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Louise Weir
Stroke Nurse Practitioner
Candidate- The Royal Melbourne
Hospital
Stroke Mimics and
Differential Diagnosis
ANNA Stroke Seminar 2010
RMH Comprehensive Stroke Centre
Clinical assessment
Aims
(1) Is it a stroke? (What is the diagnosis)
(2) What part of the brain is affected?
(3) Is it a haemorrhage or an infarct?
(4) What caused this stroke? (Can we prevent a
further stroke)
(5) What are this patient‟s problems?
+
(6) What can we do to treat this patient?
(1) Is it a stroke?
(ii) The nature of the event
• onset: usually sudden• course: maximal at onset, occasionally evolves
over days • were symptoms focal: focal vs general• “negative”: loss of function• associated symptoms: headache - 25% infarcts,
seizures & vomiting
What are Focal Neurological Symptoms?
• Weakness of face/ arm/ leg on one side
• Sensory disturbance face/ arm/ leg on one side of the body (NB –Caution if this is the only symptom & Caution if sensory symptoms only last minutes)
• Amaurosis Fugax (transient monocular blindness)
• Language disorder (aphasia)
• Homonymous hemianopia (visual field loss)
• Sudden bilateral blindness
• Diplopia (NB –Caution if this is the only symptom)
• Dysarthria (NB –Caution if this is the only symptom)
Symptoms unlikely to be TIA or Stroke
i.e. Non- focal symptoms
• Light headedness/ faintness
• „Blackouts‟ with altered or loss of consciousness or fainting
• Generalized weakness and/or generalized sensory disturbance
• Incontinence of urine or faeces
• Episode of confusion
• Drop attacks
Symptoms if isolated unlikely to indicate
TIA or Stroke
• A spinning sensation
• Vertigo only
• Ringing in ears
• Difficulty swallowing
• Slurred speech
• Double vision
• Loss of balance
Two clinical scenarios
1. The patient with resolved symptoms
• A completed TIA
• A pseudo/mimic
2. The patient with symptoms: ‘Brain
Attack’
• More relevant when seeing patient acutely
Difficulties in TIA diagnosis
• There are many causes of transient symptoms
which are not due to vascular disease
• Do not make the diagnosis until you have an
accurate account of the patients symptoms.
• Ask a witness for details as patients may often
forget because symptoms were short,
confusion was present, or there was a loss of
consciousness
Brain Attack: persistent symptoms
• An open label, not a completed diagnosis
• Implies there are differentials
• Is stroke easy to diagnose?
– Literature: ~20% of referrals are incorrect
– Prospective study of consecutive patients
presenting to hospital with brain attack
– 350 presentations:
241 strokes (69%)
109 mimics (31%)
Peter Hand et al. Stroke 2006; 37: 769-775
Conditions that mimic stroke: 350 consecutive
presentations Mimics presenting:
Condition Total Number (%)† Within 6 hrs
‡ After 6 hrs
‡
Seizure 23 (21.1%) 18 (29.0%) 5 (10.6%)
Sepsis 14 (12.8%) 6 (9.7%) 8 (17.0%)
Toxic / metabolic 12 (11.0%) 6 (9.7%) 6 (12.8%)
Space occupying lesion§ 10 (9.2%) 3 (4.8%) 7 (14.9%)
Syncope / presyncope 10 (9.2%) 9 (14.5%) 1 (2.1%)
Acute confusional state 7 (6.4%) 3 (4.8%) 4 (8.5%)
Vestibular dysfunction 7 (6.4%) 3 (4.8%) 4 (8.5%)
Acute mononeuropathy 6 (5.5%) 4 (6.5%) 2 (4.3%)
Functional/medically
unexplained symptoms
6 (5.5%) 4 (6.5%) 2 (4.3%)
Dementia 4 (3.7%) 2 (3.2%) 2 (4.3%)
Migraine 3 (2.8%) 2 (3.2%) 2 (4.3%)
Spinal cord lesion¶ 3 (2.8%) - (0%) 3 (6.4%)
Other? 3 (3.7%) 2 (3.2%) 1 (2.1%)
Total 109 (100%) 62 (100%) 47 (100%)
Peter Hand et al. Stroke 2006; 37: 769-775
Conditions that mimic stroke Systematic review of literature (n=1,265 mimics)
0.0% 2.5% 5.0% 7.5% 10.0% 12.5% 15.0% 17.5% 20.0%
seizures
toxic/metabolic
sequelae of old stroke
SOL
syncope/presyncope
vertigo
migraine
psychogenic
dementia
PN palsy
meningitis/encephalitis
wernickes/alcohol
miscellaneous
% of all stroke mimics (n=1,265)
Peter Hand et al. 2000.
