Viva 5

A 75 year old man is admitted to your unit from the Emergency Department following admission for dysphagia, dysphonia and fluctuating consciousness.

During a period of drowsiness, he was said to have had a seizure and aspirated, following which he was intubated and ventilated. 

On arrival in the intensive care unit, he is noted to be afebrile, blood pressure 190/120, pulse rate 80/min. Oxygen saturation is 98%, he is ventilated with an FIO2 of 0.5. 

What is your initial approach for the assessment and management of this patient?
 

“Initial examination and investigations are unremarkable. What is your differential diagnosis and initial plan?” was the original follow-up question.  The original viva clearly must have taken things in the direction of meningoencephalitis, because the examiner comments are "Areas that were poorly covered included post-seizure management, and the potential for CNS infection. Eleven out of sixteen candidates passed this section". However, that would be boring. So, I have removed a part of the stem which reported a normal CT brain, and used the rest to fashion a viva about endovascular clot retrieval.

To score marks with their answer for the first part of the question, the candidate should:

  • Consider stroke and intracranial haemorrhage among their differentials. 
  • Assessment should include a neurological exam
    • Specifically, ask them what they are looking for: it should be focal neuro signs
  • Investigations should include a CT brain
    • Specifically, ask them what they are looking for: it should be stroke or bleed
What neurological examination findings would lead you towards a diagnosis of non-convulsive status epileptics?

Negative symptoms:

  • anorexia,
  • aphasia/ mutism
  • amnesia
  • catatonia
  • confusion,
  • coma
  • lethargy
  • fixed-gaze staring.

Positive symptoms:

  • agitation/aggression
  • automatisms
  • uncontrollable blinking
  • delirium, delusions, psychosis
  • echolalia
  • facial twitching (particularly, small periorbital muscles)
  • nystagmus/eye deviation
You find the patient has none of those. With lightened sedation, there is a paucity of movement on the right. How does this change your approach?

An urgent CT now becomes the priority. Ideally, they should ask for a perfusion study, as this will yield more diagnostic information than a plan non-contrast scan (which may not reveal a stroke in the hyperacute phase)

The CT perfusion scan demonstrates a left MCA territory infarct. How does this change your management priorities?

The candidate should be pivoting towards thrombolysis at this stage.

What are the indications for intravenous thrombolysis for stroke?
  • Presentation within 4.5 (ideally, 3)  hours
  • Age over 18 and less than 80
  • Clinically significant stroke (NIHSS >4) is quoted as an indication by some guideline authors
What are the contraindications?
  • History of head trauma in the last 3 months
  • History of stroke in the previous 3 months
  • Arterial puncture in a non-compressible site in the past 7 days
  • Platelet count less than 100
  • Any heparin within 48 hours of the stroke
  • Current anticoagulant therapy
  • Hypoglycaemia
  • Multilobar infarction (more than one-third of a cerebral hemisphere) on CT scan
  • High stroke severity (NIHSS > 25) is a relative contraindication for some guideline-writers
What is the NIHSS score, and how does it factor into your decisionmaking?
  • The National Institutes of Health Stroke Scale (NIHSS) is a scoring system for the impairment resulting from stroke
  • It has eleven items and a total possible score of 42 (where 0 is no deficit and 42 is essentially a GCS of 3).
  • It helps risk stratification in stroke, helping you decide whether the patient will benefit from thrrombolysis
  • Very mild stroke (NIHSS <4-6) is thought to be so mild as to derive little benefit (and all the risk) from thrombolysis, and so some guidelines  recommend thrombolysis only for strokes with an NIHSS score over 4. 
The patient is six hours past the onset of symptoms. What are the alternatives to thrombolysis?
  • Conservative management
  • Intraarterial thrombolysis
  • Endovascvular thrombectomy
What are the indications for endovascular clot retrieval?
  • Ischaemic stroke with large vessel occlusion
  • Substantial neurological deficit, NIHSS ≥ 5
  • Timeframe criteria:
    • Less than six hours: "broad clinical and imaging criteria"
    • 6-24 hour window: "significant volume of salvageable tissue"
  • Good level of premorbid independence
What are the contraindications and limitations of this technique?
  • Contraindications to carotid or verterbal arterial access (eg. significant carotid atherosclerosis)
  • Peripheral vascular disease (i.e. difficult access)
  • Uncontrolled coagulopathy
  • Obvious and well-established infact on CT or MRI (thus, no point in embolectomy)
  • Contrast allergy
What does the evidence say about this technique, in terms of outcomes?
  • ​​​​​​​DAWN trial: 206 patients, 49% had good functional outcome vs 13%
  • DEFUSE-3 trial: 186 patients, 47% had good functional outcome vs 17%
  • Other trials: EXTEND1A, ESCAPE, SWIFT-PRIME, REVASCAT 
  • Lots of industry sponsorship
  • Comparisn group received essentially no treatment, as they were outside of the thrombolysis window
The patient undergoes endovascular thrombectomy and returns to the ICU. Describe your post-procedure management of this patient.
  1. E​​​​​​xtubate early, if able.
  2.  Mechanical ventilation focuses on maintenance of normoxia and normocapnia
  3. Blood pressure control:
    1. Aim for SBP <140-160 for fully revascularised patients
    2. Aim for MAP 10-20% over normal baseline and SBP <185 for partially revascularised patients
  4. Minimise sedation and maximise the opportunity for regular reassessment
    Also, scan their head after the first 24 hrs.
  5. Control of electrolytes to prevent AF
  6. Maintenance of neutral fluid balance
  7. Glucose control: hyperglycaemia is harmful
  8. Antiplatelets after 24 hrs (earlier if they had an endovascular stent)
  9. Fever is harmful: paracetamol is recommended

