Large Ventricles

Bronwyn E. Hamilton, MD

DIFFERENTIAL DIAGNOSIS

Common

Aging Brain, Normal
Encephalomalacia, General
Obstructive Hydrocephalus
- Meningitis
- Subarachnoid Hemorrhage, NOS
- Intraventricular Hemorrhage
Cerebral Atrophy, NOS
- Chronic Hypertensive Encephalopathy
- Multiple Sclerosis
- Alcoholic Encephalopathy
- Radiation and Chemotherapy
- Diffuse Axonal Injury (DAI)
- Post-Meningitis
- Drug Abuse

Less Common

Alzheimer Dementia
Normal Pressure Hydrocephalus
Multi-Infarct Dementia
Frontotemporal Dementia

Rare but Important

Choroid Plexus Papilloma
Megalencephaly Syndromes
Huntington Disease
Creutzfeldt-Jakob Disease (CJD)
Inborn Errors of Metabolism (End-Stage)

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Imaging most important to distinguish acutely obstructive causes from non-obstructive causes
Dementias best diagnosed clinically

Helpful Clues for Common Diagnoses

Aging Brain, Normal
- Ventriculomegaly in proportion to sulci
- Reflects atrophy from parenchymal loss
Encephalomalacia, General
- Volume loss from many causes (prior stroke, trauma, surgery)
- Focal, in areas of parenchymal tissue loss (with focal ventricular enlargement), or diffuse when global
Obstructive Hydrocephalus
- Surgically emergent condition
- Types of obstructive hydrocephalus
  - Intraventricular obstructive hydrocephalus (IVOH) = “non-communicating hydrocephalus”: Due to obstructed CSF at level of ventricles from focal mass effect
  - Extraventricular obstructive hydrocephalus (EVOH) = “communicating hydrocephalus”: Due to obstructed CSF resorption at level of sulci, meninges/arachnoid granulations
  - CSF overproduction (choroid plexus tumors)
- Meningitis
  - Mild hydrocephalus typical, may be earliest imaging finding (EVOH)
  - Leptomeningeal enhancement
  - Complications: Cerebritis/abscess, effusions, ischemia
- Subarachnoid Hemorrhage, NOS
  - Impaired CSF resorption (EVOH)
  - Subarachnoid blood, often aneurysmal
- Intraventricular Hemorrhage
  - Impaired CSF resorption (EVOH)
  - Ventricular blood, often related to trauma or AVM
Cerebral Atrophy, NOS
- Chronic Hypertensive Encephalopathy
  - Brain parenchymal changes due to long-standing effects of untreated or poorly treated systemic hypertension
  - May result in vascular dementia
  - Diffuse white matter (WM) atrophy with low density or high T2 signal
  - May have hemorrhagic foci on GRE (basal ganglia, thalamus, cerebellum)
- Multiple Sclerosis
  - Periventricular WM pattern of T2 hyperintensities ± enhancement
  - Often dramatic callosal volume loss & ventriculomegaly
  - Lesions generally lack mass effect
- Alcoholic Encephalopathy
  - Chronic alcohol abuse results in symmetric lateral ventricle enlargement & superior vermian atrophy
  - Wernicke involvement: Mamillary bodies, medial thalami, hypothalamus, periaqueductal gray matter
- Radiation and Chemotherapy
  - Late volume loss & diffuse T2 hyperintensity WM
  - Spares subcortical “U” fibers
- Diffuse Axonal Injury (DAI)
  - DAI best seen on GRE, FLAIR, & DWI
  - Classic locations: Gray-white matter junctions, callosum, deep nuclei
  - Accompanied by late WM volume loss
- Post-Meningitis
  - Late WM volume loss diffusely
  - May have encephalomalacia related to abscess, ischemia
- Drug Abuse
  - Consider in young patients with ischemic or hemorrhagic strokes
  - Chronic: Volume loss

Helpful Clues for Less Common Diagnoses

Alzheimer Dementia
- Parietal & temporal cortical atrophy with/disproportionate hippocampal volume loss is suggestive
Normal Pressure Hydrocephalus
- Clinical triad of dementia, gait apraxia, & incontinence
- Ventriculomegaly disproportionate to sulcal prominence, normal hippocampus
- CSF flow studies can detect increased velocity
Multi-Infarct Dementia
- Multifocal infarcts involving cortical gray matter, subcortical WM, & basal ganglia
- Strokes of multiple ages & lacunes common
- Often associated with arteriolosclerosis, WM hyperintensity
Frontotemporal Dementia
- Anterior frontotemporal atrophy with WM hyperintensity; “knife-like gyri”