LISSENCEPHALY

Lissencephaly Type I; LIS1; Classical Lissencephaly; X-Linked Lissencephaly; XLIS; Lissencephaly with Agenesis of the Corpus Callosum; Lissencephaly with Cerebellar Hypoplasia; Microlissencephaly; Miller-Dieker Syndrome

Lissencephaly is a brain malformation in which the physical structure of the brain did not develop correctly during fetal development. Lissencephaly is characterized by the absence of normal folds and ridges (convolutions) in the cerebral cortex, resulting in a nearly smooth brain and an abnormally small head (microcephaly).

Diagnostic testing: The diagnosis of lissencephaly is usually made by:

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  Computed tomography (CT), or

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  Magnetic resonance imaging (MRI).

Physical findings: Physical findings for lissencephaly may include:

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  Hypo- (loss of muscle tone) or hypertonia (increased muscle tone);

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  Trouble with feeding;

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  Poor head growth;

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  Intellectual disability;

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  Seizures;

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  Difficulty controlling muscles (ataxia);

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  Stiffness or spasticity of arms and legs;

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  Slowed growth; and

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  Developmental delays.

ICD-9: 742.2

The prognosis for children with lissencephaly is poor with many dying in infancy, and the remainder showing no significant development beyond a 3 -5 month level.

There is no way to reverse the effects of lissencephaly. Supportive management of lissencephaly includes treatment of seizures, and physical and occupational therapies to lessen spasticity. Feeding difficulties are treated with a gastrostomy tube. Respiratory problems are the most common causes of death.

Suggested MER for Evaluation:

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  Clinical history and examination that describes the diagnostic features of the impairment;

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  Cranial MRI or CT scans; and

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  Developmental assessment or psychological testing to address allegations of mental impairment may be warranted.

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