anterior cervical discectomy with fusion ( acdf ) is one of the most widely used techniques in the neurosurgical management of cervical spondylosis and disc herniation3,8,11 ) . most infections occur during the early postoperative period , as a result of operative seeding or poor wound care2 ) . but in case 1 , spinal epidural abscess ( sea ) occurred during the late postoperative period , and there was no evidence of esophageal perforation or zenker 's diverticulum . there are some studies that address low instrument failure rate or infection rate after cervical artificial disc replacement ( adr ) , but a pool of evidence is still lacking4 ) . in case 2 , both cases reveal that sea may cause ascending infection , extending to upper cervical and finally to brain , resulting in life threatening septic condition due to bacterial meningitis . a healthy 68-year - old man underwent surgery from another clinic for c5 - 6 and c6 - 7 disc herniation . the surgery was performed by the anterior cervical approach consisting of discectomy followed by fusion ( acdf ) with allograft and plate - screw construction . 14 months later , the patient was transferred to our hospital with progressive paraparesis ( upper extremities motor grade 3/2 , lower extremities motor grade 3/3 ) , urinary retention and posterior neck pain that started 2 weeks before . x - ray and computer tomography ( ct ) demonstrated moderate graft extrusion and screw loosening . but most important finding was gas collection on ventral portion of epidural space ( fig . gadolinium - enhanced magnetic resonance imaging ( enhanced mri ) was performed directly to reveal high - signal intensity sea with a diameter of 10 mm . the sea was located in the anterior epidural space from c4 to c5 , and caused marked compression of the spinal cord ( fig . but , laboratory infection markers were high . estimated sedimentation rate ( esr ) was 35mm / hr ( normal range 0 - 15 mm / hr ) , c - reactive protein ( crp ) was 193.4mg / l(normal range 0 - 3mg / l ) , and the white blood cell ( wbc ) count was 16,100/mm ( normal range 4,500 - 11,000/mm ) . epidural space was massively irrigated with normal saline . before closure , esophagus was inspected , and esophagography was performed after surgery . empirically , vancomycin was administered immediately after surgery to cover methicillin - resistant staphylococcus aureus ( mrsa)5,17 ) . but tissue culture revealed streptococcus anginosus so the patient was treated with appropriate 2 line antibiotics ( ceftriaxone+metronidazole ) . minneapolis , mn , usa ) and interlaminar fusion was performed on c3 - 7 . after surgery , there was an immediate neurological recovery - up to upper extremities motor grade 4/3 , lower grade extremities motor 4/4 . enhance mri showed an epidural abscess that ascended to the c2 ventral level ( fig . the patient was continued on antibiotics for 7 weeks , but anterior cervical wound was still unhealed and pus leaked out . 4 weeks after wound exploration , the patient showed altered mentality . enhanced brain mri showed meningeal enhancement ( fig . 2b ) and cerebrospinal fluid ( csf ) analysis showed an elevated white cell count of 870/mm ( normal range 0/mm ) , and protein concentration of 86mg / dl(normal range 10 - 45 mg / dl ) . as 3 line antibiotic therapy seemed to have failed , linezolid was started for 4 line . a 52-year - old male presented with a c6 - 7 disc herniation resulting in right arm radicular pain . he underwent an uncomplicated c6 - 7 discectomy and artificial disc replacement ( prodisc - c ; synthes , west chester , pa , usa ) ( fig . after surgery , right arm pain improved , and he was discharged home on postoperative day 4 without any event . we planned for revision the next day , and routine lab for operation preparation was held . esr / crp were elevated to 60mm / h/66.7mg / l but he was in afebrile state with no clinical evidence to suspect infection besides neck pain . upon exploration of previous operation site , small amount of yellowish pus like discharge was found at prevertebral space just anterior to c6 and artificial disc . bone graft , harvested from the iliac crest , was placed between the vertebral bodies c5/c7 , and an anterior plate was applied ( vectra ; synthes , west chester , pa , usa ) ( fig . but wbc , esr , crp were rising , wound was unhealed , pus leakage persisted , and fever did not subside . epidural abscess was noted on c3 - 7 , resulting in slight compression of the cord ( fig . we removed the implant and massive irrigation was held . but 7 days after surgery , patient showed sudden weakness on right upper extremity to grade 1 . another emergency surgery was performed . at first , c2 - 6 corpectomy was performed via previous incision . few days later , altered mentality and unstable vital sign were noted , and the symptoms continued for more than a week . patient was treated in intensive care unit because of bacterial meningitis and septic condition . esr / crp dropped continuously till 44/13.35 and there was no more discharge from wound . after another 4 weeks of absolute bed rest , we permitted walker - assisted ambulation with four poster brace wearing . 