Classification system for malformations of cortical development

Changed by Frank Gaillard, 17 Mar 2018
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Classification system for malformations of cortical development organises a myriad of conditions according tointo one of three major underlying  mechanismsgroups according to the main underlying mechanism:

    • group I: abnormal cell proliferation or apoptosis
    • group II: abnormal neuronal migration
    • group III: abnormal cortical organisation

As is to be expected a number of conditions fall outside these three groupings and are placed in a miscellaneous miscellaneous group: those associated with other diseases or yet to be classified 2. The classification present below is a summary with examples adapted from the one proposed by Barkovich et al in 1996 and updated in 2001, 20042005 and 2012 21-2,5,6. The full classification is extensive, contains numerous rare and specific abnormalities beyond the scope of this or other related articles and will certainly evolve over the coming years. As such you are encouraged, if necessary, to review the most recent (2012) update for further details 5. 

AbnormalGroup I: abnormal cell proliferation or apoptosis 

TheseGroup 1 conditions include those due to disorders of neuronal and/or glial proliferation or apoptosis. They can be further divided into twothree groups; those with abnormalities of brain size due to abnormalities in proliferation or apoptosis,– A) small and; B) large – and C) those with cortical dysgenesis with abnormal cells (neoplastic or non-neoplastic) 2.

Abnormal brain sizeGroup I.A
Group I.B
AbnormalGroup I.C

The cortical dysgenesis with abnormal cell proliferation group contains a number of both neoplastic and non-neoplastic conditions. 

Non-neoplastic
Neoplastic

AbnormalGroup II: abnormal neuronal migration

Group II.A
Group II.B 
Group III.C

Abnormal cortical organisationGroup III: abnormal post migrational development

Group III.A
Group III.B
  • cortical dysgenesis secondary to inborn errors of metabolism
Group III.C
Group III.D

Not otherwise classified

  • malformations secondary to inborn errors of metabolism
    • mitochondrial and pyruvate metabolic disorders 
    • peroxisomal disorders 
  • other unclassified malformations
    • sublobar dysplasia 

See also

For other congenital central nervous system classifications see:

