What causes upper-limb spasticity?
Upper-limb spasticity is the result of damage to the nervous system (brain and spinal cord). The job of the nervous system is to send electrical messages back and forth from the brain to different parts of the body. Normally, the brain quickly sends signals which travel through the spinal cord and then through nerves that branch out to all organs and body parts. When there is an injury or damage to the nervous system, the electrical messages are disrupted and the brain begins to send too many messages. This results in the muscles stiffening and contracting.
The following are some of the most common causes of upper-limb spasticity in adults:
Stroke. Most strokes are caused by a blockage in an artery that carries blood to the brain. This can cause that part of the brain to be damaged, and you may lose control of a function that is controlled by that part of the brain. For example, you could lose the use of an arm or leg, or the ability to speak. The damage can be temporary or permanent, partial or complete. Stroke is one of the most common causes of upper-limb spasticity.
Multiple Sclerosis (MS). MS is an autoimmune disease that affects the nervous system. In people who have MS, the immune system destroys the myelin sheath. The myelin sheath is the substance that surrounds and protects your nerve cells. When myelin around nerves is damaged or destroyed, the nerves can’t function properly to deliver these signals in the right way. This can cause a variety of symptoms, including stiffness or muscle spasms in the arms.
Spinal Cord Injury. The spinal cord is made up of bundles of nerves and nerve cells that carry messages from your brain to the different parts of your body. The spinal cord is protected by the bony rings in your back that make up the spinal column (also called the vertebral column or the backbone). The symptoms of a spinal cord injury depend on where the damage occurred. Damage to the vertebra (bones) in the neck (also called a cervical injury) can result in a loss of function in the arms as well as increased muscle contraction and muscle spasms in the arms.
Traumatic Brain Injury (TBI). TBI can occur when there is a severe, violent strike to the head, which causes the brain to bump against the inside of the skull. It can also occur when an object, such as a bullet or a piece of the skull, penetrates the brain. These types of injuries can cause bleeding or swelling of the brain, as well as damage to the nerve cells. This disrupts the way the brain sends messages out to the rest of the body. Traumatic brain injury can affect behavior, speech, sensation and movement, including upper-limb spasticity.
Adult Cerebral Palsy (CP). CP is a term for a group of neurological disabilities that affect muscle control, movement and coordination because of damage to the cerebral cortex (the area of the brain that controls muscle movement). People who have CP have trouble controlling their muscles and coordinating body movements. They may have stiff or weak muscles, which can cause them to make unusual muscle movements. Upper-limb spasticity is common in adults who have CP.
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Written by familydoctor.org editorial staff