PBL Topic 3 Case 5 Flashcards
1
Q
Identify two types of sensory relay neurons located in the grey matter of the spinal cord
A
- Anterior motor neurons
- Interneurons
2
Q
Identify two types of anterior motor neurons and what each type innervates
A
- Alpha motor neurons, which innervate the extrafusal muscle fibres
- Gamma motor neurons, which innervate intrafusal muscle fibres
3
Q
What are interneurons?
A
- Neurons found exclusively in the CNS
- Transmit signals from the brain to anterior motor neurons
4
Q
What is the function of Renshaw cells?
A
- Anterior motor neurons give off branches to Renshaw cells
- Which are inhibitory cells that send inhibitory signals to surrounding motor neurons (lateral inhibition)
- To sharpen or focus signals to motor neurons
5
Q
What are propriospinal fibres?
A
- Collections of nerve fibres that run ascending/descending/crossed/uncrossed
- That interconnect all levels of the spinal cord
- Providing pathways for multisegment reflexes that co-ordinate simultaneous movements
6
Q
Identify two types of muscle sensory receptors and they sensory information that they provide
A
- Muscle spindles, located in the belly of the muscle, providing information about muscle length or rate of change of length
- Golgi tendon organs, located in muscle tendons, providing information about tendon tension or rate of change of tension
7
Q
Identify two sensory endings of a muscle spindle, what type of fibre they are and where they are positioned
A
- Annulospiral / Primary ending, type Ia fibre that encircles the central portion of the intrafusal fibre
- Flower Spray / Secondary ending, type II fibre that innervates both sides of the primary ending
8
Q
Identify the two types of intrafusal fibres
A
- Nuclear bags, fibres are congregated into expanded bags in the central portion of the receptor area
- Nuclear chains, fibres are smaller and have nuclei aligned in a chain throughout the receptor area
9
Q
Which intrafusal fibre(s) excite primary sensory endings of the muscle spindle
A
- Nuclear bag
- Nuclear chain
10
Q
Which intrafusal fibre(s) excite secondary sensory endings of the muscle spindle
A
- Nuclear chain
11
Q
What is the static response of a muscle spindle?
A
- Muscle spindle is stretched slowly
- Impulses increase in direct proportion to degree of stretching
- From both primary and secondary nerve endings
12
Q
What is the dynamic response of a muscle spindle?
A
- Muscle spindle length increases suddenly
- The primary endings are stimulated but the secondary endings are not
13
Q
Identify the two type of gamma motor nerves
A
- Gamma-dynamic nerves, which excite mainly nuclear chain intrafusal fibres
- Gamma-static nerves, which excite the nuclear chain fibres, greatly enhancing the static response
14
Q
What is the difference between positive and negative signals from muscle spindles?
A
- Positive signals involve increased numbers of impulses to indicate stretch of a muscle
- Negative signals involve decreased numbers of impulses to indicate that the muscle is not stretched
15
Q
Describe the basic circuit of the muscle spindle stretch reflex
A
- Type Ia nerve fibres from muscle spindle enter the dorsal root of the spinal cord
- One branch goes to anterior horn of grey matter to synapse with anterior motor neurons
- That send motor nerve fibres back to the same muscle from which the muscle spindle fibre originated
- Type II fibres on the other hand terminate on interneurons which transmit delayed signals to the anterior motor neurons
16
Q
What is the damping function?
A
- Signals from the spinal cord are transmitted to a muscle in an unsmooth form
- The stretch reflex allows smoothening of muscle contractions
17
Q
What is co-activation of motor neurons and what is its importance?
A
- Activation of alpha motor neurons involves simultaneous activation of gamma neurons
- So that both the extrafusal skeletal muscle fibres and the intrafusal spindle fibres contract at the same time
- It keeps the muscle spindle reflex from opposing the muscle contraction (by keeping the length of the receptor portion the same during whole muscle contraction)
- It also maintains the damping function of the spindle
18
Q
The gamma efferent system is excited by signals from which area?
A
- Reticular formation, giving rise to reticulospinal tracts
19
Q
Identify the pathways taken by the pontine and medullary reticulospinal tracts
A
- Pontine reticulospinal tract descends ipsilaterally in the anterior funiculus
- Medullary reticulospinal tract descends partly crossed in the lateral funiculus
20
Q
Which neurons does the pontine reticulospinal tract act upon?
