Spastic paralysis Common Causes. Some of the common causes of Spastic paralysis may include: 1  Encephaloceles. 2  Microcephaly. 3  Porencephaly. 4  Upper motor lesion.5  Spinal cord compression. 6  more causes...».auses of Spastic paralysis that are rare. The offical US government definition of a rare disease is one that affects 200,000 people or less. The following causes of Spastic paralysis appear in the population at a rate of less than 200,000 people per year in the USA: