Spine structured oral questions2: Infection (epidural abscess)

EXAMINER: A 68-year-old man with a past history of a lung tumour 10 years ago presents following a fall with a 4- week history of worsening thoracic back pain. Back pain is a common presenting complaint to general practitioners and orthopaedic departments. What red flags are there to indicate possible underlying pathology?

CANDIDATE: In this individual, age, the past history of tumour, the thoracic location of his pain, and the history of trauma are all ‘red flags’. Other possibilities include: fever, weight loss, night sweats, night pain, non-mechanical pain, severe intractable pain, thoracic pain, age over 55 or below 20, a history of carcinoma, steroid use, IV drug abuse, saddle anaesthesia, urinary or bowel symptoms, deformity.

EXAMINER: Here is his MRI scan. What can you see? (Figure 5.2.)

CANDIDATE: This is a sequence of MRI scans, both T1- and T2-weighted MRI scans. There is a lesion in the thoracic spine, which appears to be compressing the spinal cord. The fact that the lesion is bright on the T2 scan implies that this is likely to be fluid filled and suggests an infective aetiology.

EXAMINER: How would you proceed?

CANDIDATE: We are aware of the history of a fall and should establish this man’s neurological status. I would start by obtaining a history and detailed neurological examination. His temperature, routine blood tests (WCC) and inflammatory markers (CRP, ESR) will help confirm the diagnosis of infection.

The most likely diagnosis is an epidural abscess with signs of neurological compression. I would therefore proceed to urgent surgical decompression of the abscess. I would not start antibiotics before obtaining a sample for microbiology and I would also send tissue to pathology (history of tumour).

Infection background knowledge

Spinal infection still remain a serious, potentially lifethreatening problem.

Diagnosis is often delayed.

MRI is the imaging modality of choice.

The vertebral body (osteomyelitis), the intervertebral disc (discitis), or the epidural space ( epidural abscess) may be affected.

In the absence of a localized collection and no neurology, initial treatment is conservative and should be treated in a similar way to osteomyelitis. (High-dose intravenous antibiotics for 6 weeks or until CRP normalizes and then oral antibiotics until there are no signs of infection.) Consider radical debridement in persistent infections.

Figure 5.2 T2-weighted sagittal MRI image epidural abscess.

Discitis is more common in younger children and vertebral osteomyelitis more common in adults. The intervertebral disc is vascular in younger children.

In the neonate intraosseous, vertebral arteries anastomose with the adjoining disc through the vertebral end plate. With increasing age the disc loses its vascularity.

Risk factors for infection include intravenous drug use, diabetes, steroid use, chronic infection and other immunocompromised states. Most infections are caused by Staphylococcus aureus or Streptococcus.

Consider decompressing an abscess in the presence of neurology and/or a localized collection. Consider radiologically guided decompression.