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Seizures: Abnormal activity of nerve cells in the brain causing strange sensations, emotions, and behavior, or sometimes convulsions, muscle spasms, and loss of consciousness.

Sensory Cortex: The sensory cortex is situated in the cerebrum. Different parts of the sensory cortex deal with the sensations experienced in different parts of the body.

Shaken Baby Syndrome: A severe form of head injury that occurs when an infant or small child is shaken forcibly enough to cause the brain to bounce against the skull; the degree of brain damage depends on the extent and duration of the shaking. Minor symptoms include irritability, lethargy, tremors, or vomiting; major symptoms include seizures, coma, stupor, or death.

Shearing: The type of brain lesion often seen as a result of an abrupt deceleration in movement, resulting in a continuation of brain movement within the skull. Shearing lesions are recognized as tears in nerve fibers, particularly of axons through the white matter.

Shunt: A devise to draw off excess fluid in the brain. A surgically placed tube runs from the ventricles and deposits fluid into either, the abdominal cavity, heart or large veins in the neck.

Soft Palate: A small flap of tissue that moves back and forth, allowing air to come out through the nose or mouth; plays an important role in speech. Damage to the brain can cause problems that prevent the soft palate from moving. Difficulties with breathing and speaking are the result.

Spasticity: A condition which causes spasms or other uncontrolled contractions of the skeletal muscles.

Stupor: A state of impaired consciousness in which the patient is unresponsive but can be aroused briefly by a strong stimulus.

Subdural Hematoma: Bleeding between the dura membrane covering the brain and the arachnoid membrane (the innermost layer).