The Parkinson Society of British Columbia (PSBC) offered a webinar in mid-September on freezing and how to prevent the condition from occurring in Parkinson’s Disease (PD). Shelly Yu, a neuro physiotherapist with PSBC, provided PD patients and caregivers on strategies to minimize freezing and maintain activity. Specifically, the webinar covered the what, when, where, and why of freezing. 

The speaker provided several strategies to reduce freezing of gait (FoG):

• take bigger and more symmetrical steps
• practice motor skills in situations where dual-tasking may be involved, in order to manipulate different environmental factors
• utilize different types of cues such as auditory, visual, and tactile
• try an agility and/or an obstacle course for both the mind and body.

The webinar was recorded and can be viewed here.

The speaker’s slides are here, including multiple references for research on FoG.

The Parkinson Society of British Columbia has a helpful document on freezing.

I listened to the webinar and am sharing a summary of the talk below.

August Besser

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Thawing Out: Strategies to Reduce Freezing

September 14, 2020

Webinar hosted by the Parkinson Society of British Columbia

Summary by August Besser, Stanford Parkinson’s Community Outreach

What is Freezing?

Freezing of Gait (FoG) is a brief, episodic absence or marked reduction of forward progression of the feet despite the intention to walk. The feet of someone who freezes tend to lock in place and tremble, and the upper legs halt as well, but the upper torso may continue beyond the freeze and pitch forward. The episode usually lasts around 10 seconds, but can go for much longer in more serious cases.

Freezing affects approximately 26% of early stage Parkinson’s patients and 80% of advanced stage Parkinson’s patients. Freezing is a common cause of falls and injury, and is triggered by certain motor, cognitive, and environmental factors, such as turning, going through doorways, and approaching an obstacle/destination (e.g., a chair). Freezing can also be triggered by emotional situations, such as being under stress, feeling the pressure of time, and embarrassment. Ironically, the very symptoms of freezing also causes freezing episodes (specifically, small quick steps, shuffling of the feet, and asymmetrical stepping). What this means is, if a PD patient is walking normally and feels fine, but starts to take small steps or have uneven steps, freezing commonly results. Freezing can be prevented if a person takes bigger and more even steps. 

Why do we freeze?

People commonly think of freezing as a physical condition. In fact, there are a lot of cognitive processes that result in the lack of mobility associated with freezing. Cognition is divided into three categories: Attention, Executive Function, and Visuospatial Function. Attention is further split into 4 parts: Divided Attention, Attention Switching, Sustained Attention, and Selective Attention. If we use the example of crossing a busy intersection, divided attention is looking both ways; attention switching is watching your posture while also listening for approaching cars; sustained attention is watching an oncoming car and taking notice of how fast the car is driving; selective attention is seeing the light turn green to cross but also noticing a car approaching the light and it seems like the car will not stop in time.

Executive Function requires Shifting and Inhibition. Shifting relates to the change in attention, as you divide, sustain, and select what holds your attention. Inhibition is deciding whether or not to take an action (using the previous example of the crosswalk, inhibition is either walking when the light turns green or staying on the sidewalk).

Lastly, Visuospatial Function consists of Visuoperceptual and Visuoconstructional Abilities, which means visually measuring the height of a curb to step off of and estimating the distance between the car and yourself. It is still unknown exactly where in the brain freezing affects, but cognitive functions are impacted, leading to mobility issues. This leads to some pharmacological considerations: some freezing episodes are caused by lessening or increasing levodopa, and FoG usually occurs in the “off” state (but not exclusively). 

Barriers to treating freezing

Why is it so hard to treat FoG? Cueing is commonly used for freezing, but cognitive dysfunction limits the ability of people with PD to deploy these strategies in real life situations. Also, positive effects of cueing are lost over time when the cue is no longer “novel.” Furthermore, the impaired implicit motor learning caused by freezing makes it difficult for people with PD to learn new motor patterns. However, some patients are still able to learn some new skills. For some patients, the risk of falls when training to prevent freezing can lead to feelings of fear, anxiety, and stress. As we saw previously, emotions during a freezing episode can extend the FoG beyond the usual amount of time per episode. 

