Test 3 Flashcards
Describe the pathophysiology, including clinical manifestations, and treatment options for Parkinson’s disease
- progressive loss of dopaminergic neurons within the substantia nigra of the BASAL GANGLIA. –> Disrupts signals bw BG and premotor cortex –> issues w initiating, stopping and intensity of movement
- Cardinal signs: Tremor (resting); muscle rigidity and/or bradykinesia/akinesia. Also posture/gait, speech difficulty, various others
- No cure, treatment to alleviate symptoms.
1. Levodopa (L-dopa): a dopamine precursor that is converted to dopamine in the substantia nigra (effectiveness reduces over time)
2. Dopamine agonists: trigger dopamine receptors to stimulate the necessary neuronal signals
3. Anticholinergics: restore the dopamine-acetylcholine balance in the basal ganglia (important for proper signaling)
4. Deep brain stimulation: electrical stimulation of certain brain regions
5. Supportive care, e.g. physiotherapy, occupational therapy
Describe the pathophysiology of multiple sclerosis, including disease progression types
- autoimmune demyelination of oligodendrocytes in the CNS (axons) and optic nerve.
- Myelination needed for AP conduction and insulating voltage
- Four main types:
1. Relapse-remitting (RRMS): periods of acute exacerbation and remission, eventually decr. ability to completely recover, causing permanent loss of neurological function (continues to relapse and remission tho)
2. Secondary progressive (SPMS): begins like RRMS, but eventually transitions to steady progression (with no periods of remission).
3. Primary progressive (PPMS): steady progression neurological dysfunction from onset of the disease without periods of remission.
4. Progressive relapsing (PRMS): steady progression with superimposed attacks of exacerbation. Rare. - The clinical manifestations are unpredictable and highly variable bc any part of the CNS can be affected.
Describe the pathophysiology of Guillian-Barré syndrome, including common signs and symptoms
- Autoimmune demyelination of schwann cells in the PNS axons
- Most commonly associated with infections, functions are eventually regained
- Clinical manifestations
1. SENSORY - paresthesia, dysesthesia, diminished reflexes, pain
2. MOTOR
A) Somatic - muscle weakness, paralysis
B) Autonomic - HR and BP alterations, increased/decreased sweating, constipation, urinary retention
- Symptoms typically start peripherally w rapid onset, usually have a complete recovery
Describe the pathophysiology of myasthenia gravis, including signs and symptoms
- decr. skeletal muscle stimulation due to autoimmune destruction of Ach receptors at the NMJ.
- muscle weakness and fatigue worsens upon exertion and typically improves with rest
- Signs/symptoms: limb weakness, difficulty swallowing and breathing, unstable gait, drooping eyelids
- Severe muscle weakness: quadriplegia, impaired ventilation and swallowing
- If ventilation muscles affected, risk of MG crisis
Describe the pathophysiology of epilepsy, including the main types, key terminology and status epilepticus
- recurrent and unprovoked seizures (hyperactive, synchronous AP discharge)
- Main types
1. Partial (focal) seizures: involve only one part of the cerebrum.
A) Simple: remains conscious, sensory and/or muscular activity
B) Complex: loss/alteration to consciousness, sensory and/or motor experiences
2. Generalised seizures: occurs w/in most brain regions and typically result in loss of consciousness.
A) Tonic: state of increased muscle tone and rigidity w LOC (stiffness incl. resp mm)
B) Atonic: muscles go relaxed
C) Absence: brief episodes of altered consciousness characterised by staring and unresponsiveness
D) Tonic-clonic: stiffness and LOC followed by convulsions
E) Myoclonic: brief muscle twitches (usually single muscle group) - Terminology:
- prodrome: feelings, perceptions, etc. PRECEDING a seizure
- aura: feelings, thoughts, perceptions, etc. as part of a seizure.
- postictal: time after a seizure (mins to days) minutes to hours. May incl. altered consciousness and/or various other symptoms
- Status epilepticus is a serious complication of epilepsy when seizure activity of tonic-clonic seizures (mostly) is sustained for longer than 5 minutes or there are recurrent seizures without recovery of consciousness in between. Emergency bc during seizures there is an increased O2 demand and a decreased ventilation; can lead to cardiorespiratory failure very quickly (w/in minutes), as well as brain death (bc O2 deprived)
Which of the following neuroglia are found in the CNS and which in the PNS?
Ependymal cells, Microglia, Schwann cells, Astrocytes, Satellite cells, Oligodendrocytes
CNS: Ependymal cells, Microglia, Astrocytes, Oligodendrocytes
PNS: Schwann cells, Satellite cells
Which of the neuroglia produce myelin?
Oligodendrocytes and Schwann cells
Which part of the brain is responsible for regulating skeletal muscle movements, particularly the initiation, intensity & ceasing of those movements?
