RESEARCH ARCHIVES

Timothy C. Hain, MD • Page last modified: May 29, 2026

"The sciences [...] mainly make models. By a model is meant a mathematical construct which, with the addition of certain verbal interpretations, describes observed phenomena." - J. von Neumann

"It is pointless to ask whether a model (which is generally of a mathematical nature) is real, only whether it agrees with observation. If two models agree with observation, neither model can be considered more real than the other." - S. Hawking

BPPV

Benign paroxysmal positional vertigo (BPPV) is the single most common cause of dizziness. It can be effectively treated by physical therapy. We have published many times on BPPV in the last 30 years.

This section has annotations and key illustrations from selected papers published since 1984.

Periodic alternating Nystagmus (PAN) -- see here.

Gaze-holding (see also: rebound nystagmus)

Robinson DA, Zee DS, Hain TC, Holmes AM, Rosenberg LF: Alexander's law -- its behavior and origin in the human vestibulo-ocular reflex. Ann. Neurology., 16:714-722, 1984. Nystagmus follows Alexander's law when it increases when looking in the direction of the fast phase, and decreases or reverses when looking in the direction of the slow phase. In this paper a feasible explanation for Alexander's law is proposed for situations where there is a vestibular imbalance-- summation of gaze-evoked nystagmus and vestibular nystagmus. Alexander's law is clearly shown to be present in normal subjects undergoing caloric irrigation.
Zee DS, Hain TC, Carl JR: Abduction nystagmus in internuclear ophthalmoplegia. Annals. Neurology., 21:383-388, 1987. The abducting nystagmus in INO appears in this patient to be under adaptive control.
Ajroud-Driss S, Sufit R, Siddique T, Hain TC. Oculomotor involvement in Myotonic Dystrophy Type 2. Muscle/Nerve Accepted 6/2008. This paper documents that myotonic dystrophy can cause rebound nystagmus through a muscular mechanism, rather than through brainstem circuitry or cerebellar lesions.
Gordon SE, Hain TC, Zee, DS and Fetter M. (1986) Rebound nystagmus. Soc. Neurosci. Abstr., 12:1091. In this work we showed that everybody develops rebound nystagmus, given that the duration of gaze holding is long enough. We also introduced a new methodology involving use of a blinking LED to provide a position stimulus without retinal slip.

Saccades

Kapoula ZA, Robinson DA, Hain TC: Motion of the eye immediately after a saccade. Experimental. Brain Research., 61:386-394, 1986. The eye movements of several normal subjects were recorded with scleral eye coils, which is a highly accurate contact lens type device. Saccades (rapid eye movements) frequently terminate with a small overshoot combined with a rapid drift backwards. This is unlikely to have any functional significance but is part of the spectrum of normal behavior..
Hain TC, Zee DS, Mordes M: .Blink-induced saccadic oscillations 19:299-301, 1986. Annals Neurology. For a summary of this case of a cerebellar disorder with blink induced ocular flutter click on the link above.
Lasker AG, Zee DS, Hain TC, Folstein S: Saccadic eye movements in Huntington's Disease: Initiation defects and distractibility. Neurology, 37: 364-370, 1987. A paradigm was used in which subjects were asked to look in the opposite direction of a target (the so-called "anti-saccade" task). Huntington's disease patients have trouble doing this.
Kapoula Z, Hain TC, Zee DS, Robinson DA: Adaptive changes in post-saccadic drift induced by patching one eye. Vision Research, 27:1299-1307, 1987. Normal subjects were recorded with scleral eye coils before and after 5 days of wearing a patch over one eye. Post-saccadic drift was optomized for the viewing eye.
Lasker AG, Zee DS, Hain TC, Folstein SF, Singer H: Saccades in Huntingtons disease: Slowing and dysmetria. Neurology, 38:427-431, 1988. This was a scleral eye coil recording of patients with Huntingtons disease.
Ashe J, Hain TC, Zee DS: Microsaccadic oscillation -- a new clinical syndrome. Brain, 114, 461-472, 1991. A collection of patients with tiny oscillations of their eyes, recorded with the scleral eye coil..

Otoliths

Hain TC: A model of the nystagmus induced by off-vertical axis rotation Biological Cybernetics, 54:337-350, 1986. For a summary of this modeling paper related to "barbeque" nystagmus click on the local link above.
Fetter M, Hain TC, Zee DS: Influence of eye and head position on the vestibulo-ocular reflex. Experimental. Brain Research., 64:208-216, 1986. The gain of eye movements in space in normal subjects do what one would expect they would do, which implies the existence of a neural mechanism that calibrates the vectorial properties of eye movements in the orbit.
Hain TC, Zee DS, Maria B: Tilt-suppression of the vestibulo-ocular reflex in patients with cerebellar lesions. Acta Otolaryngology. (Stockh), 105:13-20, 1988. This was largely a study of patients with medulloblastomas, which is a tumor of the cerebellum which arises in the cerebellar nodulus. These patients were different than normal subjects in that they did not suppress their nystagmus when their head was tilted into a pitched position. This likely reflects loss of otolithic modulation of velocity storage through the cerebellar nodulus. For a detailed summary of this paper click on this link.
Hain TC, Buettner UE: Static roll and the vestibulo-ocular reflex (VOR). Experimental Brain Research. 82:463-471, 1990. This paper explored the time constant of the VOR with the head tilted using the scleral eye coil method. The VOR time constant in different planes clearly is reduced differentially by tilt away from vertical. This causes a curvature of the VOR vector over time, which is documented and simulated.

