Epidural abscess

Clinical History

A 43-year-old immunocompetent male patient with severe abdominal pain was admitted to the emergency department (ER). Laboratory findings showed elevated acute phase reactants (APR). There were no urinary or respiratory complaints.

Imaging Findings

An abdominal ultrasound (US) was initially performed, which did not show any abnormalities. Due to the severity of the symptoms and a new onset of severe back pain along with laboratory findings, a computer tomography examination (CT) was performed with intravenous contrast administration at the ER. The abdominal CT did not show outstanding abnormalities except for changes in presacral area with some fat stranding. Spondylodiscitis was suggested as a probable diagnosis based on the narrowing of the disc space and the irregularity of the vertebral plates.
Further examination of the patient showed sudden onset of cauda equine syndrome and MRI with gadolinium was performed, revealing bilateral para-vertebral abscesses with extension to left psoas muscle and an epidural abscess with inner septa from C3 to S1. There was no clear communication between the para-vertebral and the epidural abscess, but it seems to be the most likely origin.

Discussion

Spinal epidural abscess (SEA) may cause severe neurological morbidity and its prevalence is increasing due to chronic illnesses and immunocompromised patients among other reasons [1]. They are uncommon but severe lesions with non-specific symptoms such as back pain, fever or inconclusive neurological deficits and usually the diagnosis is made after a CT or MRI is performed [2]. The most frequent pathogens are Staphylococcus Aureus, Staphylococci coagulase-negative and Streptococcus spp and the route of infections may be secondary of haematogenous spread or direct spread from an osteomyelitis [3, 4].
MRI plays a major role in the diagnosis of this condition, which usually appears hypointense in T1-WI and hyperintense on T2-WI with peripheral enhancement after the administration of Gadolinium [5].
In our patient, a high signal collection on T2-WI was found in the posterior epidural space extending from C3 to the sacrum with low signal and a rim of enhancement in T1-WI compatible with an epidural abscess. Degenerative disc diseases at the level L4–L5 with Modic type II changes in the endplates were also seen. There was no disc enhancement nor were there other findings suggestive of spondylodiscitis. Streptococcus pneumoniae was found in post-surgical samples, which probably gained access to the epidural space from the bilateral para-vertebral abscesses.
Surgical drainage along with antibiotics is the main treatment option. Surgical intervention must be performed as soon as possible, especially if neurological symptoms are present, although there is no specific guideline for the treatment of this condition [2, 6].
Our patient underwent surgical decompression with extensive laminectomy L1-L5 as well as pus drainage of the epidural space. He was discharged from the hospital after completing medical treatment, consisting in intravenous Ceftriaxone (4 weeks).
Main differential diagnosis should be made with epidural haematomas. Although the appearance of the blood varies as times passes, this condition usually shows heterogeneously T2-hyperintensity plus T1-hyperintensity-signals related to the spinal cord. Additionally, the presence of fever and para-vertebral abscesses along with the imaging findings made this diagnosis unlikely.

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Differential Diagnosis List

Final Diagnosis

Epidural abscess C3-S1 with para-vertebral abscesses.

URL:	https://www.eurorad.org/case/16031
DOI:	10.1594/EURORAD/CASE.16031
ISSN:	1563-4086