The Queen Square GP Seminars – “An Update on Stroke and TIA” – February 2018

Dr Arvind Chandratheva
Consultant Neurologist

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On Wednesday 7th February 2018, Queen Square Private Healthcare hosted the first event of the 2018 Queen Square GP Seminar series.  The topic for this popular event was ‘Stroke’ and we were pleased to welcome Dr Robert Simister (Consultant Neurologist and UCLH Stroke Lead) and Dr Arvind Chandratheva (Consultant Neurologist and UCLH TIA Lead) who provided a comprehensive update on the clinical management of stroke and TIA.

Dr Arvind Chandratheva began proceedings by presenting clinical cases in order to identify and discuss four key topics in contemporary stroke management.

Acute Vestibular Syndrome and Stroke

Dr Chandratheva began by discussing acute vestibular syndrome (AVS), a common presentation which is often due to vestibular neuritis, but can also be a result of vertebrobasilar (posterior circulation) strokes. He explained that around 25% of all cases of acute vestibular syndrome can be attributed to stroke within the posterior circulation and misdiagnosis in the emergency setting is common. Dr Chandratheva suggested that clinicians should be less concerned about the patient’s description of their dizziness (which will invariably differ between patients) but should instead focus on the timing and triggers of the dizziness.

Dr Chandratheva explained that certain features of the patient’s clinical history which relate to the timing of dizziness attacks should be considered ‘worrisome’ features of a central cause, rather than peripheral. ‘Timing’ features which would suggest a posterior circulation stroke would include:

  • Multiple prodromal episodes of brief dizziness
  • Abrupt onset while awake
  • Disproportionate vomiting or gait disturbance
  • Headache or neck pain
  • Acute hearing loss and,
  • Cerebellar signs

The presence of cranial nerve and cerebellar deficits on the general neurological exam are key indicators, and Dr Chandratheva explained that the clinical examination should always start at the point of the patient walking into the examination room. It can be said that if the patient can stand or walk normally into the examination room, they do not have a significant cerebellar infarct or haemorrhage. In such patients, truncal ataxia would be likely so severe that they could not even stand or sit to be examined.

 

The HINTS Exam

Dr Chandratheva then explained the use of the HINTS examination. The Head-Impulse-Nystagmus-Test-of-Skew or HINTS exam has been identified as a useful tool which can reliably ‘rule out’ stroke, better than a negative MRI in the first 24-48 hours after symptom onset, with a sensitivity of 100% and specificity of 96%.  Dr Chandratheva explained the following with regards to interpretation of the HINTS exam.

  • Head Impulse Test

Patients with peripheral vertigo will typically have abnormal (positive) head impulse testing, while patients with a central vertigo with typically have a normal (negative) head impulse test.

  • Nystagmus

Patients with peripheral vertigo will have unidirectional, horizontal nystagmus, while patients with central vertigo can have rotatory or vertical nystagmus, or direction changing horizontal nystagmus.

  • Test of Skew

Alternate eye cover testing may reveal skew deviation in patients with central vertigo, but should be absent in patients with peripheral vertigo.

Therefore, patients with acute vestibular syndrome with a normal head impulse test, abnormal vertical skew and direction changing nystagmus should be regarded to have red flags for posterior circulation stroke. That said, Dr Chandratheva reminded the audience that it is essential to know which patients to test.  Patients must have a spontaneous nystagmus, must be able to fixate on a visual target and must allow manipulation of their head in order for the HINTS exam to be accurate. Even awake and alert patients may also have intermittent inattention which may be misinterpreted as a refixation saccade on head impulse testing.

Dr Chandratheva then moved on to discuss the utility of imaging in posterior circulation stroke. He explained that CT scans typically have low sensitivity in general for acute ischemic infarct and particularly in the posterior fossa where imaging artefacts make interpretation even more problematic. CT remains good for looking for blood products although he explained that AVS in cases of haemorrhagic stroke is uncommon.

Whilst Magnetic Resonance Imaging (MRI) is widely regarded to be more sensitive than CT for stroke, Dr Chandratheva explained that MRI in the acute setting may still be misleading, with false negative MRI being more common in the posterior circulation vs anterior, and during the first 24 hours.

 

Summary

Dr Chandratheva explained that most strokes presenting with AVS are posterior inferior cerebellar (PICA) artery territory stroke, but also other brainstem/cerebellar location can be seen. The key to the clinical history is Timing and Triggers, rather than the symptom itself.  Key to the examination is a careful general examination with particular focus on the cranial nerve, gait/postural instability and also use of the HINTS exam. Imaging in the acute setting should be treated with caution.

 

Which antiplatelet should you choose?

Dr Chandratheva then proceeded to talk about antiplatelet therapy, and briefly outlined his preferred therapy options.

Major Stroke – Asp d14 then Clopidogrel

TIA and Minor Stroke

  • High risk – A + C d30 then clopidogrel
  • LAD – A+C d30 then clopidogrel
  • Recurrent LAD (consider resistance) -Resistance – Ticagrelor, Non-Resistance – A+D

SVD

  • Medium Risk – C Loading then C
  • Unless capsular warning syndrome – A+C (express)

SVD recurrence – A+D

 

Atrial Fibrillation (AF)

Dr Chandratheva explained that 30-40% of stroke are cryptogenic. Furthermore, only 1/3 of patients with suspected cardioembolism manifest AF even after 3 years of continuous monitoring. 30 day mortality in stroke patients with AF is 16.3%, compared to 7.5% in patients without AF (1 year mortality rate 37.4% vs 19.5%). Therefore, there is now increased drive to investigate better ways of diagnosing AF, and reducing the number of strokes which have obscure or uncertain origin.

