Cystic leukoencephalopathy without megalencephaly
Cystic leukoencephalopathy without megalencephaly, is an autosomal-recessive inherited condition that manifests in the early childhood with moderate to severe psychomotor retardation and spasticity.
On imaging, it is characterised by bilateral anterior subcortical temporal lobe cysts and extensive multifocal white matter hyperintensities in a normal sized brain.
The condition is also referred in the literature as leukoencephalopathy with bilateral anterior temporal lobe cysts and non-progressive leukoencephalopathy with bilateral anterior temporal cysts. However, those terms may cause confusion with the main differential diagnosis on imaging, which is megalencephalic leukoencephalopathy with subcortical cysts.
This is a non-progressive condition that manifests in the early childhood with psychomotor retardation and spasticity. Other commonly related symptoms are: seizures, spasticity, athetoid hand movements, dystonia, nystagmus, and hearing loss. Normocephaly or microcephaly on physical examination 2.
A variability in clinical phenotype has been observed, with patients having a normal cognitive function 3.
The pathological basis of the defect remains to be defined. Recent genetic analysis have shown that loss-of-function mutations in the gene RNAse T2, encoding the RNASET2 glycoprotein leads to cystic leukoencephalopathy 4.
Typical MRI features in brain include bilateral anterior subcortical temporal lobe cystic lesions, with multifocal white matter hyperintensities, pericystic abnormal myelination and symmetric lesions in the periventricular regions, including the occipital lobes 5-6.
History and etymology
It first described by Olivier et al. in 1998 1.
The differential diagnosis of cystic lesions of the temporal lobe are:
- with microcephaly:
- congenital muscular dystrophy merosin negative
- Aicardi-Goutieres syndrome
- with megalencephaly:
- megalencephalic leukoencephalopathy with subcortical cysts (also known as Van der Knaap disease).
Other differential diagnoses to include:
- 1. Olivier M, Lenard HG, Aksu F et-al. A new leukoencephalopathy with bilateral anterior temporal lobe cysts. Neuropediatrics. 1998;29 (05): 225-8. doi:10.1055/s-2007-973566 - Pubmed citation
- 2. Henneke M, Preuss N, Engelbrecht V et-al. Cystic leukoencephalopathy without megalencephaly: a distinct disease entity in 15 children. Neurology. 2005;64 (8): 1411-6. doi:10.1212/01.WNL.0000158472.82823.01 - Pubmed citation
- 3. Grosso S, Cerase A, De Stefano N et-al. Non-progressive leukoencephalopathy with bilateral anterior temporal cysts: a case report and review of the literature. Brain Dev. 2005;27 (1): 73-7. doi:10.1016/j.braindev.2004.04.009 - Pubmed citation
- 4. Henneke M, Diekmann S, Ohlenbusch A et-al. RNASET2-deficient cystic leukoencephalopathy resembles congenital cytomegalovirus brain infection. Nat. Genet. 2009;41 (7): 773-5. doi:10.1038/ng.398 - Pubmed citation
- 5. Faria EC, Arita JH, Peruchi MM et-al. Cystic leukoencephalopathy without megalencephaly. Arq Neuropsiquiatr.66 (2A): 261-3. doi:10.1590/S0004-282X2008000200027 - Pubmed citation
- 6. Soni N, Biswas S, Kumar S. MRI Features of a Rare Entity - Cystic Leukoencephalopathy without Megalencephaly. Journal of Rare Disorders: Diagnosis & Therapy. 2015. 1 (3) 22.