2301 final topic 11

Traumatic Brain Injury (TBI)

• an injury to the brain from an external source that results in some alteration of cognitive or behavioural functioning

• differs from ABI (acquired brain injury)

  • e.g stroke

  • distinction: external source

• results in compromised brain functioning not caused by a neurodegenerative or neurodevelopmental condition

• effects may be long-lasting or permanent

  • vary with severities and specifics

Causes of TBI

• external sources

  • being struck in the head by an object/head striking objects

  • brain experiencing rapid acceleration or deceleration (e.g slamming breaks quickly) movements

  • foreign body penetrating the brain (e.g getting shot)

  • forces generated from external events such as explosions

• specific impairments may be at the coup and/or contrecoup location

  • coup → front part of the brain

  • contrecoup → brain injury occurring on the opposite side of the skull from the initial impact

• can result in more generalized impairments due to widespread damage caused by brain movement (shearing), swelling, etc

prevalence of TBI

• ~160,000 canadians sustain TBIs each year, and incidence rates are rising

• ~450 people a day; more than 11,000 canadians die each year

  • 1 person every 3 minutes will suffer a TBI

• likely underestimations due to most estimates not including individuals either treated in outpatient settings or who do noy present for treatment at all

causes of TBI in Canada

• falls (32.2%)

  • greatest at extremely young or extremely old people due to motor skill

• motor vehicle related injuries (17.3%)

  • highest incidence in late adolescence and early adulthood

  • highest in vehicle incidence for motorcyclists but the highest rate is actually pedestrians being hit by cars

• strikes/blow to the head from/against object (16.5%)

• assaults (10%)

  • highest in 20-24 age range in lower socioeconomic conditions

• other/unknown/combo (21%)

TBI risk factors: age

• highest rates in:

  • <4 years old

  • 15-19 years old

  • elders >65 years old

    • elderly people are at risk for worse outcome/symptoms

TBI risk factors: biological sex

• higher rates in males compared to females

  • ratio 1.6-2.8

• increased rate during ages 15-19 for both groups due to motor vehicle accidents

  • men are more frequently exposed to high risk situations and 2x more motor vehicle accidents

• higher rates for females over the ages of 65

  • females tend to live longer

other risk factors for TBI

• for all types of TBI but assaults in particular

• socioeconomic status

• unemployment

• education level

• race/ethnicity

• history of substance abuse

TBI presentation

• varies and depends on severity

  • more severe → more cognitive issues, less likely to return to work/school, lower quality of life, greater depression

  • can have poor functioning mild TBI or high functioning severe TBI

• range of severity → mild to moderate to severe

  • defined by injury characteristics: level or duration of impaired consciousness

Glasgow Coma Scale

• range from 3 to 15

  • 3 = no responsiveness, 15 = full responsiveness

• 8 or less = severe TBI

• 9-12 = moderate TBI

• 13 or higher = mild TBI (mTBI)

stroke

• rapid development of clinical signs of focal or global disturbance of cerebral function, with no apparent cause other than vascular origin

• interruption of blood flow from either the blockage or bleeding of a vessel

type of strokes: Ischemic Stroke

• a blood vessel becomes blocked, and a portion of the brain becomes deprived of oxygen and stops working

• account for ~80% of all strokes

• produce impairments specific to their location

• mild compared to hemorrhagic strokes

  • thrombotic stroke: blood clot (thrombus) that forms locally in a vein or artery that supplies blood to the brain

    • atherosclerosis (fatty plaques that narrow blood vessels)

  • embolic strokes: a mass (usually a piece of a blood clot somewhere else) that travels through the bloodstream and gets stuck in a vessel or artery in the brain

FAST acronym

• stroke identifier

  • F(ace) = is one side of the face drooping down?

  • A(rm) = can the person raise both arms or is one arm weak

  • S(peech) = is the speech slurred or confusing

  • T(ime) = is critical. call 911 asap

types of strokes: hemorrhagic stroke

• occurs when a blood vessel that carries oxygen to the brain bursts and spills blood into the brain

• greater mortality rate compared to ischemic stroke

• typically results from weakened blood vessels, such as an aneurysm

• accounts for about 20% of strokes

  • causes:

    • most common — hypertension

    • bleeding disorders

    • prolonged cocaine use

    • abnormal blood vessels (AVMS)

Transient Ischemic Attack (TIA)

• mini strokes

• temporary blockage in blood flow to the brain

• Symptoms usually last for just a few minutes and go away within a day

  • usually present as mild stroke-like symptoms

  • if caused by a blood clot it breaks up on its own

• caused by hypertension and the temporary narrowing of blood vessels

• don’t cause severe or permanent brain damage but are a warning sign of a future stroke

• increases risk: within 1 month after TIA, 10-15% of people will go on to have an actual stroke

Effects of Strokes

• excitotoxicity

  • glutamate is the most prevalent excitatory neurotransmitter in the brain and plays a role in several neurological processes

  • when the brain is injuired, it releases large amounts of glutamate → over stimulating the glutamate receptors of neurons → causes a large amount of calciums to enter neurons → distruption of cellular processes and increased free radicals

    • free radicals = structurally unbalance chemicals than can destory the internal structure of neurons, resulting in cell death

stroke treatments

• thrombolytic drugs = drugs that immediately dissolve the blood clots that cause many strokes, lowering the amount of damage

  • e.g tissue plasminogen activator (tPA)

• delivered directly into the bloodstream

  • reduces mortality if administered within the first few hours of the stroke before the nerve cells deprived of oxygen suffer permanent damage

  • best time window = 3-6 hours from the efirst signs of stroke

Epilepsy

• recurring seizures resulting from abnormal or excessive electrical activity in the brain

• affects 1% of the population

  • begins at any age

  • equally present in biological sexes

  • ~10 of all people have a seizure at some point, but it does not always develop into epilepsy

• underlying causes vary

  • many forms are idiopathic

  • e.g due to TBIs, tumors, infections, genetics, etc

Focal/partial seizures

• have a localized area of onset and are generally maintained in that location

• may have motor/sensory/cognitive and/or behavioural features depending on the focal location

  • classification:

    • simple partial seizure: awareness is retained, subtle symptoms and typically affects only a small part of the brain

    • complex partial seizure: awareness is not retained, typically involves one whole hemisphere, may go on to become a generalized seizure

generalized seizures

• start at a focal location, then spread rapidly and bilaterally to involve both hemispheres

• subtypes

  • absence/petit-mal: brief unconciousness without convlusions, blank stare, abrupt start/stop

  • tonic-clonic/grand mal: involves major motor manifestationsconvlusioms, loss of conciousness

  • myoclonic: rapid, involuntary, brief contracts of modily muscles typically on limbs or face

treatment of epilepsy

• enhance the action of the inhibitory neurotransmitter GABA

  • antiepileptic drugs/ anticonvulsants

  • 30-40%

  • if drugs fail: intractable epilepsy

    • Treatment can be surgical resection of epileptogenic tissue

      • 70% success rate

      • will almost always produce some mild cognitive difficulties

    • corpus callosotomoy

      • split brain surgery