Acute hemorrhagic leukoencephalitis

MRI findings in acute hemorrhagic leukoencephalitis

The pathology is characterized by extensive signal abnormalities affecting the cortical gray matter as well as the periventricular and subcortical white matter.

Features of the lesions:

• The size of the lesions is significantly larger than in acute disseminated encephalomyelitis (ADEM).
• Marked edema and a strong mass effect are observed (decompressive craniectomy is indicated in critical situations).
• Involvement of brain structures can be symmetrical.
• Contrast enhancement of the lesions is variable.

To detect specific patterns—multiple microhemorrhages in the deep gray matter and peripheral white matter of the hemispheres—it is critically important to use T2* modes or susceptibility-weighted MRI sequences (susceptibility-weighted). Survival prognosis for this condition directly depends on the earliest possible initiation of aggressive therapy, including plasmapheresis, a combination of corticosteroids, cyclophosphamide, and immunoglobulins.

Introduction to CNS vasculitis

Central nervous system vasculitides are divided into primary and secondary. Exact epidemiological data on their incidence are lacking, but they are known to cause up to 3–5% of strokes in individuals under 50 years of age. Primary forms are relatively rare but typically have a poorer prognosis.

Clinically, vasculitis should be suspected in the presence of severe headaches, multifocal (or focal) neurological symptoms, altered consciousness, and cognitive impairment against the background of nonspecific CT or MRI findings.

Diagnostic specifics:

1. Angiography often demonstrates a compelling picture of vascular involvement.
2. The definitive diagnosis is valid only after histological confirmation (CNS tissue biopsy).
3. Because inflammation spreads segmentally and is focal in nature, a positive biopsy unambiguously verifies the diagnosis, but a negative result does not completely rule it out.

Primary angiitis of the central nervous system (PACNS)

Primary angiitis of the CNS is a severe and rare idiopathic disorder where involvement is restricted to the nervous system. The disease manifests at a mean age of 50, with men affected twice as often as women.

Pathomorphology: The basis of the disease is multifocal inflammation. Small arteries are primarily affected, but the process may also involve cortical, leptomeningeal, and subcortical arteries, as well as medium-sized veins. A key (hallmark) distinguishing feature is marked inflammatory alteration of the affected blood vessel wall.

Clinical picture:

• Disease onset: Encephalopathy and headaches are most frequently the initial signs. Seizures as a starting symptom are rarely recorded.
• Complications: Persistent neurological deficits or strokes develop in 40% of patients.
• Transient ischemic attacks (TIAs): Observed in 30–50% of patients, though they act as the very first symptom less frequently—in less than 10–20% of cases.

Neuroimaging (MRI): Abnormalities are detected in the vast majority (over 90%) of patients. A typical T2-FLAIR pattern presents as diffuse MRI signal hyperintensity. Changes are localized predominantly in the subcortical white matter, cortex, periventricularly, and in the deep gray matter. Infractions, confluent (confluent) lesions, or large mass lesions (mass lesions) are much less frequently found on tomograms.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Acute disseminated encephalomyelitis (ADEM): differential diagnosis criteria.
• Physical principles of susceptibility-weighted imaging (SWI) MRI sequences.
• CNS biopsy protocols for suspected angiitis: surgical approaches and risks.
• Secondary CNS vasculitis: systemic diseases leading to cerebral vessel damage.
• The role of cerebral angiography in the comprehensive diagnosis of cerebrovascular lesions.

Other topics in the Neuroimaging section

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