“Fall” is a four-letter word, in more ways than one, especially as people enter their later years. Most of my older patients know full well that falls can be associated with broken bones and quick decline. Most of my patients over 70 have some kind of loss of what is commonly referred to as “balance” and this is exacerbated by Parkinson’s Disease. Balance is one of those things we take for granted until we realize that it is becoming compromised. The lyrics by Tom Keifer (performed by Cinderella) sum it up pretty well in that regarding balance you “don’t know what you got ‘till it’s gone”.
Balance is often talked about as one thing, but it’s actually pretty complicated. To simplify things a bit, your overall ability to maintain your balance (i.e., stay standing upright) is dependent on how well three major things in your body are functioning:
- vestibular system. The vestibular system is located in your inner ear and sends signals to your brain about motion, head position and spatial orientation. The brain integrates all of this information and then sends signals to the rest of the body to stabilize our head while we move and maintain posture so we don’t fall down.
- somatosensory system. There are specialized structures located throughout your body that tell the brain where your joints (e.g., knees, hips, ankles) are in space and allow you to feel textures, pressure and temperature on the surface of your skin. As we will discuss, the working ability of sensory receptors in the soles of your feet play an especially important role in balance because they literally allow your brain to feel what you are walking on and where they are in space.
- visual system. Your eye sight is important for seeing where you are in space and for telling your brain what may exist in your environment that could challenge your ability to stay upright (e.g., slick surfaces, rocks to step over, stairs).
For more information on the vestibular system:
Your brain is able to integrate signals from the three major systems listed above and then send signals to your muscles (also known as motor output) to adjust your posture, take a step, tilt your head—whatever you need to do to prevent yourself from falling. This obviously happens very quickly—in a tiny fraction of a second—when working optimally. For most of our lives this happens without us even thinking about it.
However, as we age, so does our vestibular, visual and somatosensory systems, and they don’t work quite as well as they used to. When the systems that control our balance begin to decline, our ability to navigate environments we once used to, such as curbs and bumpy sidewalks, becomes compromised. Balance is also affected by a person’s mindset, fatigue/attentional capacity, muscle coordination and integrity of the skeletal system. If you are distracted by someone shouting hello to you or you have lasting effects of injury (limited joint mobility), these are going to further challenge you balance. Furthermore, when you superimpose disease, such as Parkinson’s Disease, on top of an aging visual, vestibular, and somatosensory system, one’s ability to maintain upright posture—or prevent falls—-becomes even more compromised.
Although commonly known for its association with advancing type 2 diabetes, peripheral neuropathy has also been noted to be common in people with Parkinson’s Disease (Viseux et al. 2020). Peripheral neuropathy is characterized by poorly functioning nerve fibers in the soles of the feet that transmit information to the brain, allowing one to experience touch, position in space (proprioception), vibration, pain and temperature. The transmission of this information to the brain is critical to maintaining your balance and avoiding stepping in places that may cause injury. Romagnolo et al. (2018) estimates that 55-75% of patients with Parkinson’s Disease who are treated with levodopa (by oral or intestinal infusion) could develop peripheral neuropathy. The reason for developing peripheral neuropathy is unclear and it may also be linked with vitamin B12 deficiency and/or degradation of nerve fibers in feet and other parts of the body.
So the question is, how can we best prevent falls for people with Parkinson’s Disease?
Improving balance requires a multi-faceted approach. Central to this approach is working with a physical therapist to improve strength and ability to use the visual, somatosensory and vestibular systems together to the best of your abilities. A physical therapist can provide a safe environment in which one’s balance can be challenged, but injury can be avoided. Optimizing balance also includes a checkup on the three major systems that contribute to balance. This includes making sure that one is doing everything he or she can to preserve the health of one’s eyes and improve eyesight to the greatest extent possible. Has a person been putting off dealing with cataracts? Now may be the time. How is the health of the vestibular system and ears? Believe it or not, a buildup of wax in your ears can interfere with balance. Other more serious problems such as vertigo, Meniere’s Disease, acoustic neuroma, and vestibular neuritis can also interfere with your vestibular system. If you suspect or know that these are problems, then you need to see an ENT (Ears Nose and Throat specialist), neurologist and may even be referred to a physical therapist depending on the root of the problem. Another piece of the approach is making sure that one is maximizing the sensory information coming up to the brain from their feet to better inform the brain about where the feet are in space and what kind of surface they are standing on. And this is the best news: recent research has shown that increasing the sensory stimulus to the feet can enhance motor control for improved balance (Viseux et al. 2020).
Sensory stimulus to the feet can be enhanced through the use of textured insoles.
