P2.112: Medullary abscess in an immunocompetent pediatric patient: A tough nut to crack

Introduction: Intracranial abscesses are rare but potentially life-threatening infections. Among these, brainstem abscesses are the least reported, accounting for approximately 1% of cases. In a review of 24 pediatric brainstem abscesses, only 4 involved the medulla - of which just one patient survived. We describe a case of medullary abscess in a previously healthy child, representing the youngest known survivor in the literature.

Case Description: A 14-month-old previously healthy female presented with three days of progressive fatigue and decreased oral intake. Initial evaluation revealed normal vitals, negative inflammatory markers and WBC count, and no focal neurologic deficits aside from mild difficulty latching. She was admitted to the inpatient floor for presumed dehydration. Four hours later, she developed tachypnea, global hypotonia, head lag, and fatigability. Due to exposure to a neighborhood construction site, botulism immunoglobulin was ordered, and she was transferred to the intensive care unit.

Within three hours, she developed a new-onset, right-sided weakness. Brain MRI revealed a 1.3 x 1.1 x 1.1cm ring-enhancing lesion in the dorsal medulla with restricted diffusion and surrounding T2/FLAIR hyperintensity extending into the upper cervical cord - findings consistent with a medullary abscess. Botulism immunoglobulin was withheld. After multidisciplinary consultation, operative intervention was deferred in favor of empiric antibiotics and dexamethasone due to high procedural risk.

The following day, she developed progressive bulbar symptoms including loss of gag reflex, drooling, and asymmetric chest rise concerning for diaphragmatic paresis. Although normocapnic and normoxemic, she was intubated for airway protection. Over the following five days, she required minimal ventilatory support and remained neurologically stable with persistent right-sided hemiparesis and diminished cough and gag. Steroids were tapered.

On hospital day 14, repeat MRI showed enlargement of the abscess (1.9 x 1.8 x 2.0 cm) with development of a well-defined capsule. Due to failed medical therapy, she underwent posterior fossa craniotomy for abscess drainage. Intraoperative cultures were PCR positive for Streptococcus intermedius. She was successfully extubated on post-operative day three, and transferred to inpatient rehabilitation, where she remains three months after initial presentation. She completed six weeks of ceftriaxone with complete abscess resolution on follow-up imaging one month later. Immunologic workup was unremarkable; she had a normal echocardiogram and had no clear risk factors other than a dental cleaning four days prior to presentation.

Discussion: This case highlights a rare etiology of a brainstem abscess in an otherwise healthy child without clear risk factors. Early recognition of subtle, evolving neurologic deficits enabled timely diagnosis. Imaging features, clinical progression, and failure of medical management influenced neurosurgical risk assessment and timing of procedural intervention.

Conclusion: Medullary abscess is a rare diagnosis presenting with rapidly changing neurologic exam and otherwise unremarkable laboratory evaluation, which can make for challenging management.