The key facts

  • In right-handed people, a left-hemisphere stroke is more often accompanied by speech impairments and weakness of the right limbs
  • Right-hemisphere damage affects spatial perception and the left side of the body
  • The prognosis is determined by the size of the lesion and the timeliness of treatment, not by the side of the damage

Symptoms depend on which hemisphere is affected

The side of the stroke affects which symptoms a person develops, because each hemisphere of the brain is responsible for specific functions. This was discussed with Gazeta.Ru by Artem Tolmachev, an associate professor at the Department of Neurology, Neurosurgery and Medical Genetics named after Badalyan at the Institute of Neuroscience and Neurotechnologies of Pirogov University.

How left- and right-hemisphere damage differs

According to the physician, a stroke in the left hemisphere in many right-handed people may be accompanied by impaired speech, comprehension of spoken words, reading and writing, often together with weakness or complete loss of movement in the right limbs. When the right hemisphere is affected, spatial perception, orientation, attention to one side of space and the ability to critically assess one's own limitations may suffer; motor impairments in this case more often affect the left side of the body. Tolmachev emphasized that these differences are important for diagnosis and rehabilitation, but do not mean that damage to one hemisphere is always more dangerous than the other.

What determines the severity of the outcome

The physician named the key factor in the prognosis not the side of the damage: a large stroke in either hemisphere can lead to severe disability or death, whereas a relatively small lesion with timely treatment may have a more favorable outcome. The practical significance of this distinction of symptoms is that the nature of the impairments — speech-related with weakness on the right, or spatial with weakness on the left — helps determine which hemisphere is affected and build an appropriate rehabilitation plan. The article is supplemented with a link to an earlier publication in which neuroscientists explained why the right hemisphere controls the left side of the body.