Neurological symptoms that occur due to damage to the pyramidal tract are referred to as pyramidal tract signs. In total, there are more than twelve different pathologic reflexes that are considered pyramidal tract signs. They provide evidence of damage to the motor cortex or of diseases such as multiple sclerosis or ALS.
What are pyramidal tract signs?
Pyramidal tract signs are reflexes that provide evidence of pyramidal tract damage in adults. For example, in the Gordon finger spread sign, pressure on the pea bone, a small carpal bone, causes the fingers to spread. Pyramidal tract signs are reflexes or involuntary, rhythmic muscle contractions that indicate damage to the pyramidal tract in adults. The pyramidal tract is a large descending nerve pathway. It extends from the so-called motor cortex (praecentral gyrus) to the periphery of the body, where it innervates the alpha motoneurons. The motor cortex is also called the motor cortex and is found in the brain. It is responsible for controlling voluntary movements. It sends its signals to the alpha motoneurons via the pyramidal tract. These innervate the skeletal muscles and are thus responsible for muscle contractions. In infants, on the other hand, pyramidal tract signs are physiological, i.e., part of normal development, because in them the pyramidal tracts are not yet mature. Most pyramidal tract signs are found on the lower extremities; there are few pyramidal tract signs on the upper extremity.
Function and task
The various pyramidal tract signs are used to diagnose pyramidal tract damage. In the Babinski reflex, the trigger is a forceful brushing of the outer edge of the sole of the foot from the heels toward the little toe. When damage occurs, the big toe lifts toward the instep of the foot and the little toes move downward and outward. A similar effect can be observed with the Gordon reflex. The effect corresponds to that of the Babinski reflex. However, it is triggered by brushing the edge of the tibia from the knee in the direction of the ankle joint. In the Oppenheim reflex, damage to the pyramidal tract is also seen by a tightening of the big toe and a spreading of the other toes. The Oppenheim reflex is triggered by brushing the outer edge of the foot. The Clauß sign is performed by a flexion of the knee by the therapist against the resistance of the patient. This also shows the tightening of the big toe in combination with the spreading of the small toes. In the Strümpell sign, too, the patient’s knee is bent against resistance. In this case, however, a supination, i.e., a lifting of the inner edge of the foot with a simultaneous lowering of the outer edge of the foot, is evident in the case of pyramidal tract damage. The Strümpell sign is also called the tibialis phenomenon. The Rossolimo reflex, the Piotrowki reflex, and the dorsalis pedis reflex can be grouped under the term plantar muscle reflexes. Plantar muscle reflexes are intrinsic reflexes of the plantar muscles of the foot that are enhanced when there is damage to the pyramidal tract. In the Rossolimo reflex, a blow to the plantar muscles can cause plantar flexion, that is, flexion of the foot or toes toward the sole of the foot. The same result is triggered in the Piotrowski reflex by a blow to the anterior shin muscle (Musculus tibialis anterior). In the dorsiflexion of the foot reflex, plantar flexion also occurs after a blow to the back of the foot. Upper extremity pyramidal pathway signs include the Gordon finger spread sign, the Trömner reflex, and the Wartenberg reflex. In the Gordon finger spread sign, pressure on the pea bone (Os pisiforme), a small carpal bone, causes the fingers to spread. In the Trömner reflex, the fingers flex under pathologic conditions by striking the palm side of the middle finger phalanx. If the thumb strikes against resistance when the index, middle, and ring fingers flex, this is called a positive Wartenberg reflex. The Gordon finger spread sign, the Trömner reflex, the Gordon reflex, the Rossolimo reflex, the Pitotrowski reflex, and the dorsalis pedis reflex are among the uncertain pyramidal pathway signs. This means that even if one of these pathological reflexes can be triggered, there is not necessarily damage to the pyramidal tract.
Diseases and ailments
When multiple sclerosis is suspected, pyramidal tract signs are always checked. In multiple sclerosis, the body’s own defense cells attack cells of the nervous system, causing inflammation. The so-called glial cells are attacked. These form a kind of insulating layer around nerve fibers, so that the transmission of stimuli can take place much more quickly. The inflammations damage this so-called myelin layer. This is also referred to as demyelination. In multiple sclerosis, demyelination foci are found both in the central nervous system and in the peripheral nervous system. Typical symptoms of multiple sclerosis are visual disturbances such as double vision or blurred vision, rapid fatigability, paralysis, spasticity and slurred speech. However, the symptomatology can also be very vague, so positive pyramidal tract signs can provide initial clues to the disease here. Pyramidal tract signs are also positive in motor cortex damage. The most common cause of motor cortex damage is a cerebral infarction in the middle cerebral artery (middle cerebral artery). The motor cortex can also be affected if there is an occlusion of the anterior cerebral artery (anterior cerebral artery). Other causes of damage to the brain area include cerebral hemorrhage, inflammation, tumors, or injury. A rather rare disease in which the motor neurons in the brain perish is spastic spinal paralysis. The disease is inherited and manifests as increasing spastic paralysis in the lower extremities. Bladder voiding dysfunction, eye disease, dementia, deafness, and epilepsy may also occur with spastic spinal paralysis. In addition to markedly increased intrinsic reflexes, positive pyramidal tract signs can be observed on neurologic examination. Positive pyramidal tract signs are also found in ALS, amyotrophic lateral sclerosis. The disease is caused by irreversible damage to motor neurons. The degeneration results in paralysis, muscle wasting and spasticity. Those affected can no longer walk properly and suffer from speech and swallowing disorders. After diagnosis, patients usually die within three to five years. Amyotrophic lateral sclerosis has no cure.
