Book T of C
Chap T of C
This is the 2007 version. Click here for the 2017 chapter 02 table of contents.
Epilepsy has intrigued scientists for thousands of years because of the mental phenomena associated with it. Seizures involve intense activity in brain tissue. The area can be quite localized, in which case the seizures are said to be "focal." A person with seizures of this type may have petit mal (literally "small sickness") epilepsy , characterized by brief periods of absence of thought, or trembling of a limb, or other minor symptoms. If seizures spread to the whole brain, a person has so-called grand mal ("large sickness") seizures, characterized by strong muscular convulsions and a period of unconsciousness.
What is the Rolandic March?
Seizures beginning in motor cortex may announce themselves through a trembling of the arm or a march of activity from the fingertips up through the hand, elbow, and arm. This is called the Rolandic March because it follows the Rolandic fissure on the cortex, where the body image or homunculus is represented on the sensory and motor cortex. The Rolandic March is relatively rare; it occurs only if seizure activity spreads slowly through hand, elbow, and arm areas of motor cortex.
Seizures beginning in visual cortex give rise to glowing dots. Seizures in the area of cortex that process complex visual pattern recognition (the inferotemporal cortex) can produce complex visual hallucinations. In general, the symptoms produced by seizure activity depend upon the area of the brain involved. This makes the symptoms of seizures informative to neuropsychologists.
What is a prodrome? What are some exotic auras and some common auras?
Sometimes a distinctive feeling of some kind, known as an epileptic aura or prodrome signals the beginning of a seizure. If so, an epileptic person can sometimes use the information to ward off the impending seizure by relaxing. Occasionally patients have exotic prodromes. Horowitz and colleagues (1968) described a patient who characteristically saw "pigs walking upright, like people" before a seizure. One student reported that her mother's seizures always began the same way: "She said she would start hearing a song and couldn't get it out of her head." More common auras are odors, flashing lights, feelings of dread, nausea, dizziness, and weakness in limbs. These symptoms are identical to the results of direct brain stimulation in Penfield's studies, described earlier.
What is micropsia? Macropsia? Déjà vu?
Micropsia -a common aura-is a sudden feeling that things look very far away and small, or the environment is moving away into the distance. The opposite feeling is macropsia, which occurs when things suddenly look very large, or the environment looks like it is coming closer with jerky movements. Some students are shocked to realize this phenomenon is familiar. One asked, "Does this mean there is something wrong with me?" Probably not. Normal people experience almost all the common types of auras occasionally.
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Copyright © 2007-2011 Russ Dewey