Authors: Mark Winstanley, Andy Neill, Dave McCreary, Becky Maxwell, Chris Connolly, Michelle Tipping / Codes: ELC1, ELP4, SLO2, SLO4, SuC11, SuC13, SuC7, SuP5 / Published: 02/04/2021
Dr Andy Neill @AndyNeill
Dr Dave McCreary @dmccreary85
Do ED docs use HINTS correctly? And when we do, how accurate are the findings?
Title of Paper
Diagnostic Accuracy of the HINTS Exam in an Emergency Department: A Retrospective Chart Review
Journal and Year
Academic Emergency Medicine. 2020.
– Dizziness, as a presentation, is hard. It shouldn’t be, but it is. There are a few diagnoses we’re looking for and the differences between them on examination can be subtle. Not to mention that the patients can be very difficult to assess given they feel pretty crap at the time and being examined makes them feel crapper-still.
– And HINTS is great, isn’t it? Apparently it’s the answer to the vertigo conundrum with reported sensitivity and specificity for posterior CVA in acute vestibular syndrome patients approaching 100%, maybe performing even better than MRI within 48 hours of symptom onset.
– Well, hold your horses there – unless you’re a qualified neuro-opthalmologist examining a population with high stroke prevalence (as I’m sure many of our listenership are), then you’re probably getting ahead of yourself, given that’s who was performing said test in the [Kattah paper, stroke 2009] from which the popularity of this test has stemmed.
– Despite this caveat, HINTS has become more and more popular with more and more junior doctors for broader and broader patient cohorts. It’s become a bit of a bug-bear of mine, as anyone who’s presented a dizziness history to me and said ‘HINTS is negative’ will attest. It usually leads to a long teaching session / soap-box rant.
– I feel the authors of this study may have similar feelings on the use of HINTS as they decided to look at how HINTS was being applied in their ED, and tried to work out the diagnostic utility of it when it is applied (both appropriately and inappropriately)
– Before we look at the study, we should take a moment to remind ourselves of what the HINTS is and when it *should* be used:
– **HI** – head impulse: holding the patient’s head, ask patient to fixate on your nose. Quickly and gently move patient’s head to left or right and back to neutral.
– Peripheral: Corrective saccade – large beats of nystagmus as the eyes catch up to re-fixate on your nose.
– Central: They stay fixed on your nose with no corrective saccade.
– **N** – Nystagmus:
– Central: Any vertical nystagmus or bidirectional nystagmus
– Remember: The patient will likely have horizontal nystagmus when you assess gaze in either direction. ***The direction of the nystagmus is named for the fast beat***.
– In vestibular neuronitis the nystagmus will increase when looking in the direction of the fast phase (Alexander’s Law).
– **TS** – Test of Skew: Cover one eye and then uncover that eye quickly
– Central: The eye has to realign itself vertically
Criteria for HINTS:
– Acute Vestibular Syndrome (AVS) – acute onset, continuous vertigo with associated gait unsteadiness, nausea and/or vomiting, and spontaneous or gaze-evoked nystagmus.
– NOT patients with episodic, positionally evoked vertigo (like in BPPV)
– Retrospective chart review
– 5 trained reviewers. Using [Jansen et al. guidelines for retrospective chart reviews](https://pubmed.ncbi.nlm.nih.gov/15718116/)
– All patients with a triage diagnosis of dizziness, vertigo, light-headedness, and/or unsteadiness
What they did
– Primary outcome: diagnostic accuracy of the HINTS exam – the number with a central HINTS exam (positive tests) and were diagnosed with a CNS cause for dizziness (true positives)
– Secondary outcomes:
1. Number of patients with symptoms consistent with AVS and appropriately received HINTS exam
– Criteria used by investigators were those from [Kerber et al’s 2015 study](https://pubmed.ncbi.nlm.nih.gov/26511453/):
– Continuous dizziness ongoing at time of presentation to ED
– Unsteady gait (objective or subjective)
2. Proportion of HINTS performed inappropriately performed on dizzy patients who weren’t candidates for exam
3. Number of patients who had both HINTS and Dix-Hallpike (as these should be mutually exclusive populations)
Retrospective Chart Assumptions
– Nystagmus & unsteady gait: **both** had to be documented in chart. If not documented, assumed to be inappropriate HINTS.
– Symptom timing: presumed to be appropriate unless documented that symptoms had resolved or were intermittent. No documentation was assumed to be continuous symptoms.
