Neurology exam questons Flashcards
1
Q
List four (4) examples of information that is carried by the spinothalamic tract.
A
Pain, temperature, gross touch, pressure
2
Q
When a space occupying lesion is causing the cerebral hemispheres to enlarge, a consequence may be that the hindbrain is forced caudally (herniates). Name this condition, and briefly describe the herniation
A
Coning of the medulla – tonsils of cerebellum herniate through foramen magnum, compressing the brain stem (2)
3
Q
List three (3) functional consequences of herniation and indicate in each case the specific brain area involved
A
Decreased level of consciousness – distortion of the reticular formation (2)
Decreased pupillary light reflexes & dilation of pupils – impairment of 3rd Nerve function, due to compression (2)
Decreased vital function involving both respiratory and cardiac function - compression of the medulla (2)
4
Q
Is it advisable under these circumstances to do a lumbar puncture in order to draw a sample of CSF?
A
No, a lumbar puncture should not be performed.
Removing CSF would reduce the CSF pressure below the foramen magnum and therefore the condition would be aggravated due to increased coning of the medulla.
There would also be progressive loss of consciousness and further impairment of breathing, which may ultimately be fatal.
5
Q
List three (3) different types of brain herniation
A
Subfalcine (cingulate), transtentorial (uncinate, mesial temporal), tonsillar herniation
6
Q
Outline the main mechanism of death in cerebral herniation.
A
Compression of cardiac and respiratory centres in the medulla oblongata
7
Q
Define “hydrocephalus ex vacuo”. (1½ marks)
A
Dilatation of ventricular system
Increase in CSF volume due to loss of brain parenchyma
8
Q
Use the following table to create a list of differential diagnoses for an acquired cerebral space occupying lesion
A
Inflammatory Infective Two examples:
Abscess, Tuberculosis, Toxoplasmosis, Hydatid disease
Inflammatory Non-infective One example:
Demyelinating pseudotumour
Neoplastic primary Two examples:
Meningioma, glial and neuronal neoplasms, poorly-
differentiated CNS neoplasms e.g. Medulloblastoma,
primary CNS lymphoma, germ cell tumours
Neoplastic secondary Two examples:
Carcinoma, melanoma, lymphoma, sarcoma
Traumatic Two examples:
Extradural, subdural haematoma
Vascular Two examples:
Intracerebral haemorrhage, aneurysm
9
Q
When a lesion in the nervous system occurs and nerve connections are disrupted, the injured neurons show certain distinct histological features. List these features
A
Chromatolysis, swelling of cell body, degradation of axon and myelin sheath.
The process is called Wallerian degeneraton.
10
Q
Outline the role of the following cell types after an injury to the nervous system
A
Schwann cells (2 marks)
(Phagocytosis of debris, expression of axon growth-promoting cell adhesion molecules, support of neuron survival and axon re-growth by neurotrophin secretion)
Oligodendrocytes (2 marks)
(Inhibition of axon regeneration through up-regulation of several growth inhibitory proteins)
Astrocytes (2 marks)
(Hypertrophy and formation of glial scar: mechanical barrier to axon re-growth, as well as up-regulation of inhibitory proteoglycans)
Microglia (2 marks)
(Phagocytosis of cell debris, degradation of extracellular matrix, but also promotion of inflammation and cytotoxic effects on neurones)
11
Q
Identify the three (3) features (or “red flags”) in Martha’s history, which suggest that the headache needs further investigation
A
Headaches getting progressively worse (½)
Worst in the mornings (½)
Neurological signs (pins and needles) (½) and difficulty in doing her work. (½)
12
Q
Briefly describe the typical signs you may expect to find on any patient with raised intracranial pressure in the following areas of examination:
A
Fundoscopy: (½ mark)
Papilloedema
Cardiovascular: (1 mark)
High BP, slow pulse
Neurological: (1½ marks)
Confused or decreased level of consciousness, possible cranial nerve pathology
13
Q
You are asked to obtain Martha’s consent to perform a CT scan. She says to you, “If it’s cancer, I don’t want to know.” Discuss the ethical principles in this case under the following headings:
A
Consent
Consent: should be informed. Pt should have been informed about the CT scan (should know what it entails to prepare patient for the procedure as some patients have a fear of confined spaces) and the possible results it may reveal.
Autonomy
Autonomy: pt’s right to choose based on informed choice and rational thinking. She may not be rational now and may just be expressing her fears.
Beneficence
Beneficence: need to weigh up harm of not telling vs harm of telling. Overall responsibility is to do good and to prevent harm.
14
Q
Give the medical definition of coma
A
Coma = Medical definition, “a state much like sleep in which patients are unarousable and are unresponsive to external stimulation and their own inner needs”.
15
Q
State the purpose of the Glasgow coma scale. (1 mark)
A
To assess the depth and changes in the level of consciousness. If the level of consciousness dropped this would alert medical staff to take action.
16
Q
List the components of this scale and indicate the criteria for the definition of coma. (3 marks +2 marks = 5 marks)
A
Best verbal response, motor response and eye response.
The scale is out of 15 with any score below 9 being a coma if physical limitations have been discounted, such as paralysis, eye injuries etc
17
Q
- State the recommended test for pain response. (1 mark)
A
Sternum rub, not nipple twisting.
18
Q
- If you wish to examine the burden of disease in the province due to brain cancer, a number of different measures , such as Years of Life Lost (YLL)’ and Disability Adjusted LifeYears (DALYs) can be used to characterise the burden of disease. Define the terms Years of Life Lost (YLL) (1 mark) and Disability Adjusted LifeYears (DALYs) (2 marks
A
- If you wish to examine the burden of disease in the province due to brain cancer, a number of different measures , such as Years of Life Lost (YLL)’ and Disability Adjusted LifeYears (DALYs) can be used to characterise the burden of disease. Define the terms Years of Life Lost (YLL) (1 mark) and Disability Adjusted LifeYears (DALYs) (2 marks
19
Q
Name two causes of meningitis for which there are effective vaccines. (2 marks)
A
Haemophilus influenzae grp B TB meningitis Mumps meningitis Pneumococcus Meningococcus
20
Q
If the initial CSF laboratory results indicate a possible bacterial meningitis, state the empiric antibiotic therapy that would be appropriate while waiting for the bacterial culture and antibiotic sensitivity results. Motivate why this is the antibiotic of choice. (2½ marks)
A
Ceftriaxone/ cefotaxime or “3rd generation cephalosporin” (½)
Covers the 3 common bacteria causing meningitis (1) + (1) for extra information e.g. names of organisms or something about pen resistant pneumococci.
