of presentation of c1 nerve root schwannomas , in that such lesions must be included in the differential diagnosis of asymptomatic posterior neck lumps .