It wasn’t until the 1850s through the 1950s that researchers began to take a closer look at postural control and during this time the primary focus was on postering reflexes. Certainly, those of you in the neuro background are familiar with flexion and extension posturing reflexes that can occur due to neurological insult, particularly with brain injury. We’ve seen more exposure through the media with sports-related head trauma. For example, you may have seen videos after a jolting hit and someone falling on their head that resulted in a few moments of rigid either upper extremity flexion or extension posturing. This is just one of the temporary neurological findings you can see with a concussion.
You can see the progression of this timeline that after posturing reflexes, the focus was more on gait, posture, and locomotion. Dr. Roberts was a thought leader in his expanded work on locomotion. And then in the 1970s, Dr. Lou Nashner’s research at MIT expanded the discussion on postural control to incorporate balance strategies and limits of stability based on sensory organization and motor control testing with force plate technology. As we began to do more planning and training to travel into space, the impact of G forces was further understood, as well as the impact on balance after being in an antigravity environment for prolonged periods.
And so this was really the first time that we began to look at sensory organization, how we use vision, somatosensory, and vestibular cues for balance. It was in the early 80s that Dr. Nashner, with the collaboration of his colleagues, such as physicians Dr. Owen Black and Dr. Robert Graham, as well as physical therapist Dr. Fay Horak, introduced computerized sensory organization testing into the clinical space not just for assessment, but utilizing this information for rehabilitation.
Now, to some, the 70s may seem like a long time ago, but believe me, it wasn’t. This is particularly relevant when research suggests it takes an average of 17 years for a new concept to become common practice. We certainly witnessed this in the slow adoption of the Epley Maneuver for BPPV when initially introduced by Dr. John Epley. There are still providers today that prescribe habituation exercises for BPPV. And this has also been problematic when we consider the evolving definition of concussion. For those of you that have been in the concussion space, you know that one time we graded concussions. So you have to think that 20 years ago a lecture I may have given on concussion is in the trash can. We no longer grade a concussion based on the loss of consciousness. Studies now find that the loss of consciousness actually occurs less than 10 percent of the time, particularly when we think about the gap between research and what’s accepted as best practice. Now, as more data was collected with posturography testing and more understanding of the vestibular system, it was speculated that the six sensory conditions associated with CDP or computerized dynamic posturography was not challenging enough for higher functioning individuals with vestibular dysfunction.
It was in 1998 that Dr. Neal Sheppard and Dr. Lou Nashner added a head shake test with eyes closed to the CDP SOT, resulting in a higher demand on the vestibular system to maintain balance. It was also during this time that we saw the evolution of non computerized balance testing. For those of you in the sports world, particularly the concussion space, became familiar with the balance error scoring scale or BESS test. This was introduced in 1999 by Kevin Guskiewicz and colleagues as part of the National Association of Athletic Trainers position paper on concussion management. Just as Drs. Shepherd and Nashner had discovered that standardized SOT testing was not enough, Dr. Guskiewicz and colleagues realized that single leg stance tandem or the modified CTSIB was simply not demanding enough to identify balance impairments in athletes post-concussion. So they developed the BESS test. It, too, has six conditions. For those of you not familiar with the BESS, all conditions are done with eyes closed, which includes single leg stance, tandem, and feet together on a firm surface. These conditions are then repeated on a foam surface. And for those of you familiar with the BESS test, most likely know that single leg stance in tandem with eyes closed on a foam is difficult to complete for many individuals with no associated concussion. This could be due to a previous orthopedic injury, a weakness, or range of motion limitations.
In other words, there are other factors associated with the inability to complete this test that are not related to a concussion. Despite these factors, the BESS currently remains the most widely used balance test for concussion. Well, next on this timeline, you’ll see the CDP again. This is based on the advancement in technology, particularly associated with the visual surround. It’s evolved to become more immersive. It decreases central visual cues for orientation based on the effort to assess postural control under greater sensory demands. This type of technology also creates more opportunities to expose the patient to immersive, optokinetic demands, which is becoming increasingly important in the treatment of visually induced dizziness or motion sensitivity. The advancements in this technology were through the collaboration of Dr. Nashner and Dr. Berme, founder of Bertec.
Then in 2015, also using force plate technology was COBALT. The research for COBALT was published in 2018. I do predict a growing interest in the use of COBALT, particularly because so much of the conversation today is about identifying vestibular and/or visual related components post-concussion. COBALT does integrate those domains by adding a head shake test with eyes closed on a firm and foam surface, as well as adding a trunk rotation test while tracking their thumb. Now, for those of you in the neuro background who may have been evaluating people with traumatic brain injury, have heard about the VOR cancellation test or sometimes referred to as the VOR suppression test.
