CNS Trauma - Cochran Flashcards
Describe the tissues traversed as one travels from the skull into the brain parenchyma. Include the spaces in between these tissues!
Skull (and periosteum)
Epidural space
Dura Mater
Subdural space
Arachnoid mater
Subarachnoid space
Pia mater
Brain parenchyma
What does “leptomeninges” refer to?
What is the name given to the potential space surrounding arachnoid and pial vessels?
The arachnoid and pia mater. From the greek “leptos”, meaning fine or thin.
Virchow-Robin spaces.
What venous sinuses are housed within the falx cerebri?
The tentorium cerebelli?
Superior and inferior sagittal sinuses, straight sinus.
Transverse sinuses, straight sinus (*intersection of falx)
Trace the path followed by CSF secreted in a lateral ventricle through its reabsorption into a venous sinus.
From the lateral ventricle, travels into the third by way of the Interventricular foramen of Monro. Reaches the fourth ventricle by the central aqueduct (of Sylvius). Leaves the ventricular system via the Foramina of Luschke (2x, lateral) or Magendie (1x, midline). Reabsorbed from the basal cisterna via arachnoid granulations.
Describe the components of the blood-brain barrier.
How are substances transported across it?
Comprised of vascular endothelium (with abundant tight junctions, pericytes) as well as astrocyte processes and basement membrane.
Small and lipophilic substances can freely diffuse across; large or charged must be actively transported.
In which compartment is fluid found in vasogenic edema?
What tissue does it usually affect?
Describe its pathogenesis.
The extracellular compartment.
The white matter.
Increased permeability of the BBB due to tumors, VEGF, and inflammatory states.
In which compartment is fluid found in toxigenic edema?
What tissue does it usually affect?
Describe its pathogenesis.
Intracellular compartment.
Gray matter.
Cellular energy failure causes decreased pumping. Sodium enters the cell, and water follows. (may also be due to excess glutamate, extracellular potassium, cytokines, etc)
What occurs in a subfalcine herniation?
What causes it?
Complications?
The cingulate gyrus herniates under the falx.
Asymmetric expansion (eg mass effect)
May compress the anterior cerebral artery.
What occurs in a transtentorial herniation?
What causes it?
Complications?
Inferior displacement of the uncus around the tentorium cerebelli.
Asymmetric expansion.
Ipsilateral CN III compression, contralateral brainstem compression, PCA compression, and duret hemorrhage.
Why is mydriasis seen in tentorial herniation?
What is Kernohan’s notch?
What is the prognosis for a duret hemorrhage?
Again, what do all of these stem from?
Compression of the ipsilateral third cranial nerve, in which the pupillary constrictor fibers travel along the exterior.
Creasing of the contralateral cerebral peduncle against the tentorium. Causes ipsilateral weakness & babinski signs.
Duret hemorrhages are fatal (brainstem!)
These all arise from Transtentorial herniation.
What occurs in a tonsillar herniation?
What causes it?
Complications?
Escape of the cerebellar tonsils inferiorly through the foramen magnum.
Symmetric expansion in the posterior fossa.
Compression of the medulla can cause cardiopulmonary arrest (fatal)
Distinguish a communicating hydrocephalus from a non-communicating one.
Give some causes for each.
Communicating hydrocephalus has ventricular patency; non-communicating has an obstruction.
Communicating: Overproduction of CSF or decreased absorption (meningitis, subarachnoid hemorrhage, thrombosis)
Non-communicating: Tumor, malformation (eg ventricular atresia), meningeal thickening (eg Meningitis)
In the context of head trauma:
What is the difference between open and closed?
Primary vs secondary?
Open vs closed refers to the overlying skull and skin.
Primary vs secondary refers to injury being caused directly or indirectly by the trauma (eg hemorrhage and subsequent ischemia).
Blunt trauma can feature distinctive patterns of bony, parenchymal, and vascular injury depending on how it occurs.
Describe three patterns of bony fracture.
Linear: Single full-thickness fracture.
Comminuted: Multiple radiating fractures.
Depressed: Bony fragments displacing inward.
What is a concussion?
What are its clinical features?
Pathophysiologic change resulting from CNS trauma without evident structural abnormalities.
Patients present with immediate and generally transient neurologic impairment (physical, cognitive, emotional. +/- consciousness).
