Pyramid signs

Axons of motor neurons located in the precentral gyrus of the cerebral cortex ( central motor neurons ) carry inhibitory impulses. They end on motor neurons located in the front horns of the spinal cord and the nuclei of the cranial nerves ( peripheral motor neurons ). When the central motor neuron system is damaged (either the central motor neurons themselves, or their axons, which make up the corticonuclear and corticospinal paths), the inhibitory effect of the cerebral cortex on peripheral neurons is disrupted. As a result, the older reflex system of the spinal cord is unlocked ontogenetically .

There are a number of so-called pathological reflexes that indicate damage to the central motor neuron system. These reflexes are of great importance for the diagnosis of various diseases.

In newborns, many of the reflexes that are pathological for adults are noted. This is due to the insufficient development of the cerebral cortex and, accordingly, the system of the central motor neuron. For example, the normal pathological (for adults) Babinsky's foot reflex in children persists up to 1.5 years.

Oral automatism reflexes

They are one of the manifestations of the pseudobulbar syndrome that occurs with bilateral damage to the pyramidal pathways leading to the motor nuclei of the glossopharyngeal , vagus , accessory and sublingual nerves (caudal group of cranial nerves ).

These include:

• Proboscis reflex
• Distant oral reflex Karchikyan
• Naso-labial reflex of Astvatsaturov
• Palmar-chin reflex Marinescu- Radovici (Marinescu-Radovici)
• "Bulldog" reflex Yanishevsky

Pathological Hand Reflexes

• Tremner's reflex - flexion of the fingers in response to rapid tangential irritation with the fingers of the examining palmar surface of the terminal phalanges of the patient’s fingers
• The Jacobson-Lask reflex is a combined flexion of the forearm and fingers in response to a hammer blow on the styloid process of the radius .
• Zhukovsky's reflex - flexion of the fingers of a hand when hit with a hammer on its palm surface.
• Ankylosing spondylitis - carpal flexion of the fingers during percussion with the hammer of the rear of the hand.
• Rossolimo's upper reflex - flexion of the fingers with a quick tangential impact on their pads.
• The greater- finger Klippel — Weil flexion reflex — flexion of the first finger of the hand in response to passive flexion of the second — fifth fingers of the hand.

Pathological foot reflexes

• Extensor

• Oppenheim reflex - extension of the first toe when fingers are held along the crest of the tibia down to the ankle joint.
• Gordon's reflex - a slow extension of the first toe and a fan-shaped divergence of the other toes while squeezing the calf muscles.
• Schaeffer reflex - extension of the first toe with compression of the Achilles tendon.
• Babinsky reflex - extension of the first toe with dashed skin irritation of the outer edge of the sole.
• Chaddock reflex - extension of the first toe with dashed skin irritation below the outer ankle.
• Bing's reflex - extension of the first toe when tingling its dorsum with a needle.
• Strumpel reflex - extension of the first toe in response to the doctor’s reaction (by pressing on the patella) a conscious attempt by the patient to bend the leg in the knee and hip joints.

• Flexion

• Rossolimo's lower reflex - flexion of the toes with a quick tangential impact on their pads.
• Ankylosing spondylitis - Mendel ’s flexion of the toes when struck by a neurological hammer on its back surface.
• Zhukovsky-Kornilov reflex - flexion of the toes of the foot when struck by a neurological hammer on its plantar surface directly under the fingers.
• Ankylosing spondylitis - flexion of the toes when struck with a neurological hammer on the plantar surface of the heel.
• Puusepp's reflex is a slow abduction of the fifth finger with dashed skin irritation along the outer edge of the foot.

Clonuses

Clonuses are one of the pathognomonic signs of the defeat of the pyramidal pathway. Manifested by rapid and rhythmic contractions of a muscle or muscle group in response to their stretching.

• Clonus of the foot - is caused in a patient lying on his back. The examiner bends the patient’s leg in the hip and knee joints, holds it with one hand, and grabs the foot with the other and sharply extends it after maximum plantar flexion. In response, sharp rhythmic clonic foot movements occur.
• Clone of the patella - caused by a patient lying on his back with legs straightened: I and II fingers grab the tip of the patella, pull it up, and then sharply release. In response, a series of rhythmic contractions of the quadriceps femoris and twitching of the patella appears.

Synkinesia

Synkinesia is a reflex friendly movement of a limb that accompanies an arbitrary movement of another limb. Synkinesia can be both physiological (for example, waving hands while running or walking fast), and pathological. Pathological synkinesia is divided into 3 types:

• Global synkinesia - increased flexion contracture in the paralyzed arm and extensor in the leg when trying to move on paralyzed limbs.
• Simulated synkinesia is the involuntary repetition by paralyzed limbs of arbitrary movements of healthy limbs on the other side of the body.
• Coordinate synkinesia - the performance of additional movements by the paretic limbs in the process of a complex purposeful motor act.

Synkinesia does not develop in the acute, but in the distant period of the underlying disease, which led to the defeat of the pyramidal pathways. Their pathogenesis is not fully understood. They are often perceived by patients with spinal trauma as a sign of restoration of nerve conduction of the spinal cord .

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