Severity of injury tends to increase due to heightened ICP, especially if pressure exceeds 40 mm Hg (remember CPP)
Increased pressure also can lead to cerebral hypoxia, cerebral ischemia, cerebral edema, hydrocephalus, and brain herniation
Monro-Kellie doctorine
In 1783 Alexander Monro deduced that the cranium was a "rigid box" filled with a "nearly incompressible brain" and that its total volume tends to remain constant. The doctrine states that any increase in the volume of the cranial contents (e.g. brain, blood or cerebrospinal fluid), will elevate intracranial pressure. Further, if one of these three elements increase in volume, it must occur at the expense of volume of the other two elements. In 1824 George Kellie confirmed many of Monro's early observations.
Subfalcine herniation: The cingulate gyrus of the frontal lobe is pushed beneath the falx cerebri when an expanding mass lesion causes a medial shift of the ipsilateral hemisphere. This is the most common type of herniation
Central transtentorial herniation: characterized by displacement of the basal nuclei and cerebral hemispheres downward while the diencephalon and adjacent midbrain are pushed through the tentorial notch
Uncal herniation: displacement of the medial edge of the uncus and the hippocampal gyrus medially and over the ipsilateral edge of the tentorium cerebelli foramen, causing compression of the midbrain, while the ipsilateral or contralateral third nerve may be stretched or compressed
Cerebellar Herniation
Cerebellar Herniation
infratentorial herniation in which the tonsil of the cerebellum is pushed through the foramen magnum and compresses the medulla, leading to bradycardia and respiratory arrest
Hydrocephalus
Hydrocephalus
communicating type is more common which frequently is due to the presence of blood products causing obstruction to flow of the cerebral spinal fluid (CSF) in the subarachnoid space and absorption of CSF through the arachnoid villi
noncommunicating type of hydrocephalus often caused by blood clot obstruction of CSF flow at the interventricular foramen, third ventricle, cerebral aqueduct, or fourth ventricle
Viral meningitis causes milder symptoms, requires no specific treatment, and resolves without complications
Bacterial meningitis is a very serious disease and may result in a learning disability, hearing loss, permanent brain damage, and even death
Viral infections are 2-3 times more common.
Overall incidence of bacterial meningitis in US is estimated to be more than 400 per 100,000 newborn babies, and 1-10 cases per 100,000 adults per year, or 25,000 cases yearly
Overall incidence of bacterial meningitis in US is estimated to be more than 400 per 100,000 newborn babies, and 1-10 cases per 100,000 adults per year, or 25,000 cases yearly
Approximately two-thirds of all cases are in children
Usually occurs in isolated cases without epidemics
More common in males than females
More likely in late winter and early spring
Three types of bacteria are the most common causes of meningitis in all age groups except newborns:
Three types of bacteria are the most common causes of meningitis in all age groups except newborns:
impact loading to the skull with associated laceration of the dural arteries or veins, often by fractured bones and sometimes by diploic veins in the skull's marrow
most common, a tear in the middle meningeal artery causes this type of hematoma. When hematoma occurs from laceration of an artery, blood collection can cause rapid neurologic deterioration
Subdural hematoma
tends to occur in patients with injuries to the cortical veins or pial artery in severe TBI, with associated mortality rate approximately 60-80%
