Spinal cord injury levels can be expressed in many ways and it is important to understand the correlations.
This has an important bearing in marking the level of injury and correlating with the anatomy. For example, if an injury occurs at T10-11 vertebral level, it is going to damage her lower thoracic as well as lumbar spinal segments.
Few definitions first
Neurologic level
The most caudal [Caudal means toward the tail, cephalic or cephalad means towards the head] segment with normal sensory and motor function on both sides
Sensory level
The most caudal segment with a normal sensory function on both sides
Motor level
The most caudal segment with a normal motor function on both sides
Skeletal level
Radiographic level of greatest vertebral damage
Relevant Anatomy of Spine
The spine consists of a series of vertebral segments. The spinal cord itself has neurological segmental levels marked by the spinal roots.
A spinal root is named after the vertebra it exits from. When traced back to cord spinal cord segmental levels do not necessarily correspond to the bony vertebral level due to a mismatch between the level [body height] at which the vertebra and the spinal segment are in relation to each other.
Let us have a look at vertebrae and nerve root numbers
- Cervical – 7 vertebrae and 8 cervical roots. This discrepancy is because there are total 8 nerve roots exiting from the cervical vertebrae
- Thoracic 12 vertebrae and 12 roots
- Lumbar – 5 vertebrae and 5 nerve roots
- Sacral – 5 vertebrae and 5 nerve roots
The spinal cord segments are not necessarily situated at the same vertebral levels. This has been caused by a difference in vertebral height and height of the spinal segment. Thus, while the first cervical spinal segment is within C1 vertebra, the T12 cord comes to lie at the T8 vertebra level.
Similarly, the entire lumbar spinal segment lies between T9 and T11 vertebrae and the sacral cord is between the T12 to L2 vertebrae.
The course of Spinal Roots
C1 spinal root exit the spinal column at the atlanto-occiput junction. C2 root exits at the atlanto-axis. The C3 roots exit between C2 and C3. The C8 root exits between C7 and T1.
The first thoracic root or T1 exits the spinal cord between T1 and T2 vertebral bodies. The T12 root exits the spinal cord between T1 and L1. The L1 root exits the spinal cord between L1 and L2 bodies. The L5 root exits the cord between L5 and S1 bodies.
Relation of Spinal and Vertebral Segments – Spinal Level vs Vertebral Level
- First two cervical cord segments roughly match the first two cervical vertebral levels.
- C3 – C8 segments of the spinal cords are situated between C3 through C7 bony vertebral levels.
- Likewise, in the thoracic spinal cord, the first two thoracic cord segments roughly match first two thoracic vertebral levels.
- However, T3 through T12 cord segments are situated between T3 to T8. The lumbar cord segments are situated at the T9 through T11 levels while the sacral segments are situated from T12 to L1. The tip of the spinal cord or conus is situated at L2 vertebral level. Below L2, there is only spinal roots, called the cauda equina.
A rough calculation can be done as follow to obtain a relation between vertebral and segmental level.
- From C2-C6 vertebra add 1 to obtain the spinal segment level
- From T1-T6 vertebra add 2 to obtain the spinal segment level
- From T7-T9 vertebrae add 3 to obtain the spinal segment level
- T10-T12 vertebrae have the whole of lumbar segments
- L1 vertebra has sacral & coccygeal segments
- L2 onwards is cauda equina
Regionwise Spinal Cord Injury Levels
High-Cervical Injury (C1 – C4)
- Most severe of the spinal cord injury levels
- Leads to quadriplegia [paralysis of all four limbs] and trunk paralysis may affect respiration too and the patient may require a ventilator.
- The patient may have speaking problems, and bladder and bowel incontinence and would always require assistance if no recovery occurs.
- Patients may be able to use a power wheelchair controlled with the chin or the breath.
- Patients are also able to control adaptive devices for light switches, bed controls, televisions and so with the help of adaptive devices. They will require a caregiver’s assistance for most or all of their daily needs.
Low-Cervical Injury(C5 – C8)
- This spinal injury level involves C5 to C8 nerve roots.
- There would be no breathing or speech problems
- The disability depends on the spinal injury level
C5
- Some or total paralysis of
- Wrists
- Hands
- Trunk
- Legs
- Will require assistance with most activities of daily living but can move from one place to another independently in a wheelchair.
