Fact-sheet: Cytotocix lesions of the corpus callosum CLOCCs
- Encephalopathy and transient splenial lesion of the corpus callosum (MERS)
Updated on 08/31/2019 at 11:21 AM
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Definition
CLOCCs: Cytotoxic Lesion of Corpus Callosum.
These are lesions of the splenium of the corpus callosum related to cytotoxic edema, most often reversible.
The current model includes:
- an inflammatory cytokinopathy
- significant glutamate release into the extracellular space
- the development of cytotoxic intracellular edema.
The tropism of these lesions is explained by the high density of glutamate receptors located in the splenium.
This is an epiphenomenal lesion whose underlying etiology must always be sought through the clinical context or MRI:
- seizures, antiepileptic treatments,
- infectious (most often viral encephalitis, but also bacterial and parasitic)
- Metabolic: hypoglycemia, dysnatremia, hepatic encephalopathy, Marchiafava-Bignami
- subarachnoid hemorrhage
- Diffuse axonal injury
- tumoral (cerebral OR spinal)
Clinical features
The symptomatology is heterogeneous and inconsistent:
- confusion
- interhemispheric disconnection syndrome.
- symptoms related to the underlying condition.
Interhemispheric disconnection syndrome:
- left visual/auditory/tactile anomia
- right olfactory anomia
- alien hand, capricious hand, diagonistic apraxia.
Laboratory findings
It depends on the underlying pathology.
MRI
Typical corpus callosum lesion:
- round/oval, midline, involving the splenium
- hyperintense on B1000 with restricted diffusion
- FLAIR hyperintense
- T1 hypointense
- no contrast enhancement
- Classically reversible (but not always)
Three forms of CLOCCs can nonetheless be distinguished:
- midline (the classic form)
- with lateral extension along the splenium (boomerang sign)
- with anterior extension toward the body and genu of the corpus callosum.
CLOCC lesions are most often symmetric.
The remainder of the MRI study should otherwise:
- rule out an ischemic lesion with a 3D-TOF sequence
- in the absence of a suggestive clinical context, look for evidence of an underlying condition
Management
Look for a possible differential diagnosis on MRI.
Identify and treat the underlying cause.
Differential diagnosis
It is difficult to discuss a differential diagnosis given the multitude of etiologies for this syndrome.
However, the following should be ruled out:
- posterior cerebral circulation occlusion
- a primary tumor of the splenium of the corpus callosum (glioblastomas and lymphomas have a predilection for the corpus callosum)
- a primary lesion of the corpus callosum, such as an inflammatory lesion, for example.