Vestibular and oculomotor testing

Head-shaking Nystagmus (see also here)

Hain TC, Fetter M, Zee DS: Head-shaking nystagmus in unilateral peripheral vestibular lesions. American J. Otolaryngology., 8:36-47, 1987. This is one of several papers and chapters on head-shaking nystagmus (HSN). This paper studied individuals with very well documented unilateral vestibular lesions and showed that they all had HSN directed with slow-phases toward the lesion. HSN appears to be related to a combination of the degree of unilateral loss and the amount of remaining velocity storage. Because velocity storage appears to be somewhat variable, HSN is not a very good method of determining whether or not there is a unilateral vestibular lesion.
Wei D, Hain TC, Proctor L: Head-shaking nystagmus: associations with canal paresis and hearing loss. Acta Otology. 108: 362-367, 1989. The second paper on HSN. HSN in about 100 patients with dizziness who had caloric testing was not strongly tied to caloric canal paresis. Some of this is likely related to noise in both techniques, and some to variability in the population.
Furman J, Hain TC, Paige G: Central adaptation model of the vestibulo-ocular and optokinetic systems. Biological. Cybernetics., 61:255-264, 1989. In this theoretical paper a control systems model was developed to explain PAN (periodic alternating nystagmus). An "internal model" was proposed which replaced behavior in the afferents with arbitrary behavior determined centrally. The general idea that internal models are used to replace sensor dynamics with centrally determined dynamics is the most important portion of this paper.

Static Roll and the VOR

Hain, T. C. and U. W. Buettner (1990). "Static roll and the vestibulo-ocular reflex (VOR)." Exp Brain Res 82(3): 463-471. We measured the effect of static lateral tilt (roll) on the gain and time constant of the vestibulo-ocular reflex (VOR) in five normal subjects by recording both the horizontal and vertical components of eye velocity in space for rotation about an earth vertical axis with the head either upright or rolled to either side. The time constant of the VOR in the upright position was 19.6 +/- 3.2s (mean +/- standard deviation). The time constant of the horizontal component with respect to the head decreased to 15.7 +/- 4.0s for 30 degrees roll and to 12.7 +/- 2.7s for 60 degrees roll. The time constant of the vertical component with respect to the head was 11.0 +/- 1.4s for 30 degrees roll and 7.5 +/- 1.6s for 60 degrees roll. The gain of the horizontal VOR with respect to space did not vary significantly with roll angle but a small space-vertical component to the VOR appeared during all rotations when the head was rolled away from upright. This non-compensatory nystagmus built up to a maximum of 2-3 degrees/s at 17.0 +/- 4.7s after the onset of rotation and then decayed. These data suggest that static otolith input modulates the central storage of semicircular canal signals, and that head-horizontal and head-vertical components of the VOR can decay at different rates.

OKAN

Tijssen M, Straathof C, Hain TC, Zee DS: Optokinetic afternystagmus in humans: normal values of amplitude, time constant and asymmetry. Annals Otology, Rhinolology, Laryngology, 98:741-746, 1989. Normal values for OKAN in 30 subjects are reported. OKAN is weak in normal subjects, being strongest in young women.
Hain TC, Zee DS: Abolition of optokinetic afternystagmus by aminoglycoside ototoxicity. Annals Otology. 100:580-583, 1991. OKAN is lost after significant aminoglycoside toxicity.
Hain TC, Patel G: Slow-cumulative Eye Position to Quantify Optokinetic Afternystagmus. Annals Otology. 101:255-260, 1992. The SCEP is a very reasonable method of quantifying OKAN because it is noise tolerant.
Hain TC, Herdman SJ, Holliday MS, Mattox D, Zee DS, Byskosh AT: The localizing value of optokinetic afternystagmus. Annals ORL, 806-811, 1994. OKAN is asymmetrical after unilateral vestibular lesions, but because of variability and generally reduced responses in human subjects, it is not a very powerful method.
Fletcher WA, Hain TC, Zee DS: Optokinetic nystagmus and afternystagmus in human beings: relationship to nonlinear processing of information about retinal slip. Experimental Brain Research, 1990. Essentially a sensitivity analysis relating OKAN to full field velocity.

