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).
There are many types of lissencephaly:
- 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
Walker-Warburg or HARD syndrome
Lissencephaly and bone dysplasia
Familial lissencephaly with cleft palate and cerebellar hypoplasia (three
Unknown. A global incidence of 1.2:100,000 live births
has been proposed.
Lissencephaly can be acquired
(cytomegalovirus infection) as in the isolated lissencephaly sequence or
genetically transmitted as in the other lissencephalies.
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.
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
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.
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.
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.
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.