Gray matter heterotopia

Gray matter heterotopia is a neurological disorder caused by gray matter being located in an atypical location in the brain.

Grey matter heterotopia is characterized as a type of focal cortical dysplasia. The neurons in heterotopia are otherwise healthy; nuclear studies have shown glucose metabolism equal to that of normally positioned gray matter. The condition causes a variety of symptoms, but usually includes some degree of epilepsy or recurring seizures, and often affects the brain's ability to function.

Symptoms vary in severity; the condition is occasionally discovered as an incidentaloma when brain imaging performed for an unrelated problem and has no apparent ill effect on the patient. In other cases, heterotopia can result in severe seizure disorders, loss of motor skills, and intellectual disability.

Background

During fetal development, neural matter originates in the outer, ectodermic layer of the gastrula; thus, it originates from the cell layer primarily responsible for skin, hair, nails, etc., rather than from the layers that develop into other internal organs. The nervous system originates as a tiny, simple open tube called the neural tube; the front of this tube develops into the brain (and retinas of the eye), while the spinal cord develops from the very back end.

Neurons begin to form early, but most of them become structural rather than active nerve cells. The brain generally forms from the inside-out, especially in the case of the neocortex.