Cerebral Palsy in General:

Cerebral palsy refers to a group of neurological disorders that appear in infancy or early childhood and permanently affect body movement and muscle coordination Cerebral palsy (CP) is caused by damage to or abnormalities inside the developing brain that disrupt the brain’s ability to control movement and maintain posture and balance. The term cerebral refers to the brain; palsy refers to the loss or impairment of motor function.[1]

 

Spastic Diplegia in Specific:

Spastic diplegia cerebral palsy is characterized by muscle stiffness predominantly in the legs and less severely in the arms and face (although the hands may be clumsy).  Tendon reflexes are typically hyperactive and the toes point up. Tightness in certain leg muscles makes the legs move like the arms of a scissor. Children with this kind of cerebral palsy may require a walker or leg braces. Intelligence and language skills are usually normal.[1]

 

For more spesific information see the sections below (or use the menu at the top) or click the resource links.
Resource Links:

 

References:
[1] Cerebral Palsy: Hope Through Research. National Institute of Neurological Disorders and Stroke (NINDS). May 6, 2010; http://www.ninds.nih.gov/disorders/cerebral_palsy/detail_cerebral_palsy.htm. Accessed 07/18/2014.