A stroke occurs when blood flow to a part of the brain is disrupted, leading to the rapid death of brain cells. While many people associate a stroke with sudden weakness or difficulty speaking, dizziness is a less-recognized symptom. Although dizziness is a common complaint, its sudden appearance can signal a serious neurological event. A stroke involving the brain’s balance centers can manifest with severe dizziness, making it a warning sign that should never be ignored.
Dizziness as a Standalone Stroke Sign
A stroke can cause dizziness, sometimes without the classic signs seen in other types of strokes. This typically occurs with a posterior circulation stroke, which affects the arteries supplying the back of the brain. These strokes account for approximately 20% of all strokes and present with distinct symptoms compared to strokes in the front of the brain.
In posterior circulation strokes, the symptoms can be subtle, with dizziness being the primary or isolated complaint. Dizziness or vertigo is a presenting symptom in a large percentage of these patients.
When dizziness is due to a stroke, it is typically sudden and severe, marking a distinct change from any previous experience. This suddenness is a red flag, particularly for individuals with risk factors like high blood pressure or diabetes. Approximately 25% of patients may experience dizziness or unsteadiness as an isolated symptom, which is why it is often misdiagnosed as a benign inner ear issue.
Identifying Concerning Types of Dizziness
The quality of dizziness provides important clues to distinguish a benign inner ear problem from a stroke. Stroke-associated dizziness is usually described as either vertigo or disequilibrium. Vertigo is the sensation of spinning, where you or the room is moving, and it can be accompanied by severe nausea and vomiting.
Disequilibrium is a severe feeling of unsteadiness or imbalance, where the person feels unable to walk straight or maintain posture. This unsteadiness is often so severe that they cannot walk or even sit up without falling.
A key difference between stroke-related dizziness and common inner ear problems, such as Benign Paroxysmal Positional Vertigo (BPPV), is the sudden onset and constant nature of the stroke symptoms. Benign causes like BPPV typically cause brief episodes of vertigo triggered by specific head movements and often involve associated ear symptoms like ringing or hearing loss. In contrast, stroke-related dizziness is sudden, unrelenting, and often lacks a prior history of ear issues. Concerning signs that point toward a stroke include the sudden onset of double vision, slurred speech, or an inability to walk or stand.
How Stroke Affects Balance Centers in the Brain
The mechanism behind stroke-induced dizziness relates directly to the brain structures that control balance and spatial orientation. The two main areas involved are the cerebellum and the brainstem, both supplied by the posterior circulation. The cerebellum is located at the back of the head and is responsible for fine-tuning movement, coordination, and maintaining balance.
A stroke that blocks blood flow to the cerebellum can lead to a loss of coordination, known as ataxia, which manifests as severe unsteadiness and an inability to walk a straight line. The brainstem controls basic life functions, including relaying sensory information about balance from the inner ear to the rest of the brain.
Damage to the brainstem can profoundly disrupt these sensory pathways, causing severe and persistent vertigo. When blood supply is compromised, the brain loses its ability to accurately process and coordinate sensory input from the eyes, inner ear, and muscles. This mismatch of sensory information leads to the severe symptoms of vertigo and disequilibrium. Strokes in the brainstem are dangerous because this structure also controls breathing and heart rate.
Immediate Action and Associated Stroke Symptoms
If sudden and severe dizziness occurs, especially if accompanied by other neurological symptoms, immediate medical attention is necessary. The response must be guided by the possibility of a stroke, even if the symptoms are atypical. Calling emergency services immediately is the most important step, as time is a factor in minimizing brain damage.
While dizziness can be an isolated symptom, it is helpful to look for other associated signs that are more commonly recognized as a stroke. The acronym F.A.S.T. remains a reliable tool for recognizing these symptoms.
F stands for Face drooping, which is seen when one side of the face is numb or droops unevenly. A is for Arm weakness, where one arm may drift downward when a person attempts to raise both. S represents Speech difficulty, including slurred speech or trouble understanding simple sentences. T emphasizes Time to call emergency services, noting the exact time symptoms began. Even if dizziness is the only symptom, if it is sudden, severe, and prevents normal activity, it should be treated with the same urgency as the more classic signs.