Clinical situations

Young NM, Mets M, Hain TC: Early Diagnosis of Usher Syndrome in Infants and Children. Am. J. Otology, 17:1, 30-34, 1996. Some patients with Usher syndrome have bilateral vestibular loss.
Levin S, Luebke A, Hain TC, Zee DS, Robinson DA, Holzman PS: Smooth pursuit eye movements in schizophrenics: quantitative measurements with the search-coil technique. J. Psych. Research, 22:195-206, 1988. 10 patients with well documented schizophrenia were recorded using the scleral eye coil technique. Pursuit was moderately reduced in this group. To put this into perspective, pursuit is also moderately reduced by living to be 55.
Hain TC, Luebke A: Phoria adaptation in patients with cerebellar lesions. Investigative Ophthalmology. 1990. Patients with cerebellar lesions have good phoria adaptation suggesting that phoria adaptation is not mediated through the cerebellum (which is surprising).
Tusa RJ, Kaplan PW, Hain TC, Naidu S: Ipsiversive eye deviation and epileptic nystagmus. Neurology. 1990. A case report of epileptic nystagmus.
Hain TC, Hanna P, Rheinberger M. Mal de Debarquement. Archives of Oto-HNS, 7/1999. Click HERE for more details.

Perilymph Fistula

Ostrowski VB, Hain TC, Wiet R: Pressure Induced Ocular Torsion. Archives in Otolaryngology-Head and Neck Surgery. 1997.
Hain TC, Ostrowski, VB. Limits of Normal for Pressure Sensitivity in the Fistula Test. Audiology and Neuro-otology 2:384-390, 1997
Ostrowski V, Hain TC. Vectorial analysis of the Tullio's phenomenon associated with superior canal dehiscence. Am J. Otology, 9/1999.

Head and body motor control

Herdman SJ, Sandusky AL, Hain TC, Zee DS, Tusa RJ: Characteristics of postural stability in patients with gentamicin toxicity. J. Vestibular Research. 4:71-80, 1994. In this study using moving platform posturography it was shown that balance is impaired after significant loss of vestibular input. This is not surprising.
Rogers MW, Hain TC, Hanke TA, Janssen I: Effects of stimulus parameters and inertial load on the incidence of protective stepping responses in healthy human subjects. Arch Phys Med Rehabil 77:363-368, 1996.
Peng GCY, Hain TC, Peterson BW: A dynamical model for reflex activated head movements in the horizontal plane. Biological Cybernetics, 75, 309-319, 1996. Model of Head Motor Control (yaw), 1996. Click on the link above for more details.
Peng CGY, Hain TC, Peterson BW. Predictions of vestibulo-collic (VCR) and cervico-collic (CCR) reflex contributions to head stability during trunk perturbations in the horizontal plane (accepted by Transactions in BME, 11/1998, to be published in 10/1999)
Keshner EA, Hain TC, Chen KJ. Predicting control mechanisms for human head stabilization by altering the passive mechanics. Accepted J. Vest. Research 7/1999.

Rehabilitation of Vestibular Problems

Harvey SA, Hain TC, Adamiec LC: Modified liberatory maneuver: Effective treatment for benign paroxysmal positional vertigo. Laryngoscope 104:1206-1212, 1994. This variant of the Epley maneuver cured roughly 75% of a group of 20 or so patients. No vibration was used.
Tai Chi for Balance (10/1999). published in Acta otolaryngology/HNS about 10/1999. Tai Chi exercise improves balance.
BPPV treatment (4/97). There is no difference between vibration and no vibration in outcomes when doing the Epley maneuver for BPPV.

Voice motor control (see also f0-control)

These projects were a collaboration with Dr. Chuck Larson, who obtained experimental data, and Dr. Hain, who performed mathematical modeling. Here are just a few.

Voice F0 Responses to manipulations in pitch feedback, Burnett TA, Freedland MB, Larson CR, Hain TC, J. Acoustical Soc America, 103, 3153-3161, 1998
Instructing subjects to make a voluntary response reveals the presence of two components to the audio-vocal reflex. Hain TC, Burnett TA, Kiran S, Larson CR Experimental Brain Research, 8/18/1999
Larson, C. R., et al. (2000). "Effects of pitch-shift velocity on voice Fo responses." J Acoust Soc Am 107(1): 559-564.
Larson, C. R., et al. (2001). "Comparison of voice F0 responses to pitch-shift onset and offset conditions." J Acoust Soc Am 110(6): 2845-2848.
Larson, C. R., et al. (2007). "Effects of simultaneous perturbations of voice pitch and loudness feedback on voice F0 and amplitude control." J Acoust Soc Am 121(5 Pt1): 2862-2872.
Larson, C. R., et al. (2008). "Interactions between auditory and somatosensory feedback for voice F0 control." Exp Brain Res 187(4): 613-621.
Xu, Y., et al. (2004). "Compensation for pitch-shifted auditory feedback during the production of Mandarin tone sequences." J Acoust Soc Am 116(2): 1168-1178.