<unk>  is most commonly observed in athletes involved in collision sports, such as American football. Athletes participating in collision sports most often suffer from cervical cord<unk> , also known as transient<unk> . Cervical cord<unk>  is the result of a severe collision in which a blow to the crown of the athlete's head forcefully extends or compresses the neck. Numbness, stinging, and/or weakness in the arms, legs or both, distinguish cervical cord<unk> . Typical episodes of transient<unk>  only last a few seconds and symptoms dissipate entirely. Though the severity of the injury can range, transient<unk>  does not lead to permanent paralysis of the affected muscles. Subsequent spinal cord injury after an episode of cervical cord<unk>  has not been observed. However, athletes who experience an episode of transient cervical<unk>  face an approximately 50% chance of a repeat episode if they continue to participate in collision sports. American football This tackle which occurred during an Army versus Navy game is representative of those that occur in American football.<unk>  is a common injury in all levels of football. Cervical cord<unk>  among American football players is commonly observed in athletes playing positions involving high-speed collisions and open-field tackling. Cases of<unk>  in the National Football League were first described in 1986 by Joseph S. Torg, M.D., founder of the National Football Head and Neck Injury Registry (established in 1975). As a result of Dr. Torg's findings the NFL as well as other levels of American football have outlawed the act of spearing, or the lowering of the head and hitting an opponent with the crown of the helmet. The cervical spine cannot properly absorb the force of a collision when the head is even slightly lowered as is the case in spearing. In addition to outlawing acts such as spearing, prevention of<unk>  on the football field relies on instruction and reinforcement of proper tackling technique by coaches and trainers.
Neurapraxia
Apperceptive agnosia
Constructional apraxia
Ideomotor apraxia
Visuospatial dysgnosia
Dystrophy
Acrodynia
Dyssynergia