21
Q
- List the names of the encephalopathic diseases that can be caused by measles through these different pathophysiologic mechanisms. Outline how each is brought about, indicating for each whether or not virus can be cultured from the brain. (3 marks x 2 = 6 marks)
A
Measles meningo/encephalo/myelitis [virus +ve]
Acute perivenous demyelination [virus –ve]
SSPE [subacute sclerosing panencepahlitis] [virus +ve]
22
Q
In a patient with a raised total CSF protein, state the significance of an increased IgG/albumin ratio in CSF, particularly if this ratio in plasma is normal. (2 marks)
A
Local IgG production due to an infective or autoimmune process within the CNS, rather than a non-specific increase in blood-brain barrier permeability
23
Q
Describe the psychosocial effects of deafness/hearing impairment on
A
Bart (6 marks)
Effects on the individual (6)
• Inclusion –isolation
o Difficulty with acceptance amongst groups of people due to stigmatisation
– Obstacles to developing relationships with self, family, peers, community, society - Socialising more difficult
• Has to adapt
o New communication skills
o Has to manage frustrations in a social system which is not adaptive
• Access to social resources – barriers to access
– Access to schools- learning and education, skills development
– Accessing equipment to assist functioning in living environment (accommodation telephones/teldems, door lightbells, security, driving, etc, etc)
His family (4 marks)
Effects on the family (4)
• Have to learn how to communicate with Bart differently
• Changes within family relationships including between parents
• Economic adversity – new expense, lost earnings through medical appointments, mother stopping work, cost of care
a) Increased stress – Maternal Mental Health, Problems understanding deafness (audiological, social, cultural), Concerns about the child’s progress and future options
24
Q
) Name the part of the nervous system that, if damaged, would give rise to impairment of fine motor skills with poor hand eye coordination. (1 mark)
A
Intermediate hemisphere of the cerebellum
Name one other possible consequence of damage to this structure
Impaired planning of movement, impaired learning of motor skills, difficulty maintaining balance.
25
Hyperactivity may result from a disturbance in the dopamine neurotransmitter system in the brain. Explain how dopamine acts to initiate movement. (5 marks)
Dopamine acts on D1 receptors in the striatum to stimulate the direct pathway, i.e. glutamate neurons projecting from cortex to striatum to inferior globus pallidus, or substantia nigra pars reticulate, to thalamus and back to cortex, to provide positive feedback to the cortex. At the same time dopamine acts on D2 receptors to inhibit the indirect pathway, cortex - striatum - external GP-STN - internal GP/SNr – thalamus – cortex, which is inhibitory thereby disinhibiting neurons in the thalamus to give positive feedback to the cortex to select and initiate appropriate movement.)
26
State the specific nucleus and its location in the brain to which visual information is transmitted from the retina and where it is processed before being transmitted to the visual cortex. (1 mark)
Lateral geniculate nucleus of the thalamus
27
Outline the physiological mechanism which inhibits transmission of somatosensory information to the somatosensory cortex while the child is asleep. (2 marks)
Activation of the reticular nucleus which releases GABA and inhibits activity of other thalamic nuclei
28
Outline the production, flow and reabsorption of cerebrospinal fluid. (You may make
use of a diagram).
Choroid plexus in ventricles I, II, III, IV – production.
Flow – interventricular foramina – III to aqueduct in mesencephalon – IV – central canal of spinal cord; 1 median and 2 lateral apertures in posterior medullary velum – subarachnoid space – reabsorption by arachnoid villi into superior saggital sinus
29
Outline how the canal of the cranial end of the developing neural tube in the embryo is
transformed into the various compartments of the ventricular system of the brain. (4 marks)
Telencephalon – lateral ventricles (I & II)
Diencephalon – ventricle III
Mesencephalon – aqueduct of midbrain
Rhombencephalon – ventricle IV
30
With the aid of a labelled diagram, describe the histological structure of the cranial
meninges. (4 marks)
Endosteal dura, meningeal dura, dural border cells, arachnoid barrier cells, subarachnoid space with arachnoid trabecular cells and blood vessels, pia (0.5 marks each feature)
31
```
Mark Plaatjies has difficulty walking. Use a diagram(s) to show the arrangement of
the neurones (and their neurotransmitters) involved in the efferent pathway for
locomotion, including the site of the lesion. (5.5 marks)
```
diagrams showing
Cell body of upper motor neuron in motor cortex, terminal in spinal cord (1 mark)
Cell body of lower motor neuron in ventral horn of spinal cord terminal on target muscle fiber (1 mark)
Compression of descending fibres of UMN (1 mark)
Upper motor neuron uses glutamate as a neurotransmitter (1 mark) - UMN = site of
lesion (0.5 mark)
Lower motor neuron uses acetylcholine as a neurotransmitter (1 mark)
32
With reference to ECF, indicate whether the concentrations of glucose and of protein
are higher or lower compared with CSF. (1 mark)
[Glucose] <
| [Protein] << (1 Mark)
33
Is [Cl-] in normal CSF the same as in plasma? Explain your answer. (1.5 marks)
Cl- is higher (0.5) to maintain electrical neutrality because the protein is very much
lower (1)
34
List four functions of cerebrospinal fluid. (4 marks)
functions of cerebrospinal fluid. (4 marks)
Possible Answers:
• constant external environment for neurons and glia
• specific drainage route of CSF assists removal of harmful metabolites
• mechanical cushioning
• provides buoyancy – reduces effective weight
• adjusts to changes in intracranial pressure due to alterations in cerebral blood flow
• all the functions performed by lymph
35
Describe the macroscopic appearance of normal CSF
Crystal clear (like water)
36
Name two biochemical tests commonly performed on CSF when meningitis is
suspected and state how the results change in bacterial meningitis. (2 marks)
Glucose (goes down, often to zero)
| Protein (increases many fold)
37
Define ‘xanthochromia’ of CSF. Give two causes of xanthochromia. (1.5 marks)
Yellow discoloration of CSF
| Old bleed OR high protein – eg TBM, spinal block (Froin’s Syndrome)
38
Give the full names of the three organisms likely to cause meningitis in this age
group.
Streptococcus pneumoniae
Neisseria meningitidis
Haemophilus influenzae
39
Explain why ceftriaxone is the antibiotic chosen for the empiric treatment of
meningitis in South Africa.
Covers the common organisms (1)
Is still active against penicillin-resistant S. pneumoniae. (1)
Therapeutic levels are achieved in the CSF/Crosses the BBB. (1)
40
If, when Mark first had meningitis, he had been taken to a primary care clinic and his presenting complaints were: irritability, a severe headache, nausea and a skin rash for 3 days. On examination: a high fever (39.5°C), neck stiffness, and scattered petechiae and purpura on the skin.
Neisseria meningitidis
41
Outline your initial management plan
Answer any of the following 5 (1 each):
Take specimen for culture (CSF or blood)
Establish IV access for fluids
Ensure airway, circulation if relevant
Give initial empiric IV dose of antimicrobial
Antimicrobial of choice either penicillin or 3rd generation cephalosporin
Refer to hospital
Inform the parents of the child’s condition and obtain consent for further management
Counsel the caregivers to be vigilant of similar symptoms in themselves and other
close contacts
Address the possibility of chemoprophylaxis, etc
42
What action would you take to limit potential spread to other school
pupils? (3 marks)
Ans (1 each):
Notify case urgently
Administer prophylaxis to close contacts
Prophylaxis either ciprofloxacin, rifampicin or ceftriaxone
43
In a large labelled plan diagram, indicate the histological layers of the
cerebellum.
Diagram, molecular layer, Purkinje cell layer, granule cell layer, white matter, deep
nuclei (0.5 marks each)
44
In the diagram above, draw and label the different neuronal structures forming
the neuronal circuitry and indicate the flow of information into and out of the
cerebellar cortex.
