The level of sensory loss on the trunk, as determined by perception of pinprick, is an accurate guide to the level of the lesion, with a few qualifications. (See Figs. 8-1, 8-3, and 8-4 for maps of the sensory dermatomes.) Lesions of the lower cervical cord, even if complete, may spare sensation down to the nipple line because of the contribution of the C3 and C4 cutaneous branches of the cervical plexus, which variably innervate skin below the clavicle. Or a lesion that involves only the outermost fibers of the spinothalamic pathways results in a sensory level (to pain and temperature) well below the level of the lesion. In all cases of spinal cord and cauda equina injury, the prognosis for recovery is more favorable if any movement or sensation is elicitable during the first 48 to 72 h.
If the spinal column can be examined safely, it should be inspected and palpated for angulations or irregularities and gently percussed to detect underlying bony injury. Collateral injury of the thorax, abdomen, and long bones should be sought and cranial injury is a concern if the mechanism of direct spinal impact is not known from the history.
A neurologic examination with recording of motor, sensory, and sphincter function is necessary to follow the clinical progress of spinal cord injury. A common practice is to define the injury according to the standards of the American Spinal Injury Association and to assign the injury to a point on the ASIA Impairment, or AIS (a derivative of the formerly used Frankel scale). The level of the cord injury is appended to the classification of injuries graded as severity of A through E. A paraphrased version that we have found useful is presented here with comments regarding functional ability from the Frankel scale:
A. Complete: No sensory or motor function below the level of the lesion including in the sacral segments.
B. Sensory incomplete: Sensory function is preserved but motor function is lost below the zone of injury.
C. Motor incomplete (first grade): Motor function is reduced in more than half of key muscles below the level of the lesion; this usually renders the patient unable to walk. (Reduced motor function is defined as active movement in a full range of motion only if gravity is eliminated.)
D. Motor incomplete (second grade): Motor function is reduced in fewer than half of key muscles below the level of the lesion; this usually allows standing and walking.
E. Normal: Reflexes may be abnormal.
Obviously, groups C, D, and E have a more favorable prognosis for recovery of ambulation than does groups A and B. Even minimal preserved of sensation at the outset of injury (grade B), which is usually in the perineum, is associated with a better outcome than AIS grade A.
In cases of suspected spinal injury, the immediate concern is that movement (especially flexion) of the cervical spine be avoided. The patient should ideally be placed supine on a firm, flat surface (with one person assigned, if possible, to keeping the head and neck immobile) and should be transported by a vehicle that can accept the litter. The board may be placed under the patient, gently rolling him to one side with the head, neck, and body held in alignment. If moving the patient is not feasible, the neck may be immobilized in place with a form collar or an equivalent device that is contrived at the scene, or even the examiner’s hands held firmly along the cervical spine. The patient should ideally be transported by an ambulance equipped with spine boards, to which the head is fixed by straps. This provides a more effective means of immobilization than sandbags or similar objects placed on each side of the head and neck. On arrival at the hospital, it is prudent to have the cervical spine remain immobilized until a lateral film or a CT or MRI of the cervical spine can been obtained, with the qualifications below.