Megalencephalic leukoencephalopathy with subcortical cysts
Megalencephalic leukoencephalopathy with subcortical cysts, also known as Van der Knaap disease, refers to a rare inherited autosomal recessive disease characterised by diffuse subcortical leukoencephalopathy associated with white matter cystic degeneration.
The age at symptoms manifestations ranges from birth to 25 years, with a median age of 6 months 5.
Patients typically present with megalencephaly during the first year of life associated with mild motor developmental delay and seizures 5. There is also a gradual onset of ataxia, spasticity, dysarthria, and sometimes extrapyramidal findings. Mild mental deterioration can be observed late in life.
It is sometimes classified as a megalencephalic leukoencephalopathy.
It is thought to carry an autosomal recessive inheritance, and the gene locus has been mapped as MLC1 gene at chromosome 22q 4,5.
Elevated levels of glycine have been reported in CSF 1.
The hallmarks of radiological diagnosis are the following features:
- diffuse, bilateral and symmetric T2-weighted hyperintensity and T1-weighted hypointensity in the cerebral white matter, giving a characteristic 'swollen' appearance
- there may also be abnormal diffusion signal on DWI
- subcortical white matter involved early in course of disease with involvement of the subcortical U-fibers
- relative sparing of the deep and cerebellar white matter
- bilateral subcortical cysts of CSF intensity affecting the anterior temporal regions and frontoparietal lobes that
- eventual cerebral atrophy with increase in size of the subcortical cysts
Treatment and prognosis
The disease is managed by treating the manifestations with antiepileptic drugs to control epileptic seizures and physical therapy to improve motor function.
History and etymology
Although Bhim Sen Singhal (1933-), an Indian neurologist, initially described a megalencephalic leukodystrophy series of cases in 1991 5,6, it is sometimes named after Marjo S van der Knaap (1958-), a Dutch paediatric neurologist, who detailed another series with clinical and radiological features in 1995 4,7.
- 1. Sener RN. Demonstration of glycine peaks at 3.50 ppm in a patient with van der Knaap syndrome. AJNR Am J Neuroradiol. 2001;22 (8): 1587-9. AJNR Am J Neuroradiol (citation) - Pubmed citation
- 2. Morita H, Imamura A, Matsuo N et-al. MR imaging and 1H-MR spectroscopy of a case of van der Knaap disease. Brain Dev. 2006;28 (7): 466-9. doi:10.1016/j.braindev.2005.12.006 - Pubmed citation
- 3. Sener RN. van der Knaap syndrome: MR imaging findings including FLAIR, diffusion imaging, and proton MR spectroscopy. Eur Radiol. 2000;10 (9): 1452-5. Eur Radiol (link) - Pubmed citation
- 4. Van der knaap MS, Wevers RA, Kure S et-al. Increased cerebrospinal fluid glycine: a biochemical marker for a leukoencephalopathy with vanishing white matter. J. Child Neurol. 1999;14 (11): 728-31. J. Child Neurol. (citation) - Pubmed citation
- 5. Batla A, Pandey S, Nehru R. Megalencephalic leukoencephalopathy with subcortical cysts: A report of four cases. J Pediatr Neurosci. 2011;6 (1): 74-7. Free text at pubmed - Pubmed citation
- 6. Singhal BS, Gursahani RD, Biniwale AA, Udani VP. Tokyo, Japan: In Proceedings of the 8th Asian and Oceanian Congress of Neurology; 1991. Megalencephalic leukodystrophy in India; p. 72.
- 7. van der Knaap MS, Barth PG, Stroink H, van Nieuwenhuizen O, Arts WF, Hoogenraad F, Valk J. Leukoencephalopathy with swelling and a discrepantly mild clinical course in eight children. (1995) Annals of neurology. 37 (3): 324-34. doi:10.1002/ana.410370308 - Pubmed