Afferent (0.5) mossy fibres (0.5) synapse onto granule cell (0.5) dendrites, axons of granule cells form parallel fibres (0.5) that synapse on Purkinje cell dendrites (0.5). Afferent (0.5) climbing fibres (0.5) synapse directly on Purkinje cells. The axons (0.5) of Purkinje cells (efferent, 0.5) connect to the deep nuclei (0.5) of the cerebellum) (2.5 for diagram)
45
Explain why damage to the cerebellum causes past-pointing. (1 mark)
Damage to the intermediate hemisphere causes past-pointing due to poor control of antagonist muscles at end of movement (1 mark)
46
Use a diagram (2 marks) to illustrate the different parts of the cerebellum and the
nuclei that are involved in planning complex movements (1 mark), control axial muscles (1 mark), control distal muscles of the limbs. (1 mark
Diagram showing four main subdivisions (1 mark)
The cerebrocerebellum & dentate nuclei - planning complex movements (1 mark)
The vermis & fastigial nucleus control axial muscles (1 mark)
Intermediate hemisphere & interposed nuclei control the distal muscles of
limbs (1 mark)
47
1. Describe the macroscopic pathology that would most likely be found in the brain at autopsy of such a case. Indicate the site of this pathology. (4 marks)
(i) Recent (ii) infarction in the (iii)(L) (iv) MCA territory
[To get full marks the student must have all 4 components correct]
48
State the most likely pathogenesis. (4 marks)
Atherothrombotic embolism, most probably from the (L) internal carotid
49
List 3 different predisposing factors (evident in the case) that could have contributed to Mr Olivier’s pathology
Previous TIA, hypertension, carotid atherosclerosis, cardiac failure, arrhythmia, valvular pathology, cigarette smoking, diabetes mellitus etc
50
Outline the prognosis you would expect in his case. (4 marks)
In the short term (30-days) the mortality rate would be around 15% for an ischaemic stroke.
This is considerably better than for haemorrhagic stroke, for which the 30-day mortality rate varies from 50-80% (82% for intracerebral and 46% for subarachnoid haemorrhages, respectively, to be exact) in the Framingham study; clinical surveys suggest there is often some fairly rapid initial recovery from an ischaemic (as opposed to haemorrhagic) event.
But in the long term (at the end of the first year) worse – especially if there is an underlying cardiovascular lesion.
[The students would not be expected to remember EXACT percentages]
51
Mr Olivier becomes pyrexial after four days in hospital. Examination reveals no sign of chest infection and no other visible site of local sepsis. He has no current intravenous lines. He is started on oral amoxicillin.
A blood culture taken just before the antibiotics were started becomes positive the next day and shows the presence of gram-negative bacilli.
(i) Outline how an antibiotic choice is made in general. (3 marks)
(ii) Comment on the choice of antibiotic in this case before the blood culture became positive. You decide to change antibiotics, name one you would choose and explain the reasons for your choice. (3 marks
(i) The choice of antibiotic is determined by the site of infection, the organisms that are common at that site and the common sensitivity pattern of those organisms.
(ii) The most likely site in this case is urinary tract related to the indwelling catheter.
Most organisms that cause UTI (especially if acquired in hospital) are resistant to amoxicillin which is therefore inappropriate.
Change antibiotic to something that has good activity against gram-negative bacilli in the light of the blood culture – aminoglycoside, quinolone, 3rd gen cephalosporin or broad spectrum penicillin.
52
Comment on the decision to catheterise Mr Olivier. Explain why this may or may not have been an appropriate thing to do. (3 marks)
Urinary catheterisation carries with it the risk of infection and should only be performed for a valid medical reason. If the only reason was to ease nursing care, there are other options available that do not carry the same risk of infection
53
Give a brief explaination of the mechanism of the coagulation cascade. (5 marks)
The coagulation cascade consists of a series of enzyme reactions (1), which require cofactors, Ca++ and phospholipid (1.5). E ach step amplifies the previous one (1), and the end result is the formation of large amounts of fibrin to form a stable clot (1.5)
54
The doctor may decide to put Mr Olivier on aspirin therapy.
Outline the mechanism of the anti-thrombotic action of aspirin. (3½ marks)
Aspirin irreversibly inhibits (1/2) the enzyme cyclooxygenase (1/2) in platelets (½ ).
This prevents the formation of Thromboxane A2 from arachidonic acid (1) Thromboxane A2 is a vasoconstrictor and platelet aggregator (1)
55
Give an overview of the course of the Facial nerve (Cranial nerve VII) in the region of the face. Include the groups of muscles that are innovated by this nerve, as well as their actions. You may use a fully labelled diagram, if you wish. (10 marks)
N. VII leaves the skull through the stylomastoid foramen. Travels through the parotid salivary gland. Branches (above) arise from the edges of the gland and supply the groups of muscles of facial expression.
The clinicly relevant groups of muscles that students were required to learn are:
1) orbicularis oculi – blinking, screwing up of eyelids
2) orbicularis oris – sphincter of mouth/lips
3) platysma – tensing skin of neck
4) occipitofrontalis – moving scalp
5) buccinator - blowing
6) small groups for moving ears, flaring nostrils, wrinkling forehead, changing shape of
56
10. List five clinical signs of unilateral lower motor neuron Facial nerve palsy.
(5 marks
LMN damage = flaccid paralysis – hypotonia or atonia, hyporeflexia.
Relate to the functions listed above.
For the signs of deficit, students should know to ask the patient to smile, show the teeth, close eyes, close lips, blow, suck, whistle, tense neck skin for shaving, wrinkle forehead, raise eyebrows, and so forth. Ptosis of lower eyelid only.
Loss of nasolabial folds; drooling, dribbling, drooping of angle of mouth, lack of expression/movement in hemi-face (entire half cf UMN lower quadrant only)
57
Briefly describe the arterial supply to the occipital lobe of the brain. You may use a diagram, if you wish. (5 marks)
Brief description of the arterial cerebral circle – L & R posterior cerebral arteries arising from the posterior half of the circle. These run caudally to supply the occipital lobe medially, inferiorly, caudally, superiorly, and a small portion laterally
58
Give two examples of functional losses if the arterial supply to the caudal region of one of the occipital lobes becomes obstructed. (2 marks)
Visual cortex at caudal pole of occipital lobe – all special sensation (vision) from the opposite field of vision is lost.
Visual association area surrounds visual cortex – interpreting what is seen – loss.
59
Briefly describe the following terms concerning the action potential of a neuron. (2 marks X 3 = 6 marks)
1. (i) resting membrane potential (2 marks)
2. Depolarisation
3. Voltage gated NA+ channels
(i) resting membrane potential (2 marks)
At rest, membrane potential (Vm) is negatively charged inside wrt to outside of cell in the range -65 to – 85mV. At rest Vm is close to EK ( approx -80 mV) thus as this ion dominates at equilibrium it is manly responsible for maintaining Vm at this level
(ii) depolarisation (2 marks )
This a change in the charge distribution across the membrane from RMP in a more positive direction ( i.e Vm becomes less negative) .
This is due to increased gNa+ ( sodium conductance ) in the inward direction ( i.e inward current carried by Na+ )
[May also give a diagram of the action potential with arrow indicating phase – but need to explain what is happening during this phase ]
(iii) Voltage gated (Na+) channels (2 marks)
These are special channels with two gates ( inactivation and activation gates ) that are opened/ closed ( at different rates) by a depolarizing current ( hence a change in voltage) They are specific for Na+ ions and are located both at the axon hillock and nodes of Ranvier.
60
Outline the role of myelin in the conduction of an action potential in a myelinated axon. (2 marks)
Myelin has insulating properties. Due to its high resistance to electric current flow myelin prevents leakage of current out of the axons. Since it is interrupted at the Nodes of Ranvier it causes current to flow rapidly form node to node – hence “saltatory “ conduction. Hence in myelinated axons there is more rapid transmission of the action potential than in a non -myelinated axon .
