Band heterotopia also known as double cortex syndrome is a form of diffuse grey matter heterotopia.
As is the case with many cortical malformations there is some confusion as to the terminology. For example, many authors use the term synonymously 2-3 with laminar heterotopia.
It is best thought as being on the lissencephaly type I - subcortical band heterotopia spectrum, as the genetic defects are in many cases the same and result from arrested migration of neurons, such that they form a grey matter layer within the centrum semiovale or subcortical white matter.
The majority of patients with double cortex syndrome are female on account of the genetic abnormality often being located on the X chromosome (see below) 5. The condition may be familial with X-linked dominant inheritance 2.
Seizures and delayed development are the most common presentations, usually evident in the first decade 3. Some patients however have very minor disabilities 5.
The majority of band heterotopia syndrome cases have now been attributed to an abnormality of the DCX gene (also known as XLIS gene) located on the long are of chromosome X. The DCX gene encodes for the protein double cortin responsible for stabilisation of microtubules, crucial in normal neuronal migration 5.
LIS1 (also known as PAFAH1B1) and also seen in type I lissencephaly is also implicated in some cases.
Approximately 10% of cases remain cryptogenic 5.
Although all modalities able to image the brain in cross-section (US / CT / MRI) are able to identify the abnormality, MRI is the imaging modality of choice.
As the name suggests, this condition is characterised by a band of grey matter located deep to, and roughly paralleling, the cortex, with either normal or pachygyric overlying cortex. The band of abnormal grey matter may be complete or incomplete and may even be duplicated (i.e two concentric bands) with in the temporal lobes 5.
The signal intensity is the same as normal cortex on all sequences.
Interestingly depending on the underlying genetic abnormality the anterior-posterior gradient of heterotopia is variable:
- anterior predilection suggests mutations of DCX
- posterior predilection suggests mutations of LIS1
On MRS there is reduction of NAA within the heterotopic grey as neurons therein are dysfunctional 4.
Treatment and prognosis
Treatment is symptomatic and usually targeted to controlling epilepsy, usually present.
- 1. Barkovich AJ, Kjos BO. Gray matter heterotopias: MR characteristics and correlation with developmental and neurologic manifestations. Radiology. 1992;182 (2): 493-9. Radiology (abstract) - Pubmed citation
- 2. Abdel Razek AA, Kandell AY, Elsorogy LG et-al. Disorders of cortical formation: MR imaging features. AJNR Am J Neuroradiol. 2009;30 (1): 4-11. doi:10.3174/ajnr.A1223 - Pubmed citation
- 3. D'Agostino MD, Bernasconi A, Das S et-al. Subcortical band heterotopia (SBH) in males: clinical, imaging and genetic findings in comparison with females. Brain. 2002;125 (Pt): 2507-22. Brain (citation) - Pubmed citation
- 4. Ketonen L, Hiwatashi A, Sidhu R. Pediatric brain and spine, an atlas of MRI and spectroscopy. Springer Verlag. (2005) ISBN:3540213406. Read it at Google Books - Find it at Amazon
- 5. Garel C. MRI of the fetal brain, normal development and cerebral pathologies. Springer Verlag. (2004) ISBN:3540407472. Read it at Google Books - Find it at Amazon
- 6. Dobyns WB, Das S. LIS1-Associated Lissencephaly/Subcortical Band Heterotopia. NCBI bookshelf
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Double cortex syndrome||✓|
|Double cerebral cortex syndrome||✓|
|double cerebral cortex||✗|