Parkinsonian Gait
Freezing of Gait (FOG) is one of the most debilitating gait impairments in Parkinson's disease (PD), leading to increased fall risk and reduced health-related quality of life.
Among patients with Parkinson's disease (PD), gait is typically disturbed and less automatic. These gait changes are associated with impaired rhythmicity and increased prefrontal activation, presumably in an attempt to compensate for reduced automaticity.
Parkinsonian Gait may also be sub-classified as continuous (appearing whenever the patient walks) and episodic (lasting seconds).
In this gait, the patient will have rigidity and bradykinesia. He or she will be stooped with the head and neck forward, with flexion at the knees. The whole upper extremity is also in flexion with the fingers usually extended. The patient walks with slow little steps known at marche a petits pas (walk of little steps). Patient may also have difficulty initiating steps. The patient may show an involuntary inclination to take accelerating steps, known as festination. This gait is seen in other condition causing parkinsonism, such as side effects from drugs.
Thumm et al. investigated whether during treadmill walking, when the pace is determined and fixed, prefrontal activation in patients with PD is lower, as compared to over-ground walking.
Twenty patients with PD (age: 69.8 ± 6.5 yrs.; MoCA: 26.9 ± 2.4; disease duration: 7.9 ± 4.2 yrs) walked at a self-selected walking speed over-ground and on a treadmill. A wireless functional near infrared spectroscopy (fNIRS) system measured prefrontal lobe activation, i.e., oxygenated hemoglobin (Hb02) in the pre-frontal area. Gait was evaluated using 3D-accelerometers attached to the lower back and ankles (Opal™, APDM). Dynamic gait stability was assessed using the maximum Lyapunov exponent to investigate automaticity of the walking pattern.
Hb02 was lower during treadmill walking than during over-ground walking (p = 0.001). Gait stability was greater on the treadmill, compared to over-ground walking, in both the anteroposterior and medio-lateral axes (p < 0.001).
These findings support the notion that when gait is externally paced, prefrontal lobe activation is reduced in patients with PD, perhaps reflecting a reduced need for compensatory cognitive mechanisms 1).
Freezing of Gait (FOG) is one of the most debilitating Parkinsonian gait impairments, leading to increased fall risk and reduced health-related quality of life. The utility of parkinsonian medications is often limited in the case of FOG and it frequently becomes dopamine resistant.
Studies have suggested that pre-frontal cortex (PFC) dysfunction contributes to FOG; however, most previous findings provide only indirect evidence. To better understand the role of the PFC, Dagan et al., aimed to investigate the impact of high frequency, deep, repetitive transcranial magnetic stimulation (drTMS) of the medial PFC on FOG and its mediators. Nine patients with advanced PD participated in a randomized, cross-over exploratory study. We applied drTMS over the medial PFC for 16 weeks, with real and sham conditions; each condition included an intensive (i.e., 3 times a week) phase and a maintenance (once a week) phase. Scores on a FOG-provoking test, the motor part of the Unified Parkinson's Disease Rating Scale, and gait variability significantly improved after real drTMS, but not after the sham condition. Self-report of FOG severity and cognitive scores did not improve. Due to discomfort and pain during treatment, two patients dropped out and the study was halted. These initial findings support the cause-and-effect role of the pre-frontal cortex in FOG among patients with PD. Due to the small sample size, findings should be interpreted cautiously. Further studies are needed to more fully assess the role of the medial PFC in the underlying mechanism of FOG and the possibility of using non-invasive brain stimulation to modify FOG 2).