Introduction

Epilepsy is a neurological disorder that affects the quality of life of millions of people around the world. It is characterised by frequent and chronic seizures, which occur due to sudden bursts of electrical impulses in the brain. The most common form of epilepsy in adults is the Mesial Temporal Lobe Epilepsy (MTLE).¹

The electrical impulses that trigger MTLE originate from various structures within the temporal lobe, and are usually attributed to hippocampal sclerosis (a condition where the hippocampus undergoes cell loss and scarring).² MTLE is important not only due to its high prevalence, but also because it is usually resistant to medication and treatment. Many individuals who suffer from MTLE experience significant effects on memory and cognition, which can impact their quality of life.³ In order for patients to receive appropriate treatment from caregivers and healthcare professionals, it is important to understand MTLE, its symptoms, causes, diagnosis, and treatment options.

Understanding MTLE

Anatomy and Definition

MTLE originated from the mesial (inner) structures of the temporal lobe, which are formed of:

• The Hippocampus – an essential part of the brain for the formation of memory and spatial navigation
• The Amygdala – which plays an important role in various emotions such as fear and anxiety
• The Parahippocampal Gyrus – a crucial part of memory retrieval and encoding

These structures of the inner temporal lobe are vital for cognition and the regulation of emotions. When they are affected by the electrical surges of epilepsy, it can lead to a range of symptoms that impact the daily life of the individual.

Symptoms

Individuals who suffer from MTLE usually experience a distinct series of seizure-related symptoms, which could include:

• Auras: These act as ‘warning signs’ that a seizure is about to happen. Common auras include sudden fear, déjà vu (a sense of familiarity), jamais vu (a feeling of unfamiliarity with known surroundings), or a rising sensation in the stomach
• Focal seizures with impaired awareness: In this form of seizure, the individual may look awake but is completely unresponsive to surrounding stimuli. They may also exhibit repetitions in movements such as chewing, lip-smacking, or hand-wringing
• Disturbances in cognition: Short-term memory lapses and confusion are also indicators of an epileptic episode
• Secondary generalisation: In severe cases, the electrical impulses of seizures spread to both hemispheres of the brain, resulting in full convulsive seizures (also known as tonic-clonic seizures)

Causes and Risk Factors of MTLE

The seizures that persist in MTLE can be caused by various factors, which can include:

• Hippocampal Sclerosis (HS): This is the most common cause of MTLE, which involves the loss of neurons and visible scarring of the hippocampus following years of seizures that begin in childhood⁴
• Trauma to the head: Any injury to the brain can cause damage, particularly those affecting the temporal lobe, which can trigger MTLE later in life⁵
• Brain Infections: Infections such as meningitis and encephalitis can cause inflammation and scarring of the brain tissue, increasing the risk of epilepsy⁶
• Genetic: There is some suggestion that there could be a genetic predisposition in some families to an individual’s risk of developing MTLE⁷
• Perinatal Injury: A lack of oxygen or trauma during birth can cause damage to the brain, which may contribute to the development of epilepsy later in life⁸

Diagnosis

In order to determine the best treatment approach, MTLE must be accurately diagnosed using the following diagnostic process:

• Clinical Evaluation and Medical History: A detailed medical history would be taken by a neurologist. This includes the history of the onset of seizure episodes, any known triggers, and family history
• Electroencephalogram (EEG): Brain activity is recorded using an EEG machine to detect abnormal electrical patterns that are characteristic of epilepsy
• Magnetic Resonance Imaging (MRI): The MRI machine is used to create high-resolution images of the brain in order to identify the presence of any structural abnormalities
• Video-EEG Monitoring: Some patients may benefit from prolonged monitoring in an epilepsy-specific centre to capture and determine the point of origin of the seizures
• Neuropsychological Testing: Patients are assessed on the quality of their memory, language, and cognitive function, which can help identify the affected area of the brain

Treatment Options

The management of MTLE requires each patient to be seen individually, depending on the severity of their seizures. A personalised approach can lead to better outcomes of treatment.

Medications

Medications known as anti-epileptic drugs (AEDs) are available that are the first-line treatment. The most commonly prescribed medications include:

• Carbamazepine
• Lamotrigine
• Levetiracetam
• Oxcarbazepine
• Sodium Valproate

It is important to note that approximately 30-40% of patients cannot control their seizures with medications alone, making them candidates for alternative treatment methods.⁹

Surgical Options

When MTLE is resistant to medication, patients are given the option of surgical procedures. These may include:

• Anterior Temporal Lobectomy (ATL): This is the most common type of surgery for MTLE, in which part of the temporal lobe is removed
• Selective Amygdalohippocampectomy (SAH): This surgery involves removing two structures of the brain (the amygdala and hippocampus) while preserving surrounding tissues¹⁰

Studies have shown that approximately 60-80% of individuals suffering from MTLE who undergo some form of surgery will achieve long-term seizure freedom.¹¹

Neurostimulation Therapies

Patients who are not eligible for surgery may be offered neurostimulation therapy. This can include various techniques such as:

• Vagus Nerve Stimulation (VNS): A device is implanted into the brain, sending electrical impulses to the vagus nerve to reduce the frequency of seizures¹²
• Responsive Neurostimulation (RNS): A device detects electrical activity in the brain and delivers targeted electrical stimulation to prevent seizures¹³
• Deep Brain Stimulation (DBS): Electrodes are implanted deep into the brain to regulate abnormal electrical activities¹⁴

Dietary Therapies

There are some suggestions that dietary modifications, such as the ketogenic diet (a high-fat, low-carb diet), can help reduce the frequency of seizures. In fact, studies have shown that in individuals who fail to respond to medications, adherence to a strict ketogenic diet can significantly reduce the frequency of seizures. This makes it a very appropriate non-surgical option. A more flexible and tolerable diet is the modified Atkins diet, which is easier to follow and still maintains the high-fat, low-carb principle. New evidence has emerged showing that other dietary alternatives, such as the low glycaemic index treatment (LGIT), which works by stabilising blood sugar levels, may also help in reducing the severity of seizures.¹⁵

Conclusion

Although Mesial Temporal Lobe Epilepsy is complex and affects individuals significantly, the symptoms are very well characterised. Even though individuals may find that their condition is resistant to medications, there are other options available, such as surgical techniques and neurostimulation, which can provide effective treatment. However, management of MTLE does not only involve treatment, but it also often requires a holistic approach that involves modifications in diet, psychological support, as well as lifestyle adjustments. Research into the treatment of epilepsy is ongoing and aims to expand the scope for seizure control and therefore improve quality of life. Therefore, it is important to understand the impact of MTLE in order to help individuals take a more proactive approach in seeking appropriate treatment and thereby managing their condition more effectively.¹⁶