Signs of loss of function include:

• Confusion or altered behavior, such as the inability to become fully roused from sleep or unusually aggressive or combative behavior.
• Dizziness (vertigo) or loss of balance with nausea or vomiting.
• Fainting or loss of consciousness.
• Inability to speak, difficulty speaking, or difficulty understanding speech.
• Numbness, loss of all feeling, or inability to move (paralysis) part or all of one side of the body (face, arm, and leg).
• Sudden dimness, blurring, loss of vision in one or both eyes, or double vision.
• Sudden unsteadiness that prevents walking or standing (ataxia).

Brief periods of muscle weakness are common, especially after a strenuous workout. This type of muscle weakness usually only means that you have overexerted yourself. It is not a cause for concern as long as you are able to move all parts of your body and complete your normal daily activities, even if you have to work a little harder to get things done.

True muscle weakness means that your ability to move your muscles is decreased regardless of how hard you try to move them. True muscle weakness that occurs in one area of your body along with a loss of function, even for a few minutes, may be caused by decreased blood flow to the brain.

Headache accompanied by loss of function, even for a few minutes, may mean a decrease in blood flow to the brain. These symptoms may occur before a:

• Stroke, which can cause progressive and permanent loss of function. Call 911 or other emergency services immediately if you suspect a stroke is occurring.
• Transient ischemic attack (TIA), which causes a brief and temporary loss of function.
• Migraine headache.

Prompt medical attention is required for individuals with a headache and signs of loss of function, even if the loss of function was brief and temporary.