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Group of disorders involving the neuronal migration during the period at 9 to 13 weeks' gestation. It is characterized by the absence of sulcation of the cerebral hemispheres resulting in smooth brain surface (absence of gyri). Neurologic disorder caused by incomplete development of the brain, which is caused by abnormalities in the neural migration process. The name comes from the Greek lissos (smooth) and enkephale (brain).

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There are many types of lissencephaly:

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Type I

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  • Miller-Dieker Syndrome: with facial abnormality
  • X-linked lissencephaly (gene located on Xp22.13)
  • X-Linked lissencephaly with ambiguous genitalia
  • Isolated lissencephaly sequence
  • Lissencephaly Norman-Roberts type syndrome

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Type II

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  • Walker-Warburg or HARD syndrome

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Type III

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  • Lissencephaly and bone dysplasia
  • Familial lissencephaly with cleft palate and cerebellar hypoplasia (three cases described)

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Unknown. A global incidence of 1.2:100,000 live births has been proposed.

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Lissencephaly can be acquired (cytomegalovirus infection) as in the isolated lissencephaly sequence or genetically transmitted as in the other lissencephalies.

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Lissencephaly results from a neuronal development insult before 12 weeks of gestational age. This interrupts further migration of neurons, preventing them from reaching the cerebral cortex and leading to agyria and a thickened smooth cortical surface. The causal factor can be infectious (congenital cytomegalovirus infection), genetic, or chromosomic.

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CT/MRI: smooth cerebral cortex with few primary fissures but no secondary sulci; symmetrical enlargement of ventricles; structure of hemispheres and ventricles similar to the 3- to 4-month-old fetal brain. Even though most of the syndromes resulting in lissencephaly are inherited, genetic examinations are inconclusive because most of the genes involved are still unknown.

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Presenting symptoms are mainly neurologic: infantile hypotonia; various types of seizure disorders (West syndrome, Lennox-Gastaut syndrome, massive myoclonus, tonic-clonic seizures), severe mental retardation with microcephaly; motor dysfunction with hypotonia, but also rigidity and opisthotonos. Patients also have various nonneurologic anomalies, including congenital heart disease; cataracts and various ocular anomalies; duodenal atresia; renal agenesis; polydactyly or syndactyly; cryptorchidism. Other migration disorders, such as macrogyria, micropolygyria, or gray matter heterotopias, are not uncommon.

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It is recommended to obtain an anesthesiology consult for patients affected with this condition and undergoing elective surgery. Complete evaluation of the anticonvulsant therapy must be obtained. Cardiac function must be assessed to eliminate the association of congenital heart defect, chronic congestive heart failure, and other anomalies (ECG, echocardiography, chest radiograph). Consultation with an ophthalmologist is important.

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No specific anesthetic considerations except for those necessary for patients with heart problems. Patients presenting with behavioral problems might benefit from a sedative premedication that will facilitate induction of anesthesia.

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Anticonvulsant therapy should be continued until the day of surgery and an intravenous anticonvulsant should be administered for long surgical procedures. Prophylactic antibiotics might be needed in presence of a cardiac anomaly.

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