61
Briefly describe the changes that occur in a peripheral neuron if its axon is cut (axotomy). (5 marks)
Distal to the cut, the axon degenerates – it undergoes Wallerian degeneration. Myelin becomes fragmented, Schwann cells die and distal stump atrophies. Area invaded by macrophages
Proximal to cut nerve cell bodies become swollen (oedematous) granular material in cytoplasm becomes dispersed toward the periphery ( rough endoplasmic reticulum disintegrates). The nucleus moves to an eccentric position.(process called Chromatolytic reaction)
After a variable period there may be sprouting of the axon of the proximal stump. These form growth cones which induce Schwann cells ( mitogenic response) to start laying down myelin around the endoneural tube ( if aligned ) and a new axon is formed by the extending growth cone.
62
Define the term “receptive field” giving an example in the somatosensory system.
(4 marks)
This is the area on the surface of the body (receptive surface) from where a particular receptor type or cell in the sensory relay pathway en route to the Somatosensory area of the cortex receives its input (i.e. stimulus).
RF’s of specialized receptors vary in size depending on location in epidermis eg Merkel Disks, Meissner’s corpuscles ( both are superficial) have small receptive filed while Ruffini endings and Pacinian corpuslces (lie deeper)have large receptive fields
63
Describe 3 main functions of cerebrospinal fluid.
Provides bouyancy – brain weighs less in CSF
Provides a cushioning effect against impact
Helps maintain a stable external microenvironment around the brain (i.e homeostasis)
Acts as a lymphatic system for removal of waste products draining into the venous system
64
Draw and fully label a cross section through the developing neural tube in the thoracic region of the embryo, giving a short explanation of the functional implications for each of the structures that you have labelled. (10 marks)Draw and fully label a cross section through the developing neural tube in the thoracic region of the embryo, giving a short explanation of the functional implications for each of the structures that you have labelled. (10 marks)
Neural tube is divided into:
• ventricular zone – giving rise to ependymal layer, lining the central canal
• mantle layer – giving rise to grey matter (neurones)
• marginal layer – giving rise to white matter (tracts)
Mantle layer is divided by the level of the sulcus limitans into alar plate dorsally and basal plate ventrally –>> alar plate = sensory / afferent = dorsal horn, & basal plate = motor / efferent = ventral horn.
Asking for the thoracic region will, hopefully, trigger recall of the lateral horn – autonomic (sympathetic) outflow, and the resulting lateral horn (visceral), versus the dorsal and ventral horns (somatic).
See diagram of the functional anatomy of the spinal cord, below.
65
List four organisms that can cause genital ulceration (full names – genus and species) and name an antibiotic/antiviral agent that could be used to treat each one.
(6 marks)
Treponema pallidum, - penicillin (erythromycin, ceftriaxone)
Haemophilus ducreyi, - erythromycin (ceftriaxome, ciprofloxacin)
Chlamydia trachomatis, - tetracycline, erythromycin
Herpes simplex – acyclovir
66
Describe how the laboratory can assist in confirming any one of these organisms as the cause of the ulcer. (2 marks)
T. pallidum: Darkground microscopy of fluid from the lesion
Syphillis serology RPR, TPHA or FTA
H. ducreyi: Gram stain and culture of the organism, PCR
C. trachomatis: Immunofluorescence stain, cell culture of the organism, PCR
H. simplex: culture of the virus
67
State which two of the above organisms can also infect the brain? (2 marks)
T. pallidum and H. simplex
68
Give an overview of neurulation with respect to the spinal cord. You may use diagrams if you wish
Above diagram will suffice. Also need to say induction of neurulation by notochord and process begins at day 22 and completed by day 25 (closure of rostral neuropore) and day 27 (closure of caudal neuropore).
69
Give a short description of a meningomyelocoele. (2 marks
Bulging fluid-filled “sac” on surface of the body – contents could be meninges, cerebrospinal fluid, neural elements (caudal end of spinal cord).
70
3. Based on your description of neurulation, briefly explain the process of development of a meningomyelocoele. (5 marks
Explain how the overlying ectoderm and mesoderm need to seal off the neural tube from the surface by growing over the top of the neural tube. Ectoderm forms epidermis; mesoderm forms dermis, hypodermis, connective tissue, bone (vertebrae) and skeletal muscles. Failure of this process will result in elements bulging onto the surface of the body – in this case meninges and neural elements.[ Possible tethering of the neural tube, leading to hydrocephalus later.]
71
Explain what LMN lesion is, and how it is deduced from the clinical examination. (5 marks)
Lower motor neurones lie in the grey matter of the ventral horn – fibres pass out of ventral root to innervate muscle bellies. Damage to motor neurones at this level will compromise the nerve supply to muscle bellies, resulting in hypotonia and hyporeflexia, atrophy, etc. Flaccid paralysis, of agonist / antagonist, etc.
72
Draw a diagram to explain why the motor reflexes were reduced in strength. (10 marks)
Drawing is a diagram of a pathway from a sensory neuron , into the spinal cord, decussaton, interneuron, and motor neuron - showing the possible areas which could be damaged in the pathway
73
```
List two (2) unrelated investigations whereby a meningomyelocoele can be suspected in utero.
(2 marks)
```
How can the risk of this lesion be reduced? (1 mark)
[ultrasound examination(1) and maternal serum and/or amniotic fluid alpha foetoprotein levels(1)]
[planned pregnancy with folate (1) for 3 months prior to conception (1)]
74
Robbie develops hydrocephalus. Explain the likely pathogenesis.
[hydrocephalus due to Arnold- Chiari malformation causing obstruction to CSF flow at the level of the foramen magnum due to downward displacement of the cerebellum]
75
The aetiology of neural tube defect is multifactorial. List three (3) independent factors which may play a role in its aetiology and give an example of each
[genetic e.g. monogenic mutations, chromosomal trisomy 18; environmental including specific geographic areas, maternal diet – folic acid deficiency, iatrogenic - drugs taken by mother (valproate), metabolic - maternal diabetes
76
Whilst you are working as a community service doctor in a rural part of the Eastern Cape a Xhosa-speaking mother gives birth to a baby with meningomyelocoele. You decide to inform yourself about her lifestyle and circumstances in order to counsel her about future pregnancies. Describe five (5) factors that you would consider before having a discussion with her. (1 ½marks per factor = 7 ½)
1. The mother’s language and cultural orientation.
2. Her diet - particularly in terms of local and family custom.
3. Local beliefs about birth and deformity.
4. Local beliefs, attitudes and practices in respect of disability in children, (especially how
other children with disabilities have been accepted in the community).
5. The mother’s understanding of folic acid deficiency and supplementation, and that this
is an agent implicated in the aetiology of meningomyelocoecele
6. Whether the mother has a predisposition for this condition - a past history of spina
bifida in her previous pregnancies as this heightens her risk; family history of ca. oesophagus – relationship to folic acid antagonists (aflatoxin).
7. Whether there is an environmental prevalence for this condition in the local
population – see above.
