Key result
A neonate with a reversible splenium of corpus callosum lesion suggests that intramyelinic edema is unlikely the underlying mechanism, as myelination does not occur before 2 months of age.
Reversible SCC lesions with reduced ADC in neonates suggest an inflammatory mechanism rather than intramyelinic edema, given the lack of myelination at this age.
Challenges intramyelinic edema hypothesis for neonatal SCC lesions; leaves inflammatory mechanism open pending larger studies.
We read with interest the report of patients with splenium of corpus callosum (SCC) lesions, most being reversible with transiently reduced apparent diffusion coefficient (ADC) values. We previously described 15 patients with clinically mild encephalitis/encephalopathy with identical reversible SCC lesions,2 and we postulated that intramyelinic edema due to separation of myelin layers was a possible mechanism for the transiently decreased ADC. We recently saw a neonate with an identical SCC lesion, suggesting that the mechanism underlying the lesion might not be related to myelination. Magnetic resonance imaging in this neonatal patient revealed an identical reversibleSCClesion with a transiently reducedADCvalue. Pathologically, no myelination ofSCC occurs before age2months. Therefore, intramyelinicedema cannot occur in the neonatal period and is unlikely to be a possible mechanism underlying the reversible SCC lesion in the present patient. Another possible explanation is inflammatory infiltrate.Adiffusion-weighted image study of multiple sclerosis revealed decreased ADC values in some lesions from multiple sclerosis, and it was postulated that the influx of inflammatory cells and macromolecules might have caused the decreased ADC values. A decreased ADC value inSCCmaybe a result of inflammation, and theADC may return to normal if the cause resolves quickly.
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Takanashi et al. (2005) conducted a letter in Reversible splenium of corpus callosum (SCC) lesion (n=1). Reversible SCC lesion was evaluated on Mechanism of transiently decreased apparent diffusion coefficient (ADC). A neonate with a reversible splenium of corpus callosum lesion suggests that intramyelinic edema is unlikely the underlying mechanism, as myelination does not occur before 2 months of age.
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