Signs of loss of function include:

• Confusion or altered behavior, such as the inability to fully wake a person from sleep, or unusually aggressive or combative behavior.
• Dizziness (vertigo) or loss of balance that occurs with nausea or vomiting or that prevents standing or walking.
• Fainting (syncope) or loss of consciousness.
• Headache that is severe and in a specific area without another apparent cause.
• Inability to speak, difficulty speaking, or difficulty understanding speech.
• Numbness, loss of all feeling, or inability to move (paralysis) in part or all of one side of the body, such as the face, an arm, or a leg.
• Sudden inability to walk or stand or difficulty walking or standing (ataxia).
• Vision problems, such as double vision or sudden dimness, blurring, or loss of vision in one or both eyes.