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Missed diagnosis of oesophageal perforation in ankylosing spondylitis cervical fracture: Two case reports and literature review

Oesophageal perforation after blunt injury cervical fracture in patients with ankylosing spondylitis (AS) is rarely reported. The early diagnosis of oesophageal perforation is extremely important. We present two cases of patients with AS who sustained cervical fracture dislocation and spinal cord injury. The ossified sharp fragments caused oesophageal perforation, and the delayed diagnoses had serious consequences. Oesophageal perforation should be suspected in patients with AS and cervical fracture if bone fragments are pressing against the oesophagus and a gas shadow is visible around the fracture site on computed tomography imaging.


Introduction
The early diagnosis of oesophageal perforation after blunt injury is extremely important, but diagnosis is complicated by rarity and lack of specific symptoms. 1 We present two cases of patients with ankylosing spondylitis (AS) who sustained cervical fracture dislocation and resulting cervical oesophageal perforation due to sharp, dislocated bone fragments. Concern over immediate, urgent symptoms caused the early signs of oesophageal perforation to be overlooked, with serious consequences.

Case reports Case1
A 43-year-old man presented at the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China, on 28 September 2014, following a motor vehicle accident. Computed tomography (CT) imaging of the cervical spine revealed AS and fracture-dislocation at C6-C7 ( Figure 1A). Magnetic resonance imaging (MRI) showed wide-ranging oedema and contusion of the spinal cord ( Figure 1B).
On admission, physical examination revealed a midrange swelling of the neck and tenderness of the left shoulder. X-radiography indicated a C6-C7 fracture-dislocation, with an appreciable perivertebral gas shadow ( Figure 1C), but this was overlooked by medical staff. The patient's temperature increased to >38.5 C, and sudden serious dyspnoea occurred 3 days after admission to the intensive care unit (ICU). The patient was intubated via oral endotracheal catheter and was successfully resuscitated. Repeat cervical spine CT imaging indicated perivertebral gas accumulation around the fracture site ( Figure 1D). Oesophageal perforation and mediastinitis were strongly suspected. The patient was immediately treated with fluid infusion, intravenous broad-spectrum antibiotic therapy and supportive therapy, and was nil-by-mouth. His temperature gradually rose to >39 C and the neck swelling became increasingly apparent. CT imaging indicated a massive perivertebral gas accumulation at the cervical and thoracic spine ( Figures 1E and 1F). White blood cell count was 25 Â 10 9 /l with 96.2% neutrophils, and C-reactive protein (CRP) was 183 mg/l, indicating infection. After consultation with thoracic surgeons, tracheal incision and cervical drainage was carried out with extensive debridement, releasing large quantities of gas. Oesophagoscopy revealed a 17 cm-deep fistulous opening below the patient's incisor. The patient ultimately died due to complications resulting from the infection.

Case 2
A 77-year-old man presented at the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China, on 12 December 2014 with a cervical fracture resulting from a fall. Before arrival, the local hospital had placed a nasogastric tube to ensure gastrointestinal decompression. On admission, CT imaging revealed AS and fracture-dislocation at the C7 level. Bone fragments were pressing against the oesophagus, but there was no obvious gas shadow around the fracture site (Figure 2A). MRI indicated soft tissue swelling around the fracture (Figure 2B).
At 2 days after admission, the patient's temperature rose to >38.8 C, his white blood cell count was 19.6 Â 10 9 /l and his CRP was 82.01 mg/l. Chest CT imaging revealed compression of the soft tissue between the C7 fragments and the oesophagus, and a small gas shadow around the fracture site ( Figure 2C). These findings strongly suggested oesophageal perforation. Fluid infusion, intravenous broad-spectrum antibiotic therapy and supportive therapy were given immediately. Oesophagoscopy revealed a 19 cm-deep opening below the incisor. The patient recovered following surgery and long-term anti-infective therapy.
Both patients provided written informed consent for publication. The School of Medicine, Hangzhou, China, does not require ethical approval for reporting individual cases.

Discussion
The early diagnosis of oesophageal perforation is very important in blunt injury, as primary closure within 24 h results in favourable outcome (92% survival). Delayed diagnosis and treatment is associated with significantly higher mortality. 2,3 Few cases of oesophageal perforation in patients with cervical fracture have been reported 4,5 and no cases in individuals with AS. AS increases the risk that ossified sharp bone fragments will perforate the oesophagus. 6 Initial evaluation for oesophageal perforation can be performed by X-radiography, which has been shown to be suggestive in 86-88% of patients. 7,8 Lateral cervical X-radiography can identify prevertebral gas earlier than chest radiography. 9 However, X-radiography may fail to identify small-scale oesophageal leakage, especially in patients with cervical fracture (where the surgeon tends to focus on the dislocation and spinal injury). Evidence suggests that CT imaging enables better diagnosis and management than X-radiography, 10,11 and should be performed before contrast-enhanced oesophagography. 12,13 Extraluminal gas is the most common CT finding associated with oesophageal perforation, occurring in 92% of cases. 14,15 In the early stage of oesophageal perforation there may be a negligible gas shadow around the fracture site, which can be easily overlooked. If CT imaging reveals pressing of bone fragments against the oesophagus, especially in patients with AS, close attention should be paid to the possibility of erosion and perforation of the oesophageal mucosa.
Contrast oesophagography is the standard diagnostic tool for oesophageal perforation 16 and barium contrast oesophagography should be used if no perforation is detected. 17,18 This technique cannot be easily used in patients with cervical spine injury, however. Flexible oesophagoscopy has a sensitivity of 95.8-100% and a specificity of 92.4-100% in the evaluation of penetrating oesophageal injury and can provide a direct visualization of the perforation; it is thought to be a useful diagnostic tool with a good safety profile in the early evaluation of penetrating injuries. [19][20][21] In our two cases, oesophageal perforation was confirmed via flexible oesophagoscopy, but no images were taken due to the emergent situation.
Ankylosing spondylitis is a chronic inflammatory rheumatic disease that can cause extensive remodelling of the spinal axis, leading to rigidity and fragility of the spinal column. 22 Spinal fractures in patients with AS are usually sharper and more unstable than in individuals without AS. [23][24][25] The ossified sharp fragments in AS may cause oesophageal injury during the process of fracture dislocation. In the cases reported here, mediastinitis and haematosepsis were a direct result of oesophageal perforation. Close attention should therefore be paid to the possibility of oesophageal injury in patients with AS.
In conclusion, very small perivertebral gas shadows on CT imaging should be regarded as a possible early diagnostic sign for oesophageal perforation in cervical fracture, especially for any patient with AS. Pressing of sharp bone fragments against the oesophagus may be a precursor to perforation. Delayed diagnosis and treatment can have serious consequences.

Declaration of conflicting interest
The authors declare that there are no conFicts of interest.

Funding
This study received funding from The National Natural Science Foundation of China (Grant no. 81472065) and Health Research Fund for health department of Zhejiang Province (Grant no. 2007A140).