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Ketogenic Diet

The ketogenic diet is a dietary therapy used to treat epilepsy. The ketogenic diet consists mostly of fats, with limited carbohydrates and the recommended daily allowance of protein. Dietitians carefully calculate individualized meal plans for patients based on their calorie and protein needs for growth and development, and their ketogenic diet ratio. The prescribed ratio refers to grams of fat to grams of protein and carbohydrates combined. The higher the ratio, the larger the percentage of fat in the diet.

Ketones or Ketone Bodies

Ketones are the by-products of fat metabolism. Ketones are typically present in the blood, urine, and breath when the body uses fat as its primary energy source, as in the ketogenic diet. Ketones may be an important factor in seizure control associated with dietary therapies. See also Betahydroxybuterate and Acetoacetate.


Ketosis is the metabolic state in which ketones are present in the body as a result of burning fat as the primary energy source.

Landau-Kleffner Syndrome

Landau-Kleffner syndrome is a rare epilepsy syndrome characterized by a loss of speech thought to be related to abnormal electrical activity in the child's brain during sleep. Typically, an otherwise normally developing child experiences mild seizures and then slowly loses the ability to understand language and the ability to speak, as well as an interest in communicating. All individuals show electrical status epilepticus of sleep, or near continuous epileptiform activity during as much as 80 percent of their sleep. The syndrome frequently causes lifelong language deficits. Unfortunately, a deeper understanding of the syndrome's cause and possible treatment remains elusive.

Learning Disability

A learning disability is a condition that either prevents or hinders somebody from learning basic skills or information at the same rate as most people of the same age.

Lennox-Gastaut Syndrome

Lennox-Gastaut syndrome is an epilepsy syndrome that often arises between the ages of two and six and is common among children who experienced infantile spasms. The syndrome has no single cause but typically results from some developmental brain disorder or brain injury. Children with Lennox-Gastaut syndrome have two or more seizure types, one of which is the atonic type of seizure, which causes loss of muscle tone and a sudden collapse to the ground.

Lennox-Gastaut is considered a mixed seizure disorder and shows characteristic EEG patterns of slow spike and wave activity. Treatment of the syndrome typically requires multiple medications, sometimes with little improvement. Because Lennox-Gastaut syndrome is difficult to treat and often comes with a poor prognosis, it is considered a catastrophic epilepsy syndrome. Fortunately, some children with Lennox-Gastaut respond well to medications and/or other anticonvulsant therapies, such as the ketogenic diet, and experience a great reduction or cessation of their seizures.


A lesion is a wound, injury, destructive change, or area of dysgenesis (abnormal development). The term lesion is sometimes used as another word for tumor, but does not always mean tumor.

Limbic System

The limbic system is a group of structures in the mesial, or middle, brain and is responsible for regulating such autonomic functions as heart rate, blood pressure, and temperature, as well as generating and controlling emotional response and storing memories. The limbic system includes such structures as the amygdala, the hippocampus, and the thalamus.

Low Glycemic Index Treatment (LGIT)

The low glycemic index treatment (LGIT) is a new dietary therapy currently being studied to treat epilepsy. LGIT attempts to reproduce the positive effects of the ketogenic diet. The treatment allows a more generous intake of carbohydrates than the ketogenic diet, but is restricted to foods that have a low glycemic index, meaning foods that have a relatively low impact on blood-glucose levels.

Magnetic Resonance Imaging (MRI)

MRIclick to enlarge photograph

Magnetic resonance imaging (MRI) is a noninvasive procedure that uses radio waves and magnetic fields to produce images of body tissue. The images produced are more detailed than traditional x-ray images and computed tomography (CT) scans. The MRI is particularly important in identifying brain abnormalities that are small or only subtly different from normal tissue.

Magnetic Resonance Spectroscopy (MRS)

Magnetic resonance spectroscopy (MRS) is a diagnostic tool that provides information about metabolism in the brain and may be able to detect biochemical abnormalities. The MRS is often used in conjunction with structural imaging such as the MRI.

Magnetoencephalogram (MEG)

The magnetoencephalogram (MEG) is a noninvasive diagnostic test that detects and records the magnetic fields produced by the electrical activity in the brain and helps doctors determine and monitor brain function.


Meningitis is an inflammation of the meninges, the membranes surrounding the brain and spinal cord, typically caused by a bacterial or viral infection. Meningitis can cause seizures.


Metabolic refers to metabolism, which is the physical and chemical processes through which the body produces energy.

Modified Atkins Diet

The modified Atkins diet is a dietary therapy used to treat epilepsy. The diet was first developed in 2003 as an alternative to the classic ketogenic diet. The modified Atkins diet is also high in fat and low in carbohydrates. Families following this treatment regimen no longer have to weigh and measure foods or follow specific meal plans. Daily carbohydrates are restricted to 10 grams per day for the first month and subsequently liberalized to 15-20 grams per day if 10 grams is too restrictive.

Motor Strip

brain sectionsclick to enlarge photograph

The motor strip is a part of the brain located in the frontal lobe, near the border of the parietal lobe. The motor strip is responsible for movement in parts of the body such as the face, hands, arms, and legs.

Myelin Sheath

brain sectionsclick to enlarge photograph

The myelin sheath is a fatty, protein-rich covering on the axons of many neurons that aids in the transmission of electrical signals from one neuron to another, from one side of the brain to the other, and directly to the tissues such as the muscles.

Myoclonic-Astatic Epilepsy (MAE)

See Doose Syndrome.

Myoclonic Seizures

Myoclonic seizures are generalized seizures characterized by single, intense muscular contractions that may result in a powerful jerk of the limbs, trunk, or face. They are thought to result from abnormal activity in an area of the brain responsible for muscle tone and posture. When myoclonic seizures cause the contraction of large muscle groups, such as the flexor or extensor muscles of the trunk, an individual may be thrown forward or backward powerfully, often causing injury.

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This content was last reviewed on November 20, 2006.