Incomplete versus complete SCI - What am I?

You may have heard the terms ‘incomplete’ and/or ‘complete’ being used to describe spinal cord injuries. When you injured your spinal cord you would have been told the level of your injury, for example, C5,T6,L1. 

Have you found these terms confusing? If so, you are not alone, but this document will help explain these terms and some of the other terminology used by medical staff.

First, the letter and number given to the level of your injury refers to a specific part of the spine.

C = cervical spine (neck)
T = thoracic spine (back)
L = lumbar spine (lower back)
S = sacrum

The number refers to a particular vertebra (bone) within each section of the spine. There are:
- 7 vertebrae in the cervical spine
- 12 in the thoracic spine
- 5 in the lumbar spine
- The sacrum is one large, triangular shaped bone at the bottom of the spine. Although it is a single bone, it has five holes from which the nerves exit.

Terms such as quadriplegia (1) or paraplegia are also used.

In some cases, the level of bone injury can be different to the level of spinal cord injury. For example you may have broken the C5 vertebra, but your spinal cord injury may be C6. If you are unsure of the level of your spinal cord injury it is best to consult your doctor. This document will try to explain about spinal cord injury rather than bone injury.

The level at which your spinal cord is damaged can affect two main things:

  • where you can feel, and
  • what you can move

Incomplete vs complete injuries

These terms are used in two different ways.

Common usage:

Many people use the term ‘complete’ to mean no sensation or movement below the area of injury, and the term ‘incomplete’ to mean some sensation or movement below the level of injury.

Medical usage:

The ASIA (American Spinal Injury Association) Standards are used by health professionals to determine if your injury is complete or incomplete. It scores and records all spinal cord injuries in the same way, which enables records from all spinal units around the world to be accurately compared.

In the table below ASIA A is ‘complete’ and the rest are ‘incomplete’.

Classification ASIA A CompleteASIA B Incomplete ASIA C Incomplete ASIA D Incomplete ASIA E Incomplete 
Sensation below level of injuryAbsent* Present Present Present Present 
Movement below level of injuryAbsent* Absent Present, but weak, in at least 50% of muscles below the injury level Present and useful strength in at least 50% of muscles below the injury level Present in all muscles, at normal or near normal strength 
 Sacral sparingAbsent Present Present Present Present 

* May have ‘zones of partial preservation’; see below.

So, in medical usage, a complete injury is where you have no sacral sparing. All other injuries are classified as incomplete. Incomplete injuries are classified according to the above ASIA scale. 

What is sacral sparing?

Sacral sparing refers to the ability to feel sensation and have voluntary control in your anal area. This is controlled by nerves that come from S4-5. 

Why is this important?

A spinal cord is rarely severed or completely cut through an injury. Most of the time, the spinal cord is severely squashed, compressed or damaged, resulting in loss of function. In any of these cases there is an opportunity for messages to get through from the brain to the rest of the body.
The S3-5 nerves come from the spinal cord at the furthest point from your brain. If you can feel and/or control movement in the anal area there must be some nerve fibres in the spinal cord that travel through the area of injury to and/or from the brain. If there are other nerve fibres that are ‘bruised’ but intact at the region of damage, they may recover. Thus, having sacral sparing gives hope of further recovery. Unfortunately there is no guarantee of this, or any way of predicting to what degree recovery will occur.

What if I don’t have sacral sparing, but can feel and/or move below the level of my injury?

You may have some sensation and/or movement in areas below the level of your injury, but no sacral sparing. We call this the ‘zone of partial preservation’. A 'zone of partial preservation' is usually only two to three levels below the level of injury, but in some cases can extend further.

Can my ASIA classification change?

Yes, it can. Reviews will be performed intermittently throughout your inpatient stay to monitor this, and changes may even continue after discharge. This can help shape your therapy plan, and maximise your outcomes. There will be a point, however, when your condition will no longer change but when this happens this varies from person to person.

What if I don’t fit into any of the above classes?

With an ASIA incomplete injury there are some common patterns of neurological loss such as:

- Brown-Sequard Syndrome
- Central Cord Syndrome
- Anterior Cord Syndrome
- Cauda Equina Syndrome

If these words have been used to describe your injury and you would like more information, please speak to your doctor.

We hope that this information has helped you to understand your injury. better If you have further questions please speak to your doctor or a member of your treating team.


Maynard FM, Bracken MB, Creasey G, Ditunno JF, Donovan WH, Ducker TB, Garber SL, Marino RJ, Stover SL, Tator CH, Waters RL, Wilberger JE, and Young W. (1997). International Standards for Neurological and Functional Classification of Spinal Cord Injury. Spinal Cord, 35, 266-274

(1) Quadriplegia is also known as tetraplegia.