CASE 13232 Published on 07.12.2015

Spondylodiscitis with fistulization to the sigmoid colon



Case Type

Clinical Cases


Alves, Jose Eduardo1; Macedo, Carlos2; Dias, Daniel1

Neuroradiology Department 1; Radiology Department 2 - Centro Hospitalar do Porto

46 years, male

Area of Interest Spine ; Imaging Technique CT, MR
Clinical History
A 46-year-old male, heavy smoker and drinker, presented with 4-month progressive lumbar back pain with radiation to the lower extremities, weight loss (15Kg), acute rectal bleeding and no fever. Blood tests showed slight anaemia with normal white cell count and no elevation of inflammatory markers.
Imaging Findings
Abdominopelvic CT (Fig 1) showed a decrease of intervertebral space, irregularity of the vertebral endplates at L5-S1 (a), alongside thickening of anterior paravertebral soft tissues (b, black arrows in c).
Lumbar MRI (Fig 2) revealed low T1, bright T2 and intense enhancement of the L5-S1 disc and adjacent endplates, compatible with spondylodiscitis (a). It also showed anterior epidural enhancement (a) and an anterior paravertebral abscess (* in d). There is a fistula between the disc, the prevertebral abscess and the sigmoid colon (b, c and black arrows in e).
Colonoscopy confirmed the presence of an ulcer at the distal sigmoid colon, corresponding to the enteric opening of the fistula.
There were no other lesions in the colon. Biopsy of the sigmoid lesion was negative for a neoplastic process and no infectious agent was isolated.
The patient underwent empiric intravenous antibiotic therapy with ceftriaxone and vancomycin, with clinical and analytical improvement.
Spondylodiscitis is an infection affecting intervertebral discs and adjacent vertebral bodies. Although relatively rare, this is a potential life-threatening condition and its incidence has been increasing, both due to an improvement in diagnostic accuracy and an increase in susceptible populations [1, 2].
Radiologists play a crucial role in early diagnosis of spondylodiscitis, as the clinical presentation is often subtle, indolent and nonspecific – back pain, tenderness to palpation, weight loss, malaise – often leading to a delay of several months between first symptoms and diagnosis. Fever is inconsistently present and inflammatory markers may be normal [3].
In developed countries, pyogenic infections are most common, caused by bacteria like Staphylococcus aureus or Enterobacter species, and hematogenous spread is by far the most frequent route of infection. Direct inoculation is becoming more common and is frequently iatrogenic, related to spine surgery or therapeutic spinal injections [4].
Direct extension from contiguous infection is the rarest cause of spondylodiscitis. There are very few reports of spondylodiscitis secondary to digestive fistulas and those usually occur in the cervical spine, associated to oesophageal rupture (leaking anastomosis after cancer surgery) or to extension from retropharyngeal abscesses [5, 6].
Spondylodiscitis due to a fistula between the colon and lumbar spine is even rarer, and we could only find a single previous case report [7]. Contrary to that case, which occurred after sigmoid adenocarcinoma surgery, our patient didn't present any predisposing conditions, apart from chronic alcoholism. Aetiologic investigations were all negative, including for a neoplastic process and inflammatory bowel disease, and a benign ulcer of the sigmoid colon was assumed.
Although abdominal CT was suspicious for spine infection – showing endplate irregularity and a presacral mass – MR proved more useful, showing not only the classical findings in pyogenic spondylodiscitis – T1 hypointensity, fat-suppressed T2 hyperintensity and intense enhancement of both disc and adjacent vertebral endplates [3] – but also the presence of paraspinal abscess and epidural inflammation, as well as depicting the existence of a fistula to the sigmoid colon, which was then confirmed by colonoscopy.
In clinical practice, MRI, due to its higher sensitivity and specificity, is the imaging modality of choice for diagnosing spondylodiscitis and assessing possible complications [3]. CT provides excellent depiction of bone involvement, but may be normal in early-stage infection and may miss epidural involvement due to beam-hardening artifacts [8]. Nuclear medicine imaging is used only in select situations, due to its limited spatial resolution and availability [3].
Differential Diagnosis List
Spondylodiscitis with fistulization to the sigmoid colon
Granulomatous spinal infection
Modic type 1 changes
Final Diagnosis
Spondylodiscitis with fistulization to the sigmoid colon
Case information
DOI: 10.1594/EURORAD/CASE.13232
ISSN: 1563-4086