Therapeutic techniques to improve balance in neurological and developmental conditions

1. University of the Philippines Manila College of Allied Medical Professions PT 154: Therapeutic Exercise III Ms. Mary Grace M. Jordan, PTRP December 8, 2009 Therapeutic techniques to improve balance in neurological and developmental conditions

2. Balance deficits… • one of the most common problems treated by physical therapists. • are thought to be common after stroke, and they have been implicated in the poor recovery of activities of daily living (ADL) and mobility and an increased risk of falls.

3. Learning objectives… • Define balance • Define terminologies • Discuss the theoretical underpinnings of balance • Discuss the guidelines for training balance in neurologic and developmental conditions • Identify techniques that can address impairments of balance in patients with neurologic and developmental conditions

4. What is balance?

5. Balance… “…the ability to maintain the body’s center of gravity over its base of support with minimal sway or maximal steadiness.” (Emery et.al, 2005) • a complex process involving the reception and organization of sensory inputs and the planning & execution of movement to achieve a goal requiring upright posture

6. Balance… • is the set of functions which maintains man’s upright during stance and locomotion by detecting and correcting displacement of the line of gravity beyond the BOS.

7. Terminologies… • Postural control – involves controlling the body’s position in space for the dual purposes of stability and orientation. • Postural orientation –The control of relative positions of the body parts by skeletal muscles with respect to gravity and each other.

8. Terminologies… • Postural stability- The condition in which all the forces acting on the body are balanced such that the center of mass (COM)is with in the stability limits or boundaries of BOS • Normal anterior/posterior sway – 12 degrees from most posterior-anterior position. • Lateral sway - 16 degrees from side to side. • If sway exceeds boundaries, compensation is employed to regain balance.

9. Terminologies… • Static balance - the base of support (BOS) remains stationary and only the body center of mass (COM) moves. The balance task in this case is to maintain the COM within the BOS or the limit of stability (the maximal estimated sway angle of the COM). • Maintaining a stable antigravity position while at rest such as when standing and sitting

10. Terminologies… • Automatic postural reactions - maintaining balance in response to unexpected external perturbations, such as standing on a bus that suddenly accelerates forward.

11. Terminologies… • Dynamic balance - Maintaining balance when a person is moving from point A to point B, where both the BOS and COM are moving, and the COM is never kept within the BOS. • is stabilizing the body when the support surface is moving or when the body is moving on a stable surface such as sit-to-stand transfers or walking

12. Terminologies… • Reactive control - in response to external forces (perturbation). • Proactive control – in anticipation of internal forces imposed on the body’s own movements.

13. The Systems Model

14. Systems Model… • Balance control is very complex and involves many different underlying systems. • Postural control results from a set of interacting systems that work cooperatively to control both orientation and stability of the body.

15. Musculo-skeletal Components Neuro-muscular Synergies Body Schema BALANCE Sensory Systems ReactiveMechanisms Proactive Mechanisms(external) Anticipatory Mechanisms(internal)

16. Musculoskeletal components • Joint range of motion • Spinal flexibility • Muscle properties • Biomechanical relationships among linked body segments

17. Neural components • Motor processes (neuromuscular response synergies) • Sensory processes ( visual, vestibular, and somatosensory systems) • Higher-level integrative processes • Mapping sensation to action • Ensuring anticipatory and adaptive aspects of postural control

18. Adaptive vs. Anticipatory Adaptive postural control Anticipatory postural control Involves preparing the sensory and motor systems for postural demands based on previous experience and learning • Involves modifying sensory and motor systems in response to changing task and environmental demands

19. Motor Mechanisms for Postural Control

20. Factors that contribute to stability… • Body alignment • Muscle tone • Postural tone

21. Body alignment… • Minimize the effect of gravitational forces, which tend to pull us off center • The ideal alignment in stance allows the body to be maintained in equilibrium with the least expenditure of internal energy.

22. Body alignment appropriate to quiet standing and sitting Standing alignment Sitting alignment Head balanced on level shoulders Upper body erect Shoulders over hips Feet and knees a few cm apart • Head balanced on level shoulders • Upper body erect, shoulders over hips • Hips in front of ankles • Feet a few cm (10 cm) apart

23. Muscle tone… • The force with which a muscle resists being lengthened (Basmajian and De Luca, 1985) • Keeps the body from collapsing in response to the pull of gravity

24. Postural tone… • Increased level of activity in antigravity muscles • Activation of antigravity muscles during quiet stance. • Muscles that are tonically active during quiet stance: gastrocsoleus, tibialis anterior, gluteus medius, TFL, iliopsoas, and erector spinae

25. Ankle strategy Hip strategy Stepping strategy Motor strategies during Perturbed Stance

26. Ankle strategy… • Used when displacements are small. • Displaces COG by rotation about the ankle joint. • Posterior displacement of COG – Dorsiflexion at ankle, contraction of anterior tibialis, quadriceps, abdominals. • Anterior COG displacement – Plantar flexion at ankle, contraction of gastrocnemius, hamstring, trunk extensors.