77
List two (2) signs that are commonly associated with spina bifida occulta which you would find over the sacrum in the neonate. (1 mark)
Sacral depression / dimple, tuft of hair, soft fatty deposits, port wine naevus
78
Even though a patient with spina bifida occulta may initially have no symptoms or signs, problems can develop later. As the Family Practitioner you should be on the alert for signs and symptoms of neurological dysfunction. List three (3) common symptoms arising from spinal cord tethering.
foot weakness, bowel and bladder dysfunction, headache
79
Hydrocephalus is a common complication of neural tube defects. List four (4) signs that would make you concerned that an infant is suffering from raised intracranial pressure. (2 marks)
Any four of bulging fontanelles/ splayed sutures, vomiting, increased head circumference, decreased level of consciousness, irritability, sunset eyes
80
At present, routine screening specifically for Neural Tube Defects is not offered, although severe defects would be seen in routine scanning. Do you think that routine screening should be offered to every pregnant woman? Yes / No? Justify your answer. (4 marks)
Should know something about the criteria for screening? Eg. Condition must be common, important, diagnosable by acceptable methods, screening must be simple and cheap, intervention must be available, screening needs to be sensitive, specific, safe, acceptable to pt, easy to interpret, high positive predictive value. Ethics of allocation of health resources
81
Robbie’s parents come to you to discuss his long term prognosis. For each of the following subheadings, explain the prognosis to the parents. In your explanation, mention at least one member of the multidisciplinary team who would have a prominent role. (6 marks)
a) Mobility (2 marks)
b) School performance / cognitive ability (2 marks)
c) Continence (2 marks)
a) Mobility is likely to be impaired to some degree. However, with the aid of physios and orthopaedic surgeons, 70% of children with NTD will eventually walk independently.
b) Cognitive performance is nearly always affected, although the degree of severity will only become apparent with time. Some children may be able to attend mainstream schools, others will need special schools. Social workers, physios, child psychologists, and the paediatrician will be involved in determining the level of support needed.
c) Both urinary and bowel continence are common issues. The bowel can be managed with a high fibre diet and the use of bowel aperients. The urinary side may require regular intermittent catheterisation. Nurses play a big role in educating the parents how to manage the continence while the Family Physician and / or Paediatrician need to be on the alert for complications such as UTIs. Management of water intake.
82
Describe the CSF findings for cells, glucose and protein that would make you consider a diagnosis of acute bacterial meningitis. (2 marks)
.Increased polymorphs (½), decreased glucose (½) (relative to blood glucose) (½) raised protein (½)
83
The finding of organisms on the Gram stain would confirm bacterial meningitis. Given that Ayesha is 5 years old, list the three (3) most likely Gram stain results and give the full name of the organism you would expect for each result. (4 ½ marks)
gram-negative (intracellular) diplococci (½) Neisseria (½) meningitidis (½)
gram-positive diplococci (½) Streptococcus (½) pneumoniae (½)
gram-negative coccobacilli (½) Haemophilus (½) influenzae (½)
84
Name the drug of choice for empiric treatment of meningitis in a child of this age. (1 mark)
Third generation (½) cephalosporin (½)
85
Explain immunologically why the three organisms in Q17 above are the most likely. Contrast these with the two (2) organisms usually encountered in the neonatal period. (5 marks)
These have a polysaccharide capsule which requires opsonization for the polymorphs to ingest [and thus kill them]. Opsonins are IgG type antibodies. These cross the placenta from the mother, giving immunity in the neonatal period.
E coli and L monocytogenes are neonatal organisms. These require IgM for protection and there is no transplacental passage of this type of ab. The baby is thus at risk for these organisms in the neonatal period.
86
Explain the difference between leptomeningitis and pachymeningitis. (2 marks)
Leptomeningitis – inflammation arachnoid / subarachnoid space
Pachymeningitis – inflammation of dura
87
Draw a flow diagram that shows the route of flow of CSF from its production through to its reabsorption, giving detailed labels. (10 marks)
Choroid plexus [arteries] in ventricles 1, 2 and 3; separate choroid plexus in ventricle 4. (2)
Ventricle I to 3 via interventricular foramen. (1)
Ventricle 2 to 3 via interventricular foramen. (1)
Ventricle 3 to 4 via aqueduct of midbrain. (1)
Ventricle 4 to central canal of spinal cord. (1)
Through 3 foraminae in roof of ventricle 4 to subarachnoid space. (2)
Reabsorption of CSF via arachnoid granulations into superior sagittal [venous] sinus. (2)
88
Give the total volume of CSF present in the CNS at any given time. (½ mark)
150 ml
89
Give the volume of the total daily production of CSF. (½ mark)
500 ml/day
90
Explain how the CSF compartment prevents intracranial pressure changes when blood flow to the brain is increased. (4 marks)
* Increased amounts of CSF are squeezed from the ventricles (1)
* Displaced CSF flows into the subarachnoid space around spinal cord (1)
* Dura mater lining spinal column is more elastic (1)
* Dura stretches to compensate for the increased volume (1)
91
In a patient with a high total CSF protein, describe how you would distinguish increased protein permeability of the blood/brain barrier from antibody production within the CNS (such as may occur in neurosyphilis or multiple sclerosis). (2 marks)
By examining the ratio of CSF IgG to albumin, or ideally, by dividing the CSF IgG/albumin ratio by the serum IgG/albumin ratio. The value for increased permeability is <0.7, while for local IgG production it is >0.7.
92
State the most common endocrine disorder complicating meningococcal meningitis. (1 marks)
Adrenal failure (Waterhouse-Friederichson syndrome) (1)
93
Describe how you would suspect this disorder (Q.26) clinically, and how you would confirm it biochemically. (2 ½ marks)
Profound shock / circulatory collapse (1)
| Hypoglycaemia, hyperkalaemia, hyponatraemia, acidosis (1 ½) (also accept low cortisol, low aldosterone, high renin)
94
In a labelled plan diagram of a cross-section through a typical blood capillary in the CNS, indicate the structures that contribute to the blood-brain barrier. (4 marks)
(astrocyte endfeet, non-fenestrated endothelium, endothelial tight junctions, thick basement membrane: 2 marks for diagram, 0.5 marks for each structure)
95
a) Name the fluid compartments that are separated by the choroid plexus. (1 mark)
b) Name the cells that maintain the barrier function of the choroid plexus. (½ mark)
c) Name the mechanism that enables large, polar molecules to cross the choroid plexus. (½ mark)
Total (2 marks)
a) , blood and CSF (1);
b) , choroid epithelium (½);
c) transmembrane transport systems (½)
96
What are the legal obligations with respect to notifying the health authorities? (Include in your answer the following subheadings: a) the relevant Health Act, b) timing of notification relevant to laboratory results, c) people who can inform the Department of Health about a notifiable disease.) (6 marks)
Answer:
a) National Health Act, Act 61 of 2003
b) Notify when suspect the disease from clinical signs and symptoms (ie before you have
lab confirmation)
c) Any health care worker who sees and diagnoses a notifiable case or death has a legal
responsibility to notify the relevant Health Authority.
97
Using suitable examples, outline three (3) reasons why notification is performed. (3 marks)
Collection of statistics for nationally important diseases (eg TB)
Contact tracing and prevention of spread of communicable diseases (TB, meningococcus, typhoid etc etc)
Evaluation of vaccine efficacy / collecting data about vaccine failure rates (eg H influenzae B, pertussis)
98
List two (2) other causes of meningitis which are also notifiable. (1 mark)
Haemophilus influenzae B, Tuberculous meningitis.