– Considered central if one or more component → central:
– HI: no corrective saccade
– N: direction changing
– TS: vertical deviation followed by correction
– ALL three had to be consistent with peripheral for test to be ‘negative’
Summary of Results
– 2309 patients included
– 39 (1.7%) had documented symptoms of AVS (ongoing, continuous dizziness with nystagmus and unsteady gait)
– 14 (36%) of these got HINTS
– 6 (15.4%) ultimately diagnosed with central cause – NONE of these had a HINTS 🤦🏻♂️
– 450 (19.5%) had HINTS exam in ED
– 14 (3.1%) were on patients with symptoms consistent with AVS
– Remaining 436 had characteristics inconsistent with AVS
– Most often no documented nystagmus or ataxia, or documented intermittent symptoms
– 220 (49%) also had documented Dix-Hallpike
Primary – dx accuracy of HINTS
None of the 16 patients who had an appropriate HINTS performed were found to have a central cause on final diagnosis giving a specificity of 0.95
– 2×2 table for dx accuracy:
– As best I can work out this comes from:
– True Positive (pos HINTS | central cause): 0
– False Positive (pos HINTS | no central cause): 16
– False Negative (neg HINTS | central cause): 6
– True Negative (neg HINTS | no central cause): 428
No sensitivity as no true positives
And if the HINTS was deemed to have been performed appropriately there were 5 false positives giving specificity of 0.64 [0.34-0.87]
Our results suggest that the test is of limited utility as currently used by ED physicians and that additional training in how to identify appropriate candidates and interpret the results of ocular motor exam may improve its diagnostic accuracy.
Clinical Bottom Line
ED docs in general aren’t applying HINTS appropriately and even when we are it’s probably not as useful as the original studies suggest. Its retrospective chart review data, with all the issues that come with that, but I still think it serves as 1) a refresher on who is appropriate for a HINTS exam and 2) a warning about how much weight we (and in particular a lot of junior docs – both from ED and Neuro) give the HINTS exam findings.
Other #FOAMed Resources / References:
Dr Becky Maxwell @MaxiRebecca
Dr Chris Connolly @chrisconnolly83
This month Becky and Chris are looking at frailty and a toolkit released by the RCP in December of 2020 which can be found here
This toolkit is intended to be used by acute physicians, geriatricians, emergency physicians, therapists, nurses and other clinical staff caring for older people in acute hospitals.
Patients with frailty have increased LOS high readmission rates and highest rates of long term care post discharge so this is important stuff!
The toolkit urges us to identify frailty within 30mins of arrival to the unit and to do so in a structured way such as using the Clinical Frailty Scale. There are a number of medical apps which will help you with this is used by Becky.
History taking is vital and you should spend a few extra minutes getting a collateral history from care givers, ensuring aids to communication with your patient are available (do you know where and how to access new hearing aid batteries in your ED? at 0200?) and remember to assess for pain and consider using a pain scale if there are communication barriers.
It’s important to distinguish delirium from dementia and again there’s a scoring system recommended in the toolkit and this can provide a structure to that assessment.
Polypharmacy is a big burden on the frail patient and medication review should be undertaken. Consider their anticholinergic burden and again there’s an app for that.
Ensure you know how to access time critical meds especially Parkinson’s and diabetes meds at all hours of the day. Always a good time to refresh your PD knowledge with a visit to one of our most popular blogs
The toolkit urges us not to be ‘lazy’ and that we should challenge ourselves to look for at least 5 causes of a deterioration in someone’s frailty and not to use phrases like ‘off legs’ which aren’t diagnoses and can hide all manner of badness from occult fracture to metastatic cord compression.
The guideline reminds us of the importance of a comprehensive geriatric assessment (CGA) but also reminds us that hospitals may not be the safer option for a frail patient. Perhaps this is a potential SDEC project?!
– is compression therapy a useful part of cellulitis management?
– Big, beefy, oedematous legs are prone to getting infected. All of those skin cells that are seeping in interstitial fluid like your fingers in the bath for too long. Cellulitis is a common issue here. Compression stockings, used to limit the oedema may be of benefit in cellulitis. This is already widely recommended in guidelines and is apparently commonly recommended by physicians. Though clearly not by me. There is little evidence to back it up.
Compression Therapy to Prevent Recurrent Cellulitis of the Leg
Webb, 2020, NEJM
– Single centre RCT in Australia, non blinded as you might imagine
– hospitalised and GP patients who had recurrent cellulitis with oedema
– there were specialist lymphoedema physios who did the assessments
– the diagnosis of cellulitis was if the doctor said there was cellulitis. This is not ideal given the amount of “bilateral cellulitis” that we seem to diagnose which is likely spurious. That being said we do not really have a gold standard for cellulitis
– primary outcome was cellulitis recurrence
– seems to be powered for ~25% absolute reduction recurrence (from a 50% baseline). They would have needed 160 pts for this
– stopped early due to benefit after the physios doing the assessments felt the benefit was so good that it they were exposing the control group to harm. They then introduced a stopping rule half way through the trial and then stopped for benefit. This is a tad naughty
– at time of stopping recurrence had occurred in 15% in the compression group vs 40% in the non compression group
– I should clearly be thinking about compression in recurrent cellulitis.
– We probably need the full package – the stockings, the physio the follow up to make this happen effectively
– stopping the trial early (in an unblinded trial) makes me much less confident of the magnitude or accuracy of the result.
Dr Mark Winstanley @MarkWinstanley4
Dr Michelle Tipping @michelletipping1