plane. The velocity of the nystagmus must be appreciated to determine the affected ear, and the direction of the nystagmus determines whether the BPPV is due to canalithiasis or cupulolithiasis. If otoconia are free-floating (canalithiasis), the velocity and duration of the nystagmus will be higher when the patient is rolled toward the affected side. If otoconia are adhered to the cupula (cupulolithiasis), the velocity will be higher when the affected ear is up, and the duration persists. In horizontal canal BPPV, the direction of nystagmus is always lateral, but can be either geotropic (fast phase beating toward the ground/ earth), or ageotropic (fast phase beating away from the ground/ earth). In horizontal canalithiasis, nystagmus is geotropic and fatigues, while with cupulolithiasis nystagmus is ageotropic and does not fatigue. There is no doubt that interpreting findings on the Roll Test can be confusing considering that the examiner must simultaneously diagnose which side is affected and which form of BPPV is present. Using a patient case example to clarify, if the velocity of nystagmus is higher when the patient’s left ear is down (as compared to right ear down) and the direction of the nystagmus is geotropic, then the diagnosis is left horizontal canalithiasis. In contrast, if the velocity is higher when the left ear is down, but the direction is ageotropic, then the diagnosis is right horizontal cupulolithiasis. In more simplified terms, when the patient is in the position that elicits the strongest response, the direction of the nystagmus will point to the affected side, while the geotropic and ageotropic characteristic lends diagnostic value in determining the type of BPPV. In any positional tests, the examiner must be cautious not to interpret all oculomotor responses as a positive test of BPPV. Findings of non-fatiguing vertigo or nystagmus while the patient is in the testing position, direction-changing nystagmus when the head is moved to another position, or nystagmus that does not coincide with the plane of the dependent canal (e.g., a pure downbeating nystagmus), indicates a CNS lesion, necessitating referral. The Four-Square Step Test assesses multidirectional dynamic standing balance that is predictive for identifying fall risk. The patient is asked to step over four canes set up like a cross with the tips of the canes touching in the middle. The time it takes for the patient to move through the sequence of stepping over the canes forward, sideways, and backward in a clockwise and then a counterclockwise direction while facing forward is measured. Assessing the ability to make quick changes of direction and walk backward is important for the patient with vestibular disease. Patients taking greater than 15 seconds to complete the test are identified as being at risk for multiple falls with a sensitivity of 94% and specificity of 86% (Ditte & Temple, 2002). A cutoff score of 12 seconds was found to have 80% sensitivity and 92% specificity for identifying fall risk in patients with vestibular dysfunction (Whitney, Marchetti, et al., 2007). The Timed Up and Go test (TUG) is a measure of functional mobility and has been validated to predict fall risk in patients with vestibular disease. The time it takes for a patient to rise from a standard chair, walk 3 meters, turn, and return to sitting is measured. An assistive device can be used during this test. Generally, community-dwelling adults taking greater than 13.5 seconds to complete the test are identified as having a risk for falls (Shumway-Cook et al., 2000). The TUG has a sensitivity of 80% and specificity of 56% for identifying fall risk for patients with vestibular disease who take greater than 11.1 seconds to complete the test (Whitney, Marchetti, et al., 2004). The Modified Clinical Test of Sensory Interaction on Balance (mCTSIB) was developed to evaluate the sensory contribution to balance. The mCTSIB assesses the patient’s ability to maintain static standing balance under a combination of four different altered sensory and surface conditions. The four conditions of the test are (1) standing on the floor with eyes open, (2) standing
Figure 6: Hallpike-Dix Test
If in this position, the examiner sees a torsional and downward beating nystagmus, that is differential for anterior canal BPPV of the same ear. If the torsional component is toward the opposite ear, that is indicative of anterior canal BPPV of the opposite, or up ear, although it is very rare to elicit in this position. The Roll Test assesses BPPV in the horizontal canal. The patient assumes a supine position and the head is quickly rolled to one side. The examiner assesses for the presence and direction of nystagmus and symptoms of vertigo. The head is then slowly brought back to center, and then quickly rolled to the opposite side with nystagmus and vertigo again being assessed. For unilateral horizontal canal BPPV, nystagmus will be seen with rolls in both directions as the affected ear is still moving in the testing Postural control Because the vestibular system is also responsible for mediating postural control through the VSR, the examiner must employ tests that measure balance and mobility in the patient with vestibular dysfunction who also reports difficulty with balance and walking. Clinical examination should include tests of static and dynamic balance, ambulation, and fall risk. Static balance is assessed in both sitting and standing, determining the extent to which the patient is able to maintain the position independently. The surface on which the patient is seated or standing (bed, chair, foam/compliant surface, etc.) should also be considered; those features impact the level of challenge of the postural control activity. Tests of dynamic balance assess the ability to weight shift and move the center of mass within and to the edges of the base of support. This can be accomplished through measuring the direction and distance of reaching in both sitting and standing. Again, the surface conditions must be appreciated. Standardized tests of balance that can be used in patients with vestibular dysfunction include the Berg Balance Scale (BBS), the Four-Square Step Test (FSST), and the Modified Clinical Test of Sensory Interaction on Balance (mCTSIB). The BBS is a 14-item tool that assesses both static and dynamic balance in sitting and standing, as well as identifying risk for falls. Items include a transfer, reach, turn, standing in tandem, and standing on one leg, and are scored on a 0 to 4 scale with a maximum score of 56. It has been validated for use in the community-dwelling older adult population (Berg et al., 1992). The BBS has been shown to have a sensitivity of 91% for predicting fall risk with a score of =42/56 in persons without a history of imbalance, and =51/56 in persons with a history of imbalance (Shumway- Cook et al., 1997).
EliteLearning.com/ Physical-Therapy
Page 129
Powered by FlippingBook