A
- Extensor motor neurons
21
Q
Which neurons does the medullary reticulospinal tract act upon?
A
- Flexor motor neurons
22
Q
What are the two kinds of motor behaviour that the reticulospinal tract is involved in?
A
- Locomotion
- Postural control
23
Q
What is clonus and what causes clonus?
A
- Oscillation of a muscle jerk
- Caused by sensitisation of facilitatory impulses from the brain
24
Q
When is the Golgi tendon organ stimulated?
A
- When the small bundle of muscle fibres is tensed by contracting or stretching of the muscle
25
Golgi tendon organs transmit through which type of fibres?
- Type Ib fibres
26
Identify two signal pathways from the Golgi tendon organ
- Via the spinocerebellar tracts and through other tracts to the cerebral cortex
- Local areas of the cord which excite inhibitory interneurons that inhibit the anterior motor neurone
27
What is the lengthening reaction?
- Golgi tendon is stimulated by increased tension
- Inhibitory signals to spinal cord to prevent excessive tension on the muscle
- That would otherwise causing tendon or avulsion of the tendon
28
What is the flexor reflex?
- Stimulation of pain nerve endings on a limb, signals enter the dorsal horn of the spinal cord
- Synapse with anterior motor neurons that send motor nerve fibres to flexor muscles
- This withdraws the limb from the painful stimulus
- With reciprocal inhibition circuits for antagonist muscles
- After discharge, which depends on the intensity of the sensory stimulus
29
What is the crossed extensor reflex?
- Extension of opposite limb that the flexor reflex takes place in
- To push the entire body away from the object causing the painful stimulus
- Signals from sensory nerves cross to the opposite side of the cord via interneurons to anterior motor neurons that to excite extensor muscles
- Even longer duration after discharge duration
30
Identify the three subareas of the motor cortex that are involved in specific motor functions
- Primary motor cortex
- Premotor area
- Supplementary motor area
31
Where is the primary motor cortex located?
- Precentral gyrus
| - Broadmann's area 4
32
Outline the topographical representations of the different muscle areas in the primary motor cortex
- Face and mouth near lateral fissure
- Arm and hand in the mid-portion (large portion)
- Trunk near the apex of the brain
- Leg and foot areas, near the longitudinal fissure
33
Where is the premotor area located?
- Anterior to the primary motor cortex
34
What is the function of the premotor area?
- Develops a motor image of complex patterns of movement associated
- Sends fibres directly to primary motor cortex or to basal ganglia and thalamus to the primary motor cortex
35
Where is the supplementary motor area located?
- Longitudinal fissure but extends onto superior frontal cortex
36
What is the role of the supplementary area?
- Bilateral stimulation
| - Positional movements, fixation movements, body-wide attitudinal movements
37
Outline the pathway taken by the corticospinal tract
- Leaves cortex and passes through internal capsule, downward through the brainstem
- Forms the pyramids of the medulla
- Majority of fibres decussate at the pyramidal decussation and descend in lateral corticospinal tract which terminate on interneurons of cord grey matter
- Some fibres do not decussate but descend in anterior corticospinal tracts until thoracic region where they decussate and terminate on sensory relay neurons
38
What is the anterior corticospinal tract concerned with?
- Bilateral postural movements
| - By supplementary motor cortex
39
Fibres of the corticospinal tract originate from which cell type?
- Betz cell, a giant pyramidal cell
| - Found primarily in the primary motor cortex
40
What is the role of the corticobulbar tract and how are its fibres activated?
- Activate motor cranial nerve nuclei
- Mainly those of the face, jaw and tongue
- Activated by corticospinal tract
41
Where is the red nucleus located?
- Mesencephalon
42
Where does the red nucleus receive fibres from?
- Directly from corticorubral tract through the mesencephalon
- Indirectly from branching fibres from the corticospinal tract
43
Which tract arises from the red nucleus? Outline its course
- Rubrospinal tract
- Decussates in the lower brainstem
- Follows the same course as corticospinal tract to terminate on interneurons or anterior motor neurons
44
Identify three incoming fibre pathways to the motor cortex
- Somatosensory cortex
- Frontal cortex anterior to motor cortex
- Visual and auditory cortices
45
What is the tectospinal tract?