Research recently reviewed by Viseux et al. (2020) indicates that textured insoles can help not only people with Parkinson’s Disease improve their walking and balance, but also people with multiple sclerosis and healthy people too. Wearing textured insoles has been found in studies to decrease body sway from right to left (Qui et al. 2013; Robb and Kelley, 2000), improve postural stability even with eyes closed or standing on foam surfaces (Qui et al. 2013), increase step length (Qui et al. 2013), decrease the number of steps needed to complete a 180 degree turn (Robb and Kelley, 2000), improve functional reach tests (Volpe et al. 2017), improve single leg stance time and muscle activation in the lower leg (Jenkins et al. 2009) and improve ability to feel the bottom of the foot (Lirani-Silva et al. 2017).
How quickly are results achieved after wearing the insoles? Studies used different time frames for testing, but improvements in two studies were noted immediately (Jenkins et al. 2009; Qui et al. 2013).
What’s more is that data indicates that long-term use of insoles may promote increased representation of the bottom of the foot in the primary somatosensory cortex of the brain which improves ability to feel the bottom of the foot (Qui et al. 2013).
Where can you get such insoles? Below is a listing of some examples. As a disclaimer, I have no financial connection with any of these companies and I am not necessarily promoting their products—I am merely providing examples:
If you are wondering about the specific details of the research studies examining the effects of wearing textured insoles on balance and walking, please see brief summaries below:
Qui et al. 2013:
Participants: 20 healthy people and 20 people with Parkinson’s Disease
What was done in the study: Participants stood on firm and foam surfaces while barefoot, wearing smooth insoles, and while wearing textured insoles. While doing this, standing balance was measured using a force plate. Specifically, the data included measures of anterior -posterior and medial lateral sway.
Results: Only the textured insoles decreased medial-lateral sway in the Parkinson’s group on firm and foam surfaces.
Robb and Kelley 2020:
Participants: 7 people
What was done in the study: The dynamic stability of participants was examined wearing footwear only, footwear with a textured insoles or footwear with a nontextured insoles. Measurements were collected at the beginning of the study, 4 weeks later and 5 weeks later.
Results: Improved dynamic stability was noted in the frontal plane and the number of steps required to make a 180-degree turn was reduced in those wearing the textured insoles.
Volpe et al. 2017:
Participants: 20 people with Parkinson’s Disease
What was done in the study: All participants performed balance training for two weeks (5 days per week). Half of the participants wore textured insoles. Measurements on functional reach testing was completed at the beginning of the study, immediately following the 2-week balance training program and 4 weeks after the balance training ended.
Results: People who wore the textured insoles had improved functional reach tests even after the balance training program had ended.
Jenkins et al. 2009:
Participants: 40 people with Parkinson’s Disease and 40 age-matched healthy controls
What was done in the study: Study participants wore ribbed insoles (these are insoles with a ridge around the border of the insole) and regular insoles during separate walking trials. Single leg stance time was measured while walking as well as electromyography measurements of lower leg muscles.
Results: wearing ribbed insoles improved single leg stance time during walking and anterior tibialis activation was improved according to EMG measurements.
Lirani -Silva et al. 2017:
Participants: 19 participants with Parkinson’s Disease
What was done in the study: At the start of the study, sensation in the bottom of the participants’ feet was tested using Semmes-Weinstein monofilaments. At the start of the study, all participants had their walking filmed for stride length measurements. All participants wore textured insoles for 1 week and the same measurements were taken again. Participants were instructed to wear regular insoles for the week following the study. After the week following the study, a third set of measurements was collected.
Results: After one week of wearing textured insoles, stride length and sensation in the soles of feet were improved. After one week of wearing regular insoles (following the one week with textured insoles), plantar sensation improvements were still present, but walking improvements were not. Study authors concluded that continuous use of insoles may be needed to improve gait.
Jenkins et al. 2009. Plantar cutaneous sensory stimulation improves single limb support time, and EMG activation patterns among individuals with Parkinson’s Disease. Parkinsonism and Related Disorders. 15:697-702.
Lirani- Silva et al. 2017. Continuous use of textured insole improved plantar sensation and stride length of people with Parkinson’s Disease: A pilot study. Gait and Posture. 58: 495-497.
Qui et al. 2013. Effects of textured insoles on balance in people with Parkinson’s Disease. PLoS. ONE: 8(12). e83309.
Robb and Perry. 2020. Textured foot orthotics on dynamic stability and turning performance in Parkinson’s Disease. Journal of Motor Behavior. 52: 396-403.
Romagnolo et al. 2018. Levodopa-induced neuropathy: a systematic review. Movement Disorders Clinical Practice. 6:96-103.
Viseux et al. 2020. Postural instability in Parkinson’s Disease: Review and bottom-up rehabilitative approaches. Clinical Neurophysiology. 50: 479-487.
Volpe et al. 2017. Effects of a sensory-motor orthotic on postural instability rehabilitation in Parkinson’s Disease: a pilot study. Journal of Clinical Movement Disorders. 4:11.