Biomaterial Database

The "keyhole": a sign of herniation of a trapped fourth ventricle and other posterior fossa cysts. 1987

B J Wolfson, and E N Faerber, and R C Truex

When a cystic structure in the posterior fossa increases in size, the accompanying increase in pressure may cause it to herniate upward through the tentorial hiatus. In our experience this happens most commonly with a dilated trapped fourth ventricle secondary to infection or intraventricular hemorrhage. However, herniation of an arachnoid cyst or a Dandy-Walker malformation through the tentorium may also occur. When herniation occurs, the cystic structure assumes a "keyhole" configuration, indicating that it is trapped and that surgical intervention is necessary. Five cases are presented that illustrate this point, including two patients with dilatation of the fourth ventricle secondary to hemorrhage, two patients with Dandy-Walker malformation, and one patient with an arachnoid cyst.

UI	MeSH Term	Description	Entries
D007223	Infant	A child between 1 and 23 months of age.	Infants
D007231	Infant, Newborn	An infant during the first 28 days after birth.	Neonate,Newborns,Infants, Newborn,Neonates,Newborn,Newborn Infant,Newborn Infants
D008297	Male		Males
D001927	Brain Diseases	Pathologic conditions affecting the BRAIN, which is composed of the intracranial components of the CENTRAL NERVOUS SYSTEM. This includes (but is not limited to) the CEREBRAL CORTEX; intracranial white matter; BASAL GANGLIA; THALAMUS; HYPOTHALAMUS; BRAIN STEM; and CEREBELLUM.	Intracranial Central Nervous System Disorders,Brain Disorders,CNS Disorders, Intracranial,Central Nervous System Disorders, Intracranial,Central Nervous System Intracranial Disorders,Encephalon Diseases,Encephalopathy,Intracranial CNS Disorders,Brain Disease,Brain Disorder,CNS Disorder, Intracranial,Encephalon Disease,Encephalopathies,Intracranial CNS Disorder
D002543	Cerebral Hemorrhage	Bleeding into one or both CEREBRAL HEMISPHERES including the BASAL GANGLIA and the CEREBRAL CORTEX. It is often associated with HYPERTENSION and CRANIOCEREBRAL TRAUMA.	Brain Hemorrhage, Cerebral,Cerebral Parenchymal Hemorrhage,Hemorrhage, Cerebral,Intracerebral Hemorrhage,Hemorrhage, Cerebrum,Brain Hemorrhages, Cerebral,Cerebral Brain Hemorrhage,Cerebral Brain Hemorrhages,Cerebral Hemorrhages,Cerebral Parenchymal Hemorrhages,Cerebrum Hemorrhage,Cerebrum Hemorrhages,Hemorrhage, Cerebral Brain,Hemorrhage, Cerebral Parenchymal,Hemorrhage, Intracerebral,Hemorrhages, Cerebral,Hemorrhages, Cerebral Brain,Hemorrhages, Cerebral Parenchymal,Hemorrhages, Cerebrum,Hemorrhages, Intracerebral,Intracerebral Hemorrhages,Parenchymal Hemorrhage, Cerebral,Parenchymal Hemorrhages, Cerebral
D002552	Cerebral Ventricles	Four CSF-filled (see CEREBROSPINAL FLUID) cavities within the cerebral hemispheres (LATERAL VENTRICLES), in the midline (THIRD VENTRICLE) and within the PONS and MEDULLA OBLONGATA (FOURTH VENTRICLE).	Foramen of Monro,Cerebral Ventricular System,Cerebral Ventricle,Cerebral Ventricular Systems,Monro Foramen,System, Cerebral Ventricular,Systems, Cerebral Ventricular,Ventricle, Cerebral,Ventricles, Cerebral,Ventricular System, Cerebral,Ventricular Systems, Cerebral
D003388	Cranial Fossa, Posterior	The infratentorial compartment that contains the CEREBELLUM and BRAIN STEM. It is formed by the posterior third of the superior surface of the body of the sphenoid (SPHENOID BONE), by the occipital, the petrous, and mastoid portions of the TEMPORAL BONE, and the posterior inferior angle of the PARIETAL BONE.	Clivus,Cranial Fossas, Posterior,Fossa, Posterior Cranial,Fossas, Posterior Cranial,Posterior Cranial Fossa,Posterior Cranial Fossas
D003560	Cysts	Any fluid-filled closed cavity or sac that is lined by an EPITHELIUM. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues.	Cyst
D003616	Dandy-Walker Syndrome	A congenital abnormality of the central nervous system marked by failure of the midline structures of the cerebellum to develop, dilation of the fourth ventricle, and upward displacement of the transverse sinuses, tentorium, and torcula. Clinical features include occipital bossing, progressive head enlargement, bulging of anterior fontanelle, papilledema, ataxia, gait disturbances, nystagmus, and intellectual compromise. (From Menkes, Textbook of Child Neurology, 5th ed, pp294-5)	Dandy-Walker Malformation,Dandy-Walker Complex,Dandy-Walker Cyst,Dandy-Walker Deformity,Dandy-Walker Syndrome, Familial,Hydrocephalus, Internal, Dandy-Walker Type,Hydrocephalus, Noncommunicating, Dandy-Walker Type,Luschka-Magendie Foramina Atresia,Cyst, Dandy-Walker,Cysts, Dandy-Walker,Dandy Walker Complex,Dandy Walker Deformity,Dandy Walker Malformation,Dandy Walker Syndrome,Dandy Walker Syndrome, Familial,Dandy-Walker Complices,Dandy-Walker Cysts,Dandy-Walker Deformities,Familial Dandy-Walker Syndrome,Luschka Magendie Foramina Atresia,Malformation, Dandy-Walker
D005260	Female		Females