The miscellaneous group
• Cardiac cause (ischaemia, heart failure etc.) 24
• Spinal cord lesion 13
• Multiple sclerosis 12
• Transient global amnesia 11
• Parkinson‟s disease 8
• Subarachnoid haemorrhage 6
• Trauma 4
• Hypertensive encephalopathy 3
• Myasthenia gravis 3
• Acute confusional state 2
• Aortic dissection 2
• Herpes encephalitis 2
• Motor neuron disease 2
• Parasthesia of unknown cause 2
• Vertebral artery dissection 1
• Friedreich‟s ataxia 1
• Multiple systems atrophy 1
• Cerebral sarcoidosis 1
• Normal pressure hydrocephalus 1
• Sleep apnoea 1
• Perforated duodenal ulcer 1
• Weakness of unknown cause 1
• Arm stiffness of unknown cause 1
• Arm pain of unknown cause 1
• Sudden death 13
• No details provided 76
• Total 193
Peter Hand et al. Stroke 2006; 37: 769-775
Stroke mimics
• 42% of pts had previous stroke
– Around half had no residual symptoms
– Many might have an abnormal scan
• 26% of pts had cognitive impairment
• 75% of mimics were neurological conditions
– Many of these would have normal scans
• This highlights the importance of the
neurologist and or Nurse Practitioner in acute
assessment
Peter Hand et al. Stroke 2006; 37: 769-775
Reliability of clinical assessment
• Reliability is the likelihood of 2 observers
finding the same thing (i.e. agreement)
– Accuracy depends on validity & reliability
• Reliability sub-study
– 98 non-consecutive patients
– 4 different observers, blind to history
• Kappa – measure of agreement
– Allows for agreement expected by chance
– κ <0.2 poor agreement; 0.21– 0.40 = fair; 0.41– 0.60 =
moderate; 0.61– 0.80 = good; 0.81– 1.00 = excellent
agreement
Peter Hand et al. Stroke 2006; 37: 776-780
I t e m K v a l u e 9 5 % C I C r u d e A g r e e m e n t*
V a s c u l a r R i s k F a c t o r s :
H y p e r t e n s i o n 0 . 4 7 0 . 3 2 – 0 . 6 2 6 5 / 9 7 ( 6 7 % )
S m o k e r w i t h i n 1 2 m o n t h s 0 . 6 9 0 . 5 5 – 0 . 8 3 8 1 / 9 7 ( 8 4 % )
I s c h a e m i c h e a r t d i s e a s e 0 . 6 4 0 . 5 0 – 0 . 7 8 7 7 / 9 7 ( 7 9 % )
A t r i a l f i b r i l l a t i o n 0 . 5 4 0 . 3 8 – 0 . 7 0 7 3 / 9 6 ( 7 6 % )
P e r i p h e r a l v a s c u l a r d i s e a s e 0 . 4 4 0 . 2 7 – 0 . 6 2 6 9 / 9 7 ( 7 1 % )
D i a b e t e s m e l l i t u s 0 . 6 5 0 . 4 5 – 0 . 8 4 7 5 / 8 6 ( 8 7 % )
P a s t h i s t o r y o f a f o c a l n e u r o l o g i c a l d e f i c i t 0 . 5 1 0 . 3 6 – 0 . 6 6 6 9 / 9 8 ( 7 0 % )
H i s t o r y o f t h e p r e s e n t i n g c o m p l a i n t :
A n e x a c t t i m e o f o n s e t c a n b e d e t e r m i n e d 0 . 6 3 0 . 4 7 – 0 . 7 8 8 0 / 9 8 ( 8 2 % )
P a t i e n t w o k e f r o m s l e e p w i t h d e f i c i t 0 . 5 5 0 . 4 0 – 0 . 6 9 7 0 / 9 7 ( 7 2 % )
P a t i e n t c a n r e c a l l w h a t h e / s h e w a s d o i n g a t t i m e o f o n s e t 0 . 3 7 0 . 2 0 – 0 . 5 3 6 0 / 9 7 ( 6 2 % )
I m p r o v e m e n t s i n c e o n s e t 0 . 5 4 0 . 3 9 – 0 . 6 8 6 9 / 9 8 ( 7 0 % )
S y m p t o m s a r e n o w s t a b l e 0 . 5 9 0 . 4 2 – 0 . 7 7 8 1 / 9 8 ( 8 3 % )
P a t i e n t w e l l i n t h e w e e k b e f o r e o n s e t 0 . 4 0 0 . 2 4 – 0 . 5 7 6 4 / 9 8 ( 6 5 % )
A d e f i n i t e h i s t o r y o f f o c a l n e u r o l o g i c a l d e f i c i t 0 . 5 9 0 . 4 2 – 0 . 7 5 7 9 / 9 8 ( 8 1 % )
H e m i a n o p i a / q u a d r a n t a n o p i a 0 . 6 3 0 . 4 7 – 0 . 7 9 7 2 / 8 9 ( 8 1 % )
L o s s o f s p e e c h / l a n g u a g e 0 . 6 4 0 . 5 0 – 0 . 7 7 6 8 / 8 9 ( 7 6 % )
L o s s o f s e n s a t i o n 0 . 6 2 0 . 4 8 – 0 . 7 6 6 8 / 8 9 ( 7 6 % )
L o s s o f p o w e r 0 . 5 9 0 . 4 4 – 0 . 7 5 6 8 / 8 9 ( 7 6 % )
H e a d a c h e 0 . 6 5 0 . 5 1 – 0 . 7 9 7 8 / 9 7 ( 8 0 % )
N e u r o l o g i c a l E x a m i n a t i o n :
T h e p a t i e n t i s a l e r t 0 . 7 0 0 . 5 2 – 0 . 8 9 8 9 / 9 8 ( 9 1 % )
T h e p a t i e n t i s d r o w s y 0 . 7 4 0 . 5 3 – 0 . 9 4 9 2 / 9 8 ( 9 4 % )
T h e p a t i e n t i s u n c o n s c i o u s 1 . 0 0 1 . 0 0 – 1 . 0 0 9 8 / 9 8 ( 1 0 0 % )
T h e p a t i e n t i s c o n f u s e d 0 . 4 5 0 . 2 8 – 0 . 6 2 6 8 / 9 6 ( 7 1 % )
A r m w e a k n e s s 0 . 6 5 0 . 4 9 – 0 . 8 0 8 1 / 9 8 ( 8 3 % )
H a n d w e a k n e s s 0 . 7 2 0 . 5 9 – 0 . 8 6 8 4 / 9 8 ( 8 6 % )
F a c e w e a k n e s s 0 . 5 0 0 . 3 4 – 0 . 6 7 7 3 / 9 8 ( 7 4 % )
L e g w e a k n e s s 0 . 5 7 0 . 4 1 – 0 . 7 3 7 5 / 9 7 ( 7 7 % )
T h e p a t i e n t c o u l d w a l k 0 . 6 2 0 . 4 7 – 0 . 7 6 7 5 / 9 6 ( 7 8 % )
V i s u a l l o s s 0 . 4 6 0 . 2 8 – 0 . 6 4 7 2 / 9 8 ( 7 3 % )
D y s a r t h r i a 0 . 4 1 0 . 2 5 – 0 . 5 8 6 6 / 9 8 ( 6 7 % )
D y s p h a s i a 0 . 6 6 0 . 5 1 – 0 . 8 0 8 1 / 9 8 ( 8 3 % )
S e n s o r y d i s t u r b a n c e 0 . 4 9 0 . 3 4 – 0 . 6 5 6 9 / 9 8 ( 7 0 % )
V i s u a l n e g l e c t 0 . 4 1 0 . 2 5 – 0 . 5 8 6 6 / 9 8 ( 6 7 % )
S e n s o r y n e g l e c t 0 . 5 9 0 . 4 5 – 0 . 7 3 7 4 / 9 8 ( 7 6 % )
O t h e r f o r m o f n e g l e c t 0 . 3 4 0 . 1 6 – 0 . 5 1 6 3 / 9 8 ( 6 4 % )
Timing of symptom onset
• Good reliability for whether there was an exact time of onset (κ=0.63)
• Agreement for:– date, hour and minute in 19/42 (45%)
– date and hour in 11/42 (26%)
– date only in 9/42 (21%)
– complete disagreement for date & time in 3/42 (7%)
• Median difference in onset times for the 23 patients where there was disagreement was 30 minutes (IQR: 10 – 90 minutes)
• Methods to improve timing…
Peter Hand et al. Stroke 2006; 37: 776-780
Factors that caused poor reliability
• Experience of clinician:
– Greatest difference for neurological exam
• Clinician confidence:
– Lower reliability when clinician uncertain
• Time since symptom onset:
– Worse in those presenting v.early or late
• Patient factors:
– Much worse when patient had aphasia (not so
bad for confusion or older age)
Peter Hand et al. Stroke 2006; 37: 776-780
Clinical features that distinguish between stroke
& mimic
• Stroke predicted by
– exact time of onset
– patient could recall exactly what he/she was doing at
symptom onset
– well in the last week
– definite focal symptoms or signs
• Mimic predicted if
– known history of cognitive impairment
– lost consciousness or had a seizure at onset
– the patient could still walk
– no lateralising symptoms
– examination revealed confusion, signs in other non-vascular
systems and no neurological signs
Stroke vs Mimic:
value of the OCSP classification
n=9
n=4
n=3
n=19
n=41
n=48
n=21
n=11
n=7
0% 20% 40% 60% 80% 100%
Unsure
POCS
LACS
PACS
TACS
Mimic Stroke
Peter Hand et al. Stroke 2006; 37: 769-775
Stroke vs Mimic: value of the NIHSS
n=17
n=25
n=9
n=11
n=62 n=130
n=49
n=32
n=38
n=11
0% 20% 40% 60% 80% 100%
NIHSS = 0
NIHSS 1-4
NIHSS 5-10
NIHSS>10
Overall
Mimic Stroke
Peter Hand et al. Stroke 2006; 37: 769-775
C lin ic a l I t e m I m p o r t a n c e *
S u g g e s t s t h e l ik e ly
d ia g n o s i s i s :
H is t o r y
D e f in i te h is to r y o f fo c a l n e u r o lo g ic a l s y m p to m s S T R O K E
A n e x a c t o n s e t o f s y m p to m s c a n b e d e te r m in e d S T R O K E
