Nerve Injuries

Nerve Injuries:

The nervous system consists of both the central nervous system & the peripheral nervous system. The central nervous system consists of the brain & the spinal cord. The peripheral nervous system is everything that lies outside of the brain & spinal cord that gives information about the various body parts to the brain. Peripheral nerves can be divided in to 3 categories:

Motor
Sensory
Autonomic

The autonomic nervous system controls the organs function and is also responsible for fight or flight. As the name implies these nerves conduct their function automatically and they are regulated by the brain. Sensory and motor nerves can perform their function automatically as is the case with resting muscle tone and they can be consciously controlled by us when moving our bodies.

Central Nervous System

Central nervous system injuries are more severe with more wide spread symptoms, since this involves the brain and spinal cord. These only normally occur after a large scale trauma (e.g.: fall from a height, motor vehicle accident, or stroke). The symptoms can include, but are not limited to the following:

loss of bladder & bowel control
weakness or paralysis
numbness or abnormal muscle tone/spasticity

Depending on the extent of the injury these individuals usually require long term rehabilitation to make functional gains. Their rehabilitation team consists of multiple professionals such as neuro-physiotherapists, occupation therapists, speech therapists, dietitians, medical doctors and more.

These types of injuries are beyond the scope of this blog as we will be focusing on peripheral nerve injuries.

Peripheral Nervous System

Peripheral nerve injuries are more common and come from various causes. Traumatic injuries in the form of compression, traction or lacerations can injure the nerves. This will lead to functional fall out to the areas that the injured nerves supply. Peripheral nerve injuries can also be sustained due to medical conditions like diabetes or the use of antiretroviral drugs (ARV’s). Peripheral nerve injuries can even be caused by bacteria or viral infection. People who are suffering from auto-immune conditions like lupus, rheumatoid arthritis or Guillain-Barre syndrome also develop defects in the peripheral nervous system that lead to various functional fall outs.

The anatomy of a peripheral nerve is important to understanding the various classifications of nerve injuries which will then dictate your recovery times and what interventions are necessary. The most basic component of a nerve is an axon. An axon is the fibre that conducts the electrical impulses to the central nervous system. In order to make the conduction of an impulse faster the nerve is surrounded by a myelin sheath (Schwan cell).

This basic component of the nerve can be compared to an electrical cable: the myelin sheath is the insulation material that surrounds the copper cables that actually conduct the electricity. The copper cables of the body would be the axons. A peripheral nerve has multiple layers of connective tissue which surround the axons. The endoneurium is the deepest layer and surrounds an individual axon. Axons are then bundled together to form fascicles; these fascicles are held together by a connective tissue called perineurium. The fascicles are then bundled together to form a nerve that is bound together by the epineurium.

Nerve anatomy

A nerve can be purely sensory, purely motor or a mixture of the two, which will dictate what symptoms you have after the injury. Peripheral nerve injuries are classified into three categories depending on the extent of the damage to the nerve & its surrounding connective tissues.

Neuropraxia (Mildest form)

This comes with only a mild demyelination of the nerve without damage to the nerve axon & is usually the result of compression or traction injuries. These usually have healing time similar to other injuries (average 6-12 weeks) with little to no long term fall out.

Axonotmesis

There is focal demyelination & damage to the axon of the nerve. However, the nerves connective tissue is maintained which ensures the continuity of the nerve. This means that the nerve still knows the path it needs to follow to repair itself. While this is a slow process these injuries usually have good outcomes.

Neurotmesis (Most Severe)

Injury to all tissues of the nerve leading to a discontinuity of the nerve. This discontinuity means that the two ends of the nerve are no longer connected which leaves the nerve without a path to follow for regrowth. These injuries usually require surgical intervention & extensive rehabilitation to restore function.

Treatment

Physiotherapy is an essential part of the recovery from nerve injuries. The techniques used encourage blood flow around the injured site which brings the required nutrients to the tissues which are needed for optimum healing. They also help to reduce swelling & inflammation in the area. We also use techniques that restore normal movement in the nerve which will help reduce pain and symptoms like pins and needles. It is also essential to get exercises for the muscles that have been affected by the fall out to ensure they return to their previous level of function.

For condition like peripheral neuropathy there is progressive damage to the most distal portion of the nerves. This damage leads to a glove like disappearance of the sensation in the hands and feet, pain, and pins and needles. These condition are caused by internal biological processes that cannot be halted with physiotherapy however the condition can be managed by assisting to slow the progression and help you to cope with your symptoms.

Common peripheral nerve injuries: