Stroke vs. Vestibular Disorder
As a note, if you are experiencing symptoms of a stroke, please dial 911. If you are unsure, use the acronym B.E.F.A.S.T.
Balance: Are you unable to walk without assistance when you were able to before the onset of symptoms?
Eyes: Double vision? Unable to see clearly?
Face: Facial drooping?
Arms: Arm or leg weakness?
Speech: Slurred speech or unable to articulate what you want to say? Or unable to understand speech?
Time: Get to the hospital as soon as possible. If you are appropriate for tPA medication, it can greatly reduce the long term consequences of a CVA, but it needs to be administered within 3 hours after onset of symptoms.
A stroke or cerebral vascular accident (CVA) is where there is either a blood clot (ischemic) or bleed (hemorrhagic) in the brain preventing blood from getting to a certain area. If there is no blood supply to these cells then they start to die off, interrupting connections that control our bodies such as muscle movements, speech, thought, etc.
Sometimes it can be difficult to discern whether someone is experiencing a CVA or a vestibular dysfunction, especially if the CVA is involving the posterior cerebral artery. About 25% of all CVA’s involve the posterior cerebral artery (1). B.E.F.A.S.T can help with diagnosing most CVA’s but is not as helpful with posterior circulation strokes, as dizziness is not included in the acronym but can be a symptoms of this type of stroke.
What can we do to determine if someone experiencing dizziness may have a stoke or peripheral vestibular dysfunction?
The HINTS (Head Impulse-Nystagmus-Test of Skew) can help differentiate.
If you have acute vestibular syndrome (vertigo, nystagmus, nausea/vomiting, head-motion intolerance, unsteady gait) and symptomatic at rest or with looking to the side (with your eyes), then you may be appropriate for this test.
Head Impulse test is used to determine how well the vestibular ocular reflex (VOR) is functioning. This can be a reflection of whether the vestibular nerve has been affected. The vestibular system has a reflex with the eyes, when you move your head quickly the vestibular system detects it, sends a signal to your eyes to move the opposite direction, keeping your eyes on target. It acts like a camera stabilizer. If you have a vestibular neuritis or hypofunction and the nerve has been weakened, the reflex will not function as well as it should, resulting in your eyes moving with your head before they come back to the target. This would be a positive test and be an indication that you are not having a CVA. If you are dizzy and your head impulse test is normal (eyes staying on target when head moves quickly), your vestibular system is most likely functioning appropriately and a CVA needs to be considered.
Nystagmus in acute vestibular dysfunctions will be seen beating to one side. One side of your vestibular system is weakened, the intact side is sending a stronger signal, pulling your eyes toward the intact side. This is often why people experience a spinning sensation and constant dizziness with a vestibular neuritis. With a vestibular neuritis, the nystagmus will be beating one direction no matter where you are looking, although it will be stronger when looking toward the intact side and the nystagmus will be weaker when looking away from the intact side. If you are having nystagmus that changes directions (beats to the left when looking left, beats to the right when looking right), it can be another indication that you may be experiencing a CVA.
Test of skew is looking at whether there is a vertical deviation of the eyes when covering one eye and uncovering it, or when covering one eye and moving to cover the other. If you see one eye is vertically lower or higher than another and corrects when uncovered, this is the last indication of HINTS that you may have CVA instead of a vestibular dysfunction.