99
If Mr Botha had presented to you, his GP, after he had the episode of transient right-handed weakness, what would have been your likely diagnosis? (½ mark)
TIA
100
State the pharmacological treatment that would you have started then which might have actually prevented him going on to develop the symptoms and signs he had later. (½ mark)
Asprin
101
In addition to caring for Mr Botha, list three (3) issues you would be looking out for in Mrs Botha (his wife) when you performed a biopsychosocial assessment. (1 ½ mark)
Psycho: Psychological stress / depression is common in carers
Bio: As she is likely to share his diet and lifestyle, she may also have a high cardiovascular risk.
Social: May need assessment of her financial needs if her husband is unable to work/ assess level of family support
102
Identify the type of dysphasia which Mr Botha is experiencing. (½ mark)
Expressive dysphasia
103
Mr Botha seems to have some difficulty in swallowing. Name the professional who, in addition to assessing his speech, would perform an assessment of his ability to swallow. (½ mark)
Speech and Language therapist
104
List two (2) other members of the multidisciplinary team who are essential in the rehabilitation of a patient who has had a stroke. (1 mark)
Physio and OT
105
List five (5) non pharmacological treatments that are essential in your management plan of Mr Botha. (2 ½ marks)
Aim for healthy BMI, Exercise at least 3 times a week, decrease salt intake, increase fruit and veg (5 a day), stop smoking, decrease animal fat, limit alcohol intake
106
Name the famous cohort study which helped to identify risk factors for cardiovascular disease. (½ mark)
Framingham
107
If a CT scan showed that the stroke was caused by a thromboembolism, list three (3) additional special investigations you would request and explain how they would help to identify the common causes of thromboembolism. (6 marks)
a) carotid artery duplex: carotid artery atheroma
b) ECHO: cardiac abnormality
c) ECG: cardiac arrhythmia, previous MI
108
Mrs Botha tells you that her husband’s mother died at the age of 28 from a blood clot to her lungs during her 4th pregnancy. He lost his sister, who was a heavy smoker, from a stroke at the age of 48, and his brother had a deep vein thrombosis after flying overseas 10 years ago, but is now well. Mr and Mrs Botha have 2 sons.
1. Explain how knowing this family history would influence your management of Mr Botha. (2 marks)
Looking for genetic predispositions to thrombosis.
Avoidance of risk factors.
Counselling other family members about risk
109
If there is a genetic disorder in this family, state the likely inheritance pattern. (1 mark)
Autosomal dominant
110
a) List three (3) predisposing factors for a stroke. (1 ½ mark)
a) Any three of the following: Hypertension, diabetes, cardiac disease,
smoking, atherosclerosis, polycythaemia, transient ischaemic attacks.
111
b) List thee (3) different mechanisms by which a stroke occurs. (1 ½mark)
b) Thrombosis, embolism and haemorrhage
112
c) Describe the macroscopic pathology seen in a cerebrovascular accident. (4 marks)
c) Any four of the following: Soft, oedematous parenchyma; poor demarcation between
grey and white matter; intra-cerebral and intraventricular haemorrhage; lacunes; late -
cavity formation, discolouration due to haemosiderin deposition.
113
d) Describe the microscopic pathology of a cerebrovascular accident. (4 marks)
d) Any four of the following: Early – haemorrhage or ischaemic neuronal changes (red
neurons with cytoplasmic microvacuolisation, cytoplasmic eosinophilia and pyknosis),
subacute changes - (24 hours to 2 weeks) – necrosis, macrophage infiltration, vascular
proliferation and later repair with gliosis and haemosiderin deposition.
114
e) List two (2) complications of a cerebrovascular accident
e) Any two of the following: decreased level of consciousness with risk of aspiration, bed
sores, raised intra-cranial pressure, herniation, autonomic nervous system instability.
115
Name the lobe of the cerebral hemisphere in which the motor homunculus lies on each side of the brain, and name the relevant gyrus. (1 mark)
Frontal lobe - Precentral gyrus
116
Draw a detailed depiction of the motor homunculus on a coronal view of one of the cerebral hemispheres. (9 marks)
Do the drawing. Learn the differences between the motor and sensory homonculus
117
Give an explanation of the motor consequences of unilateral damage to the facial nerve nuclei (N. V11). (5 marks)
Answer:
• Facial nerve - mainly motor function
• Lesion does not affect upper half of face
• Lower half of contralateral face shows weakness
• Part of N. V11 nucleus innervating upper face receives bilateral projections from cerebral cortex (motor cortex; motor homunculus; precentral gyrus) – upper face is spared
• Part of N. V11 nucleus supplying lower part of face receives unilateral, contralateral projections from cerebral cortex (motor cortex; motor homunculus; precentral gyrus) and affects lower half of face on same side
118
List the five (5) sensory modalities that are stimulated in coma arousal therapy. (2 ½ marks)
1. vision
2. hearing
3. touch
4. taste
5. smell
119
Describe the manner in which these are best used to stimulate a coma patient’s brain to
learn. (1 ½ mark)
Frequency, intensity and duration of the stimulus is the most effective means by which the “brain can learn” (in coma arousal therapy).
120
Briefly define the term “prosencephalisation”. (1 mark)
Considerable development of the cerebral hemispheres – in both size and amount of cerebral cortex (neurones; sulci & gyri).
121
Name another portion of the brain that is also well developed alongside prosencephalisation. (½ mark)
Cerebellar hemispheres, or neocerebellum.
122
Give a short description of the advantages of the advanced developments mentioned above. (4 marks)
Prefrontal cortex – various functions; aspects of sensory and motor homunculi, planning and reflection, language and speech, non-verbal communication, problem solving exercises, powers of reasoning, variety of creative tasks, fine motor movements - examples, quality of memories, and so forth.
123
State what acid-base disturbance is present and explain why the patient has this disturbance.
Metabolic Alkalosis
| Loss of H ions in the distal tubule due to increase uptake of Na
124
In the presence of this acid-base disturbance, as well as the electrolyte findings, name the most likely cause for the hypertension in Mr Davies.
Conn’s Disease
125
Name two (2) hormones you would need to measure and what levels you would expect to see (normal/increased/decreased).
Aldosterone (elevated)
Renin (decreased)
126
With the aid of a diagram, indicate the areas of Mr Davies’ brain that are impaired.
(5 marks)
Diagram of the brain, identifying left hemisphere pre- and post-central gyri, Broca’s and Wernicke’s areas and possibly occipital and prefrontal cortices
127
```
Name ten (10) of Mr Davies’ functional impairments and list the brain regions that would be expected to be damaged in order to produce the impairment.
(10 marks)
```
Any 10 of the following:
(i) Weakness (hemiparesis) on right side of his body – left cerebral hemisphere primary motor cortex (left precentral gyrus)
(ii) Confused – prefrontal cortex
(iii) Sees double – occipital cortex (or brain stem nuclei, superior colliculus etc)
(iv) Slurred speech – Broca’s area (posterior inferior frontal gyrus in the frontal cortex of the left hemisphere)
(v) Stumbles and falls – visual cortex is required for visually guided motor activity
(vi) Diminished pinprick sensation on his right arm and right side of his head – damage to left somatosensory cortex, post central gyrus and/or other pain perceiving areas of the brain e.g. insular cortex and cingulate cortex
(vii) Diminished two-point discrimination on his right arm and right side of his head – left primary somatosensory cortex, post central gyrus.
