Tutorial 5 Alterations in CNS & PNS Flashcards
1
Q
Define consciousness and state how it is assessed
A
- The term “consciousness” has different meanings e.g. self-awareness or a state of alertness. In the context of this unit, we will define consciousness, as described to what extent a person is alert and awake, aware of their surroundings and how responsive they are to stimuli.
- In clinical situations, consciousness can be assessed using the Glasgow Coma Scale. The GCS measures the patient’s responses in terms of how the patient opens their eyes, verbal responses, and motor responses.
2
Q
Which part of the brain plays a key role in the control of consciousness?
A
Reticular activating system (RAS)
a. part of the brain stem
b. consists of nuclei and tracts
c. regulates wakefulness, arousal and sleep
3
Q
Describe common causes of altered levels of consciousness
A
- Altered level of consciousness can occur as the result of intracranial or extracranial causes
- Intracranial causes:
e. g. head injury, haemorrhage, increased intracranial pressure, degenerative conditions, space-occupying lesions, and vasospasm of cerebral vasculature - Extracranial causes:
e. g. hypoxia, HTN, pH imbalance, systematic infection, hypo/hyperglycaemia, hepatic or renal dysfunction, medications or toxins
4
Q
State how many strokes occur each year in Australia and list the major risk factors for stroke
A
- approx. 40,000 - 48,000 strokes occur each year AU
- It causes 7-10% of all deaths in AU
- Major risk factors:
e. g. HTN, diabetes mellitus, hyperlipidemia, smoking, increased age, family history, alcohol consumption and heart disease
5
Q
State the clinical manifestation of stroke
A
- Depending on the location and severity of the stroke, the patient may have problems with their motor, speech, sensory, language and cognitive functions
- The diagnosis of the cause of the stroke needs to identify whether it is haemorrhage or ischaemic
- CT, MRI and National Institute of Health Stroke Scale may be used in the assessment of the patient
6
Q
Discuss the difference between the three most clinically important CNS infections: meningitis, encephalitis, and brain abscesses
A
- Meningitis:
It can be identified as an infection of the brain and spinal cord. The majority of these infections are caused by viruses or bacteria (e.g. streptococcus pneumoniae) - Encephalitis:
It is an infection of the brain parenchyma. May be caused by viruses like herpes simplex or herpes zoster virus - Brain abscesses
They are accumulations of infective purulent material within the brain or associated with the CNS membranes. Mainly caused streptococci but can be caused by staphylococci and parasites.
7
Q
Explain the pathophysiology that causes the symptoms of Meningococcal disease.
A
- Symptoms include severe headache, stiff/painful neck, sensitivity to light, vomiting and convulsions
- After invading the body, N. meningitides causes meningitis and severe septicaemia in children and adults
- This leads to localised inflammatory responses which result in cerebral oedema, raised intracranial pressure, and vascular thrombosis
- Increased vascular permeability leads to hypotension which is compounded by a loss of vascular tone in the later stage of the illness
- Myocarditis and myocardial depression may contribute to poor tissue perfusion, which can also impact on brain function
8
Q
Define what is meant by the term “neurodegenerative disorder” and outline the common pathophysiological process implicated in neuro-degeneration
A
- Neurodegenerative disorders are disorders that produce a progressive chronic deterioration of the CNS
- This leads to observable changes in the structure and function of the brain and spinal cord
- Examples of neurodegenerative disorders include Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, motor neuron disease and multiple sclerosis
- The pathophysiology processes underlying different neurodegenerative disorders have recently been found to have some similarities.
It has been proposed that common processes include: oxidative stress, intracellular protein aggregation, and mitochondrial dysfunction. Other mechanisms, which may also play a role, neuroinflammation, excitotoxicity, and apoptosis
9
Q
Describe the clinical manifestation of Parkinson’s disease
A
- The cardinal signs of Parkinson’s are:
a. tremor at rest
b. rigidity
c. akinesia (absence of spontaneous movement) or bradykinesia (slow movement)
d. postural instability - Just remember the acronym of TRAP
10
Q
How is Parkinson’s disease diagnosed and managed?
A
- Parkinson’s disease is difficult to diagnose as usual blood tests cannot be used to diagnose Parkinson’s:
a. They can be used to rule out other causes of the symptoms the patient is experiencing
b. Neuroimaging also cannot be used to diagnose Parkinson’s but can rule out other causes
c. The diagnosis of Parkinson’s disease is made on the basis of clinical picture and neurological and physiological signs and symptoms - Loss of neurons in the substantia nigra results in dopamine deficiency and a relative increase in acetylcholine
(substantia nigra - a basal ganglion that involved in movement reflection
dopamine - neurotransmitter, induce feeling of pleasant
acetylcholine -chief neurotransmitter of parasympathetic nervous system) - Management of a patient with Parkinson’s takes a team of health professionals to manage challenges associated with dysphagia, postural HTN and postural instability
- Medication can be used to manage symptoms;
e. g. dopamine precursors reduce symptoms by stimulating dopamine receptors, which reduce rigidity and tremor - The patient may suffer from depression or anxiety as a result of their disorder and therefore may require treatment with selective serotonin reuptake inhibitor antidepressants. Constipation may also require treatment.
(serotonin - a compound/neurotransmitter which constricts blood vessel
reuptake - the absorption of presynaptic nerve ending of a neurotransmitter that it has secreted)
11
Q
Compare and contrast Huntington’s disease, multiple sclerosis and motor neuron disease
A
- Huntington’s disease:
an autosomal dominant genetic disorder that results in loss of neurons in the basal ganglia causing a decrease in activity of the inhibitory neurotransmitter GABA - Multiple sclerosis:
an autoimmune disorder whereby immune cells destroy CNS myeline leading to plaque formation and causing impairment in motor, sensory and neurological function - Motor neuron disease:
associated with degeneration of upper and lower neurons. Axons of the affected nerve degenerate leading to muscle wasting which begins as weakness and progresses to fatal paralysis
12
Q
Is dementia a normal part of ageing?
A
- No, any change in cognition in an elderly person should be investigated
- UTIs can cause delirium and confusion which may be misdiagnosed as dementia
13
Q
Compare and contrast the pathophysiology of primary and secondary head injury
A
- Primary head injury:
results immediately from trauma e.g. bleeding - Secondary head injury:
occurs from processes initiated by the trauma within days to weeks which is a leading cause of brain injury-related death.
e.g. ischaemia, increased ICP, cerebral oedema
14
Q
Outline what are the possible causes of seizures and describe the different types of seizure
A
- Causes: abnormal levels of glucose or sodium, brain infection, brain injury, drugs, drug withdrawal, epilepsy, fever, extremely HTN
- Primary generalised seizures:
begin with widespread electrical discharges across both sides of the brain. May be hereditary.
e.g.
Generalised tonic-clonic seizures:
characterised by stiffening and jerking movements
Absence seizures:
patients stare into space
3. Partial seizures: begin with an electrical discharge in one part of the brain. e.g. Simple or complex partial seizures Secondarily generalised seizures
15
Q
Describe the term pain
A
- Complex phenomenon
- Involves integration of stimulations of nociceptors - bare sensory nerve endings and input from higher brain centres
Emotions and activities do modify the pain experience - Biopsychosocial phenomenon
- Protective mechanism
