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it is a relatively rare condition , typically benign and resolves with conservative therapies ( 1 ) .
this has been occasionally described in the surgical published work , usually in the context of thoracic surgery or as a complication of spinal instrumentation ( 2 ) .
it initially described by gordon and hardman in 1977 as intraspinal air ( 3 ) . since then , especially with the advent of computed tomography ( ct ) , there has been an increasing number of case reports describing the presence of air within the spinal canal ( 4 ) . in 1987 ,
pneumorrhachis may be an indication of substantial vertebral column injury , especially when paraspinal hematoma , rib fractures , transverse process fractures , clavicle fractures , subcutaneous air , intramuscular air , pneumothorax , or hemothorax are also present ( 2 , 6 - 8 ) .
pneumorrhachis has also been reported with isolated head trauma and in the absence of an identifiable fracture within the skull or spine ( 9 , 10 ) .
nontraumatic causes of pneumorrhachis include infection ( 11 ) . despite known conditions that can result in pneumorrhachis the clinical significance and neurologic outcome for patients with pneumorrhachis
, we report a case of pneumorrhachis with fracture in lumbar spine and history of ankylosing spondylitis .   the axial thoracic spinal ct scan of patient
a 39-year - old man was admitted because of low back pain and dyspnea after locating between motor vehicle and wall 3 days before admission . he suffered from ankylosing spondylitis and was under corticosteroid therapy . on arrival , his glasgow coma scale was 15/15 with normal neurological examination .
he was able to move his lower extremity , but it was limited by pain .
vital signs were stable and in radiographic examination , there was rib fracture in three ribs , hemothorax , subcutaneous emphysema , and lumbar vertebra fracture in l2-l4 .
ct scan showed bilateral pleural effusion , fracture of ribs number 8 , 9 and 10 in lower left side of thorax , fracture of vertebra in l2-l4 , and air bubbles in upper thoracic spinal canal ( figure 1 ) .
the patient underwent lumbar surgery ( laminectomy and cord decompression ) and fusion of l2-l4 by screw . in according to neurosurgery consult no action performed on air bubbles .
pneumorrhachis , as the presence of free intra - spinal air , is also called aerorachia or epidural emphysema .
it usually occurs in the epidural space but may be spread within the subarachnoid space with the distraction of dura meter ( 1 ) . a significant increase in intra alveolar pressure and
intra alveolar pressure was increased in several conditions such as acute asthma , recurrent vomiting and closed thoracic trauma .
this led to alveolar rupture and air movement along the bronchovascular axis up to the mediastinum .
the collected air then disassociates the pleura from the aorta and the parietal pleura from the spine , subsequently inflowing the extradural space via the intervertebral foramina ( 12 ) .
in addition , subarachnoid air may easily move cranially and caudally and may cause back and/or local pain and headache and/or nervous tissue compression ( brain and spinal cord ) by a valve mechanism .
however , in the present case , there are not strong evidence of air diffusion between the pleura and the epidural space , it is the only pathophysiological mechanism stated in the literature ( 1 ) .  
magnetic resonance imaging is the most accurate investigation for the assessment of the extent of the condition .
the best explanation for the radiologic findings in our patient is that air , under pressure in the pleural space , entered the spinal canal and then the subarachnoid space directly through tears of the parietal pleura and the spinal meninges .
tension pneumothorax and thoracic spinal fracture should be considered in the differential diagnosis of both pneumorrhachis and pneumocephalus .
intraspinal air is usually asymptomatic , self - limiting and resolves with conservative therapies , but in a rare number of cases , pneumorrhachis can cause cord compression and may even require decompressive surgery .
appropriate antibiotic prophylaxis must be considered , however , due to increased risk of infection of the underlying breach in the dura in traumatic etiologies ( 2 ) . in comparison with others , sinha and mantle has been described a case of pneumorrhachis with rapid deterioration to death ( 14 ) .
, they presented a case of tension pneumocephalus and pneumorrhachis secondary to a subarachnoid pleural fistula after thoracic spinal surgery ( 16 ) .
valente et al reported a 21-year - old male with severe pneumocephalus and pneumorrhachis who was made a full recovery without any neurological complication ( 17 ) .  
it is usually asymptomatic and self - limiting , but its presence should alert the attending trauma physician to carry out diagnostic workup for associated injury and treat the underlying cause ( 18 ) . when seen in a trauma patient
all authors passed four criteria for authorship contribution based on recommendations of the international committee of medical journal editors .
pneumorrhachis as a relatively rare condition may be an indication of substantial intra - spinal column injury . here 
 we report a 39-year - old man was admitted because of low back pain and dyspenea after locating between motor vehicle and wall three days before admission . on arrival , 
 physical exams and vital signs were normal . computed tomography ( ct ) scan showed bilateral pleural effusion , fracture of ribs number 8 , 9 and 10 in lower left side of thorax , fracture of vertebra in l2-l4 , and air bubbles in upper thoracic spinal canal .