- These patients are able to flex their elbows.
- They can learn to feed and groom themselves with help of assistive devices.
- Can dress their upper body and change positions in bed.
- These patients are able to use a power wheelchair equipped with hand controls.
- Require help in transfers from bed to chair and so forth,
- Need assistance with bladder and bowel management, bathing and dressing especially in the lower part also require assistance.
- Able to drive a vehicle equipped with hand controls.
C6
- Paralysis in hands, trunk, and legs
- Able to dorsiflex wrist
- Can move in and out of wheelchair and bed with assistance/aid
- No voluntary control of bowel/bladder, but may manage on their own with special equipment.
- Can use elbows and wrists and are able to grasp objects with support.
Some are able to transfer themselves without help using a slide board.
They can learn to feed, groom, and bathe themselves with the help of assistance devices, are able to operate special vehicles.
C7
Most have normal movement of their shoulders, can do most activities of daily living, but need assistance with more difficult tasks, may be able to drive an adapted vehicle, no voluntary control of bowel or bladder but, may be able to manage on their own with special equipment.
C8
C8 injury – Able to grasp and release objects, can do most activities of daily living by themselves, but may need assistance with more difficult tasks, may also be able to drive an adapted vehicle, little or no voluntary control of bowel or bladder, but may be able to manage on their own with special equipment
Upper Thoracic Injury (T1 – T5)
These spinal cord injury levels affect muscles of the upper chest, mid-back, and abdomen. Arm and hand function is usually normal, paraplegia is present. Patients are able to use a manual wheelchair. Some can stand in a standing frame, while others may walk with braces.
Lower Thoracic Injury(T6 – T12)
- Affects muscles of the trunk, and usually results in paraplegia [paralysis of lower limbs]
- Normal upper-body movement
- Little or no voluntary control of bowel or bladder but can manage on their own with special equipment
- Can use a manual wheelchair
- Can learn to drive a modified car
- Able to stand in a standing frame [Some are able to walk with braces]
Lumbar Injury(L1 – L5)
- Generally result in some loss of function in the hips and legs.
- Little or no voluntary control of bowel or bladder, but can manage on their own with special equipment.
- May need a wheelchair or walk with braces depending on the strength of
Sacral Injury(S1 – S5)
Injuries generally result in some loss of function in the hips and legs. Little or no voluntary control of bowel or bladder, but can manage on their own with special equipment. Most likely will be able to walk
Note: For all practical purposes whenever a lesion in the spine is examined, it is always good to mention injured vertebral and spinal levels separately.
If they roughly match, the level has been ascertained. If they grossly mismatch something might have been missed. There might be another lesion or cord edema.
We shall now briefly discuss important levels of spinal cord injury sand associated functional disabilities.
Functional Abilities of the Patient Following Spinal Cord Injury at Different Levels
In the absence of medical complications, the most important factor in functional disability is the amount of muscle power remaining in the individual.
However, there are certain factors that can affect the functional outcome. These are
- Spasm
- Decubitus nature
- Insufficient motivation
- Deformity
- Urinary and fecal incontinence.
We have discussed following critical levels of injury. We would begin with C5 and move downward. The level mentioned denotes the spared level. That means the spinal cord injury level is just above.
- C5
- C6
- C7
- T1
- T6
- T 12
- L4
A Summary of Activities Possible at Different Levels
C5 Functional Abilities
The patient below C5 [C5 is spared] has full innervations of trapezius, sternocleidomastoid and upper paraspinal muscles. Therefore the patient is able to
- Stabilize and rotate his neck.
- Elevate and externally rotate the scapulae.
- Rhomboids, deltoids and all of the major muscles of the rotator cuff are functional though these are partially innervated [from C6]. Following movements can occur
- Scapular adduction
- Glenohumeral joint abduction
- Internal and external rotation
- Fflexion and extension of the shoulder
However, the shoulder is not able to perform strong depression, flexion, protraction, and adduction.
Absence of prime movers of shoulders [latissimus, pectoralis and serratus muscles] and incomplete innervation of stabilizers prevent remaining from becoming functional.
Elbow flexion is present as biceps and brachioradialis remain partially innervated.
There is no muscular function in hand or wrist.
The patient is unable to roll over or come to a sitting position in the bed.
