Revision 18 for 'Megalencephalic leukoencephalopathy with subcortical cysts'

All Revisions - View changeset

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 characterized 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.

Clinical presentation

Patients typically present with megalencephaly during the 1st year of life associated with mild motor developmental delay and seizures 5. There is also a gradual onset of ataxia, spasticity, 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 MLC 1 gene at chromosome 22q 4,5.


Elevated levels of glycine have been reported in CSF 1.

Radiographic features

MRI brain

Shows a megalencephalic brain with bilateral cystic lesions of CSF intensity mainly affecting the anterior temporal lobes. There can also be a wide diffuse signal abnormality and features of swelling affecting white matter. 

The hallmark of radiological diagnosis is

  • subcortical white matter involved early in course of disease with involvement of the subcortical U-fibers.
  • subcortical cysts especially temporal poles and frontoparietal lobes.
  • the main differential diagnosis is metachromatic leukodystrophy (MLD); however, not all symmetrical leukodystrophies are MLD. If U-fibers or cysts involved, MLC is considered.

Treatment and prognosis

The disease is managed to treat the manifestations with antiepileptic drugs to control epileptic seizures and physical therapy to improve motor function.

History and etymology

Bhim Sen Singhal described a megalencephalic leukodystrophy series of cases in 1991 5. It is named after Marjo van der Knaap, a Dutch physician 4

Differential diagnosis

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.