Dr Chandratheva explained that the key problem with AF diagnosis is that the disease has typically progressed considerably before clinical events occur. Physiological imaging studies have been used to demonstrate the early stages of AF and atrial cardiopathy, but in the future, biomarkers and new imaging techniques are needed in order to identify the disease earlier in the disease progression, and to identify treatments which may reverse the changes that occur.  Timing is key and improvements in ambulatory monitoring have already been made. In order to reduce the time taken to fit monitoring, the time to review data and the time to return reports to clinicians, new clinical devices have been developed. Smaller and more comfortable devices have now been introduced to rival the standard Holter monitor which can reduce the time burden considerably, at a comparable cost. Implantable loop recorders (ILR) are now also being fitted routinely in patients in whom AF is suspected but has not yet been shown using other devices.

 

Patent Foramen Ovale (PFO)

The final topic discussed by Dr Chandratheva was PFO.  He explained that 1 in 4 of the population will have a PFO and they have been found to be twice as common in cases of cryptogenic stroke, than in the general population. PFO can potentially increase the risk of stroke due to embolization of blood from the venous system crossing to the arterial system, in situ thrombus formation or atrial dysfunction and analysis of previous randomised controlled trials has suggested a benefit from closure using various closure devices and trials are continuing.

 

National Guidelines for Stroke (2016)

At this point in proceedings, Dr Chandratheva handed over to Dr Robert Simister, who offered guidance on the new guidelines issued for Transient Ischemic Attack (TIA) by the Royal College of Physicians. Dr Simister explained that TIA patients had a risk of recurrence and that there was ‘all to play for’. Therefore, there was a justifiable reason for developing and offering new and more effective TIA pathways.

Again, Dr Simister discussed the role of imaging and reiterated that CT is generally regarded to be poor in the early stages of ischaemia.  MRI is preferable with higher sensitivity to early ischaemic changes which may not be detected on CT imaging, or if imaging is carried out later. MRI also carries with it the ability to detect other pathologies using blood-weighted sequences, such as cerebral amyloid angiopathy and haemorrhage.

Dr Simister then discussed the role of the ABCD2 score for TIA, a tool which is commonly used to estimate the risk of stroke after a suspected TIA. Various recent studies have questioned the utility of the tool and whether it is in fact suitable for initial triage of patients with suspected TIA.  The tool requires the patient to be sat in front of the clinician, meaning inherent delays between the event taking place and the calculation of the score. Studies have also highlighted that whilst the tool is simple to apply, it does not take into account stroke and vascular mechanisms, nor does it allow incorporation of vascular and brain imaging data. Dr Simister stated that the score is notorious for providing low scores in high risk patients.

Dr Simister then explained the potential for a new pathway of urgent treatment of ischemic attack and minor stroke to reduce risk of early recurrent stroke (the EXPRESS study). This study has shown that early initiation of existing treatments after TIA was associated with an 80% reduction in the risk of early recurrent stroke. For this reason, the focus is now on providing emergency access clinics for TIA, with treatments started immediately in clinic.

Dr Simister then proceeded to discuss the new National Guidelines for Stroke (2016), with particular reference to important changes to guidelines regarding TIA. He outlined how the guidelines now place more focus on the importance of urgent access to specialist consultation and immediate treatment commencement, if appropriate. For this reason, clinics which previously provided a 5 day service are now working to extend to a 7 day week service.  Assessment by a specialist physician prior to a decision being made on brain imaging is also now recommended, except when haemorrhage requires exclusion in patients taking an anticoagulant (in which case an unenhanced CT should be performed urgently). Dr Simister reiterated that patients with suspected TIA may present with no symptoms and may be poor historians. Treatment regimens are strong and should not be administered inappropriately.  Therefore, easy access to 7 day specialist TIA clinics is essential. According to the new guidelines, referrers and neurovascular clinics should discontinue the practice of triaging patients using risk stratification tools (such as the ABCD2) and instead, ensure that all patients with suspected TIA are assessed and diagnosed early through access to a specialist appointment, with MRI within 24 hours.

Dr Simister also reported on new guidelines for the management of TIA patients in the community. People with stroke or TIA should have their blood pressure checked regularly, and a new target of a clinic systolic blood pressure below 130mmHg is now deemed appropriate. Secondary prevention should also be introduced as soon as possible, with the new guidelines now including a discussion on individual lifestyle factors including smoking cessation, alcohol (limit to less than 14 units), optimum diet and exercise (150 minutes or more of moderate activity per weeks in bouts of 10 minutes or more).

Finally, Dr Simister reminded the audience about the online referral pathway to the UCLH TIA service, which can be accessed using this link:

http://www.uclh.nhs.uk/OurServices/ServiceA-Z/Neuro/Stroke/Pages/UrgentTIAassessment.aspx

The next Queen Square GP Seminar will take place on April 25th 2018.  This event will be a special joint event with Moorfield Eye Hospital and will feature presentations from Dr Gordon Plant (Consultant Neurologist, NHNN) and Mr Sajjad Ahmad (Consultant Ophthalmic Surgeon, MEH) who will cover key topics on visual loss, the ‘red eye’ and general medical conditions of the eye.  For further information and to register, please take a look at the event page here.

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