Clinical Embryology Flashcards
An infant presents with a telencephalic vesicle; the eyes are fused and a single nasal chamber is present in the midline. What is the diagnosis?
In holoprosencephaly, loss of midline structures results in malformations of the brain and face. There is also often hypoplasia of the olfactory bulbs, olfactory tracts and corpus callosum.
An infant presents with meningohydrocenphalocele. Which bone is commonly affected?
Usually, deficits of the cranium involve the squamous part of the occipital bone and in some cases, the posterior aspect of the foramen magnum. If the herniation or protruding brain includes part of the ventricular system (most likely the posterior horn of the lateral ventricles) then it is referred to as meningohydroenecephalocele.
The deficit in the squamous part of the occipital bone usually occurs at the posterior fontanelle of the skull.
An infant was born with the vault of the skull underdeveloped, leaving the malformed brain exposed. What is the most common embryologic cause of this?
If the rostral neuropore fails to close during the 4th week of developement, the forebrain primordium is abnormal and the calvaria or vault fails to develop.
A newborn infant presents with a defective calvaria and the brain protruding from the cranium. Merocephaly is diagnosed. What is the cause of this?
Merocephaly results from a failure of the rostral neuropore to close during the 4th week of development. The calvaria is absent, with a resultant extrusion of the brain from the cranium.
An infant has a large defect in the occipital bone (cranium bifidum). Imaging reveals the defect contains meninges and part of the brain, including the ventricular system protruding through it. What is the diagnosis?
In cranium bifidum, if the protruding brain contains part of the ventricular system, the condition is known as meningohydroencephalocele.
cranial meningocele = only meninges herniate.
meningoencephalocele = also brain matter
meningohydroencephalocele = also ventricular system
A patient has nonobstructive (communicating) hydrocephalus. Between which structure is malabsorption most likely to occur?
A nonobstructive hydrocephalus occurs as a result of decreased reabsorption of cerebrospinal fluid (CSF) via the arachnoid villi. The choroid plexus produces the CSF, which flows into the subarachnoid space and is reabsorbed into the sup. sagittal sinus via the arachnoid villi.
