Stroke Mimics and Chameleons�Differential Diagnosis
J. Stephen Huff, MD
Professor of Emergency Medicine and Neurology
University of Virginia, Charlottesville, Virginia USA
Stroke - Questions
What historical or physical examination findings suggest ischemic stroke?
What processes may simulate ischemic stroke?
What are unusual stroke presentations?
Stroke Differential Diagnosis
Differential diagnostic process
Formulation of the problem
Traditional neurologic process…
Is there a problem of the neurologic system?
Where is the problem?
What is the problem?
Stroke Definition
“Stroke”- what does this mean?
Signs and symptoms with abrupt onset
Vascular disease
Often focal examination findings
Often loss of function / negative symptoms
Variety of etiologies…mostly common causes
…but what is causing the symptoms?
Stroke Subtypes
Unifying theme
interruption of brain blood flow
disruption of brain blood flow
Common-ischemic stroke
many mechanisms
many etiologies
embolic, thrombotic, hemorrhage
dural sinus thrombosis, dissection
Stroke
Aneurysmal hemorrhage
with intraparenchymal
bleeding
Stroke
Ischemic stroke
Early CT
Dense vessel sign
Stroke
Early ischemic stroke
CT mimic
Ischemic damage
left occipital
CT insensitive for
acute Ischemic stroke
Think Stroke Subtypes
Ischemic stroke
-embolic
-thrombotic
Lacunar infarction
Intraparenchymal hemorrhage
-intracerebral hemorrhage
-aneurysmal hemorrhage / subarachnoid
-arteriovenous malformation
Venous thrombosis
Case presentation 1
A 72-year old man is brought to the emergency department by EMS with altered behavior. After Sunday dinner, he was found to be “confused.” According to his family, “He could not find his way about the house…he was bumping into things.”
There is a history of stroke two years ago with residua of very mild left-sided hemiparesis. There is no recent history of trauma or seizures. The patient has a history of hypertension for which he takes a diuretic.
Case presentation
On physical examination his vital signs are blood pressure of 120/80, pulse 90, respiratory rate of 14 per minute. He is afebrile. Pulse oximetry is 96% on room air.
He is awake, alert, articulate and conversant. He looks toward the examiner when questioned. He is insistent that there is nothing wrong with him. There is a pronator drift with mild weakness of the left arm. Mild facial asymmetry is present with weakness of the left face. He is able to walk unassisted but seems to have trouble turning to his left….
A diagnostic procedure was performed….
Case presentation
Here’s what really happened….
The patient wished to leave. He disagreed with his family’s assessment and claimed that nothing was wrong. We tried to talk him into staying for further evaluation but he insisted on getting up and walked rather briskly to the restroom….
…and he could not find the restroom. He would not turn to his left and seemed unable to appreciate things to his left.
Case presentation
Abrupt onset of symptoms
Risk factors for stroke / history of stroke
Physical examination
trouble turning to left…
would not turn to left…
three right turns to reach restroom
Noncontrast CT
Ischemic changes
likely old stroke
Right occipital area
MRI DWI
“Light bulb sign”
Acute ischemic stroke
Right occipital area
Case presentation
Chief complaint – “confusion”
In reality, occipital lobe stroke
Non-dominant hemisphere
Visual field cut and neglect syndrome
“Stroke”
Looks like a stroke Is a stroke | Looks like a stroke Is not a stroke “MIMICS” |
Does not look like stroke Is a stroke “CHAMELEONS” | Does not look like stroke Is not a stroke |
Stroke Differential Diagnosis
Stroke Chameleon
-stroke appears as something else
-disguised or hidden stroke
Stroke chameleon
Retrospective chart review for one year at one center
Dupree CM et al. J Stroke and Cardiovasc Dis 2014;23:374
Abrupt onset seemed to be key…
Consider stroke chameleon / disguised stroke
Altered mental status
Syncope
Hypertensive emergency
Possible cardiac syndrome
Stroke chameleons�Initial diagnoses
Dupree CM et al. J Stroke and Cardiovasc Dis 2014;23:374
Case presentation 2
A 35-year old woman is brought to the emergency department by EMS with suspected stroke. She had the abrupt onset of right-sided weakness and inability to speak late in the morning.
There is no history of stroke, trauma, or seizures. History is limited but the patient is thought to be diabetic.
Case presentation
On physical examination vital signs are blood pressure 120/76, pulse 90, respiratory rate 14, with pulse oximetry of 98% on room air. She is afebrile. She appears alert but seemingly cannot hear or speak. She looks about the room and is in no distress.
A flaccid right hemiparesis is present.
What needs to be done immediately?
