Megalencephalic leukoencephalopathy with subcortical cysts (Van der Knaap disease): A rare case report

Clinical History

A 9 year old girl born of consanguineous marriage presented with history of Loss of consciousness one episode and seizures since 1 year. She had delayed milestones, increasing head size since the age of one year and was academically weak. EEG studies showed findings of recurrent seizures.

Imaging Findings

Axial T2 weighted and T2 weighted FLAIR sequences show bilateral, extensive and diffuse almost symmetrical white matter hyperintensity. On the T1 weighted sagittal sequence, these areas appear hypointense. The sparing of the basal Ganglia, thalami and the internal capsule is seen bilaterally. There is also evidence of well-defined cysts across the right sided anterior temporal subcortical region. Similar cystic lesions are seen across the fronto-parietal subcortical region bilaterally and asymmetrically. These cysts appear hypointense on the T1 weighted sagittal images, hyperintense on the T2 weighted axial images and are suppressed on the T2 weighted FLAIR axial images.
MR spectroscopic evaluation showed NAA/ Creatine ratio of 1.26 and Choline/ Creatine ratio of 1.14 which were within the normal range.

Discussion

Van der Knaap syndrome is an autosomal recessive disorder. There is defective myelin formation and maintainence due to mutation in the MLC1 gene in some patients. The patient presentation is anywhere from birth to ten years of age. The classical signs of disease are increasing head size, learning difficulties, spasticity, ataxia and seizures [2].
MRI brain is the investigation of choice. The MR findings are usually markedly abnormal and in typical cases often diagnostic [1]. MRI shows swollen white matter. There is bilateral, diffuse and extensive white matter hyperintensity on T2 W / T2 FLAIR sequence which appear hypointense on T1 weighted sequences, suggestive of extensive demyelination [1]. There is relative sparing of the central white matter structures like corpus callosum, internal capsules and brain stem [1]. The basal ganglia and the thalami are also spared [1, 3]. Subcortical cysts are seen across anterior temporal regions and also across the fronto-patietal region bilaterally [1].
Management consists of treatment of manifestations like Antiepileptic drugs (AED) if epileptic seizures are present, physical therapy to improve motor function, special education, speech therapy as needed [4].

Differential Diagnosis List

Final Diagnosis

Megalencephalic leukoencephalopathy with subcortical cysts (Van der Knaap disease)

URL:	https://www.eurorad.org/case/11115
DOI:	10.1594/EURORAD/CASE.11115
ISSN:	1563-4086