What is Axonotmesis?

A nerve is a collection of fibers, similar in structure to a cable, which is responsible for providing a pathway for electrochemical impulses to travel throughout the body. Axonotmesis is a term used to describe a severe nerve injury is commonly seen in peripheral nerves which causes the disruption of the axon and myelin sheath of the nerve but leaves the supporting structures of the cells intact. The peripheral nervous system, or PNS, is the auxiliary nerves which do not include the brain or spinal cord. The axon of a nerve is the slim projections stemming from the body of the nerve cell which transports signals away from the nerve. The myelin sheath is the electrically charged covering of the axon.

Axonotmesis does not typically affect the connective tissue framework of the nerve, including the epineurium and perineurium. The epineurium is the tough outermost protective layer of a nerve which contains the blood vessels. The perineurium is the middle layer of connective tissue.

Axonotmesis nerve injury is usually sustained by a severe contusion, also known as a bruise, or a crushing injury. However, it may also occur with a stretching injury. Symptoms can range from pain to dysfunction, including paralysis. Paralysis can occur to the motor, sensory or autonomic systems. Motor paralysis presents as the inability to move muscle or muscle groups. Sensory system paralysis disrupts the transportation of electrochemical signals of the nerves. Autonomic system paralysis prevents the regulatory functions of the nerves which aids in the body’s abilities to adapt to changes in the environment.

Nerves have the ability to regenerate or repair as long as the damage is not excessive and the main portion of the nerve remains intact. Depending upon the severity of the nerve injury known as axonotmesis, nerve regeneration may or may not occur. The repair of nerves may take several months as regeneration is a slow process. In some instances, electrical stimulation may speed the process of regeneration.

Initially, a treatment protocol for axonotmesis includes conservative measures such as pain and inflammation management through analgesics and anti-inflammatory medications; injury management such as supports, bracing or casting measures; and close observation to continually assess symptoms. Physical therapy may also be employed to assist in pain relief through specialized modalities such as ice application and ultrasound. A comprehensive stretching and exercise regiment assists to limit protective muscle spasms and maintain surrounding muscle strength and flexibility.