1. 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. 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. 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. 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. 5. The 20 most common stroke mimics, identified in a systematic review and meta-analysis of case series
6. 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. 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. 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. 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. 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. 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. 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. 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. 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. 15. Characteristics of Common Stroke Mimics
16. 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. 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. 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. 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. 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. 21. The differences between central lesions and peripheral lesions following a DixHallpike manoeuvre
22. 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. 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. 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. 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. 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. 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. 28. Examples of stroke chameleons
29. 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. 30. Frequency of transient ischaemic attack (TIA) mimics from 1532 consecutive suspected TIA referrals to the University College London comprehensive stroke service
31. 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. 32. Clinical features of transient ischaemic attack (TIA) and some common mimics
33. 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 (