Head Shaking Test
- This test examines for the presence of nystagmus after 40 full cycles of horizontal head shaking movements.
- The head is positioned into 30 degrees of cervical flexion in order to orient the lateral canal in the horizontal plane.
- The active head turns should be approximately two cycles per second for 20 seconds and then stopped abruptly.
- Nystagmus after this test suggests asymmetric input to the central vestibular system.
- The eyes will beat in the direction of the intact side.
- Patients with severe dysfunction unilaterally may elicit a burst of nystagmus.
- Those with acute unilateral dysfunction may not present with signs of nystagmus due to central inhibition or disabled velocity storage.
- Individuals with bilateral dysfunction will not exhibit nystagmus.
- With a result of vertical nystagmus a central lesion should be suspected.
(Slattery, 2011)