Antibiotics are insufficient treatment for large epidural abscesses

A study presented at the North American Spine Society annual meeting (NASS; 9–12 October, New Orleans, USA) indicates that patients with large epidural abscesses should be managed surgically or with a percutaneous drainage procedure. However, patients with smaller abscesses can be managed with antibiotics alone.

Sina Pourtaheri (St Joseph Medical Center, Paterson, USA) told delegates that data for the size thresholds at which epidural abscesses can be managed with antibiotics alone are limited. He added: “With other parts of the body, the criteria for a drainage procedure have been established for relative enhancement with contrast and specific size on MRI.”

In their study, Pourtaheri and his colleagues aimed to identify which infected epidural collections would resolve with antibiotics and at what size, as indicated by MRI, would a drainage procedure be required.  

The authors performed a retrospective analysis of 207 patients (121 men; 86 women) with spinal osteomyelitis who had not undergone a drainage procedure and who not received treatment prior to them attending the study centre (St Joseph Medical Center, Paterson, USA). They classified an abscess as large if it had a volume of ≥1.4ml on contrast MRI and cleared infections were defined as normalised serum levels and resolution of the osteomyelitis on MRI after six months of treatment.  

Pourtaheri reported that, overall, there was a higher rate of infection clearance with epidural abscesses compared with paravertebral abscesses but added that long-term improvement in Oswestry Disability Index scores were less with epidural abscesses. He commented: “Larger epidural abscesses had a greater infection clearance rate and a decreased mortality rate when treated with surgery or drainage compared with treatment with antibiotics alone (p=0.048 for each comparison).” However, smaller epidural abscesses that were managed with surgery or percutaneous drainage procedures had similar clearance and mortality rates to those that were managed with antibiotics alone (p=0.75 and p=0.13, respectively, for the comparisons).  

The presenter concluded: “Large epidural infected collections require surgery or a percutaneous drainage procedure. Neurologically intact patients with a small epidural abscess can be treated with antibiotics alone with good expected outcomes.”