Multiple subpial transection was pioneered as an alternative to removal of brain tissue. It is used to control partial seizures originating in areas that cannot be safely removed. For example, if the seizure focus involves the dominant temporal-lobe language area (Wernicke’s area), which is critical for comprehension, the removal of this area to control seizures would cause a devastating complication: the inability to understand spoken or written language. Similarly, if the primary motor area is part of the seizure focus, its removal would cause permanent weakness on the opposite side of the body.
The operation involves a series of shallow cuts (transections) into the cerebral cortex.
The transections are made only as deep as the gray matter, approximately a quarter of an inch deep. Because of the complex way in which the brain is organized, these cuts are thought to interrupt some fibers that connect neighboring parts of the brain, but they do not appear to cause long-lasting impairment in the critical functions served by these areas. Examination of brain tissue after multiple subpial transections reveals that some nerve cells are destroyed.
There may be bleeding at the site of the transection, but the procedure is generally well tolerated. Major complications appear to be rare. Transections in language areas may cause mild impairments in the language function served by that area. The risks and benefits of multiple subpial transections need to be better defined.
Multiple subpial transections can help reduce or eliminate seizures arising from vital functional cortical areas. Transections have been used successfully in Landau-Kleffner syndrome, a disorder in which language problems appear in a child whose language was previously developing normally. One concern is that the epileptic activity may recur after a period of 2 to 20 months. It is uncertain whether this procedure can achieve long-term seizure control.