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Timothy C. Hain, MD Page last modified: March 20, 2018

"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

Recent Research

There are many clinical research projects currently being undertaken by Dr. Hain with many collaborators. Here is a selection of ones that are ongoing.

VEMP projects:

We are presently pursuing a large number of projects using the VEMP (vestibular evoked myogenic potential) protocol. This is a simple method of eliciting vestibulospinal reflexes

Equipment used to record a VEMP, a Bio-Logic Navigator Pro.

Other projects have included assessment of bone VEMP's, as well as arm and leg VEMPs. This methodology provides a very straightforward method of determining the degree to which the inner ear controls balance reactions in the body.


Benign paroxysmal positional vertigo (BPPV) is the single most common cause of dizziness. It can be effectively treated by physical therapy.

Pedometer used to count steps in patients with BPPV.

In a student project, we looked to see whether BPPV affects mobility, by assessing steps/day before and after successful treatment of BPPV.

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


Gaze-holding (see also: rebound nystagmus)



Vestibular and oculomotor testing

Head-shaking Nystagmus (see also here)


Clinical situations

Perilymph Fistula

Head and body motor control

Rehabilitation of Vestibular Problems

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.

Sled project:

Linear Sled
Linear Sled at NUPT

With the support of NIH, we built a bobsled like device. It is very powerful and uses a magnetic drive to accelerate itself almost instantaneously at 2 gravities. A study, with Emily Keshner, Ph.D, wasperformed in which we are measuring head stability in normal subjects, patients with bilateral vestibular loss, and patients with cerebellar disorders.

Another hypothesis was that the head moves quite differently if the sled is "driven" as opposed to having the same motion "played back". This is true.

This was a rather lengthy project that unfortunately was not especially productive. We built an interesting device (see above), that was servo controlled. We acquired a large amount of data using a head tracking device that was so complex that the data outstripped our ability to process it. Dr. Hain is now in the situation of having many many gigabytes of "sled" data, without the resources to publish it.

Copyright March 20, 2018 , Timothy C. Hain, M.D. All rights reserved. Last saved on March 20, 2018