Cervical Cord Lesions: Tetraplegia

Tetraplegia, or quadriplegia as it is more commonly known, means paralysis involving all four extremities. The lesion that causes such paralysis occurs in the cervical spine.

In an analysis of tetraplegia, establishment of the level of neural involvement and evaluation of its degree (whether the cord lesion is complete or incomplete) are of primary concern. Both these factors must be known before there can be any attempt at prediction of recovery of neurologic function or before any effective program of therapeutic treatment and rehabilitation can be planned. The more rapid the rate of return of spinal cord function, the greater the amount of recovery and, conversely, the slower the rate of return, the smaller the amount of recovery. This rule of thumb makes it easier to estimate the future possibility of both ambulation and bladder and bowel function. Because, at the beginning, the patient may be in a state of spinal shock (diaschisis), from which some neural recovery may occur, a thorough neurologic examination, repeated every 2 to 4 hours for the first 48 hours, may begin to provide some answers about the potential for recovery. Each examination must include muscle testing, sensory testing, and reflex testing to permit a complete evaluation of the possibility of cord return.

Evaluation of Individual Cord Levels: C3-T1

If the cervical cord is completely transected, complete paralysis of the lower extremities occurs, but the degree of paralysis of the upper extremities depends on the neurologic level involved. Although some cervical cord lesions are, in reality, incomplete or partial (so that some function remains below the level of the lesion), we shall discuss the signs as if each cord lesion is complete, because the real issue is to determine the level of injury.

Spinal shock and associated muscle flaccidity usually pass between 24 hours and three months after trauma. Spasticity and clonus set in and gradually increase in intensity. The deep tendon reflexes become exaggerated and pathologic reflexes appear.

Neurologic Level C3 (C3 Intact)

A neurologic level of C3 means that the third cervical root is intact, whereas the fourth is not. Neurologic level C3 corresponds to vertebral level C3, C4 (Fig. 3-1).

Motor Function

There is no motor function in the upper extremities; the patient is completely tetraplegic. Muscles are flaccid as a result of denervation and spinal shock. After spinal shock has worn off,
the muscles will demonstrate varying degrees of spastic response. Because the diaphragm is supplied largely by C4, the patient is unable to breathe independently, and will die without artificial respiratory assistance. Sometimes, in what at first appears to be a C3 level, C4 later recovers, with a return of diaphragmatic function.

FIGURE 3-1 Tetraplegia: neurologic level C3.

Sensation

There is no sensation in the upper extremities or below a line three inches above the nipple on the anterior chest wall.

Reflexes

In the presence of spinal shock, all deep tendon reflexes are absent. When spinal shock has worn off, they will become brisk to exaggerated and pathologic reflexes may be evident.

Neurologic Level C4 (C4 Intact)

The 4th cervical cord segment remains intact. The lesion lies between the 4th and 5th cervical vertebrae (Fig. 3-2).

FIGURE 3-2 Tetraplegia: neurologic level C4.

Motor Function

The muscles of the upper extremity are nonfunctional. Because C4 is intact, the patient can breathe independently and shrug the shoulder. But the lack of functioning intercostal and abdominal muscles keeps the patient’s respiratory reserve low, although probably adequate for the reduced level of function.

Sensation is present on the upper anterior chest wall, but not in the upper extremities.

Reflexes

Initially, all deep tendon reflexes are absent, but the passing of spinal shock may bring changes.

Neurologic Level C5 (C5 Intact)

A lesion at this level leaves C5 intact. Because this is the first cord level to contribute to the formation of the brachial plexus, the upper extremity will have some function (Fig. 3-3).

Motor Function

The deltoid muscle and a portion of the biceps muscle are functioning. The patient is able to perform shoulder abduction, flexion, and extension, as well as some elbow flexion. However, all these motions are weakened because the muscles governing these movements usually have contributions from the C6 nerve root.
The patients cannot propel a wheelchair by themselves and their respiratory reserve is low.

FIGURE 3-3 Tetraplegia: neurologic level C5.

Sensation is normal over the upper portion of the anterior chest and in the lateral aspect of the arm from the shoulder to the elbow crease.

Reflexes

Because the biceps reflex is primarily mediated through C5, it may be normal or slightly decreased. As spinal shock wears off and elements of C6 return, the reflex may become brisk.

Neurologic Level C6 (C6 Intact)

Involvement is at skeletal level C6-C7 (Fig. 3-4).

Motor Function

Because both C5 and C6 are intact, the biceps and the rotator cuff muscles function. The most distal functional muscle group is the wrist extensor group; the extensor carpi radialis longus and brevis (C6) are both innervated (although the extensor carpi ulnaris—C7—is still involved). The patient has almost full function of the shoulder, full flexion of the elbow, full supination and partial pronation of the forearm, and partial extension of the wrist. The strength of wrist extension is normal, because power for extension is predominantly supplied by the extensor carpi radialis longus and brevis.

FIGURE 3-4 Tetraplegia: neurologic level C6.

Respiratory reserve is still low. The patient is confined to a wheelchair, which can be propelled over smooth, level surfaces.

Sensation

The lateral side of the entire upper extremity, as well as the thumb, the index, and half of the middle finger, has a normal sensory supply.

Reflexes

Both the biceps and the brachioradialis reflexes are normal.

Neurologic Level C7 (C7 Intact)

Involvement is at vertebral level C7-T1 (Fig. 3-5).

Motor Function

With the C7 nerve root intact, the triceps, the wrist flexors, and the long finger extensors are functional. The patient can hold objects, but grasp is extremely weak. Although he is still confined to a wheelchair, the patient may begin to attempt parallel bar and brace ambulation for general exercise.

Sensation

C7 has little pure sensory representation in the upper extremity. No precise zone for C7 sensation has been mapped.

Reflexes

The biceps (C5), brachioradialis (C6), and triceps (C7) reflexes are normal.