Vertigo is a specific type of dizziness characterized by the false sensation that you or your surroundings are spinning or moving. While this disorienting feeling most often arises from a problem in the inner ear, known as peripheral vertigo, it can sometimes be the sole or primary symptom of a much more serious condition. The type of stroke that causes this intense spinning sensation involves the arteries that supply the balance centers of the brain. Understanding this distinction between benign and stroke-related vertigo is a matter of recognizing a medical emergency.
Strokes Affecting Posterior Circulation
The stroke responsible for causing vertigo originates in the body’s posterior circulation, a network of arteries at the back of the brain. This system, also known as the vertebrobasilar system, is formed by the two vertebral arteries that merge to form the basilar artery. This network is responsible for supplying blood to the brainstem, the cerebellum, and the posterior parts of the cerebral hemispheres. A blockage or rupture in any of these vessels results in a Posterior Circulation Stroke (PCS).
These strokes comprise approximately 20 to 25 percent of all ischemic strokes, meaning they are caused by a blockage rather than a bleed. The interruption of blood flow starves the brain tissue of necessary oxygen and nutrients, leading to cell death in the affected areas. Common reasons for this blockage include the buildup of fatty deposits, called atherosclerosis, which narrows the arteries over time. Another frequent cause is an embolism, where a blood clot or a piece of plaque travels from a more distant location and lodges in a smaller posterior artery. When the affected areas are those responsible for processing balance signals, the result is the sudden onset of vertigo.
How Damage to Vestibular Structures Causes Vertigo
The sensation of vertigo from a stroke is a direct consequence of damage to the central vestibular structures located within the brainstem and cerebellum. These structures form the central processing unit for balance and spatial orientation, integrating information from the inner ear, eyes, and body. When a Posterior Circulation Stroke interrupts blood flow to these specific regions, it creates a serious internal mismatch in the brain’s sense of movement.
The vestibular nuclei, situated in the brainstem, are the primary relay stations for signals originating from the inner ear’s balance organs. Damage to these nuclei, or the pathways that connect them, results in a central lesion that the brain interprets as a constant, overwhelming sense of rotation. The cerebellum, particularly the nodulus and uvula, plays a crucial role in adapting and fine-tuning the balance signals.
An infarct, or tissue death, in these cerebellar areas means the brain loses its ability to correctly modulate the vestibular information, leading to severe unsteadiness and persistent vertigo. Essentially, the stroke damages the brain’s internal gyroscope, causing the central nervous system to receive conflicting and corrupted information about the body’s position in space.
Differentiating Stroke Vertigo from Benign Vertigo
For the average person, the challenge lies in distinguishing between benign vertigo, which is usually related to the inner ear, and stroke-related vertigo, which is considered central vertigo. Benign conditions, such as Benign Paroxysmal Positional Vertigo (BPPV), typically cause brief episodes of vertigo triggered by specific head movements. Stroke vertigo, however, is characteristically sudden in onset and constant, lasting for hours or days without relief.
The most important distinction involves the presence of accompanying neurological symptoms, often referred to as “red flags,” which signal a central cause like a stroke. While benign vertigo may feature nausea, stroke vertigo frequently presents with additional deficits that indicate damage beyond the inner ear. These symptoms include a sudden inability to walk or stand without severe unsteadiness, a condition known as truncal ataxia.
Other warning signs that demand immediate medical attention include double vision (diplopia), slurred speech (dysarthria), or a new, severe headache. Vertigo accompanied by any of these focal neurological deficits strongly suggests a Posterior Circulation Stroke affecting the brainstem or cerebellum. Even if vertigo is the only symptom, if it is severe and constant, it may still indicate a small stroke in the cerebellum, highlighting the need for urgent medical evaluation.