2 months later , esr / crp declined to 14/0.7 and follow up mri revealed complete resolution of the epidural abscess and no further evidence of spinal cord compression ( fig 4c ) . . the initial plan was anterior and posterior fusion , but anterior surgical plane was too adhesive and dural thinning was noted , indicating that anterior fusion had failed . in the posterior fusion approach , polyaxial screw - rod system(synapes ; synthes , west chester , pa , usa ) was used for c2-t2 fixation through the pedicle ( fig . the patient 's neurology improved - right upper motor up to grade 4 , and other motor grades 5 , and laboratory tests also returned to normal . he was discharged and there was no additional event during outpatient follow - up period . a healthy 68-year - old man underwent surgery from another clinic for c5 - 6 and c6 - 7 disc herniation . the surgery was performed by the anterior cervical approach consisting of discectomy followed by fusion ( acdf ) with allograft and plate - screw construction . 14 months later , the patient was transferred to our hospital with progressive paraparesis ( upper extremities motor grade 3/2 , lower extremities motor grade 3/3 ) , urinary retention and posterior neck pain that started 2 weeks before . x - ray and computer tomography ( ct ) demonstrated moderate graft extrusion and screw loosening . but most important finding was gas collection on ventral portion of epidural space ( fig . gadolinium - enhanced magnetic resonance imaging ( enhanced mri ) was performed directly to reveal high - signal intensity sea with a diameter of 10 mm . the sea was located in the anterior epidural space from c4 to c5 , and caused marked compression of the spinal cord ( fig . but , laboratory infection markers were high . estimated sedimentation rate ( esr ) was 35mm / hr ( normal range 0 - 15 mm / hr ) , c - reactive protein ( crp ) was 193.4mg / l(normal range 0 - 3mg / l ) , and the white blood cell ( wbc ) count was 16,100/mm ( normal range 4,500 - 11,000/mm ) . epidural space was massively irrigated with normal saline . before closure , esophagus was inspected , and esophagography was performed after surgery . empirically , vancomycin was administered immediately after surgery to cover methicillin - resistant staphylococcus aureus ( mrsa)5,17 ) . but tissue culture revealed streptococcus anginosus so the patient was treated with appropriate 2 line antibiotics ( ceftriaxone+metronidazole ) . minneapolis , mn , usa ) and interlaminar fusion was performed on c3 - 7 . after surgery , there was an immediate neurological recovery - up to upper extremities motor grade 4/3 , lower grade extremities motor 4/4 . enhance mri showed an epidural abscess that ascended to the c2 ventral level ( fig . the patient was continued on antibiotics for 7 weeks , but anterior cervical wound was still unhealed and pus leaked out . 4 weeks after wound exploration , the patient showed altered mentality . enhanced brain mri showed meningeal enhancement ( fig . 2b ) and cerebrospinal fluid ( csf ) analysis showed an elevated white cell count of 870/mm ( normal range 0/mm ) , and protein concentration of 86mg / dl(normal range 10 - 45 mg / dl ) . as 3 line antibiotic therapy seemed to have failed , linezolid was started for 4 line . a 52-year - old male presented with a c6 - 7 disc herniation resulting in right arm radicular pain . physical examination demonstrated no apparent abnormal finding . he underwent an uncomplicated c6 - 7 discectomy and artificial disc replacement ( prodisc - c ; synthes , west chester , pa , usa ) ( fig . after surgery , right arm pain improved , and he was discharged home on postoperative day 4 without any event . we planned for revision the next day , and routine lab for operation preparation was held . esr / crp were elevated to 60mm / h/66.7mg / l but he was in afebrile state with no clinical evidence to suspect infection besides neck pain . upon exploration of previous operation site , small amount of yellowish pus like discharge was found at prevertebral space just anterior to c6 and artificial disc . bone graft , harvested from the iliac crest , was placed between the vertebral bodies c5/c7 , and an anterior plate was applied ( vectra ; synthes , west chester , pa , usa ) ( fig . but wbc , esr , crp were rising , wound was unhealed , pus leakage persisted , and fever did not subside . epidural abscess was noted on c3 - 7 , resulting in slight compression of the cord ( fig . we removed the implant and massive irrigation was held . but 7 days after surgery , patient showed sudden weakness on right upper extremity to grade 1 . another emergency surgery was performed . at first , c2 - 6 corpectomy was performed via previous incision . few days later , altered mentality and unstable vital sign were noted , and the symptoms continued for more than a week . patient was treated in intensive care unit because of bacterial meningitis and septic condition . esr / crp dropped continuously till 44/13.35 and there was no more discharge from wound . after another 4 weeks of absolute bed rest , we permitted walker - assisted ambulation with four poster brace wearing . 