(Subtle) HINTS in trying to tell you something….
By Kailash Krishnan MRCP, PhD, Stroke, Division of Clinical Neuroscience, University of Nottingham and Nottingham University Hospitals, Nottingham, UK
A study analysed pitfalls in the diagnosis of cerebellar infarction in a busy emergency department (1) and the following example: a 67 year old lady presented with rapid onset dizziness and vomiting and on examination was found to have normal strength of all limbs and cranial nerves. She was diagnosed to have acute gastroenteritis and discharged. This is a common presenting symptom in the emergency room. Actually, dizziness is the third most common symptom reported in general medical clinics (2)and accounts for about 25% of emergency department visits.(3)
She reattended with vertigo, neck pain and difficulty in walking and admitted 3 days later because of persistent symptoms. CT scan of the brain showed left PICA infarct and bilateral occipital infarcts.
Acute posterior circulation stroke manifest as vertigo, nausea/vomiting, disequilibrium and unsteady gait (collectively defined as acute vestibular syndrome, AVS) accounts for a significant proportion of such visits (4)and presents significant diagnostic challenge. Nearly two-third of such patients have no signs at the time of assessment and upto 35% missed at first clinical contact.(5) A missed diagnosis would mean delays in detecting causes such as atrial fibrillation or intracranial and extracranial vessel stenosis leaving patients at risk of further stroke. The overall mortality in the above study was 40% and amongst survivors, 50% had disabling deficits.(1)
The commonly used NIHSS does not include dizziness or vertigo as a symptom of stroke or TIA and poorly quantifies symptoms from the posterior circulation. A bedside test named HINTS (Head Impulse, Nystagmus and Test of skew) may be of help, also in the acute setting. The test consists of three signs: lack of a corrective saccade on head impulse test, ‘central-type’ nystagmus (direction changing in eccentric gaze) and skew deviation suggests a central cause, including acute stroke.(6) One small study reported that the presence of one of these signs was highly sensitive and specific for acute stroke confirmed later using MRI. (7)
Given that CT scans cannot rule out acute posterior ischaemia and MRI scans may not be easily available, HINTS may aid emergency stroke physicians in diagnosing posterior circulation stroke in patients with acute vestibular syndrome and consequently provide appropriate treatment and diagnostic work-up.
1. Savitz SI, Caplan LR, Edlow JA. Pitfalls in the diagnosis of cerebellar infarction. Academic Emergency Medicine. 2007;14:63-8.
2. Kroenke K, Mangelsdorff AD. Common symptoms in ambulatory care: incidence, evaluation, therapy and outcome. American Journal of Medicine. 1989;86(3):262-6.
3. Newman-Toker DE, Hsieh YH, Camargo CAJ, Pelletier AJ, Butchy GT, al e. Spectrum of dizziness visits to US emergency departments: cross-sectional analysis from a nationally representative sample. Mayo Clin Proc. 2008;83:765-75.
4. Newman-Toker DE. Missed stroke in acute vertigo and dizziness: it is time for action, not debate. Ann Neurol. 2016;79:27-31.
5. Kerber KA, Brown DL, Lisabeth LD, Smith MA, Morgenstern LB. Stroke among patients with dizziness, vertigo, and imbalance in the emergency
department: a population-based study. Stroke. 2006;37(10):2484-7.
6. Kattah JC, Talkad AV, Wang DZ, Hsieh YH, Newman-Toker DE. HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging. Stroke. 2009;40(3504-3510).
7. Chen L, Lee W, Chambers BR, Dewey HM. Diagnostic accuracy of acute vestibular syndrome at the bedside in a stroke unit. J Neurol. 2011;258:855-61.