The pattern of movements in walking. Gait requires proper functioning and integration of the nervous system and the musculoskeletal system. Injury or dysfunction of either interferes with normal gait. The nature of the gait disturbance is key to diagnosing neuromuscular disorders. Gait analysis is an essential element of a neurological examination. In natural or normal gait, the movements of walking are smooth and coordinated, with opposing but comparable arm swing and leg stride. When the right leg steps forward, the left arm swings forward and the right arm swings back. When the left leg steps forward, the right arm swings forward and the left arm swings back. As the heel of the forward leg makes contact with the walking surface, the toe of the back leg is releasing from such contact. As contact of the forward foot rolls from heel to toe, the back foot clears contact and the back leg begins to swing forward.
For counterbalance, the shoulders and the hips also rotate opposite one another, clockwise or counterclockwise, during walking. The shoulders follow the arm swing, rotating counterclockwise when the right arm is forward and clockwise when the left arm is forward. Similarly, the hips follow the leg extension, rotating counterclockwise when the right leg is extended and clockwise when the left leg is extended. These movements are all continuous and synchronized, occurring without hesitation or exaggeration.
The moment at which the toe of one foot and the heel of the other foot are both in contact with the surface, called the stance phase of gait, is a crucial point in the gait cycle. During the stance phase the body transfers weight from the back leg to the forward leg, known in biochemical terms as load response. It requires balance, stability, coordination, and strength. The actions of motion are called the stride phase of gait. A third component of gait is the stationary phase, during which the person stands still with both feet in full (heel to toe) contact with the surface.
When gait is normal, the body maintains equilibrium upright and from side to side, both during movement (the stride and stance phases of gait) and while standing still (the stationary phase of gait). In a person with Parkinson’s disease, nearly all characteristics of gait become altered in a typical and often pronounced pattern of gait disturbances. Muscle rigidity and tremors further restrict movement and control of motion. Treatment with anti-parkinson’s medications to augment the brain’s supply of dopamine can restore movement and gait to near-normal in the early and mid stages of the disease in most people with Parkinson’s.
Clinical Gait Analysis
Clinical gait analysis is primarily observational and generally provides enough information for a neurologist or other clinician to suspect or confirm (and sometimes to rule out) a diagnosis of Parkinson’s disease. It is part of a typical neurological examination or functional assessment. To conduct a clinical gait analysis, the clinician asks the person to walk a short distance and observes movements as the person walks away and then walks back.
Gait disturbances characteristic of Parkinson’s include short, shuffling steps; limited or nonexistent arm swing; foot drag; high-stepping; and hesitation when starting, stopping, or turning. The clinician may also ask the person to repeat the process; walking the same distance only on the toes and then only on the heels. People with Parkinson’s may find it easy to, or tend to, walk on their toes but difficult to walk only on their heels. The clinician also observes the person for balance, swaying from side to side, upper body movement, and any evidence of hemiplegic gait (swinging the leg out to the side during forward movement) that might suggest damage to parts of the brain other than those that are typical in Parkinson’s disease (such as from stroke).
Instrumental Gait Analysis
Instrumental gait analysis uses videotaping, elec-trophysiologic studies, computerized modeling, and other methods to provide in-depth assessment of motor skills and movement dysfunctions. Such analysis helps to pinpoint areas of difficulty so that a physical therapist, occupational therapist, or physiatrist (physician specializing in rehabilitative medicine) can develop an individualized program of exercises to help compensate for already lost function and to preserve remaining function as long as possible. This analysis is particularly useful in early-onset Parkinson’s, in the early stages of Parkinson’s, and when gait disturbances do not follow a typical pattern. Such techniques are also very useful in research since it provides data from numerous measurements that more readily lends itself to further analysis for small improvements than the more subjective (and less readily converted to numbers) clinical gait exam.