Many children with temporal lobe epilepsy have seizures that begin in the mesial-basal temporal lobe structures – for example, the hippocampus, amygdala and parahippocampal gyrus. These structures are part of the limbic system, which shapes memory and the emotional response.
While temporal lobe epilepsy is traditionally treated with anterior temporal lobectomy, selective amygdalohippocampectomy was developed to help save the temporal lobe (or lateral temporal neocortex) which contributes to language, vision and hearing.
Three types of selective amygdalohippocampectomy surgeries exist, each with their advantages: subtemporal, transcortical and transsylvian. The transsylvian method saves the lateral temporal lobe from damage. Selective amygdalohippocampectomy produces better seizure control and cognitive outcomes than temporal lobectomy. However, but the best method of the three has not yet been determined.
Proper diagnosis of mediobasal temporal lobe epilepsy (MTLE) is best accomplished with an MRI, particularly using a 3-Tesla MRI scanner. This type of epilepsy can stem from trauma, loss of oxygen to the brain, or brain infections. Children with MTLE often begin having seizures before the age of 5, with habitual focal (complex partial) or febrile seizures between the ages of 4 and 16. It’s common for these children to experience auras or stomach upset before seizures.
A high-resolution MRI can be performed to look for abnormalities, and a continuous video EEG can help identify the focus areas of the seizures. Both procedures can predict surgical outcomes. However, if these tests do not provide enough information needed for surgery, single-photon emission computed tomography (SPECT) is helpful and is typically more sensitive than positron emission tomography (PET).
All patients should undergo a thorough neurologic examination and have a clearly documented seizure history before the surgical evaluation. Neurological tests can be combined with the Wada test to provide baseline information about memory, language, attention, frontal lobe function and spatial abilities.
Potential complications from this surgery are often related to the level of detail necessary for the surgery. For example, careful handling of the Sylvian veins decreases the risk of damage. Cerebral vasoplasm, where blood flow is reduced or halted to parts of the brain, is a common complication. Visual field defects, where vision is lost in part of the patient’s field of view, are also common.
Sources:
Kovanda TJ, Tubbs RS and Cohen-Gadol AA. 2014. Transsylvian selective amygdalohippocampectomy for treatment of medial temporal lobe epilepsy: Surgical technique and operative nuances to avoid complications. Surg Neurol Int. 5:133.
Martens T, Merkel M, Holst B, Brückner K, Lindenau M, Stodieck S, Fiehler J, Westphal M and Heese O. 2014. Vascular events after transsylvian selective amygdalohippocampectomy and impact on epilepsy outcome. Epilepsia. 55(5):763-9.
Schmeiser B, Wagner K, Schulze-Bonhage A, Elger CE, Steinhoff BJ, Wendling AS, Mader I, Prinz M, Scheiwe C and Zentner J. 2017. Transsylvian Selective Amygdalohippocampectomy for Mesiotemporal Epilepsy: Experience with 162 Procedures. Neurosurgery. 80(3):454-464.
Ture U, Kaya AH and Bingol CA. Transsylvian selective amygdalohippocampectomy. In: Cataltepe O, Jallo G, eds. Pediatric epilepsy surgery: Preoperative assessment and surgical treatment. New York: Thieme Medical Publishers, Inc.; 2010.
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Overview of transsylvian selective amygdalohippocampectomy: from Medscape