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Target of Rapamycin (TOR)

TOR is a protein in the signaling pathway involving the TSC proteins. TOR sends signals to the nucleus of a cell and to the protein synthesis machinery to tell the cell to take up more nutrients, to make more proteins, and to grow. TOR is also a drug target for the drug Rapamycin.

Tonic Seizure

A tonic seizure involves a prolonged contraction of muscles and stiffening of limbs without the rhythmic motion characteristic of most seizures. Tonic seizures may result in what experts generally refer to as drop attacks, in which an individual suddenly collapses or is thrown to the ground.

Tonic-clonic Seizure

A tonic-clonic seizure begins with the tonic phase, which often involves a fall to the floor, stiffening of the limbs, and clenching of teeth. This is followed by the clonic phase, which presents itself as the violent rhythmic jerking of the limbs and torso. Previously know as grand mal seizure.


See Target of Rapamycin.


See Cortical Tuber.


Tuberin is the protein coded by the TSC2 gene.


A tumor is an abnormal, uncontrolled growth or mass of body cells that has no physiological function. A tumor may be malignant or benign.


Renal Ultrasound
click to enlarge photograph

An ultrasound is a procedure that uses high-frequency sound waves to visualize internal organs.

Ungual Fibroma

An ungual fibroma is a flesh-colored or reddish lesion that grows under fingernails and toenails. Ungual fibromas vary in size from a few millimeters to about 1 cm in diameter.


A urologist is a physician who has specialized knowledge and skill regarding problems of the male and female urinary tract and the male reproductive organs.

Vagus Nerve Stimulator (VNS)

The vagus nerve stimulator (VNS) is an alternative therapy to treat seizures. This technique relies on a pacemaker-like device that is implanted under the skin of the chest and supplies intermittent electrical impulses to the vagus nerve as it passes through the neck. Intermittent stimulation of this nerve with low-intensity electrical impulses may reduce seizures in some people.


Vigabatrin is an antiepileptic medication shown to be effective in treating children with TSC who are suffering from infantile spasms.


See Vagus Nerve Stimulator.

Wood's Lamp

A Wood's lamp is an ultraviolet light used to help locate white patches on the skin.

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This content was last reviewed on March 30, 2006.