Proprioception deficits cause movement disorders including Parkinsonian symptoms
Neuroscience has reported that persons with Parkinson’s and other movement disorder diseases have proprioceptive deficits that profoundly impair voluntary and involuntary movement.
Proprioception is the sense of location and load on one’s own body parts. It is provided by proprioceptors:
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- Muscle spindles convey position of limbs; by reporting muscle lengths, and the rate at which muscle lengths are changing.
- Golgi sensors convey the load; tension, on muscles.
- Fibrous capsules convey movement and tension in joints.
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The vestibular sensory system provides additional sensory information;
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- Balance and spatial orientation.
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and is often referred to as proprioception.
Parkinsonian symptoms
Some symptoms are due to malfunctioning involuntary movement that do not involve the brain. They include tremors, loss of balance, postural instability and face masking. Others; rigidity, slowness of movement and shuffling gait are intensified or become apparent with voluntary movement. All are affected by proprioception deficits.
People with movement disorders cannot rely on motor plans derived from defective proprioceptors, so they establish postures that help them to maintain balance, use of other senses; mainly sight, and voluntary movements that seek to replace or correct automatic movements. That is why their movements are slow, small, rigid and uncoordinated. And that is why it is difficult for them to walk and talk at the same time.
A great many movements are almost completely automatic. For example, walking is a series of complex and coordinated muscle contractions. The brain initiates and may modulate the movements as they are being performed, but the basic movement is automatic. Furthermore, whereas the subject may change the movement at will; voluntarily walk faster or change direction, or the reflex circuits may cause changes to the motor plan in response to external stimuli, walking is almost automatic.
Proprioceptors affect all movement
As such, proprioceptor deficits can adversely affect all movement. If proprioceptor inputs to the brain and central nervous system are deficit, the resultant motor program will be incorrect and voluntary movement will be impaired. If proprioceptors are defective, muscle tone and balance will be impaired. Stated another way; deficit proprioceptors will cause Parkinson’s Disease movement disorders.