Cerebral Atrophy

Cerebral atrophy is the morphologic manifestation of brain-parenchymal volume loss on cross-sectional imaging. It is not a primary diagnosis, but the common endpoint of many central nervous system disease processes. Although no cause is often identified, regional patterns can be diagnostically helpful, particularly in neurodegenerative disease.

Atrophy is common in older adults, creating uncertainty about when volume loss should be called cerebral atrophy rather than “involutional” or “age-related” change in a cognitively normal patient.

Terminology

Atrophy causes compensatory enlargement of the CSF spaces and is therefore analogous to hydrocephalus ex vacuo.

The latter term is usually reserved for focal volume loss after a specific pathologic insult, such as hemorrhage or infarction, rather than the more generalized and often idiopathic changes associated with aging.

Clinical Presentation

Because cerebral atrophy is not a distinct disease, there is no uniform presentation. It is often incidental when imaging is obtained for another indication.

Cognitive dysfunction and acute confusion are common reasons that patients with atrophy undergo brain imaging.

Interpret the degree and distribution of atrophy in relation to patient age, cognitive status, clinical syndrome, and prior imaging.

Generalized Atrophy Causes

Age-related change
Cerebrovascular disease
End-stage multiple sclerosis
Substance use, including alcohol and nonmedical drugs
Post-traumatic injury, including diffuse axonal injury
Postinfectious injury, including meningitis
Neurodegenerative disease, including progressive supranuclear palsy

Alcohol-related disease may particularly cause cerebellar vermian atrophy.

Focal Atrophy Causes

Prior ischemic injury
Prior trauma, hemorrhage, or contusion
Alzheimer disease
Parkinson disease
Frontotemporal dementia and Pick disease
Huntington disease
Corticobasal degeneration

Focal or asymmetric volume loss generally warrants closer correlation with the clinical phenotype and any prior local insult.

Radiographic Features

CT and MRI both demonstrate cortical volume loss, but MRI is more sensitive for focal atrophy involving deep gray nuclei and other specific structures.

Core findings

Prominence of cerebral sulci, reflecting cortical atrophy.
Ventriculomegaly, reflecting central atrophy.
No bulging of the third-ventricular recesses.
Proportionate enlargement of ventricles and sulci favors atrophy over obstructive hydrocephalus.

Differentiation from normal-pressure hydrocephalus can be difficult and should incorporate ventricular configuration, high-convexity sulci, Sylvian fissures, callosal angle, and clinical findings.

Pattern Recognition

Severe frontal and anterior temporal atrophyPick disease / frontotemporal lobar degeneration.
Atrophy of the caudate headsHuntington disease.
Posterior parietal and frontal atrophyCorticobasal degeneration.
Tectal, globus pallidus, and frontal-lobe atrophyProgressive supranuclear palsy.
Generalized atrophy with substantia nigra involvementParkinson disease.
Severe hippocampal and mesial temporal atrophyAlzheimer disease.

Patterns are supportive rather than independently diagnostic and must be integrated with clinical and other imaging findings.

Differential Diagnosis

Normal-pressure hydrocephalus

The key alternative is ventriculomegaly from NPH rather than ex-vacuo enlargement.

Assess whether sulcal enlargement is proportional.
Look for disproportionate Sylvian fissure enlargement and tight high-convexity sulci.
Consider the callosal angle and clinical triad.

Hydrocephalus versus atrophy reference