A stroke occurs when blood flow to a specific area of the brain is interrupted, either by a blockage (ischemic) or a burst blood vessel (hemorrhagic). This interruption causes brain cells to quickly die from lack of oxygen. The brain is functionally divided into two cerebral hemispheres, the left and the right. Damage to one hemisphere typically affects the motor and sensory functions of the opposite side of the body, and each side manages distinct cognitive functions.
Symptoms Following a Left Hemisphere Stroke
A stroke in the left hemisphere primarily affects the right side of the body due to the brain’s cross-wired structure. This damage often results in right-sided weakness (hemiparesis) or paralysis (hemiplegia) of the arm, leg, and face. Patients may also experience a loss of sensation on the right side, along with vision problems affecting the right visual field.
The defining characteristic of a left-sided stroke is a disturbance in language, known as aphasia, as language centers are typically located here. Aphasia can manifest as difficulty producing speech (expressive) or problems understanding language (receptive). Since the left hemisphere handles logical and analytical skills, patients may also struggle with calculation, reasoning, and complex problem-solving.
The patient’s behavior often reflects a cautious and hesitant approach to tasks. This cognitive effect means they may take longer to process information and initiate actions.
Symptoms Following a Right Hemisphere Stroke
A stroke in the right hemisphere affects the left side of the body, leading to weakness (hemiparesis) or paralysis (hemiplegia). The effects center on non-verbal and spatial perception, causing issues with visual awareness, such as difficulty recognizing faces or interpreting visual cues.
A common symptom is spatial neglect, where the person ignores or is unaware of stimuli on their left side, opposite the injury. This may manifest as only eating food from the right side of a plate or neglecting to dress the left side of the body. Patients also have difficulty interpreting the emotional tone of speech (prosody), meaning they may not understand emotion based on voice.
Behaviorally, patients often display poor judgment and impulsivity. They may attempt activities they cannot safely manage, compounded by anosognosia—a lack of awareness or denial of their physical deficits.
Strokes Outside the Cerebral Hemispheres
While most strokes occur in the cerebral hemispheres, some affect smaller, deeper structures like the brainstem or cerebellum. Brainstem strokes are particularly severe because this area controls vital functions like breathing, heart rate, and consciousness. Symptoms often include profound balance and coordination problems, dizziness, vertigo, and difficulties with swallowing and speaking.
In severe cases, a brainstem stroke can result in “locked-in syndrome,” where a person is fully conscious but cannot move any part of their body except for their eyes. A cerebellar stroke affects the cerebellum, which controls fine motor control and coordination. Damage here leads to pronounced issues with balance, unsteady walking, and a lack of muscle coordination (ataxia).
How Stroke Location Impacts Rehabilitation Strategy
For individuals recovering from a left hemisphere stroke, the primary therapeutic challenge is aphasia, requiring intensive speech-language pathology sessions. Therapists help patients relearn language comprehension and expression. The patient’s cautious behavioral style can sometimes be an advantage for learning new motor skills methodically.
Rehabilitation for a right hemisphere stroke focuses heavily on safety and managing cognitive-perceptual deficits. Occupational and physical therapists constantly address spatial neglect, often using visual cues and verbal reminders to encourage the patient to attend to their left side. Interventions are designed to mitigate the effects of impulsivity and poor judgment by establishing structured, predictable routines to prevent falls and accidents.