Brooke's Flashcards
What is hyperdense on CT?
Hyperdense=bright on CT
Blood and calcifications
What is hypodense on CT?
Hypodense=dark on CT compared to surrounding brain.
Could be infarction, edema, pneumocephalus.
Pneumonic for an emergent CT head.
Blood Can Be Very Bad
- Blood - look for epidural/subdural hematomas, ICH, IVH, subarachnoid hemorrhage and (also) extracranial hemorrhage.
- Cisterns - look for the presence of blood, effacement and asymmetry in four key cisterns (perimesencephalic, suprasellar, quadrigeminal and Sylvian cisterns).
- Brain - look for asymmetry or effacement of the sulcal pattern, gray-white matter differentiation, structural shifts and abnormal hypodensities (e.g. air, edema, fat) or hyperdensities (e.g. blood, calcification).
- Ventricles - look for intraventricular hemorrhage, ventricular effacement or shift and for hydrocephalus.
- Bone - look for skull fractures (especially basal) on bone windows (soft tissue swelling, mastoid air cells and paranasal sinuses fluid in the setting of trauma should raise the possibility of a skull fracture; intracranial air means that the skull and the dura have been violated somewhere).
Things that are bright on FLAIR imaging?
- Acute SAH.
- Edema.
- Acute infarcts.
There are others but those are the big ones.
When does the anterior fontanelle normally close?
- 4-26 months of age.
When does the posterior fontanelle normally close?
- Before 2 months of age.
An enlarged posterior fontanelle can occur in what conditions?
- Congenital hypothyroidism.
- Trisomy syndromes.
- Rickets.
- Osteogenesis imperfecta.
- Hydrocephalus.
A depressed anterior fontanelle can be a sign of what condition?
- Dehydration.
When does the embryonic skull begin to form?
- Between the 23rd and 26th day of gestation.
What is thought to initiate cranial suture formation?
- Osteogenic fronts, which consist of osteoprogenitor cells and osteoblasts at the leading edges of developing bone.
What factors determine normal suture formation?
- Bone deposition by osteoblasts.
- Bone remodeling by osteoclasts.
- Apoptosis in the frontal boundaries.
- Local interactions between dura mata and the sutures.
- Growth factors (fibroblast growth factor receptor and transforming growth factor).
True or false: The primary influence for cranial growth is the growing brain.
True.
Name the sutures of the cranium.
- Metopic (between both frontal bones).
- Sagittal (between both parietal bones).
- Two coronal (between parietal and frontal bones).
- Two lambdoid (between occipital and parietal bones).
- Squamosal (between parietal, temporal, and sphenoid bones).
Which of the sutures naturally closes earliest?
- Metopic suture - usually closed by 9 months of age.
What are the 4 principles associated with suture closing?
- Calvarial bones directly next to the fused suture act as a single bone plate with decreased growth potential.
- Asymmetrical bone deposition occurs at the sutures along the perimeter of the bone plate with increased bone deposition at the outer margin.
- Nonperimeter sutures in line with the fused suture deposit bone symmetrically at their suture edges.
- Perimeter sutures adjacent to the fused suture compensate to a greater degree than the other distant sutures.
