Chapter 10 – Brain Damage & Recovery

Brain Damage & Recovery

Any source of pressure on the brain may disrupt functioning & even destroy tissue. Common sources of such pressure

1.  Brain Tumors–Neoplasms

·  Compare these 2 basic types: Mengioma vs. Infiltrating Tumor(e.g., Astrocytoma)

·  Accessible?

·  Encapsulated? not?

·  Benign? Malignant?

·  In spite of differences: all neoplasms createpressure– compete with the brain for space in the limited volume of the skull – soMengiomaorInfiltrating– competition for space will always be bad for the brain

2.  Cerebrovascular Accidents (CVA) – Stroke (vague term)

·  Compare these 2 basic types: Hemorrhage(Wet Stroke”) vs. Ischemia(“Dry Stroke”)

·  Blockage (e.g., via Thrombosis, Embolism, or Arteriosclerosis)

·  Blood-Deprived neurons malfunction

·  e.g., release massive amounts of Glutamate (excitatory NT)

·  damaged cell is further damaged by overstimulation

·  damage via overstimulation spreads to surrounding cells (“Penumbra”)

3.  Closed-Head Injuries

·  Contusion-- Hematoma (Bruise)

·  Coup(initial impact – skull slams against brain)

·  Contrecoup(secondary impact – brains slams against skull)

·  Concussion–Sx’sw/o contusion -- not necessarily temporary!

4.  Infections

·  Bacterial-- e.g.,Syphilis(General Paresis)

·  Viral-- e.g.,Rabies,Herpes

5.  Neurotoxins

·  Lead Poisoning(the British coined a term for this)

·  Mercury Poisoning(the British coined a term for this too – appears in well-known literature)

6.  Genetics

·  “Down’s Syndrome”—“Trisomy 21”– (archaic:“Mongloidism”)

Comparison of 2 Mechanisms of Cell Death: Necrosis (Traumatic Brain Injury -- TBI) versus Apoptosis (Genetic): see your text for differences in cause, duration, process, inflammation, & effects on neighboring neurons.


Treatment Protocols for TBI

·  Traditional:

·  Administering Drug Therapy: blood thickeners for Hemorrhage, blood thinners for Ischemia

·  Administering Drug Therapy: anxiolytics for sedation

·  Warming patients with blankets

·  Restricting fluids to minimize swelling (pressure)

·  Finally, passively waiting for “nature to take its course”

·  Reason to question Traditional Medical Treatment? For example, children who fall through the ice of frozen ponds can be resuscitated even if they are underwater for 30 minutes (breaking the “4 minute” rule) – so is it wise towarmpatients???

·  More recent research shows that Traumatic Brain Injury (TBI) includes a 2ndwave of damage that spreadsbeyondthe initialnecrosis

·  This 2ndphase –Penumbra– may last days or even weeks

·  Passivespread from site of initial damage –

§  inflammationdamages surrounding neurons &

§  releaseof stored NT – especially Glutamate --overstimulatessurrounding neurons, causing them also to malfunction & di

·  Activespread from site of initial damage

§  Necrotic cells from the initial site of damage stop sending Neurotrophins(seeCh9) to their presynaptic counterparts

§  agenetically-programmed process of cell death is initiated --calledApoptosis

·  Pioneering medical treatment for strokes is the opposite of Traditional:

·  Cooling patients

·  Actively monitoring & treating, e.g.:

·  Draining CSF to offset swelling &IntercranialPressure (ICP)

·  Forcing fluids & raise blood pressure to offset constricted blood flow to brain

·  Empirical evidence sufficient to label these strategies “Standards of Practice”

Nonetheless, these standard of practice are resisted or ignored by the “old guard” – earlier generations of physicians who may or may not be aware of evidence for Pioneering Medical Treatment – but either way they continue to apply Traditional Medical Treatment techniques that are worse than ineffective