This document discusses various causes and types of paraplegia including flaccid and spastic paraplegia. Flaccid paralysis results from diseases of the anterior horn cells, nerves, or muscles. Spastic paraplegia can be caused by compressive factors inside or outside the spinal cord, or non-compressive factors like multiple sclerosis. The key differences between compressive and non-compressive paraplegia are discussed. Diagnostic tests and some unique conditions like tropical spastic paraplegia and lathyrism are also mentioned.