Medical Excellence- Issue 1

Posterior fossa strokes may present with AVS mimick- ing vestibular neuritis (or labyrinthitis if auditory symptoms are present) [51]. The prevalence of cerebrovascular disease in patients presenting to the ED with dizziness is 3–6% [1, 2, 13, 23], but among AVS presentations, it is estimated at ~25% [42]. Almost all (96%) are ischemic strokes, rather than hemorrhag- es [42, 45]. CT sensitivity for acute ischemic stroke is low and probably worse in the posterior fossa [52–54]. Therefore, CT cannot “rule out” ischemic stroke in AVS, a fact often contrib- uting to misdiagnosis [5, 39, 46]. Importantly, even MRI with diffusion-weighted imaging (DWI) misses 10–20% of strokes in AVS during the first 24–48 h after symptom onset, and repeat delayed imaging (3–7 days post symptom onset) may be required to confirm the presence of a new infarct [42, 55, 56]. Fortunately, the physical examination can help make the distinction between vestibular neuritis and posterior circula- tion stroke with greater sensitivity than early MRI [55, 56]. These two studies were done by neuro-otologists performing a targeted ocular motor exam consisting of three components— the head impulse test (HIT), testing for nystagmus, and skew Table 3: Timing- and trigger-based“vestibular a syndromes ” in acute dizziness b . Syndrome Description Common causes AVS Rapid onset of acute dizziness that lasts days, often associated with nausea, vomiting, and head-motion intolerance Benign: vestibular neuritis and labyrinthitis Serious: cerebellar stroke t-EVS c Episodic dizzy episodes triggered by some specific obligate event, usually head movement or standing up and usually lasts less than 1 min Benign: BPPV Serious: orthostatic hypotension and CPPV s-EVS Episodic dizzy episodes that occur spontaneously are not triggered and usually last minutes to hours Benign: vestibular migraine, Meniere’s disease Serious: TIA CVS Chronic dizziness lasting weeks to months (or longer) Benign: medication side effects, anxiety, and depression Serious: posterior fossa mass AVS acute vestibular syndrome, t-EVS triggered vestibular syndrome, s-EVS spontaneous vestibular syndrome, BPPV benign paroxysmal positional vertigo, CPPV central paroxysmal positional vertigo, TIA transient ischemic attack, CVS chronic vestibular syndrome a Note that the use of the word“vestibular”here connotes vestibular symptoms (dizziness or vertigo or imbalance or light-headedness), rather than that the underlying causes is necessarily vestibular b This table lists the more common causes of these presenting syndromes and is not intended to be encyclopedic c Dizziness is“triggered”when it is brought on from a baseline of no symptoms, as in positional vertigo due to BPPV. This must be distinguished from dizziness that is “exacerbated”from a milder baseline state; such exacerbations are common in AVS, whether peripheral (neuritis) or central (stroke) 110 History & exam suggest a non- neurologic general medical cause? Is the dizziness triggerable? Has the dizziness been continuously present & persists at time of evaluation? Use physical exam to distinguish vestibular neuritis from stroke* Use history to distinguish vestibular migraine from TIA* Use physical exam to distinguish BPPV from CPPV and orthostatic hypotension* *For each vestibular syndrome, only the most common benign and dangerous diagnoses are listed Evaluate & treat presumed diagnosis Diagnostic “STOP” Pathologic nystagus? Arm dysmetria? Truncal ataxia sitting up? Yes Yes Yes Yes No No No No AVS s-EVS t-EVS ATTEST: Diagnostic Approach to the Acutely Dizzy Patient • • • Table 6.3 Timing- and-trigger-based “vestibular a syndromes” in acute dizziness b Syndrome Description Common causes AVS Rapid onset of acute dizziness that lasts days, oft n associated with naus a, vomiting, and head-motion intolerance Benign: vestibular neuritis and labyrinthitis Serious: cerebellar stroke t-EVS c Episodic dizzy episodes triggered by some specific obligate event, usually head movement or