Malformations Flashcards
Chiari type I
Herniation of cerebellar tonsils through foramen magnum. May be clinically asymptomatic.
Conical elongations of the cerebellar tonsils and neighboring parts of the cerebellar hemispheres that extend into the vertebral canal (i.e., below the foramen of magnum). The protruded cerebellar tissue could be histologically normal, infracted or sclerosed. The medulla is either unaffected or flattened by the cerebellar tongues. Chiari malformation type I is often associated with syringomyelia, hydromyelia, syringomyelia, and less commonly hydrocephalus.
Chiari type II
(aka “classic” Chiari malformation, Arnold-Chiari malformation) – characterized by beaking of the midbrain tectum, elongation of the brainstem often with displacement of the medulla/4th ventricle through the foramen magnum, and cerebellar tonsillar/vermis herniation (through foramen magnum). This malformation is often associated with a myelomeningocele. Symptoms may range from mild to severe.
Displacement of the cerebellar vermis combined with deformities of the medulla and tectal plate. This type is often associated with syringomyelia, hydromyelia, spinal bifida, meningocele, and hydrocephalus. It can also associate with other malformation of the brain, cranium and meninges, cardiovascular, gastrointestinal and genitourinary systems. Most, if not all, Chiari type II malformations are associated with a neural tube defect.
Chiari type III
Chiari malformation + occipital encephalocele. This malformation often is associated with severe neurologic deficits, but may be incompatible with life, depending on the extent of the encephalocele.
Encephalocele formed by herniation of the structures of the posterior fossa, including the cerebellum, through an occipitocervical or high cervical bony defect. There may also be beaking of the tectum, elongation and kinging of the brain stem and lumbar spina bifida.
Dandy-Walker syndrome
The three essential features of Dandy-Walker syndrome include complete or partial agenesis of the vermis, cystic dilatation of the fourth ventricle and enlargement of the posterior fossa. Malformation of the brainstem, however, is not one of the features of Dandy-Walker syndrome. The vermis is present in this case and is free of hydrocephalic changes. Hydrocephalus is a frequent but inconstant finding. Other CNS findings include elevation of the tentorium cerebelli and lateral, transverse sinuses and torcula (torcular Herophilli), and lack of patency of the foramina of Magendie and Luschka. Other cerebral and visceral anomalies are present. It is the presene or absence of other cerebral and viseral abnormalies that determines the prognosis.
Herniation of cerebellar tonsils
Space occupying lesion in the posterior can lead to herniation of the cerebellar tonsil. In those cases, the tonsils are typically congested and often appear fragile or necrotic on gross examination. In the present case, the cerebellar tissue appears healthy looking. In addition, it is malformed. In contrasted, herniated tonsils came from the side and should not have malformation.
Occipital encephalocele
The brain seems to be composed in a larger segment and a smaller segment and the smaller segment is darker and appeared congested. The gyral pattern of the smaller part is that of the cerebral hemisphere. It is also bi-lobed and symmetrically separated.
Dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease)
This is is a condition featured by disorganized cerebellar folia leading to characteristic, thickening of the cerebellar folia. Although the cerebellar folia are thickened, the general architecture is maintained. In the present specimen, the gyral pattern is that of that cerebral hemisphere and so it is not Lhermitte-Duclos disease. It has features of both malformation and neoplasm. It is discovered typically in the 3rd and 4th decades and is associated with Cowden syndrome and linked to germline mutations in PTEN gene.
Rhombencephalosynapsis
characterized by two cardinal features: missing cerebellar vermis and apparent fusion of the cerebellar hemispheres at the midline. It can be complete or partial. It can occur in isolation or in combination with malformation of the central nervous system or outside the central nervous system. The current specimen clearly has splitting and the smaller portion of the brain is clearly composed of cerebral tissue but not cerebellar tissue.
Lissencephaly
loss of gyral formation
Amnion rupture sequence
An umbrella term that covers three very similar but overlapping conditions namely amniotic band syndrome, amniotic adhesion sequence, and limb-body wall complex. They are probably disruptive sequences secondary to vascular disruption or tissue necrosis and adhesion. The spectrum of pathology includes encephalocele and defects of cranium, cleft palates and other facial abnormalities, autoamputation of digits and limbs, and body wall defects with anomalies of internal organs. The brain is usually normal but cases with developmental abnormalities have also been reported. Karyotypes of affected individuals are normal.
Amniotic adhesion sequence
Characterized by part of the fetus, usually the head, adhering to the placenta.
The cardinal pathologic change is the fusion of the placenta with extensive destruction of the cranium. Part of the amniotic rupture sequence, normal karyotype
Fetal alcohol syndrome
clinical triad of growth retardation, characteristic facial dysmorphology and dysfunction of the central nervous system (CNS). The degree of involvement is highly variable. Dysfunctions of the CNS include mental retardation in 85% of patients, irritability and poor suck in the newborn period, hypotonia, hypertonia, seizures and hyperactivity. In Fetal alcohol syndrome (FAS), patients must have all three chraracteristics, namely, prenatal and postnatal growth retardation (<2 SD for length and weight), characteristic facial features, and CNS dysfunction. When the features of the syndrome are not fully expressed, the term fetal alcohol effects (FAE) can be used.
Growth retardation: Patients remained more than 2 standard deviations below the norm. Some patients may have postnatal catch-up growth.
Characteristic facial features: The facial features are mainly hypoplastic in nature. These features include short palpebral fissures, maxillary hypoplasia with relative prognathism, epicanthal folds, thinning of vermilion border and hypoplastic upper lip, low nasal bridge and anteverted nostrils, hypoplastic upper helix, and apparent hypertelorism due to short palpebral fissure (blepharophimosis).
CNS malformations include microcephaly and malformations of the brain, particularly those of abnormal neuronal migration in nature.
Goldenhar-Gorlin Syndrome (oculoauriculovertebral dysplasia-hemifacial microsomia)
tetrad of epibulbar dermoids, auricular deformities, preauricular appendages, and pretragal fistulae. There may also be vertebral anomalies, hemifacial microsomia, and the first and the second branchial arch syndrome. Abnormalities of the central nervous system include occipital and frontal encephalocele, hydrocephalus, aqueductal stenosis, agenesis and hypoplasia of the corpus callosum, lipoma of the corpus callosum, holoprosencephaly, various skull and vertebral abnormalies, and other abnormalities.
Joubert Syndrome
multiple malformations of the cerebellum and brain stem
Klippel-Trenauny-Weber syndrome:
An ectomesodermal syndrome. Ocular abnormalities include glaucoma, macrocephaly, cerebral and cerebellar hemihypertrophy, arteriovenous malformation of the brain. Skin lesions include port-wine hemangioma or vascular nevi of skin, varicose veins, soft tissue and bony hypertrophy.
