Bacterial Brain Abscess with Paradoxical Reaction: Three Case Reports and Literature Review
Akira Machida1, Sawako Sakai2
1Tsuchiura Kyodo General Hospital, 2Department of Neurology, Tsuchiura Kyodo General Hospital
Objective:
To characterize the occurrence and manifestations of Paradoxical Reactions (PRs) in patients with bacterial brain abscesses.
Background:
PRs are exaggerated inflammatory responses owing to recovery of cellular immunity following initiation of anti-microbial agent. The presentation is clinical or radiological worsening of pre-existing symptoms or development of new lesions. PRs are a well-known event in tuberculosis, but are rarely reported in bacterial brain abscesses.
Design/Methods:
We conducted a retrospective review of patients diagnosed with bacterial brain abscesses and admitted to our hospital from 2018 to 2023.
Results:
Of the 13 patients with brain abscesses who were not indicated for surgical drainage, 3 had PRs. All three cases had multiple brain abscesses of less than 2.5 cm in size. PRs occurred on days 14-23 of treatment. When PRs were observed, diffusion-weighted imaging revealed high signal intensity, accompanied by a pronounced ring-enhanced gadolinium contrast effect surrounding the abscess. This was particularly notable due to the markedly high signal around the abscess on FLAIR images. In one case, symptoms were alleviated by changing antibiotics and in two others by adding corticosteroids. All three cases improved without neurological sequelae.
Conclusions:
Our findings underscore that PRs can occur in bacterial brain abscesses several weeks after the initiation of antimicrobial therapy. It is imperative for clinicians to refrain from interpreting PRs as indicative of treatment failure. Further studies are essential to determine the role of corticosteroids in managing PRs.