Pyramidal signs
Pyramidal signs indicate that the pyramidal tract is affected at some point in its course. Pyramidal tract dysfunction can lead to various clinical presentations such as spasticity, weakness, slowing of rapid alternating movements, hyperreflexia, and a positive Babinski sign. The presence of these phenomena is nearly always connected with "hyperreflexia" and some authors think that we can not count them as a pathological reactions at all. Their existence on lower extremity is more serious that on the upper ones. The most common reason for irritative phenomena is a lesion of a central motoneuron, but in the presence of  asymmetrical findings then a diagnosis of amyotrophic lateral sclerosis should be considered. Pyramidal signs occur as a normal phenomena until the age of 2, when the myelinization is finished, and so under this age they aren't considered pathological. Pathophysiology. The upper motor neurons from the central nervous system descend through the pyramidal tracts (i.e., corticospinal tracts), connecting the brain and spinal cord and help in controlling voluntary movement of muscles. Irritative phenomena on the upper extremity. The irritative phenomena are present if there is visible flection of the thumb, which goes to opposition: Irritative phenomena on the lower extremity . Extension. Extension phenomena are positive if the great toe dorsiflexes (goes up) following the stimulus: Flexion. These phenomena are positive if the toes of the foot flex: Clinical significance. Parkinsonian-Pyramidal syndrome (PPS) is a combination of both pyramidal and parkinsonian signs that manifest in various neurodegenerative diseases.