K n o w n c o g n i t iv e im p a i r m e n t M IM I C
E x a m in a t io n
A n y a b n o r m a l v a s c u la r f in d in g s S T R O K E
A n y a b n o r m a l f in d in g s in o th e r s y s te m s M IM I C
E i th e r
N IH S S 1 -4 S T R O K E
N IH S S 5 -1 0 S T R O K E
N IH S S > 1 0 S T R O K E
O r
A r m w e a k n e s s S T R O K E
D ia g n o s t ic f o r m u la t io n
S ig n s c a n b e la te r a l is e d to th e r ig h t / le f t b r a in S T R O K E
S ig n s c a n b e p la c e d in a n O C S P c a te g o r y S T R O K E
Odds Ratios -
Multivariable
Logistic regression:
2.59
2.54
0.44
7.23
3.99
2.03
5.09
0.33
7.21
How to improve accuracy: brain imaging
• Positive findings on the CT confirm the diagnosis of an ischaemic stroke
• Look for early CT signs of infarction
– Loss of tissue density
– Tissue swelling
• Pathology:
– Influx of water into ischaemic cells
– grey matter affected before white matter
Hyperdense MCA
• Occlusion of the MCA
by fresh clot
• May be seen in other
main vessels, distally
or in lenticulostriate
arteries
• frequency varies
• 50% with proven
MCA occlusion don‟t
have the sign
Basal ganglia changes
• Loss of definition
of grey matter -
best seen at
edges of internal
capsule
• Swelling
compresses the
adjacent lateral
ventricle
Cortical surface changes
• „Insular ribbon sign‟
- loss of distinction
between external
capsule and insular
cortex
• Also look for
swelling of cortical
sulci - effacement
(loss of visibility)
Investigations: Imaging• Rationale:
– to exclude (rare) stroke mimics eg SDH
– to distinguish between haemorrhage and
infarct
• Plain CT is the imaging technique of choice
– available, rapid
– reliably differentiates haemorrhage:
blood is white
PICH on CT
• Is always seen
• apparent immediately
• lasts 1 week
• then disappears and
looks like an infarct
Ischaemic stroke on CT• Infarcts seen as areas
of hypodensity
• become more obvious
as time progresses
• small infarcts appear
later than large ones -
75% TACI vs 45% LACI
• overall, 40% strokes
have normal CT
• posterior fossa difficult
MRI in acute stroke
• Advantages:
– much better at defining the anatomy
– shows ischaemic changes earlier, and in a
greater proportion of patients
– diffusion weighted imaging can show ischaemia
within minutes-hours, and differentiate between
old and new lesions
– MRA allows imaging of blood vessels non-
invasively
• Disadvantages:
– expense, time, lack of access to the patient
MRI in acute stroke: an example
A 42 year old man with headache and left hemiparesis
CT brain (3 hours) ? R MCA hypodensity
DWI (24 hrs) obvious R MCA infarct
MRA (24 hrs) dissection R ICA with distal occlusion
Take home messages:
1. Watch out for timing of symptom onset
2. Early ischaemic changes on CT confirm the diagnosis
3. Be aware of red flags for mimics
Distinguishing Between Stroke and Mimic at the Bedside:
The Brain Attack Study
Peter J. Hand, Joseph Kwan, Richard I. Lindley, Martin S. Dennis and Joanna M. Wardlaw.
Stroke 2006;37;769-775; originally published online Feb 16, 2006
DOI: 10.1161/01.STR.0000204041.13466.4c
http://stroke.ahajournals.org/cgi/content/full/37/3/769
Interobserver Agreement for the Bedside Clinical Assessment of Suspected Stroke
Peter J. Hand, Janneke A. Haisma, Joseph Kwan, Richard I. Lindley, Bart Lamont, Martin S. Dennis and Joanna M. Wardlaw
Stroke 2006;37;776-780; originally published online Feb 16, 2006;
DOI: 10.1161/01.STR.0000204042.41695.a1
http://stroke.ahajournals.org/cgi/content/full/37/3/776