An abscess is a collection of pus in a non-preformed body cavity caused by inflammatory tissue liquefaction. A symptomatic intracranial or spinal abscess is, in most cases, an urgent indication for surgical removal.

Location

A neurosurgically relevant abscess may occur intraspinally or intracerebrally.

Imaging

For diagnostic purposes, intracerebral abscesses show the following characteristics on MRI imaging[^1]:

CT	MRI T1 with contrast medium	MRI DWI sequence	MRI ADC sequence
Ring enhancement of the lesion with contrast medium	Subtle ring enhancement at the edge of the lesion	Hyperintense	Hypointense

Computed tomography

Cerebellar abscess on CT — CT image of a cerebellar abscess. The left image shows a noncontrast CT examination, and the right image shows a contrast-enhanced CT examination.

Brain abscess CT — Axial contrast-enhanced CT of the brain showing a surgically confirmed left-sided abscess.

\n MRI

Abscess MRI — An intracerebral abscess on MRI in different sequences: T1, T1 with contrast, B1000, B0

\n Treatment

Patients with an intracranial or spinal abscess require antibiotic therapy for several weeks even after surgical treatment; the regimen depends on the pathogen identified microbiologically. The occurrence of intracranial abscesses correlates with patients' socioeconomic status and therefore represents a major challenge in developing countries[^2].

Pathology

Histologically, brain abscesses can be divided into four different stages and differ in resistance during surgical puncture and aspiration[^1]. Progression through the various stages takes at least two weeks and is prolonged by administration of Steroids[^1].

Stage	Designation	Time period	Histological characteristics	Resistance during aspiration
1	Early Cerebritis	Day 1-3	Early infectious and inflammatory phase. Poor demarcation from the surrounding brain tissue. Toxic changes in neurons and perivascular infiltrates.	Intermediate resistance
2	Late cerebritis	Day 4-9	Reticular matrix and development of a necrotic center	No resistance
3	Early capsule formation	Day 10-13	Neovascularization and central necrosis with surrounding reticular network.	No resistance
4	Late capsule	> Day 14	Collagen capsule, necrotic center, and gliosis surrounding the capsule	Strong resistance and a "pop" during capsule puncture