Type of Surgery
Last updated: 02/17/2009
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.
Anterior temporal lobectomy is the complete removal of the anterior portion of the temporal lobe of the brain. It is a treatment option in temporal lobe epilepsy for those in whom anticonvulsant medications do not control epileptic seizures.
The techniques for removing temporal lobe tissue vary from resection of large amounts of tissue, including lateral temporal cortex along with medial structures, to more restricted anterior temporal lobectomy (ATL) to more restricted removal of only the medial structures (selective amygdalohippocampectomy, SAH).
Nearly all reports of seizure outcome following these procedures indicate that the best outcome group includes patients with MRI evidence of mesial temporal sclerosis (hippocampal atrophy with increased T-2 signal.) The range of seizure-free outcomes for these patients is reported to be between 80 and 90%, which is typically reported as a sub-set of data within a larger surgical series.
Open surgical procedures such as ATL have inherent risks including damage to the brain (either directly or indirectly by injury to important blood vessels), bleeding (which can require re-operation), blood loss (which can require transfusion), and infection. Furthermore, open procedures require several days of care in the hospital including at least one night in an intensive care unit. Such treatment is quite costly; a factor that may influence some health care systems to avoid referral to qualified centers.
However, a prospective, randomized trial of ATL compared to best medical therapy (anticonvulsants) demonstrated that the seizure-free rate after surgery was ~ 60% as compared to only 8% for the medicine only group. Therefore, ATL is considered the standard of care for patients with medically-intractable mesial temporal lobe epilepsy.
Select comparative data from 1999 to 2006 include a decrease of 14 percent in the number of neurosurgeons in private practice and a decrease of 13 percent in the number of neurosurgeons in solo practice.
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