  1. classification system for midline abnormalities of the brain
  2. classification system for malformations of the cerebellum
  3. classification system for malformations of the brainstem
  • -<p><strong>Classification system for malformations of cortical development </strong>organises a myriad of conditions according to one of three major underlying  mechanisms:</p><ol>
  • -<li>abnormal cell proliferation</li>
  • -<li>abnormal neuronal migration</li>
  • -<li>abnormal cortical organisation</li>
  • -</ol><p>As is to be expected a number of conditions fall outside these three groupings and are placed in a miscellaneous group: those associated with other diseases or yet to be classified <sup>2</sup>. The classification present below is adapted from Barkovich et al, 2004 <sup>2</sup>.</p><h4>Abnormal cell proliferation or apoptosis </h4><p>These conditions include those due to disorders of neuronal and/or glial proliferation or apoptosis. They can be further divided into two groups; those with abnormalities of brain size due to abnormalities in proliferation or apoptosis, and; those with abnormal cells (neoplastic or non-neoplastic) <sup>2</sup>.</p><h5>Abnormal brain size</h5><ul>
  • -<li>
  • +<p><strong>Classification system for malformations of cortical development </strong>organises a myriad of conditions into one of three major underlying groups according to the main underlying mechanism:</p><ul>
  • +<li>group I: abnormal cell proliferation or apoptosis</li>
  • +<li>group II: abnormal neuronal migration</li>
  • +<li>group III: abnormal cortical organisation</li>
  • +</ul><p>As is to be expected a number of conditions fall outside these three groupings and are placed in a miscellaneous group: those associated with other diseases or yet to be classified <sup>2</sup>. The classification present below is a summary with examples adapted from the one proposed by Barkovich <em>et al</em> in 1996 and updated in 2001, 2005 and 2012 <sup>1-2,5,6</sup>. The full classification is extensive, contains numerous rare and specific abnormalities beyond the scope of this or other related articles and will certainly evolve over the coming years. As such you are encouraged, if necessary, to review the most recent (2012) update for further details <sup>5</sup>. </p><h4>Group I: abnormal cell proliferation or apoptosis </h4><p>Group 1 conditions include those due to disorders of neuronal and/or glial proliferation or apoptosis. They can be further divided into three groups; those with abnormalities of brain size – A) small and B) large – and C) those with cortical dysgenesis with abnormal cells (neoplastic or non-neoplastic) <sup>2</sup>.</p><h5>Group I.A</h5><ul><li>
  • -</li>
  • -<li>macrocephalies (<a href="/articles/megalencephaly">megalencephaly</a>/<a href="/articles/macrocephaly">macrocephaly</a>)</li>
  • -</ul><h5>Abnormal cell proliferation</h5><p>Non-neoplastic</p><ul>
  • +</li></ul><h5>Group I.B</h5><ul><li>
  • +<a href="/articles/megalencephaly">megalencephaly</a>/<a href="/articles/macrocephaly">macrocephaly</a>
  • +</li></ul><h5>Group I.C</h5><p>The cortical dysgenesis with abnormal cell proliferation group contains a number of both neoplastic and non-neoplastic conditions. </p><h6>Non-neoplastic</h6><ul>
  • -<li><a href="/articles/focal-cortical-dysplasia">focal cortical dysplasia</a></li>
  • -</ul><p>Neoplastic</p><ul>
  • +<li>type II <a href="/articles/focal-cortical-dysplasia">focal cortical dysplasia</a>
  • +</li>
  • +</ul><h6>Neoplastic</h6><ul>
  • -<li>
  • -<a href="/articles/dysembryoplastic-neuroepithelial-tumour">dysembryoplastic neuroepithelial tumours</a> (DNET)</li>
  • -</ul><h4>Abnormal neuronal migration</h4><ul>
  • -<li>
  • -<a href="/articles/lissencephaly-type-i-subcortical-band-heterotopia-spectrum">lissencephaly type I: subcortical band heterotopia spectrum</a> (<a href="/articles/band-heterotopia">band heterotopia</a>): undermigration</li>
  • -<li>
  • -<a href="/articles/lissencephaly-type-ii">lissencephaly type II</a> (cobblestone complex): overmigration</li>
  • -<li>heterotopia: ectopic migration<ul>
  • +<li><a href="/articles/dysembryoplastic-neuroepithelial-tumour">dysembryoplastic neuroepithelial tumours (DNET)</a></li>
  • +</ul><h4>Group II: abnormal neuronal migration</h4><h5>Group II.A</h5><ul>
  • -<li>
  • -<a href="/articles/subcortical-heterotopia">subcortical heterotopia</a> (not including band heterotopia)</li>
  • -</ul>
  • -</li>
  • -</ul><h4>Abnormal cortical organisation</h4><ul>
  • +</ul><h5>Group II.B </h5><ul>
  • +<li>
  • +<a href="/articles/lissencephaly-type-i-subcortical-band-heterotopia-spectrum">lissencephaly type I: subcortical band heterotopia spectrum</a> (<a href="/articles/band-heterotopia">band heterotopia</a>): under migration</li>
  • -<a href="/articles/polymicrogyria">polymicrogyria</a> and schizencephaly<ul>
  • +<a href="/articles/lissencephaly-type-ii">lissencephaly type II</a> (cobblestone complex): over migration</li>
  • +</ul><h5>Group III.C</h5><ul><li>
  • +<a href="/articles/subcortical-heterotopia">subcortical heterotopia</a> (not including band heterotopia)</li></ul><h4>Group III: abnormal post migrational development</h4><h5>Group III.A</h5><ul><li>
  • +<a href="/articles/polymicrogyria">polymicrogyria</a> and <a title="Schizencephaly" href="/articles/schizencephaly">schizencephaly</a><ul>
  • -<li><a href="/articles/schizencephaly">schizencephaly</a></li>
  • -<li>polymicrogyria or schizencephaly as part of multiple congenital anomaly/mental retardation syndromes</li>
  • +<li>schizencephaly</li>
  • +<li>polymicrogyria or schizencephaly as part of multiple congenital anomaly/mental retardation syndromes​</li>
  • -</li>
  • -<li>
  • -<a href="/articles/focal-cortical-dysplasia">cortical dysplasia</a> without balloon cells</li>
  • -<li><a href="/articles/mild-malformation-of-cortical-development">microdysgenesis</a></li>
  • -</ul><h4>Not otherwise classified</h4><ul>
  • +</li></ul><h5>Group III.B</h5><ul><li>cortical dysgenesis secondary to inborn errors of metabolism<ul>
  • +<li>mitochondrial and pyruvate metabolic disorders</li>
  • +<li>peroxisomal disorders</li>
  • +</ul>
  • +</li></ul><h5>Group III.C</h5><ul><li>type I and type III <a title="Focal cortical dysplasia" href="/articles/focal-cortical-dysplasia">focal cortical dysplasia</a>
  • +</li></ul><h5>Group III.D</h5><ul><li>post-migrational <a title="Microcephaly" href="/articles/microcephaly">microcephaly</a> (also in group I)</li></ul><h4>Not otherwise classified</h4><ul>
  • -<a title="Mitochondrial diseases" href="/articles/mitochondrial-disorders">mitochondrial</a> and pyruvate metabolic disorders </li>
  • +<a href="/articles/mitochondrial-disorders">mitochondrial</a> and pyruvate metabolic disorders </li>

References changed:

  • 6. A Classification Scheme for Malformations of Cortical Development. (1996) Neuropediatrics. 27 (02): 59. <a href="https://doi.org/10.1055/s-2007-973750">doi:10.1055/s-2007-973750</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/8737819">Pubmed</a> <span class="ref_v4"></span>

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