The aim of static postural control is to maintain the center of mass (COM) within the base of support (BOS). The larger the BOS, the more easily static stabilization is achieved. Static postural control training should incorporate techniques, such as manual resistance in alternating agonist-antagonist muscle groups, that facilitate smooth coordination of agonists and antagonists. The aim is to create muscle co-contraction around a joint or body segment in sitting and standing, leading to stable holding of positions. Dynamic postural control includes both anticipatory and reactionary strategies. Successful dynamic postural control requires that sensory inputs provide accurate information about movement through space to allow the CNS to create an effective motor plan to maintain balance. Training anticipatory postural control requires maintenance of upright orientation during movement of the COM within and to the edges of the BOS of varying diameters. Activities that displace the COM, such as reaching, lifting, raising the arms overhead, shifting weight acceptance from leg to leg, and multidirectional walking all utilize anticipatory postural control. The patient’s balance must be challenged in order for physiological changes to take place. Increasing the direction, degree, and smooth control of COM excursion and reducing reliance on external support are important components of anticipatory postural control training. Sensory integration training The conditions under which the patient exhibits difficulty maintaining postural control on the mCTSIB can guide treatment by providing insight into which sensory cues the patient relies upon and may not be utilizing effectively. The patient with vestibular dysfunction will tend to rely on other sensory inputs for postural control, with reliance on vision the most predominant. Altering sensory cues by having patients close their eyes or stand on a compliant foam surface will systematically reduce reliance on vision and somatosensation, respectively, to drive more effective interpretation and utilization of vestibular inputs to maintain balance. However, the clinician must take care not to alter sensory inputs on which the patient is reliant due to damage to other sensory systems caused by injury or disease. For example, the patient with impaired somatosensation due to peripheral neuropathy will require both visual and vestibular information for postural control. Patients with profound vestibular loss rely on somatosensory and visual inputs to compensate for loss of vestibular inputs. Under these circumstances, the treatment program takes on an Aerobic conditioning Rehabilitation programs for patients with vestibular dysfunction should include some component of aerobic conditioning because many patients will reduce their movement and activity level to manage their vestibular symptoms. Incorporating a physical conditioning program will not only manage or prevent deconditioning, but it will provide functionally relevant balance and vestibular system challenges as the patient moves through various environments, over different terrains, and utilizing different speeds of movement to conform to different environmental demands, such as crossing a street or navigating a crowded sidewalk. Prescribing a walking program four or more times per week is a good place to start. The duration is determined by the patient’s baseline ability. The program should begin with less challenging environments (flat surfaces,
Reactionary postural control refers to postural adjustments that are made in response to unexpected perturbations. These postural adjustments are stereotypical movement strategies known as ankle , hip , and stepping strategies, mediated by synergistic muscle activation patterns. The CNS uses information from sensory inputs and muscle stretch receptors about quick unplanned movement to elicit a reflexive response. The particular strategy employed is based on the surface conditions, direction of movement, and the degree of loss of balance. An ankle strategy will be employed during small amplitude movements while standing on a firm surface, creating a net inverted pendulum movement over the ankles to maintain vertical orientation of the body with respect to gravity. An example of this would be standing on a slowly moving train. A hip strategy will be elicited when an ankle strategy is not sufficient, such as when there is a large anterio-posterior displacement of COM, or when the surface conditions are not conducive to utilizing an ankle strategy (standing on a narrow or compliant surface). In this case, the person will exhibit a forward and backward sway of the trunk over the hips. A stepping strategy is elicited when a large amplitude or velocity of movement brings the COM outside of the BOS, necessitating a step to restore the BOS under the COM. This is what happens when the train makes an abrupt stop or acceleration (Shumway- Cook & Woollacott, 2011). accommodative approach, rather than a restorative approach, training increased use of visual cues for postural control in the absence of effective vestibular inputs. In these cases, the patient should have full use of visual inputs, performing activities with eyes open and in well-lit environments, and not be placed in conditions 3 or 4 of the mCTSIB (eyes closed, standing on floor; eyes closed, standing on foam, respectively) as a rehabilitation approach. The clinician gains an understanding of the integrity of the visual, somatosensory, and vestibular systems through comprehensive impairment-level examination strategies, and these findings must be correlated with the results of the mCTSIB to determine safe and effective treatment strategies. The conceptual framework for balance training is simply summarized here, intended as a review for the practicing clinician. However, a detailed approach to balance training lies outside of the scope of this course but can be found in textbooks dedicated to that aspect of rehabilitation care for those who desire further edification (Bronstein et al., 2011). quiet areas, etc.) and gradually progress to more challenging environments (outside, busy malls, etc.), eventually incorporating recreational activities such as golf or tennis gradually. As with any rehabilitation program, safety is of utmost importance. Patients who wish to return to swimming must not swim alone initially and must be advised that ocean swimming poses the challenge of not having an adequate sense of orientation due to lack of visual and somatosensory inputs to determine where one is in relation to gravity, or a sense of the direction of “up.” Biking may not be advisable until the patient can demonstrate higher-level balance skills due to the limitations of somatosensory and visual cues to orient the patient to upright and the advanced postural control required to maintain balance while on the bike.
CASE STUDIES
Case study 1 The patient is a 42-year-old male who presents with a history of persistent vertigo that lasted for a few days without any eventful onset. Now that the persistent symptoms have subsided, the patient is noting transient vertigo with bending forward. His past medical history (PMH) is unremarkable.
Examination : Normal sensorimotor and coordination testing, normal oculomotor testing. HIT is positive to the right. Right Hallpike-Dix elicits upward and right torsional nystagmus for 25 seconds. Once that fatigues, a left-beating nystagmus is seen. Left Hallpike-Dix demonstrates persistent left-beating nystagmus without a torsional component.
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