Disclaimer: the viva stem above may be an original CICM stem, acquired from their publicly available past papers. Or, perhaps it is a slightly altered version of the original CICM stem. Or, it is a completely original viva stem, concocted by the monstrously amoral author of Deranged Physiology for nothing more than his own personal amusement. In either case, because the college do not make the main viva text or marking criteria available, almost everything here has been confabulated. It might sound like a plausible viva and it could be used for the purpose of practice, but all should be aware that it does not represent the "true" canonical CICM viva station. 

References

Nogueira, R. G., et al. "Endovascular approaches to acute stroke, part 2: a comprehensive review of studies and trials." American Journal of Neuroradiology30.5 (2009): 859-875.

Silva, Gisele S., and Raul G. Nogueira. "Endovascular Treatment of Acute Ischemic Stroke.CONTINUUM: Lifelong Learning in Neurology 26.2 (2020): 310-331.

Brinjikji, Waleed, et al. "Patient outcomes with endovascular embolectomy therapy for acute ischemic stroke a study of the national inpatient sample: 2006 to 2008." Stroke 42.6 (2011): 1648-1652.

Kidwell, Chelsea S., et al. "Design and rationale of the mechanical retrieval and recanalization of stroke clots using embolectomy (mr rescue) trial."International Journal of Stroke 9.1 (2014): 110-116.

Jansen, Olav, et al. "Neurothrombectomy for the treatment of acute ischemic stroke: results from the TREVO study." Cerebrovascular Diseases 36.3 (2013): 218-225.

Furlan, Anthony, et al. "Intra-arterial prourokinase for acute ischemic stroke: the PROACT II study: a randomized controlled trial." Jama 282.21 (1999): 2003-2011.

Ma, Alice, Gerard Moynihan, and Lachlan H. Donaldson. "Intensive Care Management Following Endovascular Clot Retrieval for Acute Stroke: A Systematic Review of the Literature.Journal of Clinical Interventional Radiology ISVIR (2019).

Rodrigues, Filipe Brogueira, et al. "Endovascular treatment versus medical care alone for ischaemic stroke: systematic review and meta-analysis." bmj 353 (2016): i1754.

Hao, Yonggang, et al. "Risk of intracranial hemorrhage after endovascular treatment for acute ischemic stroke: systematic review and meta-analysis." Interventional neurology 6.1-2 (2017): 57-64.

Nogueira, Raul G., et al. "Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct." New England Journal of Medicine 378.1 (2018): 11-21.

Albers, Gregory W., et al. "Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging." New England Journal of Medicine 378.8 (2018): 708-718.