What is the onset mechanism of internal hernia after vertebral body fracture? A case of internal hernia secondary to traumatic vertebral fracture

Background

Mechanical intestinal obstruction caused by entrapment of the small intestine within the space of fractured or dislocated vertebral bodies is exceedingly rare. Traumatic incarceration of the small bowel accompanied by vertebral fractures and dislocation is often not diagnosed until the time of laparotomy. Intravenous contrast-enhanced CT and MRI are helpful for the diagnosis of incarcerated small bowel. However, the mechanism responsible for traumatic incarceration of the small bowel is not yet known. The histopathological specimen obtained in the presently reported case may suggest the mechanism responsible for the incarceration.

Written informed consent for participation was obtained from the patient.

Case presentation

On 21 April 2020, a 67-year-old man was pinned between a basket crane and a tree while trimming trees, and he subsequently experienced severe chest and lower back pain and a decreased appetite. When his symptoms failed to improve the following day, he was transferred to another hospital by ambulance. Additional examination resulted in a diagnosis of a traumatic rib fracture and incarceration of the small bowel associated with fracture and dislocation of the third lumbar vertebra (L3) (figure 1C), and the patient was transferred and urgently admitted to our hospital. Scratches were observed on the right side of the patient’s trunk on admission (figure 2A). The rib fracture was treated conservatively. The patient’s abdominal symptoms were stable on admission, and a CT examination did not show a closed loop sign. However, the patient started to experience bile-stained vomiting and abdominal distention. We decided it would be advantageous to prioritise gastrointestinal (GI) decompression before surgery considering that a surgery would be much easier and safer. GI decompression was achieved by inserting an ileus tube because of the increased bile-stained vomiting and the aggravation of the abdominal distention. The patient underwent a laparotomy after performing GI decompression on the fifth day after his injury. After his condition had stabilised, posterior lumbar fixation was performed 2 weeks after the laparotomy. There were no abdominal complications or lower limb neurological deficits during the follow-up period.

Investigations

The patient’s leucocyte count and C reactive protein level increased to 13.57×10⁹/L, respectively, and his creatine phosphokinase level rose to 828 U/L at the time of admission.

An MRI examination revealed an L3 fracture-dislocation (figure 1E). Abdominal CT showed a severe intestinal obstruction in the space surrounded by the abdominal aorta, inferior vena cava and L3 vertebra, associated with an L3 fracture-dislocation, but no closed loop sign was observed in the intestine (figure 1A,D). A GI contrast image obtained via the ileus tube showed an intestinal migrated image (calibre change) in the small intestine at the L3 level (figure 1B). Macroscopic examination of the serosal surface of the incarcerated intestinal tract indicated adipose tissue in the damaged retroperitoneal space. The red dotted line in figure 2E indicated the area where the intestine was resected and extracted from the damaged retroperitoneal space, and the thick black arrow showed the surgical resection line in histopathological image. Histopathological examination of the serosal surface of the incarcerated intestinal tract also indicated a fusion line (showed by the thin black arrows) between the intestinal serosa and the parietal peritoneum attached with adipose tissue in the disc space. The serosa and parietal peritoneum were recognised as a single line of adhesion as a result of inflammation (figure 2E).

Differential diagnosis

Initially, the patient had no tenderness in the abdomen, and a neurological examination revealed no sensory deficit or muscle weakness. Abdominal pain can be misdiagnosed or overlooked in patients with acute spinal trauma. Paralytic ileus resulting from spinal injuries or retroperitoneal haematomas are more frequently diagnosed than small bowel incarceration since the symptoms mimic ileus. We evaluated CT scanning and MRI examinations in our diagnosis. After further examination, the patient was diagnosed with incarceration of the small bowel accompanied by a fracture and dislocation of the L3 vertebra (figure 1C).

Treatment

The rib fracture was treated conservatively. GI decompression was performed by inserting an ileus tube because of an increase in bile-stained vomiting and aggravation of abdominal distention. On day 5 after the injury, laparotomy was performed after decompressing the GI tract. An ileal loop incarcerated within L3 was observed (figure 2B). A distended intestinal segment 180 cm distal to the ileocecal valve was seen disappearing behind the abdominal aorta through a 4×5 cm hole in the retroperitoneum at the L3 level together with a rupture of the anterior longitudinal ligament (figure 2C). The damaged, perforated bowel segment was resected (figure 2D), and an end-to-end anastomosis was performed.

The initial CT scan did not show a closed loop sign. This is a weak point of CT imaging. It was thought that repeated CT examinations should be required when the diagnosis was uncertain. After the patient’s condition had stabilised, posterior lumbar fixation was performed 2 weeks after the laparotomy.

Outcome and follow-up

Seven months after the abdominal and orthopaedic surgery, the patient is now back at work and doing well. The patient had no abdominal complications or lower limb nerve function deficiency during the follow-up period.