During this test, the patient extends their arms with their thumbs up and rotates their head and trunk in block or together while focusing on their thumb. The examiner is looking for corrective eye movement while the patient is tracking their thumb. This is known as a corrective saccades. You would only expect to see a corrective saccades during tracking if the patient had a central nervous system disorder. Although concussion is considered a brain injury, you wouldn’t expect to see this finding post-concussion. But what’s been discovered through the years is that people do have a provocation of symptoms with this test. This became much more apparent with the introduction of the vestibular ocular motor screen, or VOMS Test for concussion. In the VOMS, however, this test is referred to as the visual motion sensitivity test.
Let’s move on to the evolution of vestibular rehabilitation. Now, many of you know about Cawthorne-Cooksey Exercises. These were started in the 1940s and are known as habituation exercises. As I mentioned earlier, we still see people receiving these exercises today. In our clinic, when patients walk in the door with Cawthorne-Cooksey exercises, we try to kindly tell them that we’re going to recycle these. It’s not that they’re bad. It’s just that we know more from the 1940s. We now know about more specific customized exercises and Cawthorne-Cooksey exercises are not considered best practice for vestibular dysfunction. And then in the 1950s, we saw the introduction of the Dix-Hallpike for benign paroxysmal positional vertigo or BPPV.
Now I added back SOT testing and added computerized VOR testing because the advancement in these technologies increased our understanding of vestibular function as well as the understanding that vestibular suppressants and decreased activity actually limited recovery of vestibular dysfunction. Brandt-Daroff became used as a habituation exercise, particularly for BPPV. And then in 1988, the Semont or the liberatory maneuver was introduced.
It was in the early 1990s that the Epley Maneuver gained traction as the preferred canalith repositioning maneuver for BPPV, at least in the U.S. That remains true today, although Semont is used more frequently in other countries. Please keep in mind that studies show the same efficacy rate between these two maneuvers, particularly for the treatment of posterior canal BPPV.
It took several years for these successful maneuvers to be accepted as best practice. And it was in the late 1990s that the […] roll test was introduced. We continued to see an evolution of both assessments and treatments of BPPV today, especially treatments for BPPV not associated with the more common occurrence of posterior canal BPPV. It was also during this time we began to see more research into postural control, not just sensory organization, but the impact of motivation, cognition, and other variables.
There was also the introduction of gaze stabilization assessment and training in vestibular rehabilitation, and then research of gaze stabilization exercises continued to be a focus in the early 2000s to better understand VOR adaptation. And that remains true today, especially with discussions on VOR times one versus incremental progressive VOR exercises times two. For those of you who may not be familiar with these terms, VOR times one is when the patient is asked to focus on a target and rotates their head. VOR times two is that the eyes and the target move opposite of each other. Now the latter or VOR times two exercises appear to result in the most beneficial outcomes for VOR adaptation based on the more current research. Keep in mind, however, that the duration, the frequency, the amplitude, the velocity of VOR exercises to have the most optimal outcomes is still not fully known.
So as we wrap things up, you know, just a quick look at where do we go from here, what’s next? We will continue to see more studies on VOR adaptation. We’ll also see more focus on treatment techniques to address motion sensitivity. Sometimes you’ll hear this called visually induced dizziness or visually induced motion sensitivity. Right now, the research is suggesting optokinetic stimulation yields the most promising results for this type of dizziness. We’ll see advancements in head mounted displays and wearable. In space travel we’ll continue to drive the gains in vestibular assessment and rehabilitation therapies. It’s likely we’re going to see a growing trend in therapies addressing visual spatial processing. I certainly have a lot of interest, especially in questioning: are we doing too many activities in our central visual field, whether that’s convergence training, even VOR training? We know our patients have this tendency to focus too centrally on visual cues for balance instead of looking around them, especially during multi sensory input.
I’m particularly interested in the impacts of virtual reality, especially on when do we introduce this with sensory processing dysfunction versus a tool to increase performance. So it’ll be really interesting to see where we are in the next 5, 10 years in vestibular rehab. We should expect to see advancements in these non therapies, such as vestibular implants, which are already occurring today.
So in closing, we’ve come a long way. And again, I didn’t touch base on every component. It was just a quick overview. And I’d like to take this time to thank all the individuals who have dedicated their lives to this research. We all agree there’s a great demand for more research in this area. I think we can get there faster with more clinicians contributing to research, especially through case studies. And when I’m saying that, I’m reminding myself of that as well, because for so many of us who don’t practice as part of a research institution, we’re simply not publishing enough.
Practicing clinicians have so much to contribute based on your clinical experience, whether that’s acute care, home health, long term care, outpatient. It’s important because so often in research, it doesn’t replicate what we see in the clinic or that space outside the research environment. So this growth in translational research will create new opportunities to bridge the gap between clinical practice and research.
I certainly appreciate, you know, your interest in this topic and look forward to seeing what we can accomplish together.
About the Author
Bridgett Wallace, PT, DPT, has a doctorate of physical therapy and holds competency-based certifications in vestibular rehabilitation and concussion management. Dr. Wallace has been treating patients with dizziness and balance disorders for more than 20 years and is the founder and President of 360 Balance & Dizziness Center.
