Mesial Temporal Lobe Epilepsy

The motivation to select the subject to epilepsy is that I had an experience of assisting epilepsy research in a hospital on patients who underwent epilepsy surgery. In this project I investigated about an epilepsy patients case and correlated with the knowledges learnt through this course.

EpilepsyEpilepsy is a group of long-term neurological disorders characterized by epileptic seizures. These seizures are episodes that can vary from brief and nearly undetectable to long periods of vigorous shaking. The causes of epilepsy is mostly the result of brain injury, stroke, brain cancer, and drug and alcohol misuse, among others. Epileptic seizures are the result of excessive and abnormal cortical nerve cell activity in the brain.Mesial temporal lobe epilepsy(MTLE) is the most common type among epilepsy, and 40 to 67% of MTLE are known to have febrile seizures in their early ages.

Patient CaseThe patient I studied has been diagnosed as Left MTLE. The patients detail is as follows:Name: WLAge: 22Sex: MPast Medical History: Febrile seizure when 2 years oldEEG findings: Ictal onset on left temporal areaSemiology: Chewing and lip smacking, right arm posturingBrain MRI: Left hippocampal sclerosis (Figure 1)SPECT, SISCOM, PET: Left anterior basal, mesial temporal significanceHippocampal volumetry: Right: 3068.4 , Left: 1615.6 difference(Rt-Lt): 1452.8

Figure 1

InterpretationAccording to the brain MRI, WL has a lesion on his left hippocampus, a limbic system in anatomical point of view, neuroimaging evaluations also shows signal changes from mesial temporal area and left hippocampal volumetry reduction, all of those are parts of telencephalon.

In semiology, chewing and lip smacking has shown in his every starting moment of seizures and those behaviors could be regarded as being controlled by Central Pattern Generator,as it happened without the patients intention. His stereotyped behavior is also called as automatism which is common symptom in MTLE. When seizure begins, he has shown right arm posturing, which is controlled by left motor cortex and also involved by right cerebellum.

Memory TestEpilepsy cannot be cured, but seizures are controllable with medication in about 70% of cases. In those whose seizures do not respond to medication, surgery, neurostimulation or dietary changes may be considered.

WLs case was intractable partial epilepsy so he decided to take a surgery. But hippocampus is doing a crucial role in memory function. As we have learned from the case of HM, HM got dense amnesia after bilateral hippocampal resection. Declarative memories(both semantic and episodic) first go to hippocampus and then reconsolidated in neocortex. This means that without hippocampus, a person cannot remember about any new information or events.So before his hippocampus and some part of temporal lobe are resected, he had to take presurgical test to check memory and language dominance area, which is called Wada test.

Wada test is used to determine localization, that is which functions are located in which part of the brain. The test consists of administering a drug, sodium amytal, to the internal carotid artery one hemisphere at a time, thereby inducing a temporary lesion lasting only a few minutes. Before injecting the drug, the patient is given tests measuring his or her abilities in speech, object naming, and memory. While one hemisphere is anesthetized, the neuropsychologist then tests the other hemisphere to evaluate how well it manages speech, naming, and memory.(Figure 2)

Figure 2

Table 1

In WLs result(Table 1), he had aphasia when drug injected and underwent to the left hemisphere anesthesia. That means WL has language center on the left hemisphere and the Brocas area did not function well. The red box shows only left hemisphere awakened, percentage of successful memory function is higher than that of right hemisphere awakened even right hemisphere's function is also above 50%. So WLs memory dominance is bilateral but left temporal lobe and hippocampus has greater role in mediating memory.

Surgery OutcomeBased on the presurgical investigations above, surgeons operated left amygdalohippocampectomy with left anterior temporal lobectomy. Post surgery follow up result shows that he has no seizure and no clear memory function problem. This means that the presurgical evaluations are properly conducted and interpreted.

Influence of this CourseThrough this course I realized how important it is to sustain neural developing during childhood. Any accidental impact ( febrile seizures, viruses, physical attacks, trauma) on neural network or brain can cause severe disease in someones adulthood which influences on quality of life.

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Referencehttp://radiopaedia.org/encyclopaedia/quizzes/all/9007/studies/9766http://en.wikipedia.org/wiki/Epilepsyhttp://www.cse.buffalo.edu/~rapaport/575/memory.htmlhttp://www.3icreative.com/psych/forebrain-telencephalon-diencephalon.html