Brain Research : Spinal cord injury


Spinal cord injury is the damage caused to the spinal cord that results in functional changes either temporary or permanent. Depending on the severity of spinal cord injury symptoms vary widely which includes loss of sensation, loss of muscle function termed as complete injury. Incomplete injury includes few of the nervous signals are able to travel across the injured area of spinal cord. Symptoms can vary from numbness to paralysis. Spinal cord injuries are caused by physical trauma such as falls, sports injuries, accidents, can also result from infection, insufficient blood flow (ischemic), tumors. Spinal cord injuries are categorized into primary injuries where cell death occurs immediately and biochemical cascade triggers are generated and secondary injuries are followed by inflammation, swelling, ischemic cascade, neurotransmitter imbalances.

A spinal cord injury (SCI) is damage to the spinal cord that causes temporary or permanent changes in its function. Symptoms may include loss of muscle function, sensation, or autonomic function in the parts of the body served by the spinal cord below the level of the injury. Injury can occur at any level of the spinal cord and can be complete injury, with a total loss of sensation and muscle function, or incomplete, meaning some nervous signals are able to travel past the injured area of the cord. Depending on the location and severity of damage, the symptoms vary, from numbness to paralysis to incontinence. Long term outcomes also range widely, from full recovery to permanent tetraplegia (also called quadriplegia) or paraplegia. Complications can include muscle atrophy, pressure sores, infections, and breathing problems.

In the majority of cases the damage results from physical trauma such as car accidents, gunshot wounds, falls, or sports injuries, but it can also result from nontraumatic causes such as infection, insufficient blood flow, and tumors. Just over half of injuries affect the cervical spine, while 15% occur in each of the thoracic spine, border between the thoracic and lumbar spine, and lumbar spine alone. Diagnosis is typically based on symptoms and medical imaging.

Efforts to prevent SCI include individual measures such as using safety equipment, societal measures such as safety regulations in sports and traffic, and improvements to equipment. Treatment starts with restricting further motion of the spine and maintaining adequate blood pressure. Corticosteroids have not been found to be useful. Other interventions vary depending on the location and extent of the injury, from bed rest to surgery. In many cases, spinal cord injuries require long-term physical and occupational therapy, especially if it interferes with activities of daily living.

In the United States, about 12,000 people a year survive a spinal cord injury. The most commonly affected group are young adult males. SCI has seen great improvements in its care since the middle of the 20th century. Research into potential treatments includes stem cell implantation, engineered materials for tissue support, epidural spinal stimulation, and wearable robotic exoskeletons.


A human spinal column          A person with dermatomes mapped out on the skin

The effects of injury depend on the level along the spinal column (left). A dermatome is an area of the skin that sends sensory messages to a specific spinal nerve (right).

diagram of vertebrae and spinal nerves

Spinal nerves exit the spinal cord between each pair of vertebrae.

Spinal cord injury can be traumatic or nontraumatic, and can be classified into three types based on cause: mechanical forces, toxic, and ischemic (from lack of blood flow). The damage can also be divided into primary and secondary injury: the cell death that occurs immediately in the original injury, and biochemical cascades that are initiated by the original insult and cause further tissue damage. These secondary injury pathways include the ischemic cascade, inflammation, swelling, cell suicide, and neurotransmitter imbalances. They can take place for minutes or weeks following the injury.

At each level of the spinal column, spinal nerves branch off from either side of the spinal cord and exit between a pair of vertebrae, to innervate a specific part of the body. The area of skin innervated by a specific spinal nerve is called a dermatome, and the group of muscles innervated by a single spinal nerve is called a myotome. The part of the spinal cord that was damaged corresponds to the spinal nerves at that level and below. Injuries can be cervical 1–8 (C1–C8), thoracic 1–12 (T1–T12), lumbar 1–5 (L1–L5), or sacral (S1–S5). A person's level of injury is defined as the lowest level of full sensation and function.[10] Paraplegia occurs when the legs are affected by the spinal cord damage (in thoracic, lumbar, or sacral injuries), and tetraplegia occurs when all four limbs are affected (cervical damage).

SCI is also classified by the degree of impairment. The International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI), published by the American Spinal Injury Association (ASIA), is widely used to document sensory and motor impairments following SCI. It is based on neurological responses, touch and pinprick sensations tested in each dermatome, and strength of the muscles that control key motions on both sides of the body. Muscle strength is scored on a scale of 0–5 according to the table on the right, and sensation is graded on a scale of 0–2: 0 is no sensation, 1 is altered or decreased sensation, and 2 is full sensation. Each side of the body is graded independently.

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