- Crossed descending pathway
- From tectum to anterior grey horn at cervical and upper thoracic regions
- Orientation of head in response to visual (superior colliculus) and auditory (inferior colliculus) stimulation
46
What is the vestibulospinal tract?
- Uncrossed descending pathway
- From vestibular nucleus to appropriate antigravity muscles when the head is tilted to one side
- To keep centre of gravity between the feet.
47
What is the raphespinal tract?
- Descending pathway within tract of Lissauer
- From raphe nucleus in medulla oblongata
- Modulates sensory transmission between first and second order neurons in the posterior grey horn, particularly with respect to pain
48
What is pronator drift?
- With arms outstretched and eyes closed
- Affected limb drifts downwards and medially
- Forearms pronate
- Fingers flex
49
What are hemiplegia and hemiparesis?
- Hemiplegia: Paralysis of one half of the body
| - Hemiparesis: Weakness of one half of the body
50
What is paraplegia and paraparesis?
- Paraplegia: Paralysis of both lower limbs
| - Paraparesis: Weakness of both lower limbs
51
What is tetraplegia and tetraparesis?
- Tetraplegia: Paralysis of all four limbs
| - Tetraparesis: Weakness of all four limbs
52
Identify five features of an upper motor neurone disease
- Pronator drift
- Weakness with characteristic distribution
- Exaggerated tendon reflexes
- Extensor plantar response
- Changes in tone: flaccid-spastic
53
Identity five features of a lower motor neurone disease
- Hypotonia
- Reflex loss
- Weakness
- Wasting
- Fasciculation
54
Define stroke
- A syndrome of rapid onset cerebral deficit (usually focal)
- Lasting over 24 hours or leading to death
- With no apparent cause other than a vascular one
55
Define transient ischaemic attack
- A brief episode of neurological dysfunction
| - Due to temporary focal cerebral or retinal ischaemia without infarction
56
Outline the epidemiology of strokes
- Third most common cause of death
- Higher in Asian and black African populations
- Increases with age
- Death rate folllwing a stroke is 25 per cent
57
Outline 10 risk factors for stroke
- Hypertension
- Smoking
- Sedentary lifestyle
- Alchohol
- High cholesterol
- Atrial fibrillation
- Obesity
- Diabetes
- Carotid stenosis
- Sleep apnoea
58
Identify the two types of stroke
- Ischaemic stroke caused by thrombosis, stenosis, embolism, hypo-perfusion, 80% of strokes
- Haemorrhagic stroke, caused by intracerebral haemorrhage or subarachnoid haemorrhage, 20% of strokes
59
What is the main cause of a TIA
- Microemboli
60
What is amaurosis fugax?
- Transient loss of vision in one eye
| - Due to passage of emboli through the retinal arteries
61
Outline the clinical features of a TIA originating from the anterior circulation
- Amaurosis fugax
- Aphasia
- Hemiparesis
- Hemisensory loss
- Hemianopic visual loss
62
Outline the clinical features of a TIA originating from the anterior circulation
- Diplopia, vertigo, vomiting
- Choking, dysarthria
- Ataxia
- Hemisensory loss
- Bilateral visual loss
- Tetraparesis
63
Which scoring system can be used to assess the severity of a TIA?
- ABCD2
- A: Age, 1 point if over 60
- B: BP, 1 point if over 140/90
- C: Clinical features, 2 points if hemiparesis, 1 point for aphasia
- D: Duration of symptoms, 2 points if longer than one hour, 1 point if between 10 minutes and 1 hour
- D: 1 point if diabetes
- Admit if a score greater than 4
64
Once admitted following a score >4 on the ABCD2 scoring system, outline 3 investigations that should be carried out
- Routine bloods (ESR, polycythaemia, vasculitis, thrombophilia)
- CXR
- ECG
- Carotid Doppler
- MR Angiography
65
Outline the pathophysiology of cerebral infarction
- Reduced blood flow so less oxygen hence ATP
- H+ is produced by anaerobic metabolism of available glucose
- Ionic pumps fail, allowing calcium entry and glutamate release
- Activation of destructive enzymes, destruction of organelles and fatty acid release for pro-coagulation
- Leading to inflammatory damage, necrosis, apoptosis
66
What is the most likely cause of a cerebral infarction?
