(Image from Dr S. Olvey's presentation slides at the ICMS 2016 AGM)
More concussion. We can't get enough of it. It has mushroomed over the past few years and is firmly in the public awareness, especially amongst sports competitors.
Until recently, there have been two levels of diagnosis; point of care and clinic-based. Point of care testing occurs on the sidelines or in the event medical centre and needs to be:
- easily applied,
- easily accessible
- and have good test characteristics (sensitivity, specificity, PPV, NPV, repeatability, reliability and validity).
Clinic testing, while more accurate, tends to:
- require specialised training to conduct and interpret
- need a specific appointment to attend which take a reasonable amount of time
- be conducted only at specific centres
- be expensive
If only there was something to bridge the gap.
Luckily, some plucky researchers and engineers have taken a simple concept that uses bulky equipment and applied virtual reality style technology to try and develop a portable, easy to use and interpret diagnostic modality for concussion called the IPAS Goggles. And they sound great.
Prof. Michael Hoffer is one of the lead researchers on this project and I met him briefly at the recent ICMS meeting in Indianapolis where he showed me how the goggles work. He agreed to come on the podcast and discuss the background to the goggles and the evidence that his team has produced to date. He also talks about issues such as the potential to game some of the current sideline assessment tools that use a baseline, the potential for young, fit athletes to outperform tests even when impaired (similar to how they may outrun a treadmill ECG during assessment for chest pain) and a little bit about the potential for placing commercial gain over test validity for conditions such as concussion that may be hard to diagnose and yet have significant possible consequences and popular and media attention.
Here's the podcastHere are three papers that link vestibulo-occular deficit to concussion
The IPAS set up at the ICMS conference.
An example of the real-time data display
And an overview of occular defects in concussion in general:Sports-Related Concussion: The Eyes Have It
- A Brief Vestibular/Ocular Motor Screening (VOMS) Assessment to Evaluate Concussions. Anne Mucha, Michael W. Collins et al. Am J Sports Med. 2014 Oct; 42(10): 2479–2486.
- Occurrence of oculomotor dysfunctions in acquired brain injury: a retrospective analysis. Ciuffreda KJ, Kapoor N, Rutner D, Suchoff IB, Han ME, Craig S. Optometry. 2007 Apr;78(4):155-61. (Open access pdf if you Google the title)
- Visual impairment and dysfunction in combat-injured servicemembers with traumatic brain injury. Brahm KD, Wilgenburg HM, Kirby J, Ingalla S, Chang CY, Goodrich GL.Optom Vis Sci. 2009 Jul;86(7):817-25.
. Leonard V Messner. Department of Optometry, The Illinois College of Optometry, USA. Here are the two published papers mentioned by Michael in the podcast:Oculomotor, Vestibular, and Reaction Time Tests in Mild Traumatic Brain Injury
. Balaban C, Hoffer ME, Szczupak M, Snapp H, Crawford J, et al. PLoS ONE 11(9)(2016): e0162168. doi: 10.1371/journal.pone.0162168. PubMed PMID:27654131 Clinical trials in mild traumatic braininjury
. Hoffer ME, Szczupak M, Balaban C. J Neurosci Methods. 2016 Apr 30. pii: S0165-0270(16)30073-5. doi: 0.1016/j.jneumeth.2016.04.021. [Epub ahead of print] PubMed PMID: 27141855.
One concern regarding these goggles is that they rely on the concept of occulovestibular dysfunction (measured via reaction time; hence OVRT) reflecting the presence of concussion through disturbance of vestibulo-occular reflexes such as the optokinetic relex, cervico-occlar reflex and the vestibulocolic (not what you think that is) reflex. Reports suggest that anywhere between 10-80% of concussed patients with have an occulovestibular defect (either of version or vergence). So while the sensitivity of the goggles might be excellent in patients with an occulovestibular defect following concussion, what is it for a concussed patient with no OV deficit and therefore should test candidates be pre-screened for dizziness, vertigo, balance and visual impairment first?
(Version = saccadic movement, gaze fixation and smooth pursuit. Vergence = diplopia, accomodation, strabisumus
If you want to know more, you can email Michael Hoffer
directly or go and have a look at the NKI website
What do you think? Possible game-changer?