Abnormal Postural Control Flashcards
In patients with stroke, falls range from __ to __%
25-46%
In patients with Parkinson’s disease, falls range from __ to __%
40-68%
What are the majority of falls in neurologic pathologies associated with?
- mobility (gait)
- transfers
- climbing stairs
Postural control problems vary according to the variability of what 6 things?
- Type of neurological injury
- Degree of lesion
- Location
- Age
- Premorbid condition
- Extent of compensation
How do neurologic pathologies affect postural stability?
There are changes in the systems responsible for controlling posture which leads to an inability to adapt to the requirements of stability and orientation within any environment.
What 5 things contribute to abnormal postural control?
- Problems in the Action System
- Problems in the Sensory/Perceptual System
- Loss of Anticipatory Postural Control
- Problems in Cognitive System
- Impaired Seated Postural Control
What 2 problems in the action system (1) contribute to abnormal postural control?
- Problems in the quiet stance
- Impaired movement strategies during perturbed stance
Give 2 examples in which abnormal alignment can cause postural disturbances
- children with CP
- Parkinson’s Disease patients
How does postural alignment affect stability?
It influences how muscles are recruited and coordinated for recovery of stability and also determines the characteristics of body sway in quiet stance.
How do elderly people in fear of falling position themselves?
In a forward lean posture, with their center of mass displaced anteriorly.
Describe postural sway in individuals with Parkinson’s disease
They have abnormal postural sway in stance, including increased sway area and velocity
What has been found to decrease spontaneous/postural sway in patients with PD?
L-dopa
What sequencing problems can be found in a spastic leg compared to a normal one in response to forward sway?
significantly less torque and larger shifts of the body’s CoM in the spastic leg
What is a common postural coordination strategy in people with neurologic conditions (CP, CVA, Down syndrome and PD) as well as in young healthy children?
coactivation
Define coactivation
the simultaneous contraction of muscles on both anterior and posterior aspects of the body.
What are the downfalls to coactivation strategies?
Rigidity and loss of balance
What can also contribute to instability in persons with neurologic deficits?
Delays in the onset of postural responses
It has been found that onset latencies in paretic distal muscles of those with neurogenic pathologies is significantly ____ and _____ in amplitude than on the nonparetic side.
longer and smaller
How are delays in the activation of distal muscles in the paretic limb compensated for?
By early activation of proximal muscles in the nonparetic limb
Another characteristic of people with neurologic pathologies is the inability to _____ postural strategies in response to changing tasks and environmental demands
modify/adapt
Why do children with CP tend to have difficulty adapting to changing tasks and environmental demands?
They exhibit difficulty in increasing muscle activity in the gastroc muscle in response to platform perturbations
Why do people with cerebellar disorders tend to have difficulty adapting to changing tasks and environmental demands?
They tend to have hypermetric postural responses, which are too large and associated with excessive body sway in the direction opposite the initial direction of instability
Why do people with Parkinson’s tend to have difficulty adapting to changing tasks and environmental demands?
They lack movement strategies that help modulate muscle activity pattern quickly to adapt to various support surfaces
Normal postural control requires what 2 things from the sensory/perceptual systems (2)?
- organization of sensory information to provide information about body’s position and movement with respect to the environment
- coordination of sensory information with motor action
The effect of a loss of sensory input depends on what 3 things?
- the availability of other senses to detect the position of body in space
- the availability of accurate orientation cues
- the ability to accurately interpret and select sensory information for orientation
In what conditions are people who are visually dependent considered “unsteady” or abnormal?
When they are blind-folded on both steady and unsteady surfaces.
When they are wearing a visual dome on both steady and unsteady surfaces.
In what conditions are people who are surface dependent considered “unsteady” or abnormal?
On unsteady surfaces (eyes open, eyes closed, and with visual dome)
In what conditions are people who experience vestibular loss considered “unsteady” or abnormal?
On unsteady surfaces with their eyes closed or when wearing a visual dome.
In what conditions are people who experience sensory selection problems considered “unsteady” or abnormal?
When wearing a visual dome on a steady surface and when on unsteady surfaces under any circumstance (eyes open, eyes closed, and with visual dome)
What does sensory selection problems refer to?
The inability to appropriately select a sense for postural control in environments in which one or more orientation cues inaccurately report body’s position in space.
In what pathological conditions have sensory selection problems been reported?
- stroke
- TBI
- CP
- Down syndrome
- learning disabilities
What do anticipatory processes (3) do?
activate postural adjustments in advance of potentially destabilizing voluntary movements
What is anticipatory postural activity heavily dependent on?
previous experience and learning
In what pathological conditions have problems with anticipatory postural control been reported?
- TBI
- PD
- CVA
- CP
What do EMG results reveal when children with cerebral palsy are asked to push or pull on a handle while standing?
Onset of activity in postural muscles in the trunk and leg of the intact side preceded activity in the prime movers of the arm.
In contrast, in the hemiparetic side, muscle activity in the arm preceded that in the postural muscles.
Lesions to what 3 areas can disrupt critical pathways contributing to anticipatory postural control?
- supplementary motor cortex
- basal ganglia
- cerebellum
Under what cognitive situations (4) do people have difficulties maintaining balance?
- dual-task conditions
- in patients with dementia
Sitting balance (5) is a critical part of what?
functional independence in ADLs
Acquisition of sitting balance is a good predictor of what?
functional outcomes
What muscles are important to sitting balance? Explain why…
Trunk muscles play important roles in maintaining sitting balance.
Leg muscles are used for support and balance in reaching while seated.
