stenosis of the cervical spine at the level of atlas is a rare entity in children .
there are scattered case reports in the medical literature but little is mentioned in the text books .
we report this case of a 10-year - old boy who presented with progressively deteriorating quadriparesis which was preceded by a trivial injury .
a 10-year - old boy presented with complaints of progressively increasing weakness of all four extremities for one year .
complaints of painful and restricted neck movements both on the vertical and horizontal axis were present since one year .
child had wasting of left hand and forearm muscles and occasional symptoms of lhermitte s phenomenon .
there was a history of trivial trauma three months prior to the onset of complaints .
the child fell from a running bullock cart but had no symptoms at the time of fall . on examination
there was wasting of trapezius , sternocleidomastoid , suboccipital group of muscles on the left side along with left forearm and hand muscles wasting .
posterior column sensation was impaired and pain and temperature was lost from c2 to t4 dermatome on the left side .
radiogram of the cv junction did not reveal any abnormality on the neutral or flexion and extension views .
high - resolution thin - section computed tomography of the cv junction revealed a fusion defect of atlas posterior arch in the center with a faint bony bar in the canal [ figures 1 and 2 ] .
magnetic resonance imaging showed a posteriorly compressing atlas stenosis with a syringomyelia extending from medulla to c5 vertebra level [ figure 3 ] .
part of occiput up to c3 spinous process was exposed . on dissection we found that there was no fusion defect of c1 arch ,
rather the posterior arch was incurved inward towards the canal in an odd fashion , which was severely compressing the cord .
the posterior arch was excised in the midline along with the compressing incurved element and immediately the pinched cord was released of compression and started pulsating wonderfully .
ct scan axial section showing the posterior arch defect reconstructed ct scan showing the compressing element mri sagittal section showing severe constriction a per - operative flexion  extension radiograph of the cv junction  was taken to look for any instability which was not there and therefore no instrumentation was attempted .
post - operatively the child did well . there was immediate improvement in his respiratory embarrassment and gradually the spasticity came down .
sutures were removed on the seventh post - operative day and the child was discharged with advice of physiotherapy .
fissures and defects of atlas arch are very rare but when present they are commoner in posterior arch compared to anterior arch .
the incidence of posterior arch defect is 0.69% on a study of 1440 lateral cervical film .
posterior midline cleft is the most common defect of all posterior arch defects comprising more than 90% of all posterior arch defect and an incidence of 3 to 4% . according to hinck , the sagittal diameter of spinal canal at the level of c1 ranges between 15 and 20 mm . in our patient
the diameter of spinal canal at the level of atlas was only 7 mm on thin cut high - resolution computed tomography .
there are sporadic case reports but most of them are in adults.[38 ] radiologically similar picture has been mentioned by sharma et al . only a single case report of a similar fashion was reported in 2000 by po - chou lilang , et al .
developmental stenosis usually occurs below the c3 vertebral level and rarely above c2.[1012 ] in children the atlantal stenosis may be due to a variety of congenital anomalies ranging from achondroplasia , aplasia , dysplasia or hypoplasia of the atlas arch .
various defects have been mentioned by a. currarino et al , , which is shown in [ table 1 ] .
the defect of this child do not fit in any of this described categories by curranino et al .
this patient radiologically has the appearance of a bifid arch but on operative view it was rather an incurved oblong - shaped posterior arch where it was continuous with no evidence of any discontinuity .
the incurved part was hence not picked up in ct scan and there was an impression of bifid arch .
histopathology of the excised posterior arch did not reveal any abnormal structure other than the osseous components .
compression due to bifid posterior arch has been reported in five children by devi et al .
goel et al reported on the association of spinal stenosis due to posterior compression in three patients with atlantoaxial dislocation . they may remain asymptomatic and diagnosis may not be made up to 510 years of age as hemi - arches may remain unfused normally .
on the other hand they may be symptomatically critical as they may cripple patients completely .
this child was already having respiratory embarrassment and further delay in treatment could have proved fatal .
the contribution of trauma can not be ruled out as there was a history of trivial injury but there was no radiological or per - operative evidence for a traumatic origin .
the inward mobility of the posterior fragment during extension of the cervical spine is well demonstrated in two patients in a study by sharma et al .
this could be the possible reason in our patient in response to the trivial trauma .
compensatory hypertrophy of c2 spinous process may occur due to insertion of ligament and musculature , which would normally have been inserted in the c1 posterior tubercle .
impingement of the cord due to buckling of the posterior arch leads to compressive symptoms .
radiograph remains the first line of investigation but in this case the defect was not very clearly defined .
computed tomography vividly revealed bony pathology at the level of atlas when thin high resolution section was taken . on retrospective review of the scan
postoperatively , we could make out the curved shape of the posterior arch compressing the cord .
isolated stenosis of the atlas in children is a rare event and the incidence is not known so far .
 we report here a rare case of high cervical stenosis at the level of atlas who presented with progressively deteriorating quadriparesis and respiratory distress . a 10-year - old boy presented with above symptoms of one - year duration with a preceding history of trivial trauma prior to onset of such symptoms . 
 cervical spine mri revealed a significant stenosis at the level of atlas from the posterior side with a syrinx extending above and below . 
 high - resolution computed tomography of the above level yielded an ill - defined osseous bar compressing the canal at the level of c1 posterior arch , which appeared bifid in the midline . the patient was immediately taken up for surgery in view of his respiratory complaints . 
 the child showed an excellent recovery after excision of the posterior arch of atlas and removal of the compressing osseous structure . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSIONS