1. Introduction The clinical presentation of stroke varies. It
is common to mistake other diseases for strokes (stroke mimics) and
strokes for other diseases (stroke chameleons). Different
approaches to assessment ,different diagnostic skills, &
occasional difficulty distinguishing stroke from its mimics very
soon after onset, may affect eventual diagnosis of stroke .
2. The proportion of suspected stroke patients with an eventual
diagnosis of stroke or transient ischaemic attack (TIA), from a
systematic review and meta-analysis of case series, stratified by
the context of assessment (emergency department, primary care,
stroke unit/neurovascular clinic, ambulance or other referral
sources). The width of each diamond represents the 95% CI of the
pooled proportion.
3. Rapid recognition of stroke is important: The sooner
ischaemic stroke patients receive thrombolysis3 or Are investigated
and given secondary prevention to avoid further vaso-occlusive
events, The better the outcome. The correct diagnosis for patients
without stroke leads to appropriate treatment and avoids the
potentially harmful effects of secondary stroke prevention
therapies.
4. MIMICS Stroke mimics account for 2025% of suspected stroke
presentations, depending on the context (figure 1). There is a
diverse array of mimics (figure 2), and we will deal with a small
selection of them. Unfortunately, brain imaging is not the simple
answer to distinguishing stroke from its mimics. The reference
standard for the diagnosis of stroke can only be clinical history
and examination, supported by brain imaging (which may be
normal).
5. The 20 most common stroke mimics, identified in a systematic
review and meta-analysis of case series
6. Seizures Postictal Todds paresis can be difficult to
differentiate from stroke Accounts for almost 20% of stroke mimics
. The diagnosis is more readily apparent if patients have recurrent
focal motor seizures (which can be subtle). There may be a history
of epilepsy, although this may not necessarily have been diagnosed
before admission. The substrate for the seizure is often an old
ischaemic or haemorrhagic stroke, easily mistaken for an acute
stroke when brain imaging is reviewed.
7. T1-weighted axial MR brain scan showing cavitation in the
left centrum semiovale (arrow), in keeping with an old infarction,
and an old cortical infarction. Seizure mimic
8. Hypoglycaemia Hypoglycaemia normally presents with autonomic
symptoms but can present with focal neurological symptoms and signs
alone. There may be episodes of focal neurological disturbance at
the same time each day, associated with diabetic medication.
Although blood glucose measurement at the time of onset of
neurological deficit can help, it may be normal at the time of
assessment Brain MRI may show transient DWI high signal in the
context of hypoglycaemia. The airway, breathing, circulation, dont
ever forget glucose (ABC-DEFG) approach is important: blood sugar
should always be measured before thrombolysis is given
9. Hypoglycaemia mimic case A 75-year-old right-handed man woke
with severe left-sided hemiparesis. Capillary blood sugar in the
ambulance was 1.8 mmol/l, successfully treated with intravenous
dextrose. Neurological examination was normal by the time of
arrival in the emergency unit, as was brain CT. Full blood count
showed an elevated mean corpuscular volume. The patient did not
take any hypoglycaemic agents but did admit to alcohol excess,
including a heavy intake of gin the evening before presentation.
Diagnosed hypoglycaemic hemiparesis and the patient was counselled
over his alcohol intake.
10. Sepsis Sepsis accounts for 12% of stroke mimics , so a
thorough systemic examination is always necessary. Raised
inflammatory markers and fever support a diagnosis of sepsis,
although sepsis may itself be a risk factor for stroke: the risk
from mycotic emboli is well established and severe sepsis can
induce a hypercoagulable state. Differentiating sepsis and stroke
is difficult when patients have both conditions simultaneously, for
example, aspiration pneumonia secondary to stroke. Collateral
histories from relatives or the general practitioner may help to
distinguish exacerbation of an old deficit from new stroke.
11. Migraine and other headache disorders Headache is a common
feature of acute ischaemic stroke: 27% of patients experience a
headache at stroke onset. Primary headache disorders are
responsible for 10% of stroke mimics Severe neurological deficits
associated with headacheincluding familial hemiplegic migraine and
headache with associated neurological deficits and lymphocytosis
are difficult to disentangle from strokes
12. Migraine and other headache disorders A family history may
help to identify cases of familial hemiplegic migraine, which is an
autosomal dominant disorder with high penetrance. Patients with
this condition are typically young (average age of onset 17 years),
female (70%) and tend to have fewer attacks as they age. Patients
with headache with associated neurological deficits and
lymphocytosis (HaNDL) report recurrent neurological deficits and
headache, and have cerebrospinal fluid abnormalities
(lymphocytosis, elevated protein and high opening pressures) The
neurological deficits typically last for hours and may include
dysphasia, focal weakness or confusion. CT and MRI are normal,
although perfusion imaging may show focal deficits
13. Functional disorders Functional disorders often manifest as
acute weakness or sensory disturbance, mimicking stroke. There is
frequently a trigger, such as a panic attack or dissociative
episode. When diagnosing functional disorders, the positive
features of functional disease are more important than the absence
of features of organic diseasefor example, a positive Hoovers sign
is more important than a normal brain CT. The key finding in the
examination of functional weakness is inconsistency. Inconsistency
in the extent of impairment is illustrated by task-dependent
weaknessthe patient who walks into the room but cannot move their
leg at all when examined on the couch.
14. Brain tumours Tumours typically cause slowly progressive
deficits but 5% of tumours have a stroke-like presentation. Acute
deficits are commonly due to haemorrhage into the lesion but may
also be secondary to extrinsic compression of vascular structures
by oedema, obstructive hydrocephalus or Todds paresis. The presence
of very early mass effect suggests a tumour, as large artery
strokes usually take 2448 h to develop cerebral oedema.
15. Characteristics of Common Stroke Mimics
16. CASE An 82-year-old woman was seen by the acute stroke
intervention team for the sudden onset of speech difficulty 90
minutes earlier. She had been working with a physical therapist at
home when she became unable to speak. There was no associated
weakness, alteration of consciousness, or headache. Per report, she
had experienced a minor stroke approximately 2 weeks earlier but
had made some improvement. The woman was afebrile, her initial
blood pressure was 142/72 mm Hg, and the finger-stick glucose level
was 188 mg/dL. She was awake, alert, and appropriate. Language
examination was remarkable for impaired fluency with the ability to
say only fragments of words. She was able to follow simple midline
commands but was unable to follow complex commands. She was unable
to repeat, read, or name objects. There was no limb weakness or
sensory disturbance. Her NIHSS score was 6.
17. Noncontrast head CT demonstrated a subtle hyperdense lesion
with mass effect involving the left temporoparietal region (Figure
1-4, top, arrows). Given the radiographic findings suggestive of an
underlying structural lesion, the patient did not receive
thrombolytic therapy. Follow-up MRI demonstrated an ill- defined
enhancing lesion involving the white matter and cortex of the left
parietal lobe suggestive of a low-grade neoplasm
18. Comments This case is an example of a stroke mimic. The
abrupt onset of symptoms might not prompt initial consideration of
an underlying structural lesion as a potential etiology. However,
one study found that 6% of patients with brain tumors presenting to
an emergency department had symptoms of less than 1 days duration
(Snyder et al, 1993). Sudden onset of focal symptoms in patients
with either diagnosed or undiagnosed tumors may result from
seizures, hemorrhage into the tumor, or obstructive hydrocephalus
caused by increasing mass effect.
19. CHAMELEONS Stroke chameleons imitate other diseases due to
their tempo of onset (eg, gradual progression or stuttering) or
have symptoms that do not necessarily implicate an arterial
territory. It is uncommon to consider these patients for
thrombolysis, but their recognition enables patients to benefit
from secondary prevention.
20. Vertigo Stroke is rarely the cause of dizziness: only 3% of
patients presenting with dizziness and additional symptoms have had
a stroke or TIA The presence of new or worsened unilateral hearing
loss, headache, tinnitus or neurological symptoms is uncommon in
isolated vestibular neuronitis. Lateral medullary, lateral pontine
and inferior cerebellar patterns of infarction may mimic the
clinical features of vestibular neuronitis.
21. The differences between central lesions and peripheral
lesions following a DixHallpike manoeuvre
22. Vertigo chameleon- case A 75-year-old woman presented to
the emergency unit with a 1-day history of dizziness, vertigo and
vomiting. She had a history of sick sinus syndrome with permanent
pacemaker and also of Mnires disease. On examination, she had
atrial fibrillation, an ataxic gait, nystagmus (fast phase to the
left) and marked unsteadiness. The initial diagnosis was recurrent
Mnires disease and she was prescribed prochlorperazine. However,
the symptoms, signs and lack of improvement with vestibular
suppressants prompted a neurologist to organise a brain CT, which
showed a subacute left cerebellar hemisphere infarction.
23. Monoplegia Isolated monoparesis is a rare presentation of
stroke, comprising fewer than 5% of all strokes. Monoparetic stroke
most commonly affects the arm, where the causative lesion is often
a middle cerebral artery stroke. Most strokes presenting with
monoparesis are subcortical or deeper, although about 30% are
caused by cortical lesions.
24. A 70-year-old woman had an episode of right leg weakness of
sudden onset, fully resolving within an hour. The right leg
weakness recurred the next day, prompting admission to hospital.
She had a history of rheumatoid arthritis. On examination, there
was weakness of the right leg. The initial diagnosis was of a
myelopathy. Brain MRI showed acute ischaemia in the territory of
the left anterior cerebral artery Acute infarction in the left
parasagittal frontal lobe shown by high signal on fluid-attenuated
inversion recovery MRI brain (arrow). Acute infarction in the left
parasagittal frontal lobe shown by restricted diffusion on
diffusion weighted MRI brain (arrow).
25. Delirium Non-dominant anterior circulation strokes
affecting the temporoparietal region may cause visual agnosia,
prosopagnosia, loss of spatial orientation and disinhibition of
speech. The excessive speech production and difficulty in path
finding often lead to a diagnosis of delirium, with a search for an
underlying infective or metabolic cause. Patients with non-dominant
hemisphere deficits may have problems with attention, lack of usual
expression of emotion, lack of empathy with others, lack of prosody
of speech, lack of judgement of time and inability to comprehend
non- verbal communication or to recognise familiar sounds
26. Delirium chameleon A 79-year-old man went for his usual
local walk. On his way home he could not recognise his house,
despite his wife standing at the window waving. He was brought to
the hospital where he was very talkative and would frequently get
lost in the ward. There were no other symptoms and no focal
neurological deficit. He had a past history of paroxysmal atrial
fibrillation and hypertension. Brain CT showed a right frontal
infarction Recent right frontal cortical infarction on plain brain
CT (arrow).
27. Cauda equina syndrome chameleon A 75-year-old woman
presented at midnight with bilateral leg weakness and numbness. She
had a history of hypertension and of type 2 diabetes mellitus. One
month previously she had an episode of haematuria. Her symptoms had
started at midday with back pain radiating down both calves. By
14:30 she had pain, numbness and paraesthesia affecting both legs,
and difficulty walking. Her general practitioner assessed her at
18:00, at which point she could only move her toes. There was
reduced tone strength and reflexes in both legs. In the emergency
unit, she had a flaccid paraplegia, areflexia, sensory level at T11
and painless urinary retention. She was admitted under the
neurosurgical team with a diagnosis of cauda equina syndrome.
Urgent MR scan of the spine showed a cord infarction from T9 to the
conus , with an additional left renal cell carcinoma. Acute
infarction of the spinal cord from T1 to conus shown by high signal
on sagittal T2- weighted MRI (arrow). Acute infarction of the
spinal cord at T12 shown by high signal on axial T2-weighted MRI
(arrow).
28. Examples of stroke chameleons
29. Up to 60% of patients referred to a TIA clinic do not have
a final diagnosis of TIA, but this will depend on how patients are
referred and the method of diagnosis. Of 1532 consecutive patients
attending our TIA service, 1148 (75%) had either definite or
possible TIA, 46 (3%) had minor stroke and the remaining 338 (22%)
had one of 25 alternative diagnoses
30. Frequency of transient ischaemic attack (TIA) mimics from
1532 consecutive suspected TIA referrals to the University College
London comprehensive stroke service
31. Frequent causes of transient neurological symptoms that can
mimic TIA Frequent causes of transient neurological symptoms that
can mimic TIA include: Migraine aura Seizure Syncope Functional or
anxiety related
32. Clinical features of transient ischaemic attack (TIA) and
some common mimics
33. Limb-shaking TIAs Rhythmic, involuntary jerky limb
movements can occur in haemodynamic TIAs, which may thus be
mistaken for focal motor seizures. The presence of limb shaking is
a well-established sign of hemisphere hypoperfusion, due to severe
carotid or middle cerebral artery disease. The episodes tend to be
brief (