Ischemic Stroke: This is the most common cause of hemiparesis, resulting from a blockage of blood flow to a part of the brain, leading to tissue damage and loss of motor function on one side of the body.

Intracerebral Hemorrhage: Bleeding within the brain tissue can cause hemiparesis by damaging brain cells and disrupting normal brain function.
Traumatic Brain Injury: A head injury can cause hemiparesis if it results in damage to the motor areas of the brain or the spinal cord.
Brain Tumor: Tumors in the brain, whether benign or malignant, can compress or invade brain tissue, leading to hemiparesis.
Cerebral Vasculitis: Inflammation of the blood vessels in the brain can lead to ischemia or infarction, causing hemiparesis.

Subarachnoid Hemorrhage: Although less common, this condition, often due to an aneurysm rupture, is critical to identify promptly because of its high mortality rate and the need for urgent intervention.
Spinal Cord Compression: Compression of the spinal cord, which can be due to trauma, tumor, or infection, requires immediate attention to prevent permanent damage.
Meningitis or Encephalitis: Infections of the meninges or brain tissue can cause hemiparesis and are medical emergencies due to their potential for severe complications and high mortality if not treated promptly.

Multiple Sclerosis: An autoimmune disease that affects the brain and spinal cord, leading to a wide range of neurological symptoms, including hemiparesis, though it typically presents with more diffuse or multifocal symptoms.
Acute Disseminated Encephalomyelitis (ADEM): A rare autoimmune disease characterized by a sudden, widespread attack of inflammation in the brain and spinal cord, which can cause hemiparesis among other symptoms.
Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes (MELAS): A rare genetic disorder that affects many of the body's systems, particularly the nervous system and muscles, and can cause stroke-like episodes leading to hemiparesis.