Craniotomy for Epileptic Focus

In partial onset (focal) epilepsy, seizures tend to start in the same place in the brain time after time, and we refer to this spot as an “epileptic focus.” Much of the preoperative testing we perform for epilepsy surgery is to help identify where in the brain a patient’s epileptic focus is, and whether it is safe to remove it.

A craniotomy for an epileptic focus is a procedure in which the abnormal brain tissue causing seizures is removed (resected) to try to prevent future seizures.

A craniotomy is a procedure in which an opening is made in the skull with a high-speed drill to reach the brain. The piece of bone that is removed is usually replaced at the end of surgery and secured with tiny titanium plates and screws that are not visible from the outside.

Resection is considered in patients with drug-resistant epilepsy when there is a single epileptic focus and the risks of removing it are acceptable.

Before surgery, we work to find the focus and to make sure that removing it is safe. Testing generally includes a video EEG, a brain MRI, a PET scan, and neuropsychological testing, and sometimes SEEG. I review each case with the epilepsy team, and I will meet you in the office to discuss the benefits, risks, and alternatives. It is helpful to bring a family member.

Craniotomy is a versatile tool that can be customized and used for epileptic foci all over the brain. Here are some examples.

• Anterior temporal lobectomy, which removes part of the temporal lobe.
• Craniotomy for brain tumor/lesion that is causing seizures, such as a cavernous malformation or developmental anomaly.

My philosophy is to use the smallest possible craniotomy to safely achieve the goals of surgery. Smaller craniotomies are less invasive and easier to recover from. Ultimately, the driving factor is safety.

I use a variety of advanced technologies during craniotomies for epilepsy, including 3D navigation, microscopy, electrocorticography, intraoperative ultrasound, and motor mapping. When the epileptic tissue is close to an area that controls speech, movement, vision, or memory, we plan carefully to protect these functions, or I consider alternatives such as RNS/NeuroPace. Some resections may require awake speech mapping.

• For more detail about preparing for surgery and recovering afterward, please see my patient guide for resection.
• Most resections are performed with you asleep, under general anesthesia, and the operation takes 1-2 hours.
• After surgery, you will recover in the neurologic intensive care unit. Most patients stay in the hospital 1-2 nights.
• We will not reduce your anti-seizure medications for 6-12 months. After that, we may be able to reduce your medications under the guidance of your neurologist.

If the brain tissue in the epileptic focus is also important for normal function, or if seizures begin in more than one place, a resection may not be the right choice. Alternatives include neuromodulation with responsive neurostimulation (NeuroPace), deep brain stimulation, or vagus nerve stimulation. Deep and small lesions may be best treated with laser ablation. I will go over the options that make sense for you at your visit. There are usually several reasonable options for each patient.

The greatest risk of a craniotomy for epileptic focus is that the seizures are not entirely eliminated, which is why there is such careful and extensive preoperative testing. Other general risks of craniotomy include infection or an issue with wound healing, bleeding, spinal fluid leak, and new neurologic problems.

The risk of neurologic deficits or problems depends on where the epileptic focus is. After a temporal lobectomy, for example, memory can worsen, and a small area of peripheral vision is lost. Careful testing before surgery helps contextualize and minimize such risks. I will review the pertinent risks specific to you before your surgery.