averaged electromyogram beginning at a mean latency of 8.2 ms. The earliest potential changes, a biphasic positive-negative wave, is generated by afferents from the ipsilateral sacculus. The potential is abolished in patients with lesions of the inferior vestibular nerve subserving the sacculus but is preserved in subjects with severe sensorineural hearing loss. It is proposed that the response is generated by activation of vestibular afferents arising from the saccule, and transmitted via a rapidly conducting oligosynaptic pathway to anterior neck muscles [50].

Conclusions

With the new VOR test methods described, a more thorough investigation of vestibular function at the level of single SCC function and the otoliths has become possible. Modern techniques are now available such as 3-D eye movement analysis for the evaluation of SCC function, measurement of the SVV for utricular, and click-evoked myogenic potentials for saccular testing. These new techniques have the potential to significantly improve our diagnostic capabilities in dizzy patients.

References

1Lorente de No R: Vestibulo-ocular reflex arc. Arch Neurol Psychiatr 1933;30:245–291.

2Baloh RH, Honrubia V: The vestibular system; in Baloh RH, Honrubia V (eds): Clinical Neurophysiology of the Vestibular System, ed 2. Philadelphia, FA Davis, 1990, pp 1–17.

3Szentágothai J: The elementary vestibulo-ocular reflex. J Neurophysiol 1950;13:395–407.

4Grüsser OJ, Pause M, Schreiter U: Localization and responses of neurons in the parieto-insular vestibular cortex of awake monkeys (Macaca fascicularis). J Physiol (London) 1990;430: 537–557.

5Lisberger SG, Miles FA, Zee DS: Signals used to compute errors in monkey vestibuloocular reflex: possible role of flocculus. J Neurophysiol 1984;52:1140–1153.

6Blanks RHI, Curthoys IS, Markham CH: Planar relationships of the semicircular canals in man. Acta Otolaryngol (Stockh) 1975;80:185–196.

7Goldberg JM, Fernandez C: Physiology of peripheral neurons innervating semicircular canals

of the squirrel monkey. I. Resting discharge and response to constant angular acceleration. J Neurophysiol 1971;34:634–660.

8Fernandez C, Goldberg JM: Physiology of peripheral neurons innervating semicircular canals of the squirrel monkey. II. Response to sinusoidal stimulation and dynamics of the peripheral vestibular system. J Neurophysiol 1971;34:661–675.

9Bach-Y-Rita P: The Control of Eye Movements. New York, Academic Press, 1971.

10Suzuki J-I, Tokumasu K, Goto K: Eye movements from single utricular nerve stimulation in the cat. Acta Otolaryngol 1969;68:350–362.

11Fernandez C, Goldberg JM, Abend WK: Response to static tilts of peripheral neurons innervating

otolith organs of the squirrel monkey. J Neurophysiol 1972;6:978–987.

12 Robinson DA: Adaptive gain control of the vestibulo-ocular reflex by the cerebellum. J Neurophysiol 1976;39:954–969.

13Brodal A: Anatomy of the vestibular nuclei and their connections; in Kornhuber HH (ed): Handbook of Sensory Physiology. The Vestibular System. New York, Springer, 1974, vol VI, part 1.

14Büttner-Ennever JA: Vestibular oculomotor organization; in Fuchs AF, Becker W (eds): The Neural Control of Eye Movements. Amsterdam, Elsevier, 1981.

15Dix R, Hallpike CS: The pathology, symptomatology and diagnosis of certain common disorders of the vestibular system. Ann Otol Rhinol Laryngol 1952;6:987–1016.

16Barany R: Physiologie und Pathologie des Bogengangsapparates beim Menschen. Vienna, Deuticke, 1907.

17Sills AW, Baloh RW, Honrubia V: Caloric testing 2. Results in normal subjects. Ann Otol Rhinol Laryngol 1977;85:7–23.

18Schuknecht HF: Cupulolithiasis. Arch Otolaryngol 1969;90:765–778.

19Baloh RW, Honrubia V, Jacobson K: Benign positional vertigo. Neurology 1987;37:371–378.

20Brandt T: Positional and positioning vertigo and nystagmus. J Neurol Sci 1990;95:3–28.

21Brandt T, Steddin S: Current view of the mechanism of benign paroxysmal positioning vertigo: cupulolithiasis or canalolithiasis? J Vestibular Res 1993;3:373–382.

22McCabe BF, Ryu JH, Sekitani T: Further experiments on vestibular compensation. Laryngoscope 1972;82:381–396.

23Brandt T, Dieterich M: Central vestibular syndromes in roll, pitch, and yaw planes. Neuroophthalmol 1995;6:291–303.

24Dieterich M, Brandt T, Fries W: Otolith function in man: results from a case of otolith Tullio phenomenon. Brain 1989;112:1377–1392.

25Halmagyi GM, Brandt T, Dieterich M, Curthoys IS, Stark RJ, Hoyt WS: Tonic contraversive ocular tilt reaction due to unilateral meso-diencephalic lesion. Neurology 1990;40:1503–1509.

26Brandt T, Dieterich M: Skew deviation with ocular torsion: a vestibular brainstem sign of topographic diagnostic value. Ann Neurol 1993;33:528–534.

27Kasai T, Zee DS: Eye-head coordination in labyrinthine-defective human beings. Brain Res 1978;144:123–141.

28Halmagyi GM, Curthoys IS, Cremer PD, Henderson CJ, Todd MJ, Staples MJ, D’Cruz DM: The human horizontal vestibulo-ocular reflex in response to high-acceleration stimulation before and after unilateral vestibular neurectomy. Exp Brain Res 1990;81:479–490.

29Cremer PD, Halmagyi GM, AW ST, Curthoys IS, McGarvie LA, Todd MJ, Black RA, Hannigan IP: Semicircular canal plane head impulses detect absent function of individual semicircular canals. Brain 1998;121:699–716.

30Hain TC, Fetter M, Zee DS: Head-shaking nystagmus in patients with unilateral peripheral vestibular lesions. Am J Otolaryngol 1987;8:36–47.

31Ewald R: Physiologische Untersuchungen über das Endorgan des Nervus Octavus. Wiesbaden, Bergmann, 1892.

32Baloh RW, Honrubia V, Konrad HR: Ewald’s second law re-evaluated. Acta Otolaryngol 1977;83: 474–479.

33Raphan T, Matsuo V, Cohen B: Velocity storage in the vestibulo-ocular reflex arc (VOR). Exp Brain Res 1979;35:229–248.

34Fluur E: Interaction between the utricles and the horizontal semicircular canals. IV. Tilting of human patients with acute unilateral vestibular neuritis. Acta Otolaryngol 1973;76:349–352.

35Singleton GT, Post KN, Karlan MS, Bock DG: Perilymph fistulas: diagnostic criteria and therapy. Ann Otol Rhinol Laryngol 1978;87:797–803.

36Leigh RJ, Zee DS: The Neurology of Eye Movements, ed 2. Philadelphia, F.A. Davis, 1991, pp 384–385.

37Scherer H, Clarke AH: The caloric vestibular reaction in space. Physiological considerations. Acta Otolaryngol 1985;100:328–336.

38Baloh RW, Sills AW, Honrubia V: Caloric testing. 3. Patients with peripheral and central vestibular lesions. Ann Otol Rhinol Laryngol Suppl 1977;86(suppl 43):24–30.

39Baloh RW, Sakala SM, Yee RD, Langhofer L, Honrubia V: Quantitative vestibular testing. Otolaryngol Head Neck Surg 1984;92:145–150.

40Nelson JR: The minimal ice water caloric test. Neurology 1969;19:577–585.

41Baloh RW, Honrubia V, Yee RD, Hess K: Changes in human vestibulo ocular reflex after loss of peripheral sensitivtiy. Ann Neurol 1984;16:222–228.

42Cohen B, Suzuki J: Eye movements induced by ampullary nerve stimulation. Am J Physiol 1963;204:347–351.

43Suzuki J, Cohen, B: Head, eye, body and limb movements from semicircular canal nerves. Exp Neurol 1964;10:333–405.

44Fetter M, Dichgans J: Vestibular neuritis spares the inferior division of the vestibular nerve. Brain 1996;119:755–763.

45Aw ST, Fetter M, Cremer PD, Karlberg M, Halmagyi GM: Individual semicircular canal function in superior and inferior vestibular neuritis. Neurology 2001;57:768–774.

46Aw ST, Haslwanter T, Fetter M, Dichgans J: Three-dimensional spatial characteristics of caloric nystagmus. Exp Brain Res 2000;134:289–294.

47Fetter M, Sievering F: Three-dimensional (3-D) eye movement analysis in patients with positioning nystagmus. Acta Otolaryngol (Stockh) 1995;520:369–371.

48Fetter M, Aw ST, Haslwanter T, Heimberger J, Dichgans J: Three-dimensional eye movement analysis during caloric stimulation used to test vertical semicircular canal function. Am J Otology 1998;19:180–187.

49Dieterich M, Brandt T: Ocular torsion and tilt of subjective visual vertical are sensitive brainstem signs. Ann Neurol 1993;33:292–299.

50Colebatch JB, Halmagyi GM, Skuse NF: Myogenic potentials generated by a click-evoked vestibulocollic reflex. J Neurol Neurosurg Psychiatry 1994;57:190–197.

Prof. Michael Fetter, MD

SRH Clinic Karlsbad-Langensteinbach, Department of Neurology Guttmannstrasse 1

DE–76307 Karlsbad (Germany)

Tel. 49 7202 610, Fax 49 7202 616180, E-Mail Michael.Fetter@kkl.srh.de