- Infarction in internal capsule
| - Following thromboembolism in middle cerebral artery
67
Outline the clinical features of a cerebral infarction
- Contralateral limb weakness
- Contralateral hemilegia
- Aphasia
68
What is Wallenberg's syndrome
- Brainstem infarction
| - Presenting as acute vertigo with cerebellar signs
69
A brainstem infarction of which area would produce a coma?
- Reticular activating system
70
The locked-in syndrome is caused by infarction of which region of the brainstem
- Upper brainstem
71
Pseudobulbar palsy is caused by infarction of which region of the brainstem?
- Lower brainstem
72
Hemiparesis or tetraparesis is caused by infarction of which region of the brainstem?
- Corticospinal tracts
73
Sensory loss is caused by infarction of which region of the brainstem?
- DCML tracts
| - Spinothalamic tracts
74
Facial numbness is caused by infarction of which region of the brainstem?
- Trigeminal nuclei
75
Facial weakness is caused by infarction of which region of the brainstem?
- Facial nerve
76
Dysphagia and dysarthria are caused by infarction of which region of the brainstem?
- Glossopharyngeal nuclei
| - Vagus nuclei
77
Diplopia is caused by infarction of which region of the brainstem?
- Oculomotor nuclei
78
What is a lacunar infarct and which risk factor is it associated with?
- Small infarcts seen on MRI, often symptomless
| - Hypertension
79
What causes hypertensive encephalopathy and what are the symptoms?
- Cerebral oedema
| - Causing headaches, nausea and vomiting
80
What is Weber's syndrome and what is its cause?
- Ipsilateral oculomotor nerve plasy
- With contralateral hemiplegia
- Due to unilateral infarct in the midbrain
81
Identify neurological deficits associated with problems in the middle cerebral artery
- Unilateral weakness involving face and arm, then legs
82
Identify neurological deficits associated with problems in the lateral medulla
- Ipsilateral Horner's syndrome
- Vagus nerve plasy
- Facial sensory loss
- Contralateral spinothalamic sensory loss
83
Identify neurological deficits associated with problems in the posterior cerebral artery
- Homonymous hemianopia
| - Due to parietal and or temporal lobe
84
Identify neurological deficits associated with problems in the internal capsule
- Motor or sensory loss
| - Dysarthria from involvement of corticobulbar fibres
85
Identify neurological deficits associated with carotid artery dissection
- Ipsilateral Horner's syndrome from compression of sympathetic plexus
86
What is FAST?
- Used by public and paramedics to make diagnosis of stroke and history based on simple history and examination
- Face: Sudden weakness of face
- Arm: Sudden weakness of one or both arms
- Speech: Difficulty speaking, slurred speech
- Time: Importance of rapid treatment
87
Identify the main treatment in cerebral infarction and one contraindication to its use
- Thrombolysis e.g. altelapse
| - Intracranial haemorrhage, head trauma within last 3 months
88
What is an alternative treatment to thrombolysis?
- Aspirin 300 mg
89
Identify a surgical treatment used in cerbral infarction
- Decompressive hemicraniectomy
| - Reduced intracranial pressure in a middle cerebral artery infarct
90
Identify two advantages and adisadvantage of using a CT in acute stroke?
- Detects haemorrhage, more widely available
| - Does not detect infarction
91
Identify an advantage of using MRI over a CT acute stroke?
- Detects infarction
92
What is the role of MRI or CT with angiography?
- Detects arterial stenosis in internal carotid artery
93
What is the role of carotid doppler / duplex scanning with angiography?
- Detects arterial stenosis in carotid and vertebral artery
94
Outline six features of long-term management of stroke
- Risk factors identified and addressed
- Long term aspirin (75 mg)
and clopidogrel following infarction
- Internal carotid endarterectomy (removal of atheromatous intima from underlying media)
- Physiotherapy
- Speech and language therapy
- Occupational therapy
95
Outline the DVLA guidance following a stroke
- Patients must stop driving for at least one month following a stroke
- Patients must stop driving for a minimum of three months without recurrence of a TIA
- Doctor must be happy that patient is safe to return to driving
96
Outline the prognosis of a stroke
- 25% die within 2 years, 10% die within first month
- Mortality is higher following a haemorrhage than an infarction
- Poor prognostic features include coma, defect in gaze, hemiplegia
97
Identify three types of intracranial haemorrhage
- Intracerebral / cerebellar haemorrhage
- Subarachnoid haemorrhage
- Subdural / extradural haemorrhage / haematoma
98
What is a Charcot-Bouchard aneurysm?
