Agnosia is loss of the ability to identify objects using one or more of the senses.
Agnosia is relatively rare. Agnosia is caused by damage to the parietal, temporal, or occipital lobe of the brain. These areas store memories of the uses and importance of familiar objects, sights, and sounds and integrate memory with perception and identification. Agnosia often occurs suddenly after a head injury or stroke. Usually, only one sense is affected.
Symptoms vary depending on the lobe that is damaged:
Doctors ask the person to identify common objects by sight, touch, or another sense. Doctors also do a physical examination to determine whether symptoms are caused by another disorder such as an eye or a hearing disorder.
Certain standardized tests of brain function (neuropsychologic testing) may be done. These tests may involve questions and/or requests to do specific movements.
Imaging tests, such as computed tomography (CT) or magnetic resonance imaging (MRI), are done. Other tests may be done depending on the suspected cause.
Some people with agnosia improve or recover spontaneously. Others may benefit from speech and occupational therapy, which can help them learn to learn to compensate for their impairments. No specific treatment exists.
Last full review/revision October 2013 by Juebin Huang, MD, PhD