Arachnoiditis with epidural abscess

Case contributed by Dr Andrei Diacon


Severe lower back pain overnight after exercising earlier in the day. Fever and positive MSSA blood cultures on admission the following morning.

Patient Data

Age: 50 years
Gender: Male

MRI on admission

Findings consistent with L5/S1 disc degenerative changes. No epidural abscess identified.

Extensive work-up performed for source of MSSA septicaemia. Intravenous antibiotics commenced. Transoesophageal echocardiogram found no vegetations. No skin source identified.

Despite appropriate antibiotics, the CRP continued to stay around 200 and blood cultures persisted to be positive. The patient went on to develop a left L5 grade 3 and S1 grade 4 radiculopathy. No other neurology. No meningism.

A repeat MRI was ordered 9 days after the initial MRI.


Nine days later

Conus dural enhancement and clumping of the nerve roots suggestive of arachnoiditis. Small area of loculated fluid at the left L5/S1 level posterolaterally. Right L5/S1 facet joint fluid.

Case Discussion

The patient went on the following morning to have an L5/S1 laminectomy and drainage of extradural pus. Intraoperatively there was considerable pus under pressure. Multiple samples were sent which all came back positive for polymorphs but no new bacteria were cultured.

Postoperatively he regained some power in his left L5 and S1 myotomes to grade 4 and 5 respectively. His back pain improved and his CRP four days later came down to 50. No further washouts were performed and the patient was discharged home on intravenous antibiotics.

This case highlights the need for appropriate serial examination and investigation despite an initially unconcerning MRI.

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Case information

rID: 54195
Published: 28th Jun 2017
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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