2 months later , esr / crp declined to 14/0.7 and follow up mri revealed complete resolution of the epidural abscess and no further evidence of spinal cord compression ( fig 4c ) . . the initial plan was anterior and posterior fusion , but anterior surgical plane was too adhesive and dural thinning was noted , indicating that anterior fusion had failed . in the posterior fusion approach , polyaxial screw - rod system(synapes ; synthes , west chester , pa , usa ) was used for c2-t2 fixation through the pedicle ( fig . the patient 's neurology improved - right upper motor up to grade 4 , and other motor grades 5 , and laboratory tests also returned to normal . he was discharged and there was no additional event during outpatient follow - up period . postoperative spine infections are rare due to the rich blood supply of the vertebrae and the prophylactic use of antibiotics12 ) . however , the use of instrumentation exhibit a higher risk of infection13 ) . the pathogenetic mechanism of postoperative sea is assumed to be a result of direct inoculation of the offending pathogen during surgery , and/or dissemination from other infection sites18 ) . in general , infections associated with acdf occur in the early postoperative period . if they occur late after surgery , esophageal perforation or zenker 's diverticulum should be suspected16 ) . many patients have one or more predisposing factors such as underlying disease , previous intervention , or a potential local or systemic cause of infection6 ) . case 1 is a unique example of a sea in the absence of , esophageal perforation , diverticulum , and other previously reported risk factors for late infection . the presence of spinal implants may be a risk factor for deep , delayed wound infection in the setting of surgery . micro injury of esophagus due to implants or microtrauma effect must be strongly considered in pathophysiology2 ) . adr associated infection rate and implant failure rate are both low4 ) . in case 2 , both complications occurred concomitantly , and such cases have not been reported well previously . but in real field , it is not easy to suspect sea , and if diagnosed after severe neurologic deficit , its morbidity and mortality are high5,17 ) . in our cases , both patients showed ascending extension of sea that led to bacterial meningitis and septic conditions . fever , back pain , and progressive neurologic deficits have been thought as the triad of spinal epidural abscess1,17 ) . the crp level rises faster at the onset of inflammation and returns to normal sooner than the esr19 ) . staphylococcus aureus has been reported as the most frequently causative organism for spinal epidural abscess5,17 ) . therefore , before pathogen confirmation , prophylactic antibacterial therapy should cover a broad spectrum that includes staphylococcus aureus . enhanced mri is the imaging method of choice because it is highly sensitive , less invasive , delineates both the longitudinal and paraspinal extensions of the abscess , and may help differentiate infections from cancer on the basis of the appearance and the signal intensity of the image15 ) . the management of sea has remained controversial , with both proponents of non - operative and of operative treatments reporting good results . however , nonoperative managements require longer protracted courses of antibiotics and close neurological monitoring7 ) . if neurological abnormalities occur , there is no doubt in performing surgical interventions in early period1 ) . a surgery is performed with the aim of obtaining a definitive pathological and microbiological diagnosis , followed by decompression of neural tissue . posterior longitudinal ligament ( pll ) should be eliminated because pll and epidural venous plexus are important routes of ascending infection10 ) . but once such a case of deep infection as sea occurs , aggressive surgical intervention should be considered . we assume aggressive surgical intervention with anti - bacterial treatments are necessary for prevention of life - threatening courses in such cases .
we report two cases of cervical spinal epidural abscess ( sea ) , which are related to anterior cervical surgeries . 
 the first case reveals a late postoperative infection without any predisposing factor . 
 the second case reveals combined complication of infection and instrument failure ( artificial disc ) . both two cases manifested ascending infections that are unusual courses of anterior cervical infections . 
 the abscess extended upwards and , finally , caused life threatening bacterial meningitis . 
 we suggest aggressive surgical interventions with anti - bacterial therapies in such cases .