Falling and loss of balance occur in people with PD and can result in major injuries: fractured shoulders, hips, ankles, and even skulls. To decrease falling, it helps to understand why you lose your balance and fall.
Falls result from postural instability or loss of “righting reflexes:” the ability to right yourself and take measures to prevent a fall. Thus, if you trip or are pushed, by the time you realize it, your righting reflexes have changed the position of your head, neck, trunk, arms, and legs so that you either avert the fall or cushion yourself if you do fall.
The righting reflexes are alerted to your changed position (sense of “falling through space”) by sensors in your feet (position sense), inner ears, and by your eyes. The alerting information from your feet and inner ears travels to a region of your brain called the thalamus. Your eyes are less important in righting yourself than the sensors in your feet or those in your inner ears.
Thus, a blind man can right himself and not fall after he trips. A person with impaired sensors in his feet or inner ears is less likely to right himself and more likely to fall after tripping. The information sent to the thalamus is acted upon, enabling your cerebellum to try to avert the fall by ordering several rapid adjustments in muscle tone. In PD, these adjustments may not be rapid enough to prevent a fall.
In PD, because of the decreased ability to right your-self when you trip and a decreased ability to maintain your balance when you stand, the following advice may be helpful:
Avoid snow, ice, wet or slippery surfaces. When you slip on ice, the change in your body’s position is more rapid than when you trip on a dry surface. The messages signaling the change in your position reach your cerebellum and thalamus quicker and there is less time for you to react, so you are more likely to fall.
Avoid uneven or hilly surfaces—these result in the position sensors in your feet and inner ears bombarding your vestibular nuclei with messages, one after the other, each telling of a change in direction, position, or velocity of your legs. This bombardment may over-whelm your ability to respond and you’re more likely to fall.
Avoid walking in the dark. Your brain also senses the environment through your eyes. In the dark, you depend on the position sensors in your feet and inner ears; they are your “fall back” systems. If, as may happen, one of these systems fails, you are likely to fall in the dark.