What is Paralysis? What are the Types of Paralysis? How Does Someone Become Paralyzed?

What is Paralysis?
Paralysis is the inability—whether temporary or permanent—to move a part of the body. In almost all cases, paralysis is due to nerve damage, not to an injury to the affected region. For instance, an injury in the middle or lower regions of the spinal cord is likely to disrupt function below the injury, including the ability to move the feet or feel sensations, even though the actual structures are as healthy as ever.
So what happens to the body when it is paralyzed? That depends on the cause of the paralysis, but generally at least one of the following factors is in play:
The brain is unable to relay a signal to an area of the body due to injuries to the brain.
The brain is able to sense touch and other sensations in the body, but is unable to effectively relay a response due to injuries in the spinal cord.
The brain can neither send nor receive signals to an area of the body due to injuries in the spinal cord.
The spinal cord is like the brain’s relay system, so when something in the spinal cord doesn’t work or is injured, paralysis is often the result. These injuries can be the product of traumatic accidents, or diseases such as strokes and polio. Most spinal cord injuries are incomplete, which means that some signals still travel up and down the cord. With an incomplete injury, you may retain some sensation and movement all the time, or the severity of the paralysis may change—sometimes on a highly unpredictable basis. A complete spinal cord injury, by contrast, completely compressed or severs the nerves in the spinal cord, making it impossible for the signal to travel.
How Does Someone Become Paralyzed?
There are many different causes of paralysis—and each one may result in a different kind of paralysis, such as quadriplegia (paralysis of arms and legs), paraplegia (being paralyzed from the waist down), monoplegia (paralysis in one limb), or hemiplegia (being paralyzed on one side of the body). According to the Christopher Reeve Foundation, approximately “1.2 million Americans are living with paralysis resulting from spinal cord injuries.” Car accidents, falls, sporting injuries, and acts of interpersonal violence are the cause of most spinal cord injuries.
Types of Paralysis
What is Monoplegia?
Monoplegia is paralysis of a single area of the body, most typically one limb. People with monoplegia typically retain control over the rest of their body, but cannot move or feel sensations in the affected limb.
What Causes Monoplegia?
Though cerebral palsy is the leading cause of monoplegia, a number of other injuries and ailments can lead to this form of partial paralysis, including:
Stroke
Tumors
Nerve damage due to injuries or diseases
Nerve impingement
Motor neuron damage
Brain injuries
Impacted or severed nerves at the affected location
What is Hemiplegia?
Hemiplegia affects an arm and a leg on the same side of the body. With hemiplegia, the degree of paralysis varies from person to person, and may change over time. Hemiplegia often begins with a sensation of pins and needles, progresses to muscle weakness, and escalates to complete paralysis. However, many people with hemiplegia find that their degree of functioning varies from day to day, and depending on their overall health, activity level, and other factors.
What Causes Hemiplegia?
As with monoplegia, the most common cause is cerebral palsy. However, other conditions, such as incomplete spinal cord injuries, brain injuries, and nervous system disorders can also result in hemiplegia.
What is Paraplegia?
Paraplegia refers to paralysis below the waist, and usually affects both legs, the hips, and other functions, such as sexuality and elimination. Though stereotypes of being paralyzed below the waist hold that paraplegics cannot walk, move their legs, or feel anything below the waist, the reality of paraplegia varies from person to person—and sometimes, from day to day.
What Causes Paraplegia?
Spinal cord injuries are the most common cause of paraplegia. These injuries impede the brain's ability to send and receive signals below the site of the injury.
Quadriplegia
What is Quadriplegia?
Quadriplegia, which is often referred to as tetraplegia, is paralysis below the neck. All four limbs, as well as the torso, are typically affected. As with paraplegia, though, the degree of disability and loss of function may vary from person to person, and even from moment to moment. Likewise, some quadriplegics spontaneously regain some or all functioning, while others slowly retrain their brains and bodies through dedicated physical therapy and exercise.
What Causes Quadriplegia?
Occasionally, quadriplegia is a temporary condition due to brain injuries, stroke, or temporary compression of spinal cord nerves. Some spinal cord injury survivors temporarily suffer from quadriplegia immediately after the injury, then experience a less systematic form of paralysis as swelling goes down, the nerves become less compressed, or surgery reverses some damage.