(viii) BP of 160/110 – impaired subcortical control of autonomic nervous system (hypothalamus & amygdala)
(ix) Brisk deep tendon reflexes on the right – reduced cortical inhibition by left hemisphere
(x) Babinski reflex on the right – damage to upper motor neuron in left motor cortex (left hemisphere precentral gyrus)
(xi) Difficulty speaking – Broca’s Areas ( Brodmans area 44 & 45 ( inferior left frontal gyrus)
128
With the aid of an annotated diagram showing the relevant pathways, explain how Mr Davies’s brain controls movement of his right arm.
(5 marks)
Diagram indicating
(i) Upper motor neuron in motor cortex, anterior to central sulcus
(ii) projecting axon through internal capsule, brain stem, decussating in pyramids of the medulla
(iii) to synapse in cervical level of spinal cord on lower motor neuron in ventral horn of spinal cord
(iv) The upper motor neuron releases glutamate which stimulates the lower motor neuron to release acetylcholine onto the target muscle at the neuromuscular junction
(v) Acetylcholine acts on nicotinic receptors in the postsynaptic membrane to depolarize the muscle membrane, opening voltage-gated sodium channels, producing an action potential in the muscle membrane which leads to muscle contraction.
129
Explain why Mr Davies is experiencing diminished pin-prick sensation on the right side of his head. Include in your answer the appropriate pathways and structures involved. Use a diagram if you wish.
Diagram indicating
(i) Nociceptor in skin on right side of head
(ii) Trigeminal nerve (cranial nerve V)
(iii) Sensory (spinal) trigeminal nucleus in brain stem, axon of 2nd order neuron project to opposite side of brain
(iv) To ventrolateral region of the primary somatosensory cortex (gyrus posterior to central sulcus) representing the skin of the head
(v) Damage to this region of the somatosensory cortex will impair perception (feeling) of pain. The sensation would normally be projected to the site of injury but damaged somatosensory neurons unable to function
130
A CAT scan is performed and this shows the presence of an intracerebral bleed in the region of the basal nuclei, extending into the internal capsule.
8. Name (½ mark) and describe the lesions that are likely to be found in the walls of the thalamostriate/lenticulostriate vessels [penetrating cerebral arteries] in Mr Davies.
(1 ½ marks)
```
Charcot Bouchard aneurysms / microaneurysms [1/2]
Vessels show damage to wall
i] intimal thickening [1/2]
ii] medial fibrosis [1/2]
iii] rupture of elastic lamina [1/2]
```
131
Name one sign that is most likely to be present on cardiac examination.
Heaving L apex [1] signs of hypertension
132
The CAT scan also shows the presence of an additional lesion. A ring enhancing lesion is present in the L middle cerebral artery territory. The Chest X-Ray reveals a large lung mass which on Fine Needle Aspiration Biopsy is a moderately differentiated squamous cell carcinoma. It is presumed the ring enhancing lesion is due to a metastatic squamous cell carcinoma.
10. Describe the components seen in the ring enhancing lesion, and explain how they are pathophysiologically brought about by a metastatic carcinoma.
(3 marks)
1. Central black : necrosis [Ca outgrows blood supply]
2. White ring : leaking vessels , ruptured by Ca. Leaks contrast media
3. Black outer ring : oedema fluid [vasogenic oedema]
133
Describe the process of Wallerian degeneration.
| (2 marks)
Chromatolysis, swelling of cell body, degradation of disconnected axon and associated myelin sheath
134
Outline the role of Schwann Cells in the regeneration of peripheral nerves.
(4 marks)
Remove debris, provide growth promoting substrate and guidance for regenerating axon, promote neuron survival by secreting neurotrophic factors, re-myelinate
135
Briefly explain how the Amyloid Beta protein fragment is thought to contribute to neuron degeneration in Alzheimer’s disease.
(3 marks)
Direct toxicity to neurons causes neuronal damage and disruption of synaptic contacts; promotes glial reactivity and inflammatory response which damages and kills neurons
136
Briefly outline to what extent the smoking legislation has been successful in South Africa
The following has been observed since the introduction of the smoking legislation:
• The recent implementation of comprehensive tobacco control policies has significantly reduced smoking prevalences across South Africa.
• millions of people have stopped smoking
• By 2003, cigarette sales fell for the twelfth consecutive year in South Africa. Annual cigarette consumption decreased drastically (a 33% decrease).
• The number of students who had never smoked increased (by 20% )
• and the number of frequent smokers (smoked on 20 or more days in the past month) declined
137
Name the organism that is the most common cause of UTIs in general.
(1 mark)
E. coli
138
Certain organisms are more likely to cause UTIs in the presence of an indwelling urinary catheter. Name one such organism
(1 mark)
Candida albicans, coagulase negative staphylococci
139
Briefly explain how Mr Davies’ UTI could have been prevented.
(1 mark)
Use of a condom catheter / Paul’s tubing rather than an indwelling catheter.
140
Mrs Davies mentions her husband fell off a ladder two days ago. The doctor notices he has a lot of bruises. Mrs Davies tells the doctor they aren’t concerned about that because he always bruises easily and it is “in the family” with his father and sister and their son also having the same problem. The doctor considers a genetic disorder of blood coagulation.
State the likely inheritance pattern.
(½ mark)
Autosomal dominant
141
State the risk that their son’s baby daughter has inherited this disorder.
(½ mark)
50% / 1in 2
142
Mr Davies has a number of relatives who developed hypertension in their 50’s and 60’s.
State the likely inheritance pattern of hypertension in his family.
(½ mark)
Multifactorial / complex
143
```
Outline six (6) psychosocial factors that would contribute to Mr. Davies feelings of distress following his stroke.
(6 marks)
```
```
Cognitive impairment
Inability to communicate
Capacity to understand but not respond appropriately
Level of physical disability
Social isolation
Stigma
Depression
```
144
Outline six (6) reasons why his family would find the consequences of his stroke stressful.
(6 marks)
```
Lack of emotional readiness for the news
Difficulties in communicating
Problems understanding his ‘stroke’
His inability to fit in with mainstream society
Stigmatisation of stroke
Work and future financial stability
Access to social opportunities and roles
Changes within the family system roles
Grief and loss
```
145
Describe the likely laboratory findings on CSF examination in a case of TB meningitis.
(4 marks)
```
Increased cells, lymphocyte predominance (2)
Raised protein (1)
Low glucose (1)
```
146
17. State the condition that Dr Johnson was treating when he started ceftriaxone.
(1 mark)
Acute bacterial meningitis
147
18. Name three (3) organisms that can cause the condition named in Question 25 in a child of Sipho’s age (3 marks). Describe the Gram stain appearance of each organism.
(3 marks)
Streptococcus pneumoniae – Gram positive cocci in pairs
Haemophilus influenzae – Pleomorphic Gram negative cocco-bacilli
Neisseria meningitides – Gram negative diplocococci
148
19. Describe how the cerebrospinal fluid (CSF) findings in this condition would differ from those described for TB meningitis.
(2 marks)
Predominance of polymorphonuclear cells rather than lymphocytes
Glucose is lower and or Chloride is normal
149
20. Explain why Dr Johnson started ceftriaxone before the lumbar puncture results were available.
(2 marks)
Acute bacterial meningitis is a life threatening condition, and therapy must NEVER be delayed while waiting for lab results / other investigations.
150
21. Name three (3) factors in the case that may have predisposed Sipho to getting TB.
(1½ marks
Overcrowding
Contact with uncle
Possibly no BCG vaccination (no RTH card, thus no proof)
151
22. Name the drugs used to treat TB in an adult (Sipho’s uncle)
(2 marks– ½ each)
Rifampicin
Isoniazid (INH)
Ethambutol
Pyrazinamide (PZA)
152
In light of the history of Sipho’s uncle having TB, Sipho’s mother was asked to bring her two other children to the clinic for evaluation – particularly Thandi, the three year old.
