The Oppenheim reflex, or Oppenheim sign, is a natural reflex in babies and a pathological reflex in adults. Neurology associates this reflex movement with pyramidal tract signs, as seen when central motor neurons are damaged. Diseases such as multiple sclerosis (MS) or ALS can cause such damage.
What is the Oppenheim reflex?
The Oppenheim reflex is a foot reflex that can be triggered by brushing the front edge of the shin. Neurologists understand the Oppenheim reflex to be a pathologic reflex, such as may be symptomatically present in the context of central nervous system disorders. The symptom is also known as the Oppenheim sign. The reflex movement is a foot reflex that can be triggered by brushing the front edge of the shin. The Oppenheim reflex is one of the so-called pyramidal tract signs, referring to damage to the pyramidal tract or central motor neurons responsible for controlling muscle movement. The pyramidal tracts are central nervous system motor pathways in the spinal cord that control voluntary movements of the entire body. The pathological reflex was named after its first describer, Hermann Oppenheim. The German neurologist discovered the reflex movement, which is pathological only in advanced age, already in the 19th century.
Function and task
The pyramidal tracts in the human spinal cord are the control center of voluntary motor activity. They are connected to alpha motor neurons in skeletal muscle fibers and are among the descending or efferent pathways of the nervous system. Information is carried away from the central nervous system by efferent pathways. In the case of the pyramidal tracts, the target of this conduction is the skeletal muscles. This is how the muscles receive their movement commands. The central nervous system in the spinal cord controls reflexes in particular. A large part of these reflexes are the protective reflexes, which are primarily intended to prevent injuries. Such reflexes are each triggered by a so-called trigger. As a rule, this trigger is a specific perception. If the switching point for the reflex movements were not located in the spinal cord but in the motor cortex of the brain, then the movement information would not reach the muscles quickly enough. The reflexes would thus no longer be able to protect the person. Consequently, protective reflexes in particular must be wired along the shortest possible paths in order to fulfill their purpose. For example, if a ball or other object flies toward the human face, the corresponding reflex movement is a defense against the object by the arms. If this movement were controlled by the brain, the person would not raise his arms until the object had long since reached him, and the protective reflex would thus no longer serve any purpose. The reflex control via the pyramidal pathways has thus evolutionary practical reasons. In contrast, the muscle movements of the organs are not controlled by the pyramidal pathways. They are connected in the enteric and vegetative nervous system. Some reflexes of the human body are restricted to infancy. These include, for example, the sucking reflex. This reflex movement occurs as soon as an infant’s lips are touched. The Oppenheim reflex is also physiological in infants. When the front edge of a baby’s shin is firmly brushed with the fingers, the big toe moves tonically upward as part of the reflex. The rest of the toes usually spread apart. When this reaction is observed in an adult, we are no longer talking about a physiological reflex, but a pathological one. Thus, the Oppenheim reflex is not present in healthy adults.
Diseases and complaints
The Oppenheim reflex is a symptom. Reflex movement often occurs along with other pathologic reflexes. The Babinski reflex, the Gordon reflex, and the Chaddock reflex, as well as the Strümpell signs, belong to the so-called Babinski group associated with the term pyramidal tract signs, as does the Oppenheim sign. This group of symptoms is an indication to the neurologist of damage to the central motor neurons. Reflex examination is a standard procedure in neurology. Many
neurological diseases can be associated with pathological reflexes from the Babinski group and thus damage to central motoneurons.One of the best-known diseases in this context is multiple sclerosis. In this central nervous system autoimmune disease, the patient’s own immune system mistakenly attacks the body’s own nerve tissue in the central nervous system and causes an immunological inflammatory reaction. As part of the inflammation, the insulating myelin sheath in the central nervous tissue breaks down. Thus, the conductivity of the nerve tissue is reduced or lost. In the worst case, permanent damage occurs in the brain and spinal cord. In connection with multiple sclerosis, the pyramidal tract signs and thus also the Oppenheim reflex are primarily relevant for the prognosis. If pyramidal pathway signs are already present at an early stage of the disease, the physician speaks of a rather unfavorable course. Other diseases can also damage the central motor neurons and thus trigger pyramidal tract signs. One example is the degenerative disease ALS. In this disease of the motor nervous system, the nerve cells responsible for muscle movements are degraded bit by bit. Both the motor neurons in the brain and those in the anterior horn of the spinal cord are affected by the degenerative phenomena. The degeneration cannot be stopped. At best, the degeneration can be delayed. If the first motoneuron is affected, then progressive muscle weakness up to paralysis occurs. If, on the other hand, the second motoneuron is affected, then this usually manifests as spasticity.