- Cause of intracerebral haemorrhage
- Rupture of micro-aneurysms
- Degeneration of small deep penetrating arteries
99
Identify the clinical features of a cerebellar haemorrhage
- Stupor/coma
- Nystagmus / ocular palsies
- Gaze deviates towards the haemorrhage and skew deviation may develop
100
Identify four causes of subarachnoid haemorrhage
- Saccular / berry aneurysm
- AVM Malformation
- Marfan's Syndrome
- Autosomal dominant polycystic kidney disease
101
Identify a complication of a subarachnoid haemorrhage
- Hydrocephalus
102
Where do saccular aneurysms taken place?
- Arterial junctions e.g. between PCA and ICA, between ACA and ACA
103
What is an arteriovenous maformation
- Tangle of blood vessels (cavernomas) in which oxygenated arterial blood is shunted into veins
- Resulting in poor oxygenation
104
Outline the clinical features of a SAH
- Occipital headache
- Followed by coma and death
- Survivors experience neck stiffness and a positive Kernig's sign
105
Outline the investigations carried out if an SAH is suspected
- CT imaging
- Lumbar puncture shows xanthochromic CSF
- Spectrophotometry - bilirubin in CSF
106
Outline the treatment of an SAH
- Placement of coils via a catheter in the aneurysm sac to promote thrombosis and ablation of the aneurysm
- Hypertension should be controlled e.g. calcium channel blocker such as nimopidine
- Bed rest and support
107
Identify five causes of an intracranial venous thrombosis
- Contraceptives
- Pregnancy
- Dehydration
- Head inhury
- Paranasal sinus infection
108
Identify the two main locations of an intracranial venous thrombosis
- Cortex, resulting in headache, hemiparesis, epilepsy, fever
- Dural venous sinuses, resulting in ocular pain, fever, proptosis, chemises
109
Outline the investigations used if a intracranial venous thrombosis is suspected
- MRI which shows occluded sinuses and veins
110
Outline the treatments of an intracranial venous thrombosis
- Heparin initially
| - Followed by warfarin for 6 months
111
Identify the two main components of neurovascular repair following a stroke
- Angiogenesis
| - Neurogenesis
112
Identify three trophic factors secreted by cerebral endothelium that communicate with neural precursor cells
- MAtrix metalloproteinases
- Vascular Endothelial Growth Factor
- HMGB1
113
What is neuroplasticity?
- Brains ability to modify is structure and function
| - In response to stimulation or injury
114
Outline the mechanisms involved in neuroplasticity
- Generation of new neurons
| - Remodelling of synaptic connections
115
What is positive memory?
- Storage of important information
| - Results from facilitation of synaptic pathways (sensitisation)
116
What is negative memory?
- Ignoring of information that is of no importance
| - Results from inhibiting synaptic pathways (habituation)
117
Outline the long-term potentiation model of memory
- High frequency action potentials lead to release of glutamate
- Entrance of Na+ at AMPa receptor which depolarises cell
- Removal of Mg2+ and entry of Ca2+ at NDMA receptor which increases presynaptic glutamate synthesis and release
- Long lasting increase in glutamate receptors and sensitivity
118
What is the difference between short-term and long-term memory?
- Short term refers to that which is held briefly in the mind
- Long term is that which is stored and is capable of retrieval at the appropriate moments
119
Identify the two types of long-term memory
- Explicit: Recollections of facts and events that can be explicitly stated
- Implicit: Performance of learned motor procedures such as riding a bike
120
What is working memory?
- Retrieval of items from long-term memory for a task at hand such as driving a car among a familiar route while making decisions based on past experiences
121
What is consolidation?
- Storage of new information in long-term memory
| - Sensory information is relayed from sensory association areas to hippocampal complex for encoding
122
Where does short-term declarative memory occur?
- Hippocampus and other limbic system structures
123
Where does long-term declarative memory occur?
- Association areas of the cortex
124
Where does short term implicit memory occur?
- Widely distributed
125
Where does long term implicit memory occur?
- Basal ganglia
- Cerebellum
- Sensorimotor cortex
126
What is retrograde amnesia?
- Loss of ability to access previous memories
| - Damage to thalamus which helps search the memory storehouse to find memories
127
What is anterograde amnesia?
