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Parkinson’s disease (PD) is a neurodegenerative disorder that primarily affects dopamine-producing neurons within the brain's substantia nigra area. PD can cause tremors, bradykinesia, rigidity in the limbs as well as both gait and balance problems. One specific type of gait problem that affects many PD patients is freezing of gait (FoG), which, despite having the intention to walk, prevents them from moving their feet forward. FoG is a sudden, short, and temporary episode that essentially leaves the patient stuck and can only make quick-stepping movements in place. Several laser technologies have been produced to help PD patients' quality of life. This article discusses some of these in more detail.
Freezing of Gait and Laser Light Visual Cueing
Although FoG prevents the patient’s feet from moving forward, their intention to walk causes the torso to have forward momentum. This imbalance within the body leads to an increased risk of falls and can also be frustrating and even embarrassing for the affected individual. It is estimated that between 30% to 60% of individuals with PD are affected by FoG.
FoG can be improved with dopaminergic therapy in many PD patients. However, as PD continues to progress, the frequency and duration of FoG can intensify, reducing the effectiveness of this type of approach.
Certain drugs used to treat FoG can also increase leg trembling and festination, which is otherwise known as the small shuffling steps that occur during FoG.
In addition to the limitations associated with current therapies, the widespread prevalence of FoG in PD patients has led many researchers to investigate alternative interventions that could improve these patients' quality of life (QoL). Some of these approaches include visual, auditory, and haptic cueing strategies. For example, a visual cue can be in the form of lines on the floor, whereas auditory and haptic cues can use sounds or touching to guide movements, respectively.
While each of these cues has been found to improve both FoG and other gait deficits in PD patients, visual cues appear to be optimal for most patients. Some of the different visual cueing strategies that have been tested in clinical trials include high-contrast transverse line visual cues on the floor, laser beam visual cues, and the U-Step rolling walker. Of these approaches, visual cues utilizing a laser have emerged as the best option for PD patients. In clinical studies that have compared a laser cue with auditory cues in the form of vibrations, the laser device was found to be more effective in improving forward, backward, and side-to-side movements during freezing episodes.
The laser cues used in these studies also significantly reduce the total number of freezing episodes faster than when the auditory cues were used.
The ExoBeam Device
MedEXO Robotics is a Hong Kong-based robotics technology company that has recently developed the ExoBeam walking device to assist PD patients, as well as other individuals with movement disorders.
The ExoBeam system comprises a small laser projector that can be attached to the wearer’s pants, belt, or cane for continuous monitoring.
The laser unit projects a laser beam onto the ground directly in front and perpendicular to their travel direction. The specific placement of this laser trains the user to maintain smooth movements while simultaneously improving their balance and reducing FoG symptoms.
In addition to projecting the laser beam for walking assistance, the ExoBeam also provides a customizable vibrating alert. This form of tactic stimuli helps the user maintain an average walking pace by acting as a physical reminder to walk in unison with the rhymic vibrations' frequency.
The ExoBeam also provides audio cues to the wearer with sound beeps. As previously discussed, these audio cues have been shown to reduce potential distractions from surrounding noises that often contribute to FoG symptoms.
The Path Finder Solution
Walk with Path has developed the Path Finder LaserShoes for PD patients. These shoes utilize a visual cueing device that assists patients with walking during FoG episodes.
The Path Finder is an adjustable shoe attachment that projects parallel green laser lines in front of the patient, activated by the pressure that arises when the wearer places their foot to the ground.
The Path Finder lasers can be calibrated to each patient's unique step length to ensure that it meets the specific needs of each wearer. The laser on the standing food will project a line for the opposite foot, which activates the motor cortex in the brain.
Since this area of the brain is often affected by Parkinson’s disease, the Path Finder's visual cue can help refocus the wearer's attention on initiating their movement and ultimately begin walking again.
As a Class 1 medical device, the Path Finder has been found to reduce freezing episodes and falls by 50% and 35%, respectively, and increase confidence in PD patients by up to 93%.
Future Direction: LaserShoes and Stroke
Physiotherapists who assist in rehabilitating stroke patients typically utilize treadmill exercises into their treatment protocols to increase their patients' walking speed, balance, and confidence.
Recent studies have shown that incorporating visual cues into stroke rehabilitation programs can improve both stride length and walking speed by more than 10% and improve walking symmetry, balance, and functional mobility.
The success of LaserShoes in treating FoG in PD patients has led Walk With Path to begin investigating how this product might also be helpful for stroke patients. Although further studies must still be conducted, preliminary studies have shown a positive correlation between the use of Path Finder LaserShoes and improved gait in stroke patients.
References and Further Reading
Parkinson’s Foundation. [Online] What is Parkinson’s? Available from: https://www.parkinson.org/understanding-parkinsons/what-is-parkinsons
The American Parkinson Disease Association (APDA) [Online] Freezing of Gait in Parkinson’s Disease. Available from: https://www.apdaparkinson.org/article/freezing-gait-and-parkinsons-disease/
Walk With Path. [Online] Lasers that prevents Parkinson’s walking problems. Available from: https://walkwithpath.com/what-are-pathfinder-lasershoes-old/
Walk With Path. [Online] Path Finder for Professionals. Available from: http://walkwithpath.com.linux143.unoeuro-server.com/?page_id=1216
Parkinson’s Life. [Online] How these laser-guided shoes keep Parkinson’s patients on their feet. Available from: https://parkinsonslife.eu/laser-guided-shoes-parkinsons-patients-path-finder-lise-pape/
Barthel, C., van Helvert, M., Haan, R., et al. (2018) Visual cueing using laser shoes reduces freezing of gait in Parkinson’s patients at home. Movement Disorders 33(10). doi:10.1002/mds.27455
Bunting-Perry, L., Spindler, M., Robinson, K. M., et al. (2013) Laser light visual cueing for freezing of gait in Parkinson’s disease: A pilot study with male participants. JRRD 50; 223-230. doi:10.1682/JRRD.2011.12.0255
Medexo Robotics. [Online] Our Product & Solution ExoBeam. Available from: https://www.medexorobotics.com/menu
Tarantola, A. (2020) This laser aid helps Parkinson’s patients maintain their mobility [Online] engadget. Available from: https://www.engadget.com/2020-01-08-exobeam-parkinsons-aid-ces-2020.html