23. Explain why the children have been brought to the clinic, and what intervention (if any) should be considered
(3 marks)
Childhood contacts (particularly those under 5 yrs old) should be evaluated to determine whether they have any features of TB. If they do not have active TB, they should be given chemoprophylaxis in the form of INH for 6 months.
153
24. Describe the difference in eye signs typically seen in a long standing case of TB meningitis occurring in a 3 year old versus a 14 month old infant. Explain the mechanism.
(4 marks)
Setting sun sign, Papillodoema+-
| Dilated pupil, papillodoema ++
154
25. List the three (3) true barrier systems that contribute to the physiological blood-brain barrier.
(1 ½ marks)
Cerebral capillaries, choroid plexus, arachnoid mater/meninges
155
26. The inner ear contains three (3) distinct receptive structures.
(i) List these and their primary functions.
(3 marks)
Organ of Corti – detection of sound waves; Macula – static equilibrium; Crista Ampullaris – dynamic equilibrium or acceleration and deceleration
156
(ii) Identify the type of receptor cell that is common to these receptive structures.
(½ mark)
Hair cells
157
27. State two (2) structural features that distinguish the Blind Spot from other parts of the neural retina.
(1 marks)
No photoreceptor cells; exit point of optic nerve/retinal ganglion cell axons
158
28. Briefly explain why the blind spot is not normally perceived in the field of vision.
(2 marks)
The visual centres in the brain extrapolate visual information from the areas of the visual field adjacent to the Blind Spot to fill the space of the receptor-free area
159
29. If a lumbar puncture had been done and the CSF glucose was found to be 20mmol/l, what would you suspect and how would you confirm your suspicions?
(2 marks)
As well as TB meningitis, the child has uncontrolled diabetes (presumably type 1, given the age). Confirm with a markedly raised blood glucose (>20mmol/l).
160
30. Name two (2) causes for a bloodstained CSF, and suggest two (2) ways by which they can be differentiated, explaining how the responses differ in each case
(6 marks)
```
Subarachnoid haemorrhage (SA), bloody tap (BT). By collecting sequential samples (clears in BT, remains uniformly bloodstained in SA). By spinning down and observing supernatant (clear in BT, possibly xanthochromic in SA).
```
161
Name the aetiological agents responsible for poliomyelitis.
| 1 ½ marks
Poliovirus 1, 2 and 3
162
32. Describe the pathogenesis of poliomyelitis
| 5 marks
Virus gains access to the body via ingestion. It replicates in gut associated lymphoid tissues. In some individuals this may be followed by a viraemia and haematogenous spread to the CNS. Lytic infection of motor neurons in the anterior horns of the spinal cord leads to a lower motor neuron weakness of muscles supplied by affected motor neurons (Flaccid paralysis.
163
33. State what percentage of infected individuals develop paralysis.
(½ mark)
1%
164
34. Name the most appropriate sample to send to the laboratory to diagnose poliomyelitis.
(½ mark)
Stool sample
165
State how poliomyelitis has been brought under control.
Through the use of 2 effective vaccines.
166
36. Name three (3) viruses that commonly cause aseptic meningitis.
(1 ½ marks)
Enteroviruses, mumps virus, Herpes Simplex type 2
167
Randomized control trials have been conducted to determine the efficacy of vaccines against meningitis.
37. Discuss the particular features of this study design that makes it superior to other study designs.
(4 marks)
The fact that participants are randomly selected into a control or intervention group means that each participant has an equal chance of being allocated to either of the groups. This prevents selection bias as it prevents clinicians, researchers and participants from using their own subjective view to decide which groups to place participants. Randomization also ensures that the groups being compared are equivalent in terms of baseline characteristics, including known and unknown risk factors for the disease in question. It therefore also assists with the control for confounding by maximising the chances that the two groups are comparable at the beginning of the study. Blinding of participants and/or researchers would minimize measurement bias when measuring the outcomes
168
38. State the recommended test for pain response.
| 1 mark
Fingernail pressure
169
39. List the words that describe appropriate care for patients suffering from coma in the “A Bit of Care” acronym.
(5 marks)
Atmosphere
Breathing
Introduction
Touch
Observation with interpretation
Feedback
Copying
Amplifying
Resisting
Enabling expression
170
58. Describe the different types of neural tube defects that occur. Include in your answer the anatomical structures involved in each defect.
(10 marks)
May occur on the head (anencephaly, encephalocoele) or on the vertebral column (spina bifida), or both (e.g. severe forms such as myeloschisis, rachischisis).
(4 Marks)
Spina bifida may be hidden (spina bifida occulta) or visible as a cyst on the back (spina bifida cystica).
(2 Marks)
Spina bifida cystica may contain only CSF (meningocoele, rare) or CSF and neural elements (meningomyelocoele).
(4 Marks)
171
59. Draw and label a set of diagrams that illustrate similarities and differences between the embryonic neural tube, the fully developed spinal cord, and the fully developed medulla.
(25 marks)
Just do the drawing
Grey matter on inside, white matter on outside, central canal
Alar plate – afferent – somatosensory
Basal plate – efferent – somatomotor
Spinal cord:
(9 marks)
Grey matter on inside, white matter on outside, central canal
Dorsal horn – afferent – somatosensory
Ventral horn – efferent – somatomotor
Medulla:
(7 marks)
Alar plates have moved laterally and pia stretched over the 4th ventricle as the caudal medullary velum; grey matter able to migrate outwards to form the cortex; cortical & subcortical grey matter; white matter on inside; ventricles of brain.
172
60. Explain why the AFP is elevated
| 2 marks
The open neural tube allows flow of AFP from CSF into the amniotic fluid that is then absorbed into the circulation.
173
61. State the gestational age at which the abnormality occurs.
(1 mark)
By 4 weeks embryonal development (~ 6 weeks post LMP)
174
62. State whether this couple may legally terminate the pregnancy and explain your answer.
(1½ marks)
Yes – TOP allowed legally for “severe malformation of the fetus” at any gestation.
175
63. List six (6) factors which may influence Mr and Mrs Jacobs’ decision to terminate or not.
(3 marks)
Risk perception, acceptance of burden, religion, value system, interpersonal relationship, lifestyle and educational level, emotional state
176
64. Describe the immediate management for baby Yusuf.
| 3 marks
attention to general condition – temperature, breathing , circulation etc
cover lesion with clean dry dressing
early neurosurgical referral for closure (within 24 – 48hrs)
opportunity to bond with parents wherever possible
177
65. List signs and symptoms that would suggest the development of an established hydrocephalus.
(3 marks)
disproportionately large head circumference
full fontanelle
dilated scalp veins
vomiting
lethargy / irritability
ocular symptoms (squint / setting sun eyes)
178
66. List two (2) main treatment options for hydrocephalus.
| 1 mark
endoscopic 3rd ventriculostomy
| ventriculoperitoneal shunt
179
67. State the risk of a further child of this couple having a neural tube defect.
(½ mark)
Approximately 5%
180
68. Outline how this risk can be reduced.
| 2 marks
Periconceptional folic acid supplementation (high dose) 4mg/day one month before and 3 months after conception
Avoidance of teratogens (alcohol, medication such as antiepileptic meds etc.)
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Where did you stop?
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