Basal ganglia
Describe the cerebral cortex and identify some of the key functional areas of the cerebral cortex and what they do.
- Prefrontal cortex: integrative functions, incl. many higher cognitive functions
- Primary motor cortex: decides on skeletal muscle movements in coordination w basal ganglia and cerebellum
- Primary somatosensory cortex: sends signals along upper motor neuron down spinal cord
- Somatosensory association area: determines type, location and intensity of somatic sensory stimuli (touch, temp, pain, etc.)
- Posterior association area: integrative functions, particularly higher cognitive functions associated w the senses, language and memory
- Special sense cortices: specialised area processing signals coming from the special sense organs
Outline the homeostatic mechanisms regulating cerebral blood flow and intracranial pressure (ICP)
- Cerebral Blood Flow
- cerebral blood vessel diameter adjustment to maintain adequate blood flow.
- Responds to changes in blood pressure and blood gases (PaCO2 or PaO2) - ICP
- Intracranial vol made up of 80% brain tissue, 10% blood and 10% CSF
- fixed space; an increase in volume in one of the three components requires a decrease in volume of one of the other components
- normally between 5-15mmHg
Relate consciousness and arousal (incl. which part of brainstem responsible) and outline the Glasgow Coma Scale (GCS) for measuring consciousness
- Consciousness is awareness of oneself and environment and ability to elicit expected responses. This involves arousal, a state of wakefulness and vigilance to immediate surroundings (reticular formation of the brainstem is responsible for maintaining arousal)
- GCS assesses an individual’s ability to open their eyes and manage verbal and motor responses, taking into account the individuals context/local factors (e.g. swelling which may prevent eye opening or hearing loss which may reduce response to commands).
- Score bw 3-15:
Eye opening
—- spontaneous (4)
—- sound (3)
—- pain (2)
—- none (1)
Verbal response
—- orientated (5)
—- confused (4)
—- words (3)
—- sounds (2)
—- none (1)
Motor response
—- obeys commands (6)
—- localized (5)
—- normal flexion (4)
—- abnormal flexion (3)
—- extension (2)
—- none (1)
Distinguish between blunt and penetrating traumatic brain injury (TBI) and between primary and secondary injury
- Blunt: brain is NOT exposed to external environment
- Penetrating: broken skull/dura and neural tissue IS exposed
- Primary injury: initial tissue damage that occurs at impact. (incl. penetration, compression and shearing forces)
- Secondary injury: occurs after the primary injury and involves the inflammation, swelling/oedema and bleeding that follows the primary injury.
Identify key factors in the evaluation and management of TBI, including use of the GCS
- Involves a thorough history and neurological examination. Brain imaging is used to distinguish between focal and diffuse injuries and to identify any intracranial hemorrhage/hematoma
- Glasgow Coma Scale is often used to assess the neurological impact of a TBI and provides a rough guide to the severity of the TBI:
Mild is score 13-15
Moderate is score 9-12
Severe is score 3-8 - Major component of treatment is management of ICP and CCP. Monitoring ventilation and BP is also important, as is maintaining electrolyte levels, BGL and temp
Describe the pathophysiology of focal and diffuse TBI
- Focal TBI
- localized tissue damage due to blunt OR penetrating trauma. Can cause:
A) contusion injury: brain tissue damage due to the impact of the brain against the skull, associated w the compression and shearing forces. Can be:
i) coup: injury at initial impact point(s)
ii) countercoup: rebound injury
B) Hematoma: accumulation of clotted blood within the cranium. Increases ICP. - Diffuse TBI
- widespread neural damage assoc. w blunt trauma
- Ranges from concussion (mild) to severe diffuse axonal injury (DAI) w coma
- DAI occurs due to massive shearing forces and causes large numbers of damaged axons –> simultaneous AP firing –> excitotoxicity –> disruption of ATP formations –> decr. AP and coma
Which neuroglia form the BBB? What’s the role of the BBB?
Astrocytes
Ensures that neurons do not come into direct contact with blood or substances in blood that could be harmful to neurons. It also regulates the ECF environment around neurons
Briefly describe autoregulation and outline why this is so important for the brain.
Is when organs regulate the blood flow and blood pressure within their own capillary networks.
This is important to ensure that the brain receives adequate blood flow at adequate pressure, regardless of what is happening with blood flow/pressure in the rest of the body.
What is the circle of Willis?
This network of blood vessels found at the base of the brain includes numerous connecting arteries which supply the vast majority of the cerebrum.
Order these protective layers surrounding the CNS from superficial (1) to deep (5). Arachnoid mater Dura mater Skull bones Pia mater CSF
Skull bones Dura mater Arachnoid mater CSF Pia mater
What are the ‘spaces’ in the brain where CSF is produced called? And how many are there?
Ventricles, of which there are 4
After circulating through the subarachnoid space, where does CSF flow into?
Into the dural sinus/venous blood within the dural sinus
