Areas of the frontal lobes other than the motor strip are less well defined; they have to do with personality, memory, anxiety, alertness, and awareness. With many connections to the temporal lobes, it is often difficult to determine from the way the seizure looks whether the function (or the dysfunction of seizures) comes from the frontal or the temporal lobes. Some areas near the “motor strip” (supplementary motor area) seem to control the coordination of movements of groups of muscles. Electrical stimulation of the supplementary motor area (or seizures) thus may cause the eyes, head, and body to turn away from the side stimulated. Other seizures originating here may appear to cause a brief staring and loss of awareness before some of the stereotyped seizures called complex partial seizures appear.*67\208\8*
Another type of operation is sometimes considered for someone who has very severe epilepsy in which the seizures arise all over the brain and cause ‘drop attacks’ during which they may be badly hurt. This is callosotomy, an operation to cut, either partially or completely, the nerve tracts (corpus callosum) that connect the two halves of the brain. Occasionally the operation is also offered to people with severe partial complex seizures.
Usually about a third of the corpus callosum is cut to begin with. If this does not prove successful, another third of the fibres will be cut, and finally a total split may be made.
Success of callosotomy
Callosotomy will not end the seizures, but it will change their nature. The operation will stop the seizures spreading from one side of the brain to the other, which in turn will help prevent the drop attacks. Between 65 and 100 per cent of patients have at least a 50 per cent reduction in drop attacks, rising to nearer 100 per cent some time after the operation.
Some patients are mute for a few days after the operation, but, perhaps surprisingly, it has been found that full callosotomy proves to be no more of a disadvantage to the patient than partial callosotomy. There may be some unwanted effects, for example a lack of co-ordination between the two hands.