Anterior Temporal Lobectomy Health Article

Definition

An anterior temporal lobectomy (ATL) is the complete removal of the anterior portion of the temporal lobe of the brain.

Purpose

ATL surgery has been recognized as an efficient treatment option for certain types of seizures in patients diagnosed with temporal lobe epilepsy (TLE). Characterized by transient disturbances of brain function and seizures, TLE is the most common form of epilepsy. ATL is optimal for patients with seizures that do not respond to medications, patients who are unable to tolerate medication side effects, or patients with seizures caused by structural abnormalities in the brain.

Demographics

Epilepsy is the most common serious neurological condition in the United States. Its incidence is greatest in young chidren and in the elderly, with five to 10 cases diagnosed per 1,000. The lifetime prevalence amounts to 2–5% of the population. Epilepsy is slightly more common in males than females. The frequency of seizure activity in the epileptic population is as follows.

• 33% have less than one seizure per year
• 33% have one to 12 seizures per year
• 33% have more than one seizure per month
• 60% also have other neuropsychiatric problems

Description

ATL surgical procedures:

• Anesthesia. The patient is anesthetized with a combination of drugs that achieves a state of unconsciousness.
• Preparation of the surgical field. An antiseptic solution is applied to the patient's scalp, face, and neck. Surgical drapes are placed around the surgical region to maintain a sterile surgical field.
• Temporal incision. Using a scalpel blade, the neurosurgeon makes an incision in the skin and muscle of the temporal region of the head located on the side of the head above the ear, and pulls away the flap of scalp.
• Control of bleeding. Blood obstructing the surgeon's view of the surgical field is irrigated and suctioned away as surgery proceeds.
• Craniotomy. Using a high-speed drill, the neurosurgeon removes a section of bone (bone flap) from the skull and makes an incision through the protective membranes of the brain (dura) in order to expose the temporal lobe.
• Removal of the anterior lobe. Using an operating microscope to enlarge the features of the surgical area, the neurosurgeon removes the temporal anterior lobe.
• Closure. Once bleeding is under control, every layer of tissue cut or divided to reach the surgical site is closed. The cavity is irrigated completely and the dura is closed in a watertight manner using tack-up sutures. The bone flap is returned into place. Muscle and tissues are closed with sutures, while the skin is closed with staples. No drain is needed.

Diagnosis/Preparation

An ATL pre-surgical diagnosis requires reliable diagnostic levels classified as (1) seizure, (2) epilepsy, and (3) syndrome. The epilepsy and syndromic diagnoses are usually combined. The seizure diagnosis is determined from the physical and neurological manifestations of the condition recorded in the patient's history and from electroencephalogram (EEG) evaluations. Because seizures commonly result from cortical damage, neuroimaging techniques are used to identify and localize the damaged area. They include:

• Magnetic resonance imaging (MRI). Brain MRI is the best structural imaging technique available. Every ATL surgical evaluation usually includes a complete MRI study.
• Positron emission tomography (PET). Unlike MRI, PET provides information on brain metabolism rather than on structure. Typically, the epileptic region's metabolism is lowered unless the scan is obtained during a seizure.
• Single photon emission tomography (SPECT). SPECT scans visualize blood flow through the brain and are used as another method for localizing the epileptic site.

Routinely, all ATL candidates also undergo neuropsychological testing.

To prepare for ATL, the patient discontinues any medication being taken and that has been associated with bleeding disorders at least three weeks prior to ATL surgery. Antibiotics may be administered intravenously one hour before surgery. Minimal hair is shaved over the temporal area of the head.

Aftercare

After ATL surgery, the neurosurgeon provides instructions for the nurses, pharmacists, therapists, and other physicians caring for the patient postoperatively. Once the anesthesiologist determines that the patient is stable, the surgeon authorizes transport to the postoperative care area. Most patients go to the recovery area, but some critical patients may be taken to an intensive care unit (ICU) for close monitoring. As is the case for almost all types of brain surgery, the patient is initially nursed with the head of the bed elevated to 30 degrees.