Corpus Callosum Splenium Lesion

Karen L. Salzman, MD

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Corpus callosum (CC) has 4 named parts: Rostrum, genu, body, & splenium
Splenium is most likely portion to be affected by various pathologies
- Possibly related to posterior pericallosal artery vascular supply
Splenium lesions may have similar imaging appearance, history often key to diagnosis
Many etiologies may cause a reversible T2 hyperintense lesion
- Pathophysiology for reversible lesions is thought to be cytotoxic edema

Helpful Clues for Common Diagnoses

Diffuse Axonal Injury (DAI)
- Punctate hemorrhages at gray-white interfaces, corpus callosum (CC), deep gray matter, & upper brainstem typical
- CC involved in 20%; 75% involve splenium & undersurface of posterior body
- T2*/GRE & SWI typically shows multiple additional lesions
Multiple Sclerosis
- Callososeptal T2 hyperintensities characteristic
- Focal splenium lesion less common
- CC almost always involved, callosal striations seen early
- May have characteristic incomplete ring or horseshoe enhancement
Status Epilepticus
- T2 hyperintensity in supratentorial gray matter &/or subcortical white matter (WM) with mild mass effect typical
- May focally involve hippocampus or CC splenium
Drug Toxicity, NOS
- Multiple drugs have been associated with a reversible splenium lesion
  - Anti-epileptic agents, metronidazole, sympathomimetic-containing diet pills
- Focal T2 hyperintensity, DWI positive
- Metronidazole encephalopathy may also affect dentate, brainstem, & WM

Helpful Clues for Less Common Diagnoses

Transient Metabolic Derangement
- Focal T2 hyperintense splenium lesion, DWI positive
- Typically reversible
Encephalitis (Miscellaneous)
- Multiple infectious agents may cause focal T2 hyperintense splenium lesion
  - Influenza type A, rotavirus, E. coli, measles, mumps, adenovirus, herpes, varicella, EBV, West Nile, salmonella
- Typically reversible & DWI positive
Hypoxic-Ischemic Encephalopathy, NOS
- Most common in deep gray nuclei
- DWI positive acutely
- Focal splenium lesion less common
Alcoholic Encephalopathy
- Marchiafava-Bignami: Sudden onset of altered mental status, seizures, dysarthria, ataxia, hypertonia, pyramidal signs
  - T2 hyperintense CC (middle layers) virtually pathognomonic
- Toxic leukoencephalopathy with demyelination, rare complication, often involves splenium & periventricular WM
- Superior vermian atrophy common
Neoplasms
- Lymphoma & glioblastoma (GBM) classically cross CC splenium or genu
- Enhancing WM mass with CC extension
- Lymphoma: Homogeneous enhancement
- GBM: Heterogeneous enhancement
PML
- Occurs in immunosuppressed or immunocompromised patients
- T2 hyperintensity in subcortical & deep WM, crosses CC splenium & genu
- Involves subcortical U-fibers
Hypoglycemia
- Severe parietooccipital edema &/or infarcts in a newborn
- T2 hyperintensity in occipital & parietal lobes; commonly affects splenium
- DWI positive
- May be reversible if treated early