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Types of Spinal Cord Injuries: Complete vs Incomplete, Levels, & ASIA Scale

Updated: Apr 6

Spinal cord injuries can be classified in various ways. Some classifications focus on the injury's severity, while others consider the level of injury.


This article will help you distinguish between different types of spinal cord injuries by explaining the various classification methods and their meanings.


This guide covers the following types of spinal cord injury:

  • Complete vs. incomplete

  • SCI Levels of Spinal Cord Injury

  • ASIA Impairment Scale



General Types of Spinal Cord Injury




Spinal cord injuries are primarily classified into two categories: complete and incomplete. The term "completeness of injury" indicates the extent of the spinal cord damage. This classification is the broadest method to differentiate spinal cord injuries. The functional outcomes and potential for recovery can vary greatly depending on the completeness of the injury.


In the sections that follow, we will explore the key differences between these two types of spinal cord injuries.



Complete Spinal Cord Injury

A complete spinal cord injury occurs when the spinal cords electrical signals are non existent to both touch and absent of motor skills.. Typically, spinal cord damage cannot heal itself. Consequently, in a complete injury, brain signals cannot pass beyond the injury site, as there are no intact neural pathways.


Similarly, sensory signals from areas below the injury level cannot reach the brain. Thus, individuals with complete spinal cord injuries face both paralysis and a loss of sensation below the injury level.


Incomplete Spinal Cord Injury

The effects of incomplete spinal cord injuries can vary widely. Incomplete spinal cord injury involves a lesion that does not fully sever the spinal cord. As a result, some neural pathways remain unaffected, allowing individuals to potentially control or feel certain areas below the injury level.


The extent of preserved sensorimotor functions depends on the severity of the injury. A key distinction between complete and incomplete spinal cord injuries is that those with incomplete injuries often have the potential for functional recovery due to intact neural pathways at the injury site.


Neuroplasticity refers to the central nervous system's capacity to reorganize itself. Functions impacted by incomplete injuries can be reassigned to healthier spinal cord regions and enhanced through repetitive practice. However, neuroplasticity has limitations. Generally, the less severe the spinal cord injury, the more intact neural pathways exist, leading to greater recovery potential.


With an understanding of the differences between these spinal cord injury types, let's explore the various levels of injury.




Levels of Spinal Cord Injury



Regardless of being complete or incomplete, every spinal cord injury can also be classified by its level of injury. The level of injury denotes the lowest area of the spinal cord where motor and sensory functions remain normal.

Identifying the level of injury is crucial to understanding which functions might be affected.


The spinal cord is shielded by the spine and divided into 5 regions (from top to bottom):

  • Cervical: comprises 8 nerve segments (C1-8) that innervate the neck, diaphragm, shoulders, arms, and hands

  • Thoracic: includes 12 nerve segments (T1-12) that innervate the chest, back, and abdominal muscles

  • Lumbar: consists of 5 nerve segments (L1-5) that innervate parts of the external genitalia and the legs

  • Sacral: contains 5 segments (S1-5) that innervate the legs, feet, and remaining genitalia

  • Coccygeal: a single coccygeal nerve that innervates the skin around the tailbone


For both complete and incomplete spinal cord injuries, determining the level of injury helps individuals comprehend which functions will or will not be affected.


Learn more about spinal cord injury levels »



Types of Spinal Cord Injuries According to the ASIA Impairment Scale (AIS)


Another common method to classify different spinal cord injuries is the ASIA impairment scale, a standardized neurological exam to identify the sensory and motor levels affected by SCI.


The ASIA impairment scale includes 5 categories:

  • AIS A indicates no motor and no sensory function remain below the injury level. All complete spinal cord injuries are AIS A, and this represents the most severe ASIA level.

  • AIS B refers to an incomplete injury where sensory function is retained below the injury level, but no motor function remains.

  • AIS C indicates an incomplete injury where sensory or motor function is preserved in the S4/5 segment.

  • AIS D also describes an incomplete injury with partial motor function; however, those with AIS D have full range of motion against gravity for at least half of the key muscle functions below the injury level.

  • AIS E denotes a full functional recovery. Generally, individuals regain normal motor control and sensation below the injury level after previously experiencing deficits. (This suggests that individuals can progress in ASIA levels during their recovery, although this does not occur for everyone).


The ASIA classifications mentioned above have more detailed criteria that your physician(s) and therapist(s) may use to better understand your injury and predict functional outcomes.


Instead of merely categorizing a spinal cord injury as complete or incomplete, the ASIA impairment scale assists the rehab team in understanding the extent of sensorimotor functions a patient retains.


Types of Spinal Cord Injuries: Key Points


Comprehending the different types of spinal cord injuries is crucial as it helps care providers identify which functions may or may not be affected and develop a tailored rehabilitation plan.


While the type of SCI is vital in the rehabilitation process, numerous controllable factors can influence functional recovery.


For instance, patients can manage the intensity of their exercises, their daily movement, and their diet. These factors can impact energy levels, circulation, and stimulate neuroplasticity in the spinal cord.


Hopefully, this article has helped you better understand the various ways to classify a spinal cord injury. Good luck!



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