Читать книгу Vestibular Disorders - Группа авторов - Страница 15

With the patient sitting up, look for spontaneous nystagmus in the primary position, leftward and rightward gaze (15 degrees to either side). In a brightly lit room, spontaneous nystagmus may not be visible until visual fixation is removed. Use optical frenzels, video frenzels or a pair of inexpensive take-away Frenzels [8] to remove fixation. To record the absence of spontaneous nystagmus without removing visual fixation is as meaningful as commenting on the state of the tympanic membranes without an otoscope. Typical peripheral nystagmus is seen in vestibular neuritis, the paretic phase of Ménière’s disease or after an acute surgical resection of the vestibular nerve and is horizontal torsional, beating away from the lesion. It enhances when visual fixation is removed (Fig. 2; online suppl. Video 1; for all online suppl. material, see www.karger.com/doi/10.1159/000490267) and when looking in the direction of the fast-phase of the nystagmus (“Alexander’s Law”) and is unidirectional (i.e., beating in the same direction in the primary position, leftward and rightward gaze; Fig. 3; online suppl. Video 2). Central vestibular disorders could present with spontaneous vertical, torsional or horizontal nystagmus. Cerebellar nystagmus, unlike peripheral nystagmus is bidirectional (i.e., left beating on left gaze and right beating on right gaze; Fig. 3; online suppl. Video 3). It is vexing that many central causes of vertigo, including stroke, can present with “typical peripheral nystagmus” because they could affect the vestibular nucleus or nerve root entry zone [5].

Table 1. Common vertigo syndromes, their differential diagnoses, findings on history and examination that could help their separation

Fig. 1. a Right Horners’ syndrome with partial ptosis and myosis. b Right ocular tilt response. A right-sided ocular tilt response characterised by a right head tilt, skew deviation with right hypotropia, and left hypertropia, rightward ocular torsion.

Fig. 2. Suppression of nystagmus by visual fixation. Typical peripheral nystagmus enhances when the subject dons a pair of Frenzel goggles (top panel) and is suppressed in bright light. Central nystagmus is unaffected by visual fixation.