One may, in certain cases, eat using special hand devices.
The patient is unable to push the wheelchair.
Endurance is low due to reduced respiratory reserve.
The patient cannot ambulate and is confined to a wheelchair. She requires an attendant for life who would assist in self-care, to lift and transport to back chair.
Removable armrests, swinging removable footrests and detachable back make shifting easier.
A gatch bed can be used for care. It is a bed with a frame in three movable sections equipped with mechanical spring parts that permit raising the head end, foot end, or middle as required.
A tilt board is used for an hour daily to maintain vascular tone and bone density for compensating inability to stand.
A patient with C5 injury is not able to earn a living by use of his hands.
C6 Functional Abilities
As compared to C5, a substantial functional increase occurs at C6 level.
- Rotator cuff of the shoulder becomes fully innervated
- Serratus, latissimus and pectoralis major receive partial but significant innervations.
- Nerve supply to biceps becomes complete.
- Muscles appear at the wrist particularly extensor carpi radialis and sometimes flexor carpi radialis.
– There is good rotation and abduction of the glenohumeral joint.
– As prime movers are working, true adduction, flexion, extension and scapular protraction is possible.
However, as the nerve supply of prime movers is partial only, the strength varies.
The respiratory reserve would still be low.
Biceps and brachioradialis provide strong flexion.
The extensor and flexors of the wrist work and extensors of the wrist could utilize the remaining elasticity of the flexors to provide a weak closure of the hand.
However, more elaborate hand devices are required.
Even with an absent grasp, the patient may take advantage of elbow flexors to sit up independently.
Rolling over in the bed is permitted by shoulder strength.
But the patient cannot move in the bed while recumbent without help.
An attendant is essential in lifting the patient to and from the wheelchair.
The patient may be able to feed himself with help of hand devices. She can perform part of his toilet and dressing activities.
But the patient cannot be termed as independent in self-care. Use of a Gatch bed and tilt board is recommended.
Ambulation is not possible and the patient is confined to the wheelchair but can propel his own wheelchair on a smooth leveled floor.
The grasp is absent but she uses elbow flexors and shoulder adductors for this.
The patient is not able to do any job with hands. However, some may develop sufficient skill to use for the specially adapted machinery.
C7 Functional Abilities
The patient with spared C7 has three important additions
- Triceps
- Common finger extensors
- Long finger flexors
Primary innervation for each of these groups varies between C7 and C8. Triceps is especially strong as the innervations come as high as C6.
This enables the patient to stabilize the elbow in extension and can assist in lifting the body weight.
Finger extensors and flexors offer grasp and release but are not powerful.
As the intrinsic muscles of the hand are not yet significantly innervated, the hand lacks strength and dexterity.
The patient is more independent in bed and wheelchair than C6 patients.
Exceptional individuals may be able to make the transition to wheelchair independence.
These patients can roll over, sit up in the bed, and move about in a sitting position.
Assistance is required to lift the pelvis while recumbent, as in putting on the trousers.
Most of the patients require help in transferring to and from the wheelchair but the help is just an assistive push than a real lift.
Some assistance is required for toileting and dressing activities.
Eating can be done independently.
If adequately braced, some C7 lesions are able to ambulate with crutches to some extent. The fingers permit grasping the crutches and triceps provides stability to the elbow.
To maintain an upright posture, the patient needs long leg braces with the pelvic band and a high spinal attachment.
The only independent gait possible is the “drag to” gait.
As applying braces and attaining the erect position cannot be done without a great deal of assistance, this kind of ambulation cannot be considered functional.
C7 quadriplegic is still confined to a wheelchair, and needs a part-time/ full-time attendant. Endurance is affected by a low respiratory reserve.
Occupations requiring the use of hands are more feasible since finger flexors and extensors are functional.
The type of work is limited by the weakness of grasp. The activities involving a tight grasp are not recommended.
Possible vacations include book-keeping, telephone services, and mimeographing or typing.
T1 Functional Abilities
The patient has full innervations of the upper extremity musculature, including essential intrinsic muscles of the hand.
This patient would have strength, dexterity and fully innervated proximal musculature.
As the ulnar side of the wrist has full blood supply now, crutch walking is better controlled.
