Chapter 11 Flashcards
traumatic brain injury (TBI)
happens when a sudden, external, physical assault damages the brain
- TBI is a broad term that describes a vast array of injuries that happen to the brain. The damage can be: focal, diffuse
focal damage
confined to one area of the brain
- contusions (visible)
- concussion (non-visible)
- chronic traumatic encephalopathy (CTE) brain degeneration suffered by professional football players
- hematomas (subdural and epidural)
diffuse damage
happens in more than one area of the brain
two ways TBIs may happen
closed brain injury, penetrating brain injury
closed brain injury
- happen when there is a non-penetrating injury to the brain with no break in the skull
- a rapid forward or backward movement and shaking of the brain inside the bony skull (e.g., car accident or violently shaking a baby)
- diffuse axonal injuries (DAI)
penetrating brain injury
- open head injuries
- happen when there is a break in the skull, such as when a bullet pieces the brain
diffuse axonal injury (DAI)
a type of TBI that occurs due to shearing of a brain’s long connecting nerve fibers (axons) that happens when the brain is injured as it shifts and rotates inside the boney skull
classifications of TBI based on the Glasgow coma scale (GCS)
mild (13-15), moderate (9-12), severe (below 8)
symptoms of diffuse axonal injury (DAI)
- can present in a spectrum of neurological dysfunction
- can range from clinically insignificant to a comatose state
- most patients are identified to be severe and commonly have a GCS of less than 8
etiology of DAI
- most common etiology involves high-speed motor vehicle accidents
- most common mechanism involves an accelerating and decelerating motion that leads to shearing forces to the white matter tracts of the brain
- commonly affects white matter tracts involved in the corpus callosum and brainstem
coup contra coup
- coup injury refers to the brain damage that occurs directly under the point of impact
- coutra coup injury occurs on the opposite side of the brain from where the head is struck
(when a blow is taken to one side of the skull/brain and then the skull/brain rocks back and forth in reaction)
bad design of the skull
if brain slides against ethmoid ridge and/or sphenoid ridge, it can get wrecked
ethmoid ridge
bone separating the hemispheres
sphenoid ridge
bone separating frontal and temporal lobes
one consequence of contusions
orbitofrontal cortex damage
- affects executive function
clinical features of mild traumatic brain injury: initial presentation
- initial loss of consciousness lasting seconds to minutes, but not lasting longer than 30 minutes
- period of confusion (post-traumatic amnesia) lasting minutes to hours, but can last up to 24 hours
- any combination of headaches, neck ache, dizziness, and nausea
- typically no focal findings on the remainder of the neurological examination
clinical features of mild traumatic brain injury: follow-up presentation
“neural injury”
- cognitive deficits (attention, memory, and executive function)
- behavioral deficits (depression, anxiety)
“non-neural injury”
- systemic deficits (head/neck ache, dizziness, poor sleep)
recovery from a mild traumatic brain injury
- typical patient (loss of consciousness [LOC] <1-minute, post-traumatic amnesia [PTA] <20-40 minutes) usually recovers within 3 months
- if injury is more severe (LOC > 10 minutes, PTA > 4-6 hours) recovery can take months to years, or not at all
- older patients (>55 years) will take longer to recover
- 10-15% of mild TBI patients have symptoms at 1 year (called persistent post-concussive syndrome [PPCS])
other causes of TBI
- epidural hematoma
- subdural hematoma
treating hematoma
decompressive craniectomy
- remove portion of skull so brain can inflame and go out through that removed portion rather than pushing down inside the skull
seizure
abnormal discharge of neurons that causes sudden and brief (seconds to minutes) abnormalities of brain function (sensory, motor, behavioral, cognitive)
epilepsy
recurrent seizures of unknown etiology
neurotransmitters in epilepsy
1) influx of sodium
2) influx of calcium
3) release of glutamate
4) activation of excitatory receptors
5) inhibition of GABAergic system
- thought that glutamate is implicated
causes of seizures
- genetic
- trauma/brain injury
- tumors
- vascular - stroke, hemorrhage, AVM
- toxic - alcohol, cocaine
- infections - encephalitis, meningitis
- metabolic - hyponatremia, hypoglycemia, hypocalcemia
- other - sleep deprivation, fainting, fever (children)
epilepsy - generalized
- tonic/clonic (Grand Mal)
- absence (petit Mal)
- complex partial (most common in adults) (unconscious)
epilepsy - focal (partial)
simple partial (conscious)
generalized tonic-clonic epilepsy
- impaired consciousness
- aura (20%) –> feel that it is coming
- collapse to floor
- tonic body extension followed by clonic jerking
- loss of bowel or bladder (20%)
- prolonged post-ictal state up to hours
petit mal seizures
- generalized (absence)
- impaired consciousness, brief 2-3 second episodes
- chewing movements in 20% of cases
- NO post-ictal state; 3 per second spike-wave discharge
complex partial seizures
- a focal onset impaired awareness seizure
- starts in temporal lobe then moves to other areas of the brain that affect symptoms
- impaired consciousness
- dreamy state, deja vu
- formed auditory hallucinations - music
- formed visual hallucinations
- chewing movements, automatisms (picking at clothing)
- language disturbance
simple partial (focal) seizures
- consciousness
- somatosensory - tingling
- motor - twitching, head turning, grimacing
- visual - flashes of light
- auditory - ringing, hisses, noises
- olfactory - bad odors
- autonomic - sweating, flushing, epigastric pain
treatment of epilepsy
- anti-epileptic medications
- surgery
anti-epileptic medications
- decrease membrane excitability by interacting with neurotransmitter receptors or ion channels
- act on sodium channels, gamma-aminobutyric acid (GABA) receptors, or calcium channels
surgery to treat epilepsy
remove affected brain tissue
types of brain tumors
primary, secondary
primary brain tumors
- intraparenchymal –> glioma (astrocytoma)
- extraparenchymal –> meningioma
secondary brain tumors
intra or extraparenchymal –> metastases
started outside the brain then traveled into the brain
intraparenchymal
inside the brain
extraparenchymal
outside the brain
location of brain tumors
- adults: cerebral hemispheres
- children: brainstem and cerebellum
symptoms of brain tumors
- depends on location
- slowly progressive
- if cortex involved, seizures are common
childhood brain tumors
- almost always in the posterior fossae: cerebellum and brainstem
- balance (ataxia) and cranial nerve problems (double vision) typical
- 4 types: 2 treatable, 2 not very treatable
watershed zones
areas of the brain that are fed by two main artery supplies
- the artery diameter is small and circulating tumors get stuck
- metastasis often found at first in watershed zones
usual sources of secondary tumors
- lung
- colon
- breast
- melanoma
- kidney