Stroke Mimic
Hypoglycemic hemiplegia syndrome
Rapid glucose determination performed
- less than 40 mg/dl
- (very low)
Rapid resolution of hemiparesis and aphasia with administration of intravenous dextrose
“Stroke”
Looks like a stroke Is a stroke | Looks like a stroke Is not a stroke “MIMICS” |
Does not look like stroke Is a stroke “CHAMELEONS” | Does not look like stroke Is not a stroke |
Stroke Mimics
Unusual manifestation of nonvascular disease with clinical picture of stroke
May result from systemic or CNS events
May be indistinguishable from stroke
Stroke Mimics
Why is this important?
As we move toward stroke therapies, increasingly important to have correct diagnosis…
Misapplied therapy costly, risky
Stroke Mimics
Metabolic problems
hypoglycemia
hyperglycemia
hepatic
hypertensive
Psychiatric problems
factitious
conversion
CNS problems
seizure/postictal
migraine
subdural hematoma
brain abscess
tumor
multiple sclerosis
How frequent are Stroke Mimics?
Stroke mimics are discovered at different times during clinical investigation
Stroke misdiagnosis rates (mimic rate) will vary depending on when the diagnosis of stroke is assigned
Stroke diagnosis after history and physical?
Stroke diagnosis after laboratory work?
Stroke diagnosis after neuroimaging?
Stroke Mimic articles
Norris JW. Misdiagnosis of Stroke Lancet 1982;1:1523
821 patients consecutively admitted to a stroke unit from an emergency room
Evaluators –interns, then neurology
Initial studies not clear – history, physical
Further studies – LP, EEG, brain scan
Stroke Mimic articles
Norris JW. Misdiagnosis of Stroke. Lancet 1982;1:1523
Stroke mimic rate 13%
Postictal state, nonconvulsive status epilepticus
Confusional states –metabolic, toxic
Subdural hematoma
CNS tumor
Radial nerve palsy
Vertigo
Encephalitis
Cardiac failure
Multiple sclerosis
Stroke Mimic articles
Norris JW. Misdiagnosis of Stroke. Lancet 1982;1:1523
Stroke mimic rate 13%
Most common misdiagnosis seizures
Unwitnessed or unrecognized (5%)
Most had postictal confusion
Focal neurologic signs in about half
1/3 had previous history of stroke
Stroke Mimic articles
Libman RB. Conditions that mimic stroke in the emergency department. Arch Neurol 1995; 52:111.
411 consecutive patients to ER with initial diagnosis of stroke
Evaluators-neurologists, EPs (75%)
Definition – sudden onset deficit >1 hour
Initial studies – history and physical
Further studies – CT. laboratory work
Stroke Mimic articles
Libman RB. Conditions that mimic stroke in the emergency department. Arch Neurol 1995; 52:111.
Four conditions – majority of stroke mimics
Unrecognized seizures / postictal
Systemic infections
Brain tumor
Toxic-metabolic
14 others
(Cerebral hemorrhage counted as stroke)
Stroke Mimic rate 19%
Seizure and postictal state
Systemic infection
Brain tumor
Toxic-metabolic
Positional vertigo
Cardiac
Syncope
Trauma
Subdural hematoma
Herpes encephalitis
Transient global amnesia
Dementia
Multiple sclerosis
Cervical spine fracture
Myasthenia gravis
Parkinsonism
Hypertensive encephalopathy
Conversion disorder
Libman RB. Conditions that mimic stroke in the emergency department. Arch Neurol 1995; 52:111.
Stroke Mimic rate 19%
Libman RB. Conditions that mimic stroke in the emergency department. Arch Neurol 1995; 52:111.
Increased chance of stroke mimic
IF level of consciousness decreased
AND normal extraocular eye movements
Increased chance of true stroke if abnormal visual fields, DBP >90, atrial fibrillation, or history of angina
Stroke Mimic articles
Kothari RU. Emergency physician’s accuracy in diagnosis of stroke. Stroke 1995;26:2238.
446 patients admitted to hospital with diagnosis of ischemic stroke; compared admission and discharge diagnoses.
Evaluators- EPs at teaching hospital
Initial studies – H&P, CT, labs
95% agreement between diagnoses
Stroke Mimic articles
Kothari RU. Emergency physician’s accuracy in diagnosis of stroke. Stroke 1995;26:2238.
All patients with intracerebral hemorrhage and subarachnoid hemorrhage were correctly diagnosed by EPs
19/351 patients with final diagnosis of stroke or TIA diagnosed by EPs had a final discharge diagnosis other than stroke.
5% disagreement between diagnoses
Stroke Mimic articles
Conclusion: EPs could accurately diagnosis stroke, particularly hemorrhages
Incongruent diagnoses
Paresthesias of unknown cause
Seizure
Migraine
Neuropathy
Psychogenic
Others
Kothari RU. Emergency physician’s accuracy in diagnosis of stroke. Stroke 1995;26:2238.
