Paraplegia is the loss of movement and sensation in the lower body, typically affecting both legs and sometimes the trunk. It results from damage to the spinal cord in the mid or lower back, below the neck. Around 7.2 million people worldwide live with below-neck-level spinal cord injuries, and new cases are most common among men between the ages of 20 and 34.
Which Part of the Spine Is Involved
The spinal cord acts as the communication highway between your brain and the rest of your body. When that highway is damaged at or below the upper mid-back, signals can no longer travel to and from the lower body. The higher up the damage occurs, the more of the body is affected.
The nerves involved in paraplegia span three regions of the spine. The thoracic nerves (T1 through T12) control the chest muscles, parts of the back, and many organ systems. The lumbar nerves (L1 through L5) control the lower abdomen, buttocks, and parts of the legs. The sacral nerves (S1 through S5) control the thighs, lower legs, feet, and pelvic organs. Damage at any of these levels can cause paraplegia, but the exact pattern of lost function depends on where and how severely the cord is injured.
Complete vs. Incomplete Paraplegia
Not all paraplegia looks the same. Doctors classify spinal cord injuries on a scale from A to E based on how much function remains below the injury site. A Grade A injury is complete, meaning all motor and sensory function below the damage is gone, including in the lowest spinal nerve roots. Grades B through D represent incomplete injuries where some sensation, some movement, or both are preserved. A person with a Grade B injury, for example, can feel touch or pressure in their legs but cannot move them. Someone with a Grade D injury retains meaningful muscle strength below the injury.
This distinction matters enormously for recovery. People with incomplete injuries generally have better prospects for regaining function over time, because some nerve pathways are still intact and can potentially be strengthened through rehabilitation.
Leading Causes
Paraplegia can result from either physical trauma or medical conditions. On the traumatic side, motor vehicle crashes account for more than 37% of all spinal cord injuries, making them the single largest cause. Falls are close behind at about 31%. Violence, including gunshot and knife wounds, makes up roughly 15%.
Non-traumatic causes are also common and tend to produce incomplete injuries. These include spinal tumors (both cancerous and benign), blood vessel problems that cut off circulation to the cord, infections, and inflammatory diseases like transverse myelitis, where the immune system attacks the spinal cord’s protective covering. Some people are born with conditions that affect the spinal cord, and certain genetic disorders, such as hereditary spastic paraplegia, cause progressive stiffness and weakness in the legs over years or decades.
How Paraplegia Is Diagnosed
When a spinal cord injury is suspected, MRI is the preferred imaging tool because it shows the soft tissue of the cord itself, revealing compression, swelling, bleeding, or disruption of nerve fibers. CT scans and standard X-rays are used alongside MRI to evaluate the bones of the spine for fractures or dislocations. The combination of imaging with a hands-on neurological exam, where a doctor tests sensation and muscle strength at specific points down the body, determines both the level and severity of the injury.
MRI findings also help predict outcomes. Visible bleeding or bruising within the cord tissue on an early scan generally signals a more severe injury with a harder road to recovery, while swelling alone tends to carry a more favorable outlook.
What Recovery Looks Like
The body’s response to spinal cord damage unfolds in phases. In the first 48 hours, bleeding, nerve fiber damage, and inflammation set off a cascade of cellular events at the injury site. Over the following two weeks, the body begins forming scar tissue around the damaged area. By about two weeks after injury, that scar starts to harden into a barrier that blocks nerve regrowth, which is one reason early treatment matters so much.
Surgery to relieve pressure on the cord within 24 hours of injury has shown meaningful benefits. One major study found that nearly 20% of patients who had early decompression surgery improved by two full grades on the impairment scale. That could mean going from no movement at all to having usable muscle strength in the legs.
People with incomplete injuries often experience some degree of spontaneous recovery in the weeks to months following the injury, as surviving nerve circuits in the spinal cord reorganize. This process varies depending on injury severity, which specific nerve pathways were spared, and how much time has passed. Targeted rehabilitation can enhance this natural rewiring.
Rehabilitation Goals
The central aim of rehabilitation for paraplegia is independent mobility. For someone with a complete injury, this typically means mastering wheelchair use, learning to transfer in and out of a chair, and building upper body strength. For people with incomplete injuries, the goals are more ambitious and are broken into three tiers.
Social ambulation means being able to walk at least 50 meters without help or with an assistive device like crutches or a walker. Domestic ambulation means getting around the home independently or with minimal assistance. Exercise ambulation applies to people who need significant help to walk but benefit from the physical and cardiovascular effects of upright movement. Occupational therapy plays a key role alongside physical therapy, helping people adapt to daily tasks, find meaningful work, and address the depression that commonly follows a life-changing injury.
Secondary Health Complications
Paraplegia affects far more than the ability to walk. The spinal cord controls organ function throughout the lower body, so damage to it creates ongoing health challenges that require active management.
Bladder and bowel dysfunction are nearly universal. The nerves that coordinate urination and bowel movements run through the sacral region of the cord, and damage above that level disrupts normal signaling. Most people with paraplegia need some form of bladder management program, and constipation or fecal impaction is the most common bowel complication.
Pressure ulcers are a persistent risk for anyone who spends long hours in a wheelchair or in bed. Skin that doesn’t receive adequate blood flow breaks down, and because sensation is reduced or absent, the person may not feel the early warning signs of a developing sore. Regular repositioning and skin checks are essential.
Autonomic dysreflexia is a potentially dangerous complication for people with injuries above the T6 spinal level. It happens when something below the injury, such as a full bladder, constipation, or even tight clothing, triggers an extreme spike in blood pressure. The body can’t regulate the response normally because the signals can’t travel past the injury. Recognizing the symptoms, which include sudden headache, flushing, and sweating above the injury level, is important because untreated episodes can become medical emergencies.
Spinal Cord Stimulation
One of the most promising developments for people with chronic paralysis is epidural electrical stimulation. In this approach, a small electrode is surgically placed in the space around the spinal cord below the injury, and a pulse generator implanted under the skin delivers carefully tuned electrical signals to the nerves that control the legs. Clinical trials are currently testing whether this technology, combined with intensive daily physiotherapy over 12 months, can restore the ability to stand and walk in people who have been paralyzed for six months or longer.
Early results from similar research programs have shown that some participants regain voluntary leg movement when stimulation is active, and secondary benefits may include reduced spasticity, less pain, and improvements in bladder and bowel function. The technology is still in the trial phase and not yet widely available, but it represents a shift in what’s considered possible for people living with paraplegia.