- Loss of ability to create new memories
| - Damage to hippocampus which determines what information is useful to remember and what isn't
128
Which region of the brain is associated with fear?
- Amygdala
129
Which region of the amygdala do the sensory association areas have access to?
- Lateral nucleus of the amygdlaa
130
Which region of the amygdala send signals to the hypothalamus to generate a stress response?
- Bed nucleus
| - Stria terminalis
131
What hormone does the hypothalamus secrete as part of the stress response? From which nucleus of the hypothalamus does this occur?
- Corticotrophin releasing factor from paraventricular nucleus
- Carried to pituitary
132
What is the endocrine target of CRF?
- Anterior pituitary gland
| - Which releases ACTH in response to CRF
133
What is the endocrine target of ACTH?
- Adrenocortical cells
| - Which produces cortisol via a CAMP second messenger system
134
Identify two stimuli that can enhance secretion of cortisol
- Pain stimuli such as physical stress transmitted through spinothalamic tract
- Mental stress from amygdala from sensory association areas and areas involved in memory
135
Identify the benefit of cortisol release in stressful situations
- Mobilisation of amino acids and fats from cellular stores
- To be used in synthesis of glucose
- As part of a fight or flight response
136
Outline the negative feedback effects of cortisol
- Effects on hypothalamus to decrease formation of CRF
- Effects on anterior pituitary to to decrease formation of ACTH
- To help regulate plasma concentration of cortisol
137
What is generalised anxiety disorder (GAD)?
- Ongoing state of excessive anxiety lacking any clear reason or focus
138
Outline the epidemiology of GAD
- 5% of people
| - More common in women
139
Outline the clinical features of GAD
- Psychological symptoms include apprehension, fear, irritability, concentration difficulties and distractibility
- Physical symptoms include crushing chest pain, palpitations, diarrhoea, sleep disturbance
- On presentation patient looks worried, has a tense posture, restless behaviour, pale and sweaty skin
140
Outline five other types of anxiety
- Mixed anxiety and depressive disorder, with equal elements of both
- Panic disorder, with severe physical symptoms of hyperventilation, tremor, sweating
- Phobias, with a fear response to a stimulus of no particular concern e.g. agoraphobia fear of leaving home
- PTSD, with anxiety triggered by past stressful experience
- OCD, with compulsive, ritualistic behaviour driven by irrational anxiety
141
Identify relaxation techniques for mild anxiety
- Meditation
- Yoga
- The aim is to slow breathing, and produce muscle relaxation and mental imagery
142
Identify the two stages of anxiety management
- Cues and imagery to arouse anxiety
| - Training to reduce this anxiety by relaxation, distraction and reassuring self-statements
143
What is biofeedback?
- Highlighting to patient a physiological measure that is abnormal in anxiety e.g. heart rate, EMG
- To show patients that they are not relaxed even if they fail to recognise this
144
Identify a therapy for phobia
- Systematic desensitisation
- Patient is exposed to a hierarchy of worsening fears
- They practice exposure to each fear and work their way up the hierarchy
145
Outline the application of CBT to anxiety
- Identification of mental cues that provoke exacerbations
| - Alteration of the patients schema (the way they loo at themselves, the future and their situation) that feeds anxiety
146
What is GABA?
- Gamma-aminobutyric acid
| - Main inhibitory neurotransmitter in the brain
147
Identify the two types of GABA receptors
- GABAa (ligand gated ion channel)
| - GABAb (G-protein coupled receptor)
148
Outline the mechanism of action of benzodiazepeines
- Bind to an accessory site on GABAa receptor
| - Opening of chloride channels and entrance of Cl- which hyperpolarises the cell
149
Identify three example of benzodiazepines
- Diazepam
- Flurazepam
- Clonazepam
150
What is the dosage of diazepam
- 2-15 mg daily
| - Taken orally
151
Outline four side effects of benzodiazepines
- Sedation and memory problems
- Dependence and tolerance
- Withdrawal syndrome
- Interaction with alcohol producing a hangover syndrome
152
What are 5-HT1a receptors?
- Auto-inhibitory receptors
- Located on 5-HT neurons in the raphe nuclei of the reticular formation
- Which limit firing of these cells
153
Identify three examples of SSRIs
- Fluoxetine
- Paroxetine
- Sertraline
154
Outline the dosage of SSRIs
- Orally 20 mg daily
- Can be increased over a month
- Maximum dose of 60 mg daily
155
What is buspirone and what is it used to treat?
- Partial 5-HT1a agonist
| - Used to treat generalised anxiety disorder
156
How do buspirone and SSRIs work?
- Induce desensitisation of of somatodendritic 5-HT1A autoreceptors
- Resulting in increased excitation of serotonergic neurons and enhanced 5-HT release
157
What are the main side effects of SSRIs?
- Nausea
- Diarrhoea
- Agitation
- Insomnia
- Anorgasmia
158
What are the main side effects of buspirone?
- Nausea
- Headache
- Restlessness
159
Why are beta blockers used in the treatment of anxiety?
- Inhibiting beta-adrenoreceptors on adrenal medulla and sympathetic nerves
- To reduce physical symptoms such as sweating, tremor, tachycardia
160
Identify an antipsychotic used in the treatment of anxiety
- Olanzapine
161
Identify three antiepileptics used in the treatment of anxiety
- Gabapentin
- Pregabalin
- Valproate
162
What type of synapse is involved between the Renshaw cell and alpha motor neuron
- Glycinergic
163
Where do aminergic pathways arise?
- Specialised cell groups in pons and medulla
| - E.g. raphe nucleus
164
What are the main types of neurotransmitters are involved in aminergic pathways?
- Noradrenaline
| - Serotonin
165
What are the two effects of aminergic pathways?
- Inhibitory effects on sensory neurons
| - Facilitatory effects on motor neurons
166
Where do the corticobulbar tracts arise?
- Central sulcus in precentral gyrus
| - Superior to lateral fissure
167
Which part of the internal capsule do the corticobulbar tracts descend through?
- Genu
168
Which cranial nerves are bilaterally innervated?
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Glossopharyngeal
- Vagus
- Accessory
169
How is the hypoglossal nerve innervated?
- Contralateral innervation
170
How is the facial nerve innervated?
- Superior part is bilaterally innervated
| - Inferior part is contralaterally innervated
171
What is a reperfusion injury?
- Oxygen-dependent damage to ischaemic area when blood flow returns
- Caused by release of of oxygen dependent free radicals
172
Identify two causes of a reperfusion injury
- Blood flow encounters tissue where calcium transport is impaired
- Neutrophils and macrophages (inflammatory response)
173
What is an ischaemic penumbra?
- Swollen area of brain surrounding infarcted area
- That does not function but is structurally intact
- Which is detected on MRI
174
Identify three treatments following a cerebral infarction
- Thrombolysis (alteplase)
- Aspirin 300 mg if thrombolysis is contraindicated
- Decompressive hemicraniectomy if massive middle cerebral artery infarct
175
When should heparin and warfarin be given following a stroke?
- If there is atrial fibrillation
176
Outline the mechanism of action of alteplase
- Tissue plasminogen activator
- Converts plasminogen to plasmin
- Which is a proteolytic enzyme that digests fibrin fibres
- Resulting in lysis of clot
177
Identify a potential adverse effect of thrombolysis
- Hypocoagulabiltiy of the blood
178
Why is CT scanning important before administering thrombolysis?
- To rule out haemorrhagic stroke
179
Outline the mechanism of action of aspirin
- Irreversibly inactivation of COX-1 and COX-2
- Reduced thromboxane A2 production
- Reduce platelet aggregation / thrombosis
180
Identify three adverse effects of aspirin
- GI effects e.g. nausea and vomiting
- Post viral encephalitis (Reye's syndrome)
- Risk of bleeding if given with warfarin
181
Outline the mechanism of action of clopidogrel
- Irreversible inhibition of P2Y12 receptors on platelets
| - Resulting in reduced platelet activation
182
Identify two adverse effects of clopidogrel
- Prodrug, metabolised by CYP2C19, those with a genetic variant where CYP2C19 is less activate have an increased risk of thrombosis
- Higher mortality rates compared to ticagrelor
183
Outline the mechanism of action of nimopidine
- Calcium channel antagonist
- At L-type calcium channel
- Vasodilation of resistance vessels
184
Outline three side effects of nimopidine
- Ankle swelling
- Flushing
- Headaches
185
What is flumazenil? Identify two uses of flumazenil
- Inverse agonist at GABAA receptor
- Reverse effects of benzodiazepine overdose
- Reverse sedative effects of benzodiazepines in anaesthesia during surgical procedures
186
What is meant by bias?