27. Hip strategy… • Employed when ankle motion is limited, displacement is greater, when standing on unstable surface that disallows ankle strategy. • Preferred when perturbation is rapid and near limits of stability. • Post. Displacement COG – Backward sway, activation of hamstring and paraspinals. • Ant Displacement COG – Forward sway, activation of abdominal and quadricep muscles.

28. Stepping strategy… • If displacement is large enough, a forward or backward step is used to regain postural control

29. Sensory Mechanisms Related to Postural Control

30. Triad of Balance

31. Sensory processes… The maintenance of balance is based on an intrinsic cooperation between the • Vestibular system • Proprioceptive • Vision • Postural control does not only depends on the integrity of the systems but also on the sensory integration with in the CNS, visual and spatial perception, effective muscle strength and joint flexibility

32. Visual inputs… • Provides information regarding: (1) The position of the head relative to the environment; (2) The orientation of the head to maintain level gaze; (3) The direction and speed of head movements because as your head moves, surrounding objects move in the opposite direction. • Provide a reference for verticality • Visual stimuli can be used to improve a person’s stability when proprioceptive or vestibular inputs are unreliable by fixating the gaze on an object.

33. Visual inputs are important source of information for postural control, but are they absolutely necessary?

34. No… • Since most individuals can keep their balance when vision is occluded • In addition, visual inputs are not always an accurate source of orientation information about self-motion. • Visual system has difficulty distinguishing between object motion, referred to as exocentric motion, and self-motion, referred to as egocentric motion.

35. Somatosensory inputs… • Provides the CNS with position and motion information about the body with reference to supporting surfaces • Report information about the relationship of body segments to one another • Receptors: muscle spindles, Golgi tendon organs, joint receptors, and cutaneous mechanoreceptors

36. Vestibular inputs… • A powerful source of information for postural control • Provides the CNS with information about the position and movement of the head with respect to gravity and inertial forces, providing a gravitoinertial frame of reference. • Distinguish exocentric and egocentric motions

37. Vestibular receptors Semicircular canal Otolith organs Signal linear position and acceleration Source of information about head position with respect to gravity Respond to slow head movements (those that occur during postural sway) • Sense angular acceleration of the head • Sensitive to fast head movements ( those that occur during gait or imbalance such as slips, trips, and stumbles)

38. Sensory organization… • Vestibular, visual, and somatosensory inputs are normally combined seamlessly to produce our sense of orientation and movement. • Incoming sensory information is integrated and processed in the cerebellum, basal ganglia, and supplementary motor area.

39. Sensory organization… • Somatosensory information has the fastest processing time for rapid responses, followed by visual and vestibular inputs • When sensory inputs from one system are inaccurate the CNS must suppress the inaccurate input and select and combine the appropriate sensory inputs from the other two systems.

40. The Motor Control Model

44. Causes of balance impairments • Injury to or diseases of the structures (e.g. eyes, inner ear, peripheral receptors, spinal cord, cerebellum, basal ganglia, cerebrum) • Damage to Proprioceptors • Injury to or pathology of hip, knee, ankle, and back have been associated with increases postural sway and decreased balance • Lesions produced by tumor , CVA, or other insults that often produced visual field losses

45. Following a stroke… • Patients with muscle weakness and poor control lack effective anticipatory, ongoing, and reactive postural adjustments and therefore experience difficulty in: • Supporting the body mass over the paretic lower limb • Voluntarily moving the body mass from one lower limb to another • Responding rapidly to predicted and unpredicted threats to balance

46. Spatiotemporal adaptations • Changing the base of support • Restricting movement of body mass • Using hands for support

47. Changing the base of support • Wide BOS • Shuffling feet with inappropriate stepping • Shifting on the stronger leg

48. Restricting movement of body mass • Stiffening the body with altered segmental alignment • Moving slowly • Changing segmental alignment to avoid large shifts in COG • standing reaching forward - flexing at hips instead of dorsiflexing ankles • standing reaching sideways - flexing trunk sideways instead of moving body laterally at hips and feet • sitting reaching sideways - flexing forward instead of to the side • in standing - not taking a step when necessary.

49. Using the hands for support • holding on to support • grabbing

50. Guidelines for training balance