Additional pressures of Covid-19 on Balance Clinics

I’d like to share with you some thoughts and discussions regarding vestibular and balance services I have had with clinicians. These discussions existed before the pandemic but have certainly become a much more frequent topic of conversation as services move to tackle the ‘fall out’ from over 12 months of disruption.

Are the additional pressures on vestibular clinics due to pent up demand or also due to the suggested Covid related dizziness?

Its fair to say that we have seen some important publications within the field of hearing science that has questioned the impact on inner ear function for individuals who have had Covid-19. Whilst I think it is too early to say what the extent of this might be, or the long-term impact of interventions and medications to preserve life might have for individuals, there are more reports and case studies that indicate it is something that will be on our radar for some time to come.

So, what can we do to effectively and safely to assess the backlog of patients waiting for vestibular assessment’?

Whilst it can at times seem a challenge to know where to start when assessing the dizzy or imbalanced patient, lets try to focus on what might be the area of focus in a patient who has been referred for assessment with concerns of having an inner ear event that has left the patient with dizziness and / or functional impairment.

If we are suspecting the patient is experiencing a change in peripheral vestibular function or has not recovered from an event or pathology that has disrupted vestibular then we have the opportunity to ‘target’ the vestibular end organ and physiological pathways.

Whilst we have a range of diagnostic tools that may be available in our vestibular / dizzy clinic, let’s consider which assessments can quickly provide information on the status of the vestibular organ and associated pathways.

The assessments in the vestibular toolbox

When we think about the peripheral vestibular organ, we can consider its function in relation to the detection of angular acceleration, which we assess through the function of the semi-circular canals (SCC) via the vestibular ocular reflex (VOR), and the sense of body position relative to gravity, through the assessment of the otolith organs, the utricle and saccule.

From a patient’s perspective, we often have described symptoms or functional changes that correspond to head movement, and / or a sense of imbalance. To assess these functions, we can use video head impulse testing using EyeSeeCam vHIT to establish the functional status of SCC by measuring the VOR, and for the Otolith organs we can utilise evoked potential testing by examining muscular responses with Vestibular Evoked Myogenic (VEMP).

The table below summarises the assessment of physiological pathways of the peripheral vestibular end organ using vHIT and VEMP.

Is it possible to do less, but be more clinically and time efficient?

As we discussed earlier, the challenge many clinics have because of the Covid-19 pandemic is that they may have a backlog of patients waiting to be seen and assessed, or due to the additional cleaning and reducing the number of patients in the hospital at any one time, less time per patient in clinic. One strategy could be in patients where we are most interested in establishing the status of the peripheral vestibular end organ, to use assessments that examine these pathways. Video Head Impulse Testing is an accurate, non-invasive method to look at the function of the VOR at natural (physiological) head movement speeds. This assessment can be completed in 10 minutes, and as we can see from the table, examines 8 functions (6 semi-circular canals, and 2 branches of the vestibular nerve) of the vestibular system when detecting angular acceleration during head movement.

To examine the otolith organs, we can utilise cervical and ocular VEMP testing. This can be conducted in less than 30 minutes for both the utricle and saccule to be examined. Again, we are assessing an additional 4 functions per side (utricle plus superior vestibular nerve, saccule plus inferior vestibular nerve).

When combined, from start to finish, vHIT and VEMP assessment can be conducted in less than 45 minutes, is non-invasive, and can provide a very comprehensive assessment of the status of vestibular end organ.

Summary

Whilst we know not every dizzy patient has a peripheral vestibular impairment, and there is the possibility that the amongst patients that are referred we will have those with central pathologies and impairments, and we have tools such as Videonystagmography to examine eye movements in detail. We also know that not all peripheral vestibular pathologies can be detected with vHIT and VEMP, and that in conditions such as Endolymphatic Hydrops, a caloric assessment has great value to examine the peripheral vestibular end organ at an ear specific and lower frequency of stimulation. However, for those patients where the question might be ‘Is there a peripheral vestibular impairment that explains the patients ongoing reported symptoms?’ the combination of vHIT and VEMP can be a very sensitive assessment of establishing underlying vestibular impairment and efficient use of clinical time when resources are being stretched.