Analysis Of Dizziness and Vertigo in the Emergency Department
By Dr Stephen Sheridan
According to existing international literature, patient presentations with dizziness to the emergency department (ED) accounts for approximately 2-3% 1, 2 3. Citing data from the Ottawa hospital, dizziness there was reported as 2% of all ED presentations. Acute vertigo presents a significant challenge to ED physicians in distinguishing peripheral causes (e.g. benign positional peripheral vertigo) from central nervous system conditions including cerebellar strokes. Incidentally, literature reports of central causes are reported to have an incidence of 3.2-12.5% in the ED 4. Missed diagnosis of these conditions can result in significant consequences, most importantly patient mortality 5. Investigations commonly performed for these presentations including computed tomography (CT) scanning in addition to magnetic resonance imaging (MRI), where MRI is more sensitive in the acute setting for diagnosis of the posterior circulation strokes 4.
Dizziness as a symptom is caused by numerous medical conditions and is as a term considered to encompass light-headedness, spinning, rocking, vertigo, off-balance amongst many others 1. Existing data on dizziness causes as presenting to the ED were found to be benign in nature, whereby peripheral vestibular problems, orthostatic hypotension and migraine were diagnosed. Further, nonstroke cerebrovascular diagnoses in addition to the otovestibular forms were found to be substantially responsible 6. CNS causes for dizziness is considered in adult ED patients, with an incidence of approximately 5%, where stroke is the considered diagnosis of urgency 1. Increased risk factors for stroke include increasing age, history of vascular disease or previous stroke in addition to instability, where there is abnormal gait or focal neurological signs 7 8. Of note however, whilst stroke, in particular the posterior circulation strokes are considered key diagnoses not to miss, screening patients who present with dizziness purely with risk factors can miss young patients who present with acute dizziness where this symptom can be purely the only presentation in those with basilar stroke or vertebral artery dissections. These medical events can themselves precipitate posterior circulation strokes, including cerebellar vascular events1.
Dizziness in the context of this study is described under the term acute vestibular syndrome, where there is acute onset of persistent dizziness associated with nausea or vomiting, gait instability, nystagmus and head-motion intolerance. These patients are usually symptomatic at presentation and have focused neurological examinations that can be diagnostic the most common cause for these patients in ED is vestibular neuritis or labyrinthitis (dizziness plus hearing loss or tinnitus)9. However the most dangerous cause here is posterior circulation ischaemic stroke, in the brainstem or cerebellum. Multiple sclerosis in addition to cerebellar haemorrhage or thiamine deficiency are minority diagnoses for AVS 9. The key distinguishing feature for AVS is the distinction between exacerbated dizziness (present at baseline, worse with movement) vs. triggered (not dizzy at baseline, triggered by movement). AVS patients experience symptoms worse with movement but this is not BPPV. Instead BPPV involves those with brief episodic symptoms of dizziness, with persistent symptoms of malaise or nausea 10 11. And this is may be brought about by small inadvertent head movement. Vestibular neuritis is the most common cause of AVS and its benign, self-limiting and occurring post-viral infection of the vestibular nerve. Herpes simplex infection is the most common viral aetiology, however patients can present with Ramsay hunt with herpes zoster and hearing loss, facial palsy and vesicular eruption12. The primary issue that exists with AVS is that the paradigm of CT brain imaging followed by MRI brain for this patient cohort is not in itself wholly diagnostic. Sensitivity of CT brain for acute posterior fossa stroke is estimated to be between 7-14%, with MRI brain within 24-48hrs of onset missing 10-20% of strokes 5 13 14 15. However, physical examination can tease out the distinguishing factors of a peripheral or central cause, and has been illustrated to be sensitive than an early MRI 16.
The HINTS exam was developed as a means of assessing patients with acute vestibular syndrome (AVS), defined as previously including acute on-going vertigo/ head motion intolerance, unsteady gait and accompanying nystagmus 9. Each component is separately assessed, with the findings determining central or peripheral causes for the described signs 17 . Any one component positive for central findings indicates the need for neuroimaging, as such its utility has been ascribed to having greater sensitivity in ruling out stroke in AVS patients, including when compared to current stroke risk stratification rules18 19 20.
The conundrum that exists however is the performance of said testing in the ED given that the HINTS exam was demonstrated to have 96.5% sensitivity when performed by trained neurologists or neuro ophthalmologists 21 . The literature presently does not reflect routine use of the HINTS by ED physicians, in keeping with training, lacking awareness and physician confidence in employing this in practice. Further barriers to use of this test, as demonstrated in recent studies is the uncertainty or lacking inclusion criteria awareness by physicians in whom the test is appropriate 22 23. This may be reflective also of patient experience of their vertigo, particularly BPPV patients where their experience of vertigo may be reported as continuous owing to feeling unwell between discrete episodes1.
No existing literature exists on the current incidence of dizziness in patients presenting to Irish emergency departments, nor is there any existing data to distinguish the differential diagnoses that make up those presentations. As such, there is an existing research need to evaluate the epidemiology of dizziness in adult patients presenting to Irish EDs and to understand the current much needed insight to the approach of dizziness in the ED, in addition to the roles imaging practices of ED physicians in their evaluation of these patients. Capturing this data will provide a modalities play where neurology or ENT services may not exist to provide subspecialty care to these patients.