standing up and usually last less than 1 min Benign: BPPV Serious: orthostatic hypotension and CPPV s-EVS Episodic dizzy episodes that occur spontaneously are not triggered and usually last minutes to hours Benign: vestibular migraine, Meniere’s disease Serious: TIA CVS Chronic dizziness lasting weeks to months (or longer) Benign: medication side effects, anxiety, and depression Serious: posterior fossa mass AVS acute vestibular syndrome, t-EVS triggered vestibular syndrome, s-EVS spontaneous vestibu- lar syndrome, BPPV benign paroxysmal positional vertigo, CPPV central paroxysmal positional vertigo, TIA transient ischemic attack, CVS chronic vestibular syndrome a Note that the use of the word “vestibular” here connotes vestibular symptoms (dizziness or vertigo r imbalance or light-headedness), rather than that th underlying causes is necessarily vestibular b This table lists the more co mon causes of these presenting syndromes and is not intended to be encyclopedic c Dizziness is “triggered” when it is brought on from a baseline of no symptoms, as in positional vertigo due to BPPV. This must be distinguished from dizziness that is “exacerbated” from a milder baseline state; such exacerbations are common in AVS, whether peripheral (neuritis) or central (stroke) J.A. Edlow History & exam suggest a non- neurologic general medical cause? Is the dizziness triggerable? Has the dizziness been continuously present & persists at time of evaluation? Use physical exam to distinguish vestibular neuritis from stroke* Use history to distinguish vestibular migraine from TIA* Use physical exam to distinguish BPPV from CPPV and orthostatic hypotension* *For each vestibular syndrome, only the most common benign and dangerous diagnoses are listed Evaluate & treat presumed diagnosis iagnostic “STOP” Pathologic nystagus? Arm dysmetria? Truncal ataxia sitting up? Yes Yes Yes Yes No No No No AVS s-EVS t-EVS ATTEST: Diagnostic Approach to the Acutely Dizzy Patient • • • Table 6.3 Timing- and-trigger-based “vestibular a syndromes” in acute dizziness b Syndrome Description Common causes AVS Rapid onset of acute dizziness that lasts days, often associated with nausea, vomiting, and head-motion intolerance Benign: vestibular neuritis and labyrinthitis Serious: cerebellar stroke t-EVS c Episodic dizzy episodes triggered by some specific obligate event, usually head movement or standing up and usually last less than 1 min Benign: BPPV Serious: orthostatic hypotension and CPPV s-EVS Episodic dizzy episodes that occur pontaneou ly are not triggered and usually last minutes to hours Benign: vestibular migraine, Meniere’s disease Serious: TIA CVS Chronic dizziness lasting weeks to months (or longer) Benign: medication side effects, anxiety, and depression Serious: posterior fossa mass AVS acute v stibular syndrome, t-EVS triggered vestibular syndrome, s-EVS spontaneous vestibu- lar syndrome, BPPV benign paroxysmal positional vertigo, CPPV central paroxysmal positional vertigo, TIA transient ischemic attack, CVS chronic vestibular syndrome a Note that the use of the word “vestibular” here connotes vestibular symptoms (dizziness or vertigo or imbalance or light-headedness), rather than that the underlying causes is necessarily vestibular b This table lists the more common causes of these presenting syndro es and is not intended to be encyclop dic c Dizziness s “triggered” when it is b ough on from a baseline of n symptoms, as in positional vertigo due to BPPV. This must be disting is ed fr dizziness that i “exacerb ted” from milder baseline state; such exacerbations are common in AVS, whether peripheral (n uritis) or central (strok ) History and exam su gest a non- r l i r l i l I i i i l H s t e dizzi s continuously re ent and persis s at tim f evaluation? Use physical t i tingui ti l iti f t Use history to i ti ui ti l i i f I Use physical exam to istingui h BPPV from t t ti t i Eval at and treat presumed diagnosis Di no i t logi t mus ? r y tri Truncal ataxia i i Yes o t VS 6  |  Issue-1 MEDICAL EXCELLENCE