What arm goes numb during a stroke
Pro Research Analysisby 
Searched over 200M research papers
Consensus Meter
Numbness in the Arm During a Stroke: Key Insights
Right Hemisphere Stroke and Left Arm Numbness
One of the most common presentations of a stroke affecting the right hemisphere of the brain is numbness and weakness in the left arm. This is due to the fact that each hemisphere of the brain controls the opposite side of the body. For instance, a case study described a woman in her 60s who experienced acute onset numbness and weakness in her left arm and leg, which was later confirmed to be due to a right middle cerebral artery territory infarction.
Pure Sensory Stroke and Hemisensory Symptoms
In some cases, strokes can present as pure sensory strokes, where the symptoms are limited to sensory loss without affecting motor functions. This can include numbness over one entire side of the body, including the face, arm, and leg. Such cases highlight that numbness can be a significant symptom of a stroke, affecting one side of the body depending on the location of the brain lesion.
Hemiplegic Arm and Sensory Symptoms
Post-stroke, some patients report a sensation of coldness in the hemiplegic arm, which is often associated with numbness and color changes. This symptom can be distressing and is sometimes linked to conditions like reflex sympathetic dystrophy (RSD). A study found that 53% of stroke patients experienced unilateral coldness in the hemiplegic arm, with numbness being a common associated symptom.
Electrical Injury and Stroke-Like Symptoms
Interestingly, stroke-like symptoms, including numbness in the arm, can also result from non-stroke events such as electrical injuries. For example, a 37-year-old man experienced global numbness and clumsiness in his left arm and numbness on the left side of his face after an electrical injury, which initially mimicked stroke symptoms.
Stroke Mimics and Post-Vaccination Symptoms
In rare cases, stroke-like symptoms can occur due to other medical events. For instance, a 24-year-old woman experienced left hemiparesis and numbness in her left arm and leg shortly after receiving a COVID-19 vaccination. Although initial symptoms suggested a stroke, further imaging studies ruled out an ischemic event, indicating that other mechanisms, such as cortical spreading depression, might be responsible.
Conclusion
Numbness in the arm during a stroke typically affects the side opposite to the brain hemisphere where the stroke occurs. Right hemisphere strokes often result in left arm numbness. Pure sensory strokes can also present with numbness on one side of the body, including the arm. Additionally, post-stroke symptoms like coldness and numbness in the hemiplegic arm are common and can be distressing. It is crucial to differentiate between true strokes and stroke mimics, as similar symptoms can arise from other causes such as electrical injuries or post-vaccination reactions.
Sources and full results
Most relevant research papers on this topic