The patient still lacks trunk stability, a respiratory reserve of intercoastal origin, and trunk fixation [required for prime movers of upper extremity]
The patient is functional in bed activities. She is able to transfer to and from the wheelchair without aid, requiring assistance sometimes.
T1 patient is independent in all activities of self-care, excluding those requiring lifting of the body while recumbent.
The patient is able to carry himself with help of crutches with a drag or swing to gait.
Because of full body bracing, attaining an erect position is laborious requiring help. Ambulation, therefore, cannot be considered functional and a well-adapted wheelchair is essential.
The patient is able to carry homebound jobs requiring the use of the hand. Some patients develop sufficient sitting balance to drive a hand-controlled car though in and out the transfer from the car may require assistance.
T6 Functional Abilities
T6 paraplegic has complete control of thoracic and upper extremity musculature, stabilized against a well-coordinated pectoral girdle including intercostals, long muscles of the upper back and transverses throracis.
The patient has a tight grasp, supported by proximal musculature which in turn is stabilized against the thorax.
Added intercostals innervations help increment in respiratory reserve.
All these factors translate into better and almost independent self-care.
Even application of full body bracing becomes possible as the patient can adequately stabilize his upper extremities to use them to lift the pelvis in applying braces.
The patient can independently transfer in and out of the wheelchair by using strong pectoral girdle and triceps.
The patient usually needs no attendant but adaptation and customization of a wheelchair may be required.
The patient is braced with low spinal attachment, pelvic band, and double long leg braces. these help to stand for longer periods.
Door –bars, parallel or stall bars are prescribed for assisting in getting to an erect position.
The use of tilt board is not required.
For those who are comfortable while standing, special standing apparatus of work equipment may be considered.
The patient is unable to do elevation activities as the hip and knee are locked and all the elevation activities must be accomplished by pure push-ups in the shoulder girdle.
This push-up is adequate in most of the patients only for the ascent of very low stairs with a handrail but not the standard 20 cm stairs, thus making public transportation impossible.
Work outside the home could be reached by private hand-controlled or chauffeured car. Most of the T6 patients have sufficient sitting balance to drive a hand-controlled car.
The patient is able to transfer from wheelchair to car.
T12 Functional Abilities
This patient has full innervations to rectus abdominis, oblique muscles of the abdomen, the transverses abdominis and all muscles of the thorax.
As lumbar innervations are absent, lower back muscles are weak. So are primary hip lifters i.e. quadratus lumborum and lower erector spinae muscles. Hip hiking can be accomplished by secondary hip hikers namely internal and external obliques and latissimus dorsi.
For ambulation, the patient is braced with bilateral long leg braces and may or may need a pelvic band, depending on his skill.
The patient may use a two-point alternate or four points or swing through gait as suits her convenience. Using these gaits, she can ambulate freely on reasonably rough surfaces, negotiate curbs as well negotiate 200 mm [achieved by pelvic tilt] stairs with handrails. This would also enable the use of public transportation.
T 12 patients have very few limitations in sedentary or semisedentary jobs away from home.
The patient’s wheelchair should be customized as per needs.
L4 Functional Abilities
The patient with a lesion below L4 has the functional assistance of quadratus lumborum, erector spinae, quadriceps, and primary hip flexors. Ankle remains flail.
A long leg brace becomes unnecessary as quadriceps extension is present. The flail ankle can be supported by a short leg brace.
The patient’s gait is bilateral maximus-medius gait with the added disability of flail ankles. Lumbar lordosis and genu recurvatum may develop as extended pelvis and the extended knee becomes necessary during ambulation.
Crutches are prescribed to prevent long-term effects though the patient may be able to walk without them.
The patient is independent in all phases of self-care and ambulation. A wheelchair may be a convenient addition at home or work.
References
- Nas K, Yazmalar L, ?ah V, Ayd?n A, Öne? K. Rehabilitation of spinal cord injuries. World J Orthop. 2015 Jan 18;6(1):8-16. doi: 10.5312/wjo.v6.i1.8.
- Karatas G , Metli N , Yalcin E , Gündüz R , Karatas F , Akyuz M . The effects of the level of spinal cord injury on life satisfaction and disability. Ideggyogy Sz. 2020 Jan 30;73(1-2):27-34. English. doi: 10.18071/isz.73.002. Lin: WJO