Section 2: Aims
The aim of this retrospective cohort study is of a descriptive analysis of dizziness and vertigo presentations to adult Irish emergency departments. The study seeks to describe the incidence and diagnoses of dizziness and vertigo in these populations with the intent to direct further research in the emergency approach to acute vertigo and its aetiologies.
Section 3: Objectives
The INVERTED study on review of the initial study design has evolved to become a retrospective study and prospective study around dizziness and vertigo. These studies are to be completed across Irish emergency departments involving adult departments.
The primary outcome of the retrospective study involves:
- Describing the incidence of vertigo presentations amongst the adult patient population presenting to the emergency department.
The secondary outcome of the retrospective study involves:
- Subgroup analysis of adult patients presenting with acute vertigo and the diagnoses for these presentations
- Incidence of acute vestibular syndrome amongst acute vertigo patients, and from that the peripheral and central causes diagnosed for these presentations.
- The examination findings and specialised vertigo tests employed by EM physicians in evaluating for the root causes of acute vertigo
- Imaging tests performed for patients with acute vertigo and the percentage yield for findings causing the acute presentation
- Patient presentation origin (primary care or self-presentation) with discharge rates amongst these patients from ED.
Section 4: Study & Methodology
4A: Study Design
The INVERTED study (retrospective) involves a retrospective cohort design, with chart review as the main method of data harvesting. This study has a projected timeline of approximately three-six months. Noted however is the impact of SARS Cov-2 on emergency department presentations and indeed a recent cyber attack impacting HSE IT infrastructure including that capacity to access patient records.
The inclusion criteria for this study are the following:
- Unsteady gait
- In addition to nausea/vomiting
Given the lack of data on the incidence of acute vertigo in the described populations, no calculated sample size has been formally calculated. However, it is known per international literature that the incidence of vertigo amongst ED presentations is approximately 2-3%. The annual projected presentations to Irish EDs in 2018 was 1.82 million presentations per Economic and Social Research Institute (ESRI) data, while no breakdown of these is involves paediatric or obstetric cases, the projected incidence of acute vertigo is 47,000 presentations annually.
A month prior to commencing the study and the principal investigators will send the resource manual via email to the site co-investigators. This resource manual details the following:
- Study background and protocol
- INVERTED data collection form and data dictionary (definitions derived from literature review and kindly from Dmitriew et al)
- Study posters
- RedCap access.
RedCap access has been recently secured by ITERN
4D: Data Collection and Management
Local co-investigators will transfer electronically stored data to the online database (RedCap). Each electronic database locally will be password protected with data collected non-identifiable. The only identifiers for data being entered to RedCap would be hospital identification and region for data inputting and analysis only. The data forms for the study will be provided by the principle investigator and lead co-ordinator, with all online database access including login details retained by these members also. They also hold responsibility for maintaining and management of the RedCap database.
Data analysis will be completed at Midland Regional Hospital Tullamore, with quantitative and qualitative statistics employed. Any quantitative analysis will be completed using GraphPad Prism Edition 9.
Section 5: Study Management
Study management will be maintained by study co-ordinators with the study committee meeting once monthly depending on need via tele-conference.
Section 6: Ethics and Regulatory Considerations
6A: Assessment and Risk Management
While this study is a retrospective cohort study, no new change to the management and clinical practices are to be raised. The data from this study are likely to support the development of a prospective cohort study on using the HINTS exam in ED with EM physician recruitment.
6B: Ethics, Review and Compliance
Ethical approval for this study is awaiting submission to the UHL Research Ethics Committee. Further, a data protection impact assessment (PIA) in accordance with General Data Protection Regulation (GDPR) is being completed as advised by a deputy data protection officer (DDPO) (Dublin mid-Leinster region). Upon approval of ethical application, this PIA will be reviewed and advised by the DDPO. All data controllers involved in this study will also be expected to complete a Good Clinical Research Practice certification and have updated GDPR compliance certification in line with HSE Staff policy via HSELand training.
All recruited ED sites will be reviewed for Clinical Indemnity Scheme coverage to ensure CIS and thereby ensure indemnity coverage present for site investigators. For research ethical approval, a furnished copy for each represented hospital is to be submitted. The State Claims Agency is currently assisting the study committee on this matter, to complete a thorough ethics application.
Costs are expected to be incurred during this study, most specifically with statistical support in review of the statistical plan and analysis on completion of data gathering. Study registration with the ISRCTN (International Standard Randomised Controlled Trial Number) is also required, in improving study transparency and enabling availability of anonymised data in an accessible data registry. Finally, on study completion, presentation at national and international conferences (IAEM and RCEM) are anticipated also.
6E: Dissemination Policy
The INVERTED study is to be brought before the IAEM Research Committee in respect of the initial NCHD survey on acute vertigo. Following this, and on completion of the study, publication of this data through a high-impact research journal is a considered aim. However, for wider awareness amongst the Irish EM community, this study and its results are intended to be discussed at national conference level to raise discussion on vertigo in the Irish ED patient population.