Clinical Staging Of Gait Disorders In Pd

The Parkinson's-Reversing Breakthrough

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In accordance with progression of nigro-striato-pallidal dysfunction, gait disorders in PD can be staged as follows:

Stage 1. Nonsignificant Gait Disturbances In this first stage, functionally nonsignificant gait disturbances, such as decreased gait speed, shortened steps, decreased arm swing, and increased stride-to-stride variability as detected by gait dynamics analysis, may be observed.10

Stage 2. Mild to Moderate Functional Gait Disturbances

In the second stage, shuffling with marked bradykinesia and hypokinetic gait becomes important functionally. Steps are short with decreased force of foot "push-off' or hip "pull-up" as well as flexed joints and stooped trunk. "Stop walking while talking"11 as a presentation of advanced dual-tasking derangement can also be seen. Abnormally enlarged gait variability in response to distractions (dual tasking—subtracting of serial sevens) may also be observed.12

Stage 3. Significant Functional Gait Disturbances

In this stage, significant episodic gait disorders (EGDs), including freezing of gait (FOG) and festinating gait

(FSG), take place on the background of continuous gait disturbances (e.g., slowed gait).13 EGD typically appear unintentionally, break the background pattern of gait, and last for a period of seconds. FOG can be defined as intermittent episodes, which last for a few seconds (rarely exceeding 30 sec), of an inability to initiate or maintain locomotion or perform a turn. Typically, most FOG episodes can be overcome by motor, sensory, or mental tricks, but habituation has been described.14,15 FOG episodes can be provoked most easily by asking the subject to turn around (turning hesitation).16,17 However, in terms of ordinary motor behavior, 360° or even 180° turns are rare and, as a result, start hesitation is experienced more frequently in daily life.17 Turning hesitation is important because of its possible contribution to falls during the act of turning. Other types of FOG occur while walking, passing through tight quarters, reaching a destination, and in stressful situations such as crossing the street ("open space") or entering an elevator ("tight quarters").17 Festinating gait is an intermittent episode that lasts a matter of seconds and involves disturbed locomotion characterized by uncontrolled propulsion associated with rapid small steps. Patients frequently report a feeling that they were "pushed from behind."18 The only clinical paper that characterized festination showed a significant association with FOG, in support of a possible pathophysiological linkage between the two.19

Previously EGD has been principally assessed by subjective measures and only recently was a validated questionnaire developed for evaluating freezing of gait (FOG).20 A new objective method for quantifying FOG consists of an ambulatory gait analysis system with pressure sensitive insoles that continuously record walking, synchronized with a video recording.21 Using this system, the episodic and unpredictable nature of FOG can be measured and assessed over several minutes. Given the transient nature of FOG, a longer walking evaluation period (i.e., minutes rather than just a few seconds) is preferred. In addition, the "tremor-like" shaking of the legs during FOG can be analyzed using time series analyses. This quantitative analysis demonstrated that the trembling during FOG is distinct from classical tremor—both in terms of frequency and complexity of the leg fluctuations—but also distinct from normal locomotion.13 In FOG, the legs fluctuate in a complex pattern with much of the power centered around 2 to 4 Hz (Figure 17.1). Although the fluctuations may seem random, the leg movements fluctuate in a fairly organized pattern. One possibility is that the movements during FOG are generated by an independent generator or by misfiring oscillators that force the legs to move too fast for effective stepping. Using this method, it was shown that the center-of-pressure fluctuations during FOG are unique and very different from normal gait.22

Gait Disorder

FIGURE 17.1 Example of freezing of gait in 77-year-old man with advanced PD (Hoehn and Yahr stage 3). The top panel shows the insole force before, during, and after a freezing episode. The bottom panel shows the results of spectral analysis for the walking period and for the freezing episode (the data before the breakthrough step were analyzed here). Note the large percentage of power in the 3 to 6 Hz band during freezing, but not during walking. (Adapted from Ref. 22.)

FIGURE 17.1 Example of freezing of gait in 77-year-old man with advanced PD (Hoehn and Yahr stage 3). The top panel shows the insole force before, during, and after a freezing episode. The bottom panel shows the results of spectral analysis for the walking period and for the freezing episode (the data before the breakthrough step were analyzed here). Note the large percentage of power in the 3 to 6 Hz band during freezing, but not during walking. (Adapted from Ref. 22.)

When stride-to-stride variation was compared during inter-episodic intervals (i.e., during regular walking, between two FOG episodes) among PD patients with FOG and those with no FOG in the "off" state, patients with FOG had significantly larger stride-to-stride variability.23,24 This observation and the report by Nieuwboer et al.25 about changes in stride length and cadence in the few steps prior to freezing episodes suggest primary disrhyth-mic locomotion in PD patients with FOG that may worsen until freezing appears. In other words, FOG might be the extreme form of a general continuous disrhythmicity.13

In the early stages of PD, a FOG episode usually lasts a second or two, occurring mainly in the form of turn or start hesitation and causing only minor disturbances in general function or quality of life, with tricks being needed only rarely to overcome the block. In a recent retrospect analysis of a group of patients who experienced FOG episodes early in the course of the disease, prior to any medical treatment, and who were followed in the Deprenyl and Tocopherol Antioxidative Therapy of Par-kinsonism (DATATOP) cohort for a mean of 6.0 ± 1.4 years, early appearance of FOG was not associated with later development of atypical parkinsonism.26

As PD progresses, FOG episodes become one of the most disabling motor symptoms in the "off' state. In most cases, they respond to L-dopa treatment, which decreases their frequency, duration and akinetic nature 1723. At this stage, they are commonly associated with postural instability and, as a result, can lead to falls.18,27-29

Stage 4. Appearance of Falls on the Background of Severe Continuous and Episodic Gait Disorders

Falls are the most serious complication of the gait disturbance in PD. Together with other accepted cardinal neurological signs of PD, falls may be recognized as a sign of disease progression and the result of decompen-sated postural instability and gait dysrhythmicity.11 Falls become increasingly important and develop into one of the chief complaints among PD patients and their caregivers. They are the leading cause of physical trauma, fear of fallings, and restriction of day-to-day activity in PD patients.10

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