THE KINDS OF SEIZURE: GENERALIZED SEIZURES – OTHER AREAS OF THE BRAIN THE OCCIPITAL LOBES AND PARIETAL LOBES
Posted by adminThe temporal lobes and the frontal lobes are the most important in a discussion of epilepsy because they are most “epileptogenic.” We don’t know why.
Scars, tumors, and other damage in the temporal and frontal lobes of the brain are much more likely to be accompanied by seizures than damage to the occipital lobes or parietal lobes. However, just for completeness, we will briefly discuss these areas as well.
The primary function of the occipital lobe, located in the back of the brain, is vision. Messages from the retina (the back of the eyeball) are transmitted by way of the optic (eye) nerves and by a pathway (the optic radiation) to the occipital lobe, where vision is registered by the brain. Objects off to your left side (when you look straight ahead) are “seen” by the right side of your retina and proceed along the path to the right side of your brain. Objects on your right (when you look straight ahead) go to the left side of your brain. Vision is complex, and when one stimulates the occipital cortex electrically, the patient sees only bright lights in a random pattern. When a seizure begins in the occipital lobe—which is not common—flashing bright lights may be experienced off to the left side, if it occurs in the right cortex, or to the left side if the right cortex is involved.
The parietal lobe is where “it” all comes together, where much of what we sense by vision or touch achieves meaning. Here, those flashing lights become patterns constituting a formed visual image; through interconnections with the frontal lobe (where memories are stored), we are able to store the images as memories or to recall the formed image as recognized faces or scenes. The posterior temporal-parietal lobe is the site where sounds heard become the pattern of words, which are recognized and remembered or given meaning by association with prior experiences stored in the frontal lobes. It is where speech that is heard becomes speech that is understood and where the sense of touch and feel of a particular object is identified as a key, a ball, or a block. Thus, the parietal lobe is called “the association cortex.” It is rarely the source of seizures and seems to play little role in our understanding of the types of epilepsy. It is not, in other words, very “epileptogenic.”
This basic and simplified lesson in anatomy should provide a better understanding of the many variations of partial seizures discussed below.
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