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Brain and spinal cord abscesses - Symptoms and diagnosis
Last reviewed: 04.07.2025
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Symptoms of Brain and Spinal Cord Abscesses
Symptoms of brain and spinal cord abscesses correspond to the clinical picture of a space-occupying lesion. There are no pathognomonic symptoms of a brain abscess. As with other space-occupying lesion, clinical symptoms can vary widely - from headache to the development of severe general cerebral symptoms with depression of consciousness and pronounced focal symptoms of brain damage. The first manifestation of the disease can be an epileptiform seizure. With subdural abscesses and empyema, meningeal symptoms are more often present. Epidural abscesses are almost always associated with osteomyelitis of the skull bones. A progressive increase in symptoms is typical. In some cases, it can be very rapid.
Diagnosis of brain and spinal cord abscesses
When making a diagnosis, a thorough anamnesis is of great importance. The appearance and increase of neurological symptoms in a patient with a diagnosed inflammatory process is a reason for conducting a neuroimaging examination.
Computer tomography. The accuracy of the diagnosis of a brain abscess in CT depends on the stage of development of the process. In case of encapsulated abscesses, the accuracy of the diagnosis is close to 100%. The abscess has the appearance of a rounded volumetric formation with clear, smooth, thin contours of increased density (fibrous capsule) and a zone of decreased density in the center. In some cases, a clear fluid level is determined in the abscess cavity. An edema zone is visible along the periphery of the capsule. When a contrast agent is introduced, it accumulates in the form of a thin ring corresponding to the fibrous capsule with a small adjacent zone of gliosis. When CT is repeated after 30-40 minutes, the accumulation of the contrast agent is not determined.
Diagnostics in earlier stages is less reliable. In the early encephalitis stage (1-e-3 days), CT reveals a zone of reduced density, often of irregular shape. When a contrast agent is administered, its accumulation occurs unevenly, mainly in the peripheral parts of the lesion, but sometimes in its center.
In the late encephalitis stage (4-9 days), the contours of the lesion become smoother and more rounded, and the accumulation of contrast agent along the periphery of the lesion is more intense and uniform. The X-ray density of the central zone of the lesion does not change immediately after the administration of the contrast agent, but with repeated CT after 30-40 minutes, it is possible to detect the diffusion of contrast into the center of the lesion, as well as its preservation in the peripheral zone, which is not typical for tumors.
When analyzing a CT scan, it should be borne in mind that glucocorticoids, often used in treatment, significantly reduce the accumulation of contrast agent in the encephalitic focus.
Magnetic resonance imaging. MRI is a more accurate method for diagnosing abscesses than CT. An encephalitic lesion appears hypointense on T1-weighted images and hyperintense on T2-weighted images. An encapsulated abscess appears on T1-weighted images as a zone of decreased signal in the center and on the periphery, in the edema zone, with a ring-shaped zone of moderately hyperintense signal between them, corresponding to the abscess capsule. On T2-weighted images, the central zone of the abscess is iso- or hypointense, the peripheral zone of edema is hyperintense, and a clearly defined capsule is visible between these zones.
Differential diagnostics
Differential diagnostics of abscess should be performed with primary glial and metastatic brain tumors. In case of doubt in the diagnosis and the need to differentiate abscess, MR spectroscopy plays an exceptional role (differential diagnostics is based on the different content of lactate and amino acids in abscesses and tumors).
If a brain abscess is suspected, the patient must be carefully examined to identify all possible foci of inflammation that could become a source of intracranial infection.
Other methods of diagnostics and differential diagnostics of brain abscess are uninformative. Fever, increased ESR, leukocytosis, increased C-reactive protein in the blood occur with any inflammatory processes, including extracranial ones. Blood cultures for brain abscesses are usually sterile. Lumbar puncture in the diagnostics of intracranial abscesses is not used today due to its low information content (in most cases, the inflammatory process in the brain is limited and is not accompanied by meningitis) and the risk of brain dislocation.
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