So what can we do?

We know that small, quick asymmetrical steps can lead to episodes of freezing. We also know that freezing is a result of multiple (and complex) cognitive, motor, emotional, and environmental demands. Furthermore, the benefits from cueing diminish when the cue is no longer novel. Therefore, in order to reduce the likelihood of freezing occurring, people with PD need to work on taking bigger and more symmetrical steps. They need to practice motor skills in situations where dual-tasking may be involved, in order to manipulate different environmental factors. To prevent cueing from becoming no longer novel, people can utilize different types of cues (e.g., auditory, visual, tactile). Lastly, people can try agility and/or obstacle courses for both the mind and body. 

Dual-Tasking Exercises

Simple dual-tasking is performing a physical activity that involves coordination while performing a cognitive task. Here are some suggestions from Shelley for patients to practice dual-tasking:

• A boxing combo while naming as many cities as you can think of starting from the letter’s “A” to “Z”
• Lateral lunges while naming “items you can find in an office” starting from the letter’s “Z” to “A”
• Walking around cones while counting backwards in 7’s, starting from 100
• Stepping over obstacles while doing math problems (e.g. 13+5-2)

These exercises are intended to both mentally and physically stimulate a patient, minimizing the potential to develop freezing. 

Agility/obstacle courses for the body and mind

Shelley Yu also has a comprehensive list of activities that are intended to work the body and mind. Here are some of those activities: 

1. Tape numbers “1-10” and letter’s “A-J” on the floor randomly. Walk across the floor, alternatively stepping on ascending numbers and ascending letters (e.g., 1-A-2-B-3-C… etc.). 
2. Have a partner create Q-cards with names of colors written in various colors (either the same color as the one written on the card or another color). Next, complete a physical exercise, such as multidirectional lunges/steps, while reading the color of the word presented on the Q-card. 
3. Designing obstacles courses simulating situations where freezing can occur, i.e. hallways, doorways, stepping over an obstacle, change in surface (carpet to hardwood), turning, walking backwards and approaching a destination (such as a chair). Start with a wide hallway, wide doorway, low/small floor obstacle, and work your way to a narrow hallway, narrow doorway, large/tall floor obstacle. When approaching a destination, perform a wide turn rather than turning on the spot. Practice side stepping and backwards walking in narrow spaces.
4. Provide conflicting stimuli: multidirectional walking cued by someone saying “forward,” “backward,” “right,” or “left” except the person moves opposite of the spoken direction. For example, if told to go “forward,” the person instead steps backward. You can also add in a number of steps to complicate the instructions further, where “right 3 steps” means stepping to the left 3 times. The same can be applied to boxing drills or other physical tasks. 

Cueing

There are many categories of cueing, and each provides its own benefits. Below are four main categories with examples, and some additional suggestions:

• ·Visual
  •  Lines on the floor
  • Laser on walker/cane
  • Step over a threshold
• Auditory
  • Metronome/music
  • 1, 2, 3… Go!
  • Right, left, right, left
• Tactile
  • Touch the leg to initiate step forward
  • External tactile cue
•  Imagery
  • E.g., palm trees swaying in the wind to turn, stomping through tall grass, etc.
• Other Strategies
  • Change directions
  • Shift weight on the spot
  • Move another part of body

Summary

Freezing of Gait is a common issue that may lead to falls. Freezing episodes are triggered by various motor, cognitive, environmental, and emotional factors. Incidentally, freezing can be prolonged by the very same triggers that begin the episode. Cueing techniques can help temporarily resolve freezing episodes, but the effects decrease over time when the cue is no longer novel. However, we can use dual-tasking or obstacle/agility courses to train both the mind and the body, and reduce the frequency of freezing episodes.