MEDSTUDY.COM
NEUROLOGY
Questions&Answers
Q-1
A 58 year old man has visual hallucinations of animals walking around his room.
He is amused by them but is conscious that they are not real. He is noted to have
M
functioning levels of awareness and attention and a decline in problem solving
ability. Signs of mild parkinsonism are also seen. What is the SINGLE most
likely diagnosis?
ED
A. Frontotemporal dementia
B. Lewy body dementia
C. Delirium tremens
D. Alzheimer’s disease
E. Huntington’s disease
ST
ANSWER:
Lewy body dementia
EXPLANATION:
U
The most important features of Lewy body dementia that differentiate it from the other
forms of dementia is the:
• Visual hallucinations
D
• Fluctuating course with lucid intervals
• Signs of mild Parkinsonism
Y
Typical presentation of lewy body dementia
• Dementia is usually the presenting feature, with memory loss, decline in problem
solving ability and spatial awareness difficulties.
• Characteristically there are fluctuating levels of awareness and attention.
• Signs of mild Parkinsonism (tremor, rigidity, poverty of facial expression, festinating
gait). Falls frequently occur.
• Visual hallucinations (animals or humans) and illusions. → This is particularly
important to differentiate lewy body from other types of dementia in the PLAB exam
• Sleep disorders including rapid eye movement sleep disorder, restless legs syndrome
,MEDSTUDY.COM
Q-2
A 67 year old female who was initially admitted to hospital for hip replacement
surgery is incidentally found to be confused and drowsy by the ward nurse. The
ward nurse also discovers that she has been receiving a continuous infusion of
5% dextrose in sodium chloride 0.45% intravenously since her admission into
hospital. The fluid was immediately stopped following this discovery and bloods
were taken for a test. Laboratory values show:
Sodium 120 mmol/L
Potassium 4.8 mmol/L
Urea 6.2 mmol/L
Creatinine 89 micromol/L
Bicarbonate 23 mmol/L
Chloride 100 mmol/L
M
What is the SINGLE most likely cause of this patient’s symptoms?
A. Osmotic shrinkage of the brain
B. Cerebral oedema
ED
C. Cerebral demyelination
D. Cytotoxicity
E. Reye’s syndrome
ANSWER:
ST
Cerebral oedema
EXPLANATION:
This patient has hyponatraemia leading to cerebral oedema. Cerebral oedema is
defined as an excess in the accumulation of fluid in the intracellular or extracellular
spaces of the brain and there are various causes for this phenomenon, but there are
U
typically four types that can be seen in clinical practice. The important type to
concentrate on for this question is the osmotic type.
D
When plasma is diluted, such as in hyponatraemic states, it creates an abnormal
pressure gradient between the brain’s internal environment and the serum. This causes
Y
the movement of water into the brain. This patient has clear hyponatraemia as
evidenced by her lab values. An important cause of hyponatraemia is hhigh blood
sugar and iatrogenic administration of a hypotonic solution. This patient has been
receiving a hypotonic solution and 5% of intravenous dextrose for an extended period of
time. This would naturally increase her blood glucose levels and dilute her intracellular
volume leading to hyponatraemia. For this reason sodium chloride 0.9% is usually used
instead of hypotonic solutions.
Osmotic shrinkage of the brain describes the end result of osmotherapy whereby the
ovlume of intracranial fluid is reduced by shifting fluid out of the brain and into the
serum. An example of this type of therapy is administering intravenous mannitol to
reduce intracranial pressure. This answer is incorrect as it is the opposite of what the
question asks for.
Cerebral demyelination describes any condition that causes the myelin sheath of
neurons to become damaged. Although a presenting symptom of demyelination is
,MEDSTUDY.COM
weakness, this answer is not corect since this patient does not present with the host of
signs and symptoms that can be seen in demyelinating diseases which can be anything
from diplopia to speech problems. A common iatrogenic cause of cerebral
demyelination is central pontine myelinolysis which is caused by rapid correction of low
blood sodium levels.
Cytotoxicity is incorrect since the stem gives no clue as to any cytotoxic drug that this
patient might have taken. An importat cytotoxic drug to remember for the exam is
isoniazid, which can lead to cerebral oedema.
Reye’s syndrome describes a rapidly progressive encephalopathy which usually
presents with liver toxicity, personality changes, confusion and even seizures. The
cause is unknown, but viral infections are thought to play a role. This answer is
incorrect since there is no clue in the stem that alludes to the patient having had a viral
infection nor are her liver function test results included.
M
Q-3
A 50 year old man, known case of hypertension and deep vein thrombosis,
presents to the Emergency Department with a sudden onset of vision loss in his
ED
right eye. It is painless and lasted for approximately 5 minutes. He describes the
vision loss as a ‘black curtain coming down’. On examination, there is a bruit on
his neck. What is the SINGLE most likely condition?
A. Retinal vein thrombosis
ST
B. Retinal artery occlusion
C. Amaurosis Fugax
D. Optic neuritis
E. Acute angle glaucoma
ANSWER:
U
Amaurosis fugax
EXPLANATION:
D
Remember to focus on causes of unilateral vision loss. Know how to differentiate all the
above options. The bruit in theneck is the examiner’s way of telling you that this man
Y
has atherosclerosis which is a risk factor for amaurosis fugax.
For amaurosis fugax, this is a classic case stem: sudden, painless, unilateral vision loss
and description of a “black curtain coming down”.
Retinal vein thrombosis and retinal artery occlusion presents as painless unilateral
vision loss but their duration would be much longer if not permanent
Optic neuritis would have clues in the stem of multiple sclerosis.
Acute angle glaucoma would produce a painful vision loss and keywords such as
“haloes” would be seen.
Amaurosis Fugax
• Painless transient monocular visual loss (i.e. loss of vision in one eye that is not
permanent)
, MEDSTUDY.COM
• It is indicative of retinal ischaemia, usually associated with emboli or stenosis of the
ipsilateral carotid artery
Presentation:
• Sudden, unilateral vision loss; “black curtain coming down”
• Duration: 5-15 minutes; resolves within < 24 hours
• Associated with stroke or transient ischaemic attack (TIA) and its risk factors (i.e.
hypertension, atherosclerosis)
• Has an association with giant cell arteritis
Q-4
A 43 year old smoker presents with double vision. She tires easily, has difficulty
climbing stairs, and reaching for items on shelves. On examination, reflexes are
absent but elicited after exercise. The power in shoulder abduction after repeated
testing is 4+/5 from 3/5. What is the SINGLE most likely pathology associated
M
with this patient’s diagnosis?
A. Thyrotoxicosis
B. Thrombotic even
ED
C. Diabetes
D. Cerebral vascular event
E. Lung cancer
ANSWER:
Lung cancer
ST
EXPLANATION:
This is a diagnosis of Lambert-Eaton syndrome. A key difference from myasthenia
gravis is that on examination the patient has increased strength on repetition of power.
It is also a paraneoplastic disorder closely associated with small cell lung cancer.
U
Because Lambert-Eaton and myasthenia gravis present similarly, the case stem usually
would provide you with an investigation or examination clue, including autoantibodies
and/or EMG results. Note that thyrotoxicosis is associated with myasthenia gravis not
D
Lambert-Eaton.
Lambert-Eaton syndrome
Y
Presentation:
- Young, female patients; mostly autoimmune
- Proximal weakness at the pelvic girdle / shoulder girdle
- Weakness improves with exercise as well as reflexes
- Cranial nerve involvement: dysphagia, dysarthria, ptosis, diplopia
- Associated with small cell lung cancer
Diagnosis:
- EMG: decreased amplitude in CMAP after single supramaximal stimulus but increases
after exercise
- Edrophonium test: may be positive but not as prominent as in myasthenia gravis
- Look for tumor: CT/MRI of chest, abdomen, pelvis + tumor markers
Treatment:
- Treat tumor – first line
- Consider methylprednisolone and IV immunoglobulin
NEUROLOGY
Questions&Answers
Q-1
A 58 year old man has visual hallucinations of animals walking around his room.
He is amused by them but is conscious that they are not real. He is noted to have
M
functioning levels of awareness and attention and a decline in problem solving
ability. Signs of mild parkinsonism are also seen. What is the SINGLE most
likely diagnosis?
ED
A. Frontotemporal dementia
B. Lewy body dementia
C. Delirium tremens
D. Alzheimer’s disease
E. Huntington’s disease
ST
ANSWER:
Lewy body dementia
EXPLANATION:
U
The most important features of Lewy body dementia that differentiate it from the other
forms of dementia is the:
• Visual hallucinations
D
• Fluctuating course with lucid intervals
• Signs of mild Parkinsonism
Y
Typical presentation of lewy body dementia
• Dementia is usually the presenting feature, with memory loss, decline in problem
solving ability and spatial awareness difficulties.
• Characteristically there are fluctuating levels of awareness and attention.
• Signs of mild Parkinsonism (tremor, rigidity, poverty of facial expression, festinating
gait). Falls frequently occur.
• Visual hallucinations (animals or humans) and illusions. → This is particularly
important to differentiate lewy body from other types of dementia in the PLAB exam
• Sleep disorders including rapid eye movement sleep disorder, restless legs syndrome
,MEDSTUDY.COM
Q-2
A 67 year old female who was initially admitted to hospital for hip replacement
surgery is incidentally found to be confused and drowsy by the ward nurse. The
ward nurse also discovers that she has been receiving a continuous infusion of
5% dextrose in sodium chloride 0.45% intravenously since her admission into
hospital. The fluid was immediately stopped following this discovery and bloods
were taken for a test. Laboratory values show:
Sodium 120 mmol/L
Potassium 4.8 mmol/L
Urea 6.2 mmol/L
Creatinine 89 micromol/L
Bicarbonate 23 mmol/L
Chloride 100 mmol/L
M
What is the SINGLE most likely cause of this patient’s symptoms?
A. Osmotic shrinkage of the brain
B. Cerebral oedema
ED
C. Cerebral demyelination
D. Cytotoxicity
E. Reye’s syndrome
ANSWER:
ST
Cerebral oedema
EXPLANATION:
This patient has hyponatraemia leading to cerebral oedema. Cerebral oedema is
defined as an excess in the accumulation of fluid in the intracellular or extracellular
spaces of the brain and there are various causes for this phenomenon, but there are
U
typically four types that can be seen in clinical practice. The important type to
concentrate on for this question is the osmotic type.
D
When plasma is diluted, such as in hyponatraemic states, it creates an abnormal
pressure gradient between the brain’s internal environment and the serum. This causes
Y
the movement of water into the brain. This patient has clear hyponatraemia as
evidenced by her lab values. An important cause of hyponatraemia is hhigh blood
sugar and iatrogenic administration of a hypotonic solution. This patient has been
receiving a hypotonic solution and 5% of intravenous dextrose for an extended period of
time. This would naturally increase her blood glucose levels and dilute her intracellular
volume leading to hyponatraemia. For this reason sodium chloride 0.9% is usually used
instead of hypotonic solutions.
Osmotic shrinkage of the brain describes the end result of osmotherapy whereby the
ovlume of intracranial fluid is reduced by shifting fluid out of the brain and into the
serum. An example of this type of therapy is administering intravenous mannitol to
reduce intracranial pressure. This answer is incorrect as it is the opposite of what the
question asks for.
Cerebral demyelination describes any condition that causes the myelin sheath of
neurons to become damaged. Although a presenting symptom of demyelination is
,MEDSTUDY.COM
weakness, this answer is not corect since this patient does not present with the host of
signs and symptoms that can be seen in demyelinating diseases which can be anything
from diplopia to speech problems. A common iatrogenic cause of cerebral
demyelination is central pontine myelinolysis which is caused by rapid correction of low
blood sodium levels.