Stroke Mimic articles
Allder SJ. Limitations of diagnosis in acute stroke.
Lancet 1999; 354:1523
Found 9% of patients diagnosed with stroke (by neurologists) had a normal detailed MRI with probably alternative diagnoses
Metabolic causes
Hemiplegic migraine
Psychogenic
Alcohol withdrawal
Moving to tissue based / imaging diagnosis
Stroke Mimics
When is a stroke mimic present?
The time a diagnosis is assigned affects the frequency of stroke mimics and eliminates many alterative diagnoses
�Rate of mimics – 1-19%
Hypoglycemia
Known as a stoke mimic for many years
Patients may be drowsy or alert
Patients may not show confusion
Reported in alcoholics as well as diabetics
Usually defined as glucose < 45mg/dl
Hypoglycemia
Hemiplegia may resolve immediately but recovery over hours is also reported
Aphasia may make discovery challenging
Mass lesions
Counterintuitive that a slowly expanding mass should cause abrupt symptoms…
Subdural hematoma
Cerebral Abscess
Tumor – primary and metastatic
6% had symptoms less one day
edema
hemorrhage into tumor
obstructive hydrocephalus
Seizures and postictal states
Theory-seizure induced alteration in neuronal function
Postictal paralysis (Todd’s paralysis)
Usually follows partial motor seizure
May follow a generalized seizure
Duration is usually brief
Cases of paralysis lasting 48 hours
Seizures and postictal states
Rare inhibitory seizures with weakness representing the seizure are reported
Beware-seizures may follow a stroke either acutely or remotely
Most studies that identified seizures as a stroke mimic either used additional history or observation to make diagnosis
Migraine mimicking stroke
Hemiplegic migraine
Hemiplegia may outlast headache
Diagnosis of exclusion
First diagnosis difficult
Family history may be present
Attacks often stereotypic but alternating hemiplegia reported
Functional hemiparesis
Little written on factitious stroke
Most case series do include a few patients
Psychiatric disorder
Conversion disorder – unaware
Malingering-conscious feigning
Encephalopathies�Toxic-metabolic conditions
Hypoglycemia
Hyperglycemia with hyperosmolar state
Aphasia, hemiplegia, hemiparesis, visual field cuts, hemisensory deficits, unilateral hyperreflexia, Babinski’s signs reported
Hyponatremia
Hepatic encephalopathy
“Stroke”
Looks like a stroke Is a stroke | Looks like a stroke Is not a stroke “MIMICS” |
Does not look like stroke Is a stroke “CHAMELEONS” | Does not look like stroke Is not a stroke |
Atypical presentation of stroke
“Chameleons”
Uncommon manifestation of an uncommon clinical problem
Abrupt onset of symptoms
Risk factors for stroke often present
Atypical presentation of stroke
Stroke commonly presents with negative symptoms or deficits
Unusually, positive symptoms are present
Movement disorders
Hemiballismus
Unilateral dyskinesia
Atypical presentation of stroke
Other stroke chameleons
Confusional states, agitation, delirium
Limbic structures may be involved
Temporal and frontal regions
Aphasias-fluent
Neglect syndromes
Sensory complaints
Cortical blindness, neglect
Atypical presentation of stroke
Aphasias
Fluent
Non-fluent
Adequate sample of speech
Ask to name objects
Ask to repeat words short sentences
Ask to write
Fluent aphasia
Patients may seem confused
Look for other signs…
Paraphasic errors
Trouble naming
Trouble repeating
Trouble writing
Other stroke chameleons
Sensory complaints
-paresthesias
-chest pain mimicking MI
-thalamic, medullary infarcts
Other stroke chameleons
Visual symptoms
Visual field cuts
Neglect
Cortical blindness
-may appear to be feigning
-may deny to be blind
-pupils will be reactive to light
“Stroke”
Looks like a stroke Is a stroke | Looks like a stroke Is not a stroke “MIMICS” |
Does not look like stroke Is a stroke “CHAMELEONS” | Does not look like stroke Is not a stroke |
Questions?
Why is this important?
As we move toward stroke therapies, increasingly important to have correct diagnosis…
Misapplied therapy costly, risky
Final thoughts…
Remember, noncontrast CT is insensitive for acute ischemic stroke.
Noncontrast CT severs mainly to exclude hemorrhages and mass lesions.
Stroke diagnosis is become a imaging tissue-level diagnosis. Distinction between TIA and stroke is blurring…
Questions?
“Errors of judgment must occur in the practice of an art which consists largely in balancing probabilities.”
-Sir William Osler
J. Stephen Huff, MD
University of Virginia, Charlottesville
jshuff@virginia.edu