- Conducting, analysing or reporting a study in a way that tends to lead to a particular conclusion
187
Identify four examples of pre-trial bias
- Selection bias
- Definition bias
- Bias in concepts
- bias in concurrent disease
188
What is meant by selection bias? How can it be reduced?
- Errors in assignment or selection of patients for a study
- Subjects studied are not representative of the target population
- Or they differ from each other by factors that may affect the outcome of the study.
- Random allocation
189
What is meant by definition bias?
- Study subject is not clearly defined resulting in ambiguity
190
What is meant by bias in concepts?
- Lack of clarity about the concept that are used in the research, resulting in subjective interpretation
191
What is meant by bias in concurrent disease
- Patients suffer from unrelated conditions which affect responses
192
Identify five examples of bias during the trial
- Information bias
- Instruction bias
- Lead-time bias
- Attrition bias
- Hawthorne effect
193
What is meant by information bias? How can it be reduced?
- Errors in measuring exposure or a disease
| - Blinding
194
Identify four types of information bias
- Observer bias
- Interviewer bias
- Recall bias
- Response bias
195
What is meant by instruction bias
- No clear instructions are prepared
| - Investigators use discretion which varies from person to person
196
What is meant by lead-time bias
- Cases of disease are not detected at same stage of disease
197
What is meant by attrition bias?
- Cases of dropout which varies between groups
198
What is meant by Hawthorne effect
- Individual knows they are being investigated
| - And their behaviour and responses alter in light of this
199
Identify two examples of post-trial bias?
- Confounding bias
| - Statistical bias
200
What is meant by confounding bias?
- Outcome is affected by other factors other than the intervention e.g. smoking on a study on effect of alcohol on heart disease
201
What is meant by statistical bias?
- Use of inappropriate statistical tests
- Or low statistical power
- Leading to misleading conclusions
202
Which test should be used when data is:
[A] Normally distributed
[B] Not normally distributed
- T-test
| - Mann-Whitney U test
203
What is a continuous variable?
- Numerical value that is measured on a continuous scale
| - E.g. height in centimetres
204
What is a binary variable?
- Categorical value that is measured as one of two possible values
- E.g. taller than a given height or not
205
What is a dependent variable?
- The variable that is being measured
| - E.g. treatment outcome
206
What is n independent variable?
- The variable that is manipulated
| - E.g. treatment used
207
When is the unpaired T-test carried out?
- Continuous DV
- Discrete IV
- Two comparable groups
- Example: FEV in those with asthma compared to those without asthma
208
When is the ANOVA test carried out?
- Continuous DV
- Discrete IV
- More than two comparable groups
209
When is linear regression carried out?
- Continuous DV
| - Groups are not comparable
210
When is logistic regression used?
- Binary DV
| - Groups are not comparable
211
When is Chi-Square test used?
- Binary DV
- Discrete IV
- Groups are comparable
212
What is sensory memory? Give two examples of sensory memory?
- Physical features of a stimulus are stored for a very brief period of time
- Iconic memory: sight
- Echoic memory: sound
213
What is the role of the the central executive?
- Portion of working memory involved in cognitive tasks such as problem solving
214
What is the role of phonological loop?
- Storage of auditory information by repetitively rehearsing it
215
What is the role of the visuo-spatial sketchpad?
- Storage of visual and spatial information
216
What is meant by episodic buffer? Which type of memory is it associated eith
- Linking information across domains e..g visual, spatial and auditory, chronology
- Semantic memory (context of memory of written and spoken words)
217
According to the levels of processing model of memory, what is meant by maintenance rehearsal?
- Repetition of verbal information simply by repeating it
| - Maintained in short term memory
218
According to the levels of processing model of memory, what is meant by elaborative rehearsal?
- Thinking deeply about information
| - To consolidate short term memory or maintain long term memory
219
According to the levels of processing model of memory. what is meant by encoding specificity? Give three examples
- Way in which we encode information affects our ability to retrieve it later
- Mnemonics (method of loci)
- Narrative stories
- Smart drugs
220
Outline four theories of forgetting
- Superficial processing (link to maintenance rehearsal)
- Decay of memory trace
- Interference
- Motivated forgetfulness
