This gait pattern is caused by paralysis of the pretibial and peroneal muscles, with resultant inability to dorsiflex the foot (foot drop). The steps are regular and even, but the advancing foot hangs with the toes pointing toward the ground. In its purest form, it is the result of peroneal nerve or fifth lumbar root damage. Walking is accomplished by excessive flexion at the hip, the leg being lifted abnormally high in order for the foot to clear the ground. There is a slapping noise as the foot strikes the floor. Thus there is a superficial similarity to the tabetic gait described just above, especially in cases of severe polyneuropathy, where the features of steppage and sensory ataxia may be combined. However, patients with steppage gait alone are not troubled by a perception of imbalance; they fall from tripping on carpet edges and curbstones.
Foot drop may be unilateral or bilateral and occurs in diseases that affect the peripheral nerves of the legs or motor neurons in the spinal cord, lumbar roots, such as chronic acquired neuropathies (diabetic, inflammatory, toxic, and nutritional), Charcot-Marie-Tooth disease (peroneal muscular atrophy), progressive spinal muscular atrophy, and poliomyelitis. It may also be observed in certain types of muscular dystrophy in which the distal musculature of the limbs is involved.
A particular disorder of gait, also of peripheral origin and resembling steppage gait, may be observed in patients with painful dysesthesias of the soles of the feet. Because of the exquisite pain evoked by tactile stimulation of the feet, the patient treads gingerly, as though walking barefoot on hot sand or pavement, with the feet rotated in such a way as to limit contact with their most painful portions. The usual cause is one of the painful peripheral neuropathies (most often alcoholic-nutritional but also toxic and amyloid types), causalgia, or erythromelalgia.
The patient with hemiplegia or hemiparesis holds the affected leg stiffly and does not flex it freely at the hip, knee, and ankle. The leg tends to rotate outward to describe a semicircle, first away from and then toward the trunk (circumduction). The foot scrapes the floor, contact being made by the toe and outer heel of the foot. One can recognize a spastic gait by the sound of slow, rhythmic scuffing of the foot and wearing of the medial toe of the shoe. With a cerebral or cervical lesion, the arm on the affected side is weak and stiff to a variable degree; it is carried in a flexed position and does not swing naturally (Fig. 6-2A). In the hemiparetic child, the arm tends to abduct as he steps forward. This type of gait disorder is most often a sequela of stroke or trauma but may result from any condition that damages the corticospinal pathway on one side.
The spastic paraplegic or paraparetic gait is, in effect, a bilateral hemiplegic gait. Each leg is advanced slowly and stiffly, with restricted motion at the hips and knees. The legs are extended or slightly bent at the knees and the thighs may be strongly adducted, causing the legs almost to cross as the patient walks (scissor-like gait; Fig. 6-2B). The steps are regular and short and the patient advances only with great effort as though wading waist-deep in water. The defect is in stiffness of the stepping mechanism and in propulsion, not in support or equilibrium.