According to recent clinical practice guidelines for the treatment of BPPV, postprocedural restrictions should not be recommended. Rather, the client may, and is in fact encouraged, Vestibular hypofunction As previously discussed, spontaneous rebalancing of tonic inputs occurs within 2 weeks for the patient with altered vestibulo- ocular and vestibulospinal responses due to disruption of function in CN VIII or the otoliths. Patients presenting with residual deficits in postural control, gaze stabilization, and symptoms of dizziness due to vestibular hypofunction require a program of vestibular rehabilitation. A wealth of studies demonstrates that recovery of the disturbances due to loss of peripheral vestibular function is dependent on activities that incorporate visual inputs and head and body movement (Gill- Body et al., 1994; Herdman, 1998; Herdman, Blatt, et al., 2000; Herdman, Clendaniel, et al., 1995; Herdman, Schubert, et al., 2003; Whitney & Rossi, 2000), which is the basis for vestibular rehabilitation. Vestibular rehabilitation programs should include habituation exercises, adaptation exercises as warranted for patients with impaired gaze stabilization, balance retraining, and exercises to restore or maintain physical conditioning. Habituation exercises Habituation exercises are performed to reduce symptoms of motion-provoked dizziness or imbalance. The underlying principle of habituation exercises is to reduce the CNS response to normal movement stimulus, or “habituating,” driving compensation in the CNS. Any head motion that the patient finds symptomatic, such as bending forward or walking with head turns, can be used as a habituation exercise. However, a habituation program should also incorporate the items in the MSQ; the MSQ is composed of the most common activities that provoke dizziness in patients with peripheral vestibular hypofunction, and is a valuable tool to document recovery (Shepard et al., 1990; Smith-Wheelock et al., 1991). The patient starts with 4 to 5 of the activities on the MSQ that moderately provoke their symptoms, repeating three times and performing them two to three times daily, resting between each exercise to allow the symptoms to return to baseline. Habituation is characterized by decreased intensity and duration of symptoms in response to performing the exercise. Once patients can tolerate an activity, with minimal or no symptoms, they can be progressed to other items on the MSQ that they found more provocative. The clinician should be careful not to overprescribe habituation exercises at the risk of overstimulating the patient. In order to drive CNS neuroplasticity and habituation, exercises must provoke symptoms, but symptoms should resolve within a few minutes. Symptoms lasting an hour or more necessitate a review of how the patient is performing the exercises and program modification. The patient may need to perform exercises for a few months before being able to modify the program, and may take as long as 6 months for habituation to take place, although incremental recovery should be observed to determine efficacy (Herdman & Clendaniel, 2014; Smith- Wheelock et al., 1991). Gaze stabilization (adaptation) exercises Gaze stabilization exercises, also called “adaptation exercises,” have been found to be effective in restoring the VOR gain (1:1 ratio of head-eye movement) in patients with vestibular dysfunction who are experiencing blurred vision or dizziness Balance retraining A problem-oriented approach to balance retraining should be directed at the particular areas of postural control that were found to be impaired on examination and through the patient subjective report. Postural control is achieved through the interplay of input and interpretation of sensory afferent information from visual, somatosensory, and vestibular systems, with effective motor output. Balance retraining should take into account: ● Addressing static, anticipatory, and reactionary postural control.
to resume normal activity, as tolerated, after undergoing a canalith repositioning maneuver (Bhattacharyya et al., 2017).
when performing activities that require visual tracking during head movement (Hillier & McDonnell, 2011). Not all patients with vestibular loss will experience difficulties with gaze stabilization, but positive findings on DVA testing or symptoms of blurred vision while walking or scrolling text on their computer screen are indicative of diminished gaze stabilization. Gaze stabilization exercises require the patient to maintain visual fixation on a target while moving the head. Visual fixation is mediated by the CNS. During visual fixation on a stationary object, any slip of the image on the retina due to drifts in ocular position will cause the brain to generate a responsive eye movement to hold the image steady on the retina. The retinal “slip” of the image on the fovea during head motion due to the altered VOR gain induces centrally mediated changes in interpretation of vestibular signals from the residual vestibular function. The retinal “slip” produces an error signal, and the CNS compensates to decrease the error signal by increasing the VOR gain. Retinal slip can be induced by both horizontal and vertical head movements applied at various amplitudes and frequencies to allow for adaptive changes to occur in the VOR gain. These changes, or adaptation, are the basis for restoring adequate VOR function. The first level of the exercise is termed X1 (“times one”) viewing. It has the patient fix gaze on a discrete target, such as a card with a single letter on it, which is held at arm’s length. The patient moves his or her head in a small trajectory (20° to 30°) from side to side as fast as possible while maintaining a clear focus on the target (see Resources section for link). He or she should continue the motion for 1 minute without stopping, modulating the speed of the head movement to perform the activity for the full minute. The tempo should also be reduced if the patient experiences any extreme nausea or dizziness. This should be performed at least 3 times with a 1-minute rest between to allow symptoms to resolve to baseline, at minimum 3 times per day, for a total of at least 12 minutes per day (Hall et al., 2016). Care should be taken not to increase the patient’s dizziness so that it becomes persistent for greater than a few minutes. The goal is to work up to 2-minute increments. This activity can start in a sitting position, and when able, progress to a standing position. The level of challenge can also be increased by having the patient perform the activity with the target taped to a blank wall 6 feet away, and then adding a visually complex field, such as a checkerboard, on the wall while the patient holds the card at arm’s length. Once patients tolerate the X1 viewing paradigm, they can then progress to the X2 viewing paradigm, where the patient’s head and the target are moving together in opposite directions. In this exercise, the patient holds the card with the letter target at arm’s length and moves the card and the head from side to side in a small trajectory in opposite directions, maintaining a clear focus on the image. As with X1 viewing, the patient performs this exercise 3 to 5 times per day for 1 minute, as fast as possible while still maintaining a clear focus, eventually working up to 2 minutes. This exercise can be progressed to standing, and then standing with a complex visual background as in the X1 viewing exercise. ● Increasing the excursion of the center of mass in all directions in sitting and standing. ● Walking in various environmental contexts such as busy environments, over different surface conditions such as compliant and uneven surfaces, and in multiple directions. ● Adding a cognitive task to increase the challenge (split attention) and train mobility in a functional context; and ● Altering the reliance on visual and somatosensory inputs.
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