What Is Multiple Subpial Transection ?

Sometimes brain seizures begin in a vital area of the brain — for example, in areas that control movement, feeling, language, or memory. When this is the case, a relatively new epilepsy treatment called multiple subpial transection (MST) may be an option. MST stops the seizure impulses by cutting nerve fibers in the outer layers of the brain (gray matter), sparing the vital functions concentrated in the deeper layers of brain tissue (white matter).

Multiple subpial transection (MST) is a relatively new treatment for epilepsy that may be an option when seizures begin in an area of the brain that cannot be removed; for example, areas associated with vital brain functions such as movement, sensation, language and memory. MST is based on the fact that normal electrical impulses in the brain generally move in an up-and-down pattern. Seizure impulses, on the other hand, mostly spread in a horizontal (side-to-side) fashion. MST stops the seizure impulses by cutting horizontal nerve fibers in the outer layers of the brain (gray matter), sparing the vital functions concentrated in the deeper layers of brain tissue (white matter).

What Happens Before Surgery ?

Candidates for MST undergo an extensive pre-surgery evaluation – including seizure monitoring, electroencephalography (EEG), magnetic resonance imaging (MRI) and positron emission tomography (PET). These tests help to pinpoint the area in the brain where the seizures occur and determine if surgery is feasible.

Another test to assess electrical activity in the brain is EEG-video monitoring, in which video cameras are used to record seizures as they occur, while the EEG monitors the brain’s activity. In some cases, invasive monitoring-in which electrodes are placed inside the skull over a specific area of the brain also is used to further identify the tissue responsible for seizures.

What Happens During Surgery ?

MST requires exposing an area of the brain using a procedure called a craniotomy. (Crani refers to the skull and otomy means “to cut into.”) After the patient is put to sleep, the surgeon makes an incision (cut) in the scalp, removes a piece of bone and pulls back a section of the dura, the tough membrane that covers the brain. This creates a “window” in which the surgeon inserts his or her surgical instruments. The surgeon utilizes information gathered during pre-surgical brain imaging to help identify the area of abnormal brain tissue and avoid areas of the brain responsible for vital functions.

Multiple subpial transection (MST) is a novel technique in surgery for epilepsy, employed in patients where some or all of the epileptogenic zone cannot be resected because it lies in a vital cortical area. Twenty one patients subjected to MST were reviewed. Eighteen patients had medically intractable epilepsy and three patients had Landau-Kleffner syndrome. Their ages ranged from 6 to 47 (mean 15-9) and duration of epilepsy ranged from 0.33 to 42 (mean 8.6) years. Preoperative MRI showed focal abnormalities in eight cases. Detailed electrophysiological examination was carried out on all patients. Brain resection was performed in addition to MST in 12 patients.

What Are the Side Effects of Surgery ?

The following side effects may occur after surgery, although they generally go away on their own over several weeks : –

• Scalp numbness
• Nausea
• Feeling tired or depressed
• Headaches
• Difficulty speaking, remembering or finding words

What Risks Are Associated With MST ?

The risks associated with MST include : –

• Risks associated with surgery, including infection, bleeding and allergic reaction to anesthesia
• Failure to relieve seizures
• Swelling in the brain
• Damage to healthy brain tissue