Cytotoxicity is incorrect since the stem gives no clue as to any cytotoxic drug that this
patient might have taken. An importat cytotoxic drug to remember for the exam is
isoniazid, which can lead to cerebral oedema.
Reye’s syndrome describes a rapidly progressive encephalopathy which usually
presents with liver toxicity, personality changes, confusion and even seizures. The
cause is unknown, but viral infections are thought to play a role. This answer is
incorrect since there is no clue in the stem that alludes to the patient having had a viral
infection nor are her liver function test results included.
M
Q-3
A 50 year old man, known case of hypertension and deep vein thrombosis,
presents to the Emergency Department with a sudden onset of vision loss in his
ED
right eye. It is painless and lasted for approximately 5 minutes. He describes the
vision loss as a ‘black curtain coming down’. On examination, there is a bruit on
his neck. What is the SINGLE most likely condition?
A. Retinal vein thrombosis
ST
B. Retinal artery occlusion
C. Amaurosis Fugax
D. Optic neuritis
E. Acute angle glaucoma
ANSWER:
U
Amaurosis fugax
EXPLANATION:
D
Remember to focus on causes of unilateral vision loss. Know how to differentiate all the
above options. The bruit in theneck is the examiner’s way of telling you that this man
Y
has atherosclerosis which is a risk factor for amaurosis fugax.
For amaurosis fugax, this is a classic case stem: sudden, painless, unilateral vision loss
and description of a “black curtain coming down”.
Retinal vein thrombosis and retinal artery occlusion presents as painless unilateral
vision loss but their duration would be much longer if not permanent
Optic neuritis would have clues in the stem of multiple sclerosis.
Acute angle glaucoma would produce a painful vision loss and keywords such as
“haloes” would be seen.
Amaurosis Fugax
• Painless transient monocular visual loss (i.e. loss of vision in one eye that is not
permanent)
, MEDSTUDY.COM
• It is indicative of retinal ischaemia, usually associated with emboli or stenosis of the
ipsilateral carotid artery
Presentation:
• Sudden, unilateral vision loss; “black curtain coming down”
• Duration: 5-15 minutes; resolves within < 24 hours
• Associated with stroke or transient ischaemic attack (TIA) and its risk factors (i.e.
hypertension, atherosclerosis)
• Has an association with giant cell arteritis
Q-4
A 43 year old smoker presents with double vision. She tires easily, has difficulty
climbing stairs, and reaching for items on shelves. On examination, reflexes are
absent but elicited after exercise. The power in shoulder abduction after repeated
testing is 4+/5 from 3/5. What is the SINGLE most likely pathology associated
M
with this patient’s diagnosis?
A. Thyrotoxicosis
B. Thrombotic even
ED
C. Diabetes
D. Cerebral vascular event
E. Lung cancer
ANSWER:
Lung cancer
ST
EXPLANATION:
This is a diagnosis of Lambert-Eaton syndrome. A key difference from myasthenia
gravis is that on examination the patient has increased strength on repetition of power.
It is also a paraneoplastic disorder closely associated with small cell lung cancer.
U
Because Lambert-Eaton and myasthenia gravis present similarly, the case stem usually
would provide you with an investigation or examination clue, including autoantibodies
and/or EMG results. Note that thyrotoxicosis is associated with myasthenia gravis not
D
Lambert-Eaton.
Lambert-Eaton syndrome
Y
Presentation:
- Young, female patients; mostly autoimmune
- Proximal weakness at the pelvic girdle / shoulder girdle
- Weakness improves with exercise as well as reflexes
- Cranial nerve involvement: dysphagia, dysarthria, ptosis, diplopia
- Associated with small cell lung cancer
Diagnosis:
- EMG: decreased amplitude in CMAP after single supramaximal stimulus but increases
after exercise
- Edrophonium test: may be positive but not as prominent as in myasthenia gravis
- Look for tumor: CT/MRI of chest, abdomen, pelvis + tumor markers
Treatment:
- Treat tumor – first line
- Consider methylprednisolone and IV immunoglobulin
