Decompression SicknessNCT06370897
Prediction & Mechanisms of Recovery Following IEDS
An observational study of Decompression Sickness, run by University of Plymouth.
Trial summary
Inner Ear Decompression sickness (IEDS) accounts for 20% of all types of decompression sickness (the bends) in divers. The condition commonly affects the peripheral vestibular system (inner ear). IEDS results in acute symptoms of dizzyness (vertigo) and imbalance. Read more about this study
- Who is it for?
- Ages 18 to 85 years
- Conditions the study is for
- Decompression Sickness
- How many people
- 41 participants
- Where
- No sites listed yet
- Study dates
- Jun 2024to Sep 2028
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 85 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Population: Divers Exposure: Dive resulting in IEDS symptoms
Who may be able to join
- Divers admitted with suspected IEDS
- Divers diagnosed with IEDS at DDRC within past 10 years
- Adults over 18 years
Who cannot join
- Medically unstable
- Unstable orthopaedic deficits
- Retrospective study :
- We will include all co-morbidities as these could affect prognosis and recovery following IEDS.
- Healthy control comparator group :
- Normative data will be gathered on an age matched group. There will be at least 10 participants for each decade (<30yrs ,30-40yrs, 40-50 yrs,50-60yrs,60-70 yr.)
- Neurological, sensory or orthopaedic conditions that could affect balance.
About this study
Official title: A Prospective and Retrospective Observational Study of Symptoms and Mechanisms of Recovery in People With Inner Ear Decompression Sickness (IEDS)
Inner Ear Decompression sickness (IEDS) accounts for 20% of all types of decompression sickness (the bends) in divers. The condition commonly affects the peripheral vestibular system (inner ear). IEDS results in acute symptoms of dizzyness (vertigo) and imbalance. Even with the recommended treatment of hyperbaric oxygen therapy some people do not recovery fully. However, even in the presence of a permanent vestibular deficit many people can show a behavioural recovery where symptoms improve over time. Recovery can be aided by vestibular rehabilitation (VR) which is now routine for acute IEDS but was not provided before 2021, and is not widespread across the UK (United Kingdom) or world, meaning people may have a suboptimal recovery.
This project will investigate if and how people recover after an acute episode of IEDS and whether people who had IEDS in the past show changes in the central (brain) processing of vestibular function and in symptoms of dizziness, balance and posture.
This project has two main parts. Part one is a prospective observational study where people with an acute onset of IEDS are serially monitored while they are receiving hyperbaric treatment and VR over 10-14 days. Part two is a retrospective observational study where who have had IEDS in the past 15 years are re-assessed in a one-off session. The tests in both parts involve clinical tests and specialist eye movement recordings that assess vestibular function. We will also determine the site of any vestibular pathology by using selective stimulation of the vestibular end organ or nerve and assess whether there are any changes in how the structure and function of central vestibular pathways in the brain. In people with chronic IEDS with vestibular symptoms we will offer participants a course of VR over 12 weeks and assess whether this is associated with any improvement in symptoms.
Read the detailed description
Decompression sickness after diving can occur following a rapid ascent. Here, nitrogen, absorbed by the body when breathing compressed air at depth, comes out of solution and forms microbubbles in the blood. Inner ear decompression sickness (IEDS) accounts for approximately 20% of all cases of decompression sickness. The vestibular system is involved in ~85% cases of IEDS resulting in symptoms of vertigo, nausea, vomiting and unsteadiness with hearing loss and tinnitus.
The strong association of IEDS with a patent foramen ovale (50-73% of cases) suggests that a shunted venous gas embolism causes damage to the vestibular apparatus, which is particularly vulnerable due to its low perfusion and thus slow inert gas washout, compared to the cochlea and other brain structures. It is hypothesised that the nitrogen bubbles within the blood vessels trigger an inflammatory reaction in the endothelium with a coagulation cascade that leads to hypoxic injury and/or that there is direct damage to the membranous labyrinth. Animal models of rapid decompression suggest that it can cause a haemorrhage within the labyrinth with ectopic bone growth and fibrosis occurring over the next month. Advances in the imaging of the inner ear using a gadolinium-based contrast agent (GBCA) allow us to explore structural changes in human divers. Imaging can also help to differentially diagnose another potential cause of diving induced dizziness, superior structural dehiscence syndrome
Decompression sickness and the subsequent inflammatory response requires emergency treatment using with hyperbaric oxygen. The effects of hyperbaric therapy and rehabilitation are not uniform across participants, factors affecting recovery include a high clinical score on admission and a delay in hyperbaric recompression of over 6 hours. Complete recovery is seen in only about 30% of cases. Previous studies have highlighted that people who do not fully recover can have a variety of symptoms that can affect work, hobbies and well-being. These include feelings of instability in some situations (working at a height and with movement) and imbalance in the dark or when changing position.
In people with permanent vestibular pathology, symptoms can still improve due to central adaptive processes within the brain termed vestibular compensation. Clinical studies in other types of peripheral vestibular dysfunction show that it is possible to facilitate the compensation process and symptom recovery through vestibular rehabilitation. Early access to vestibular rehabilitation is now routine practice at the Diving Diseases Research Centre (DDRC) where patients are treated in the South-West UK. This is coupled to diagnosis and monitoring of vestibular function using objective laboratory tests (rotary testing) and clinical tests.
Animal studies highlight the mechanisms underlying vestibular compensation following a peripheral nerve lesion. These focus on changes in the interconnections between brainstem nuclei (e.g. vestibular nuclei) and the cerebellum and re-weighting of the relative importance of multi-sensory sensory inputs. Human studies in chronic peripheral dysfunction also suggest there are recovery-related changes in cortical areas that normally process vestibular information over time. Functional changes in the acute stages include an increase in contralesional activity in the parietoinsular vestibular cortex as well as interlinked subcortical areas (posterolateral thalamus, anterior cingulate gyrus, pontomesencephalic brainstem, hippocampus) with a decrease in activity was seen in the visual, somatosensory and auditory cortices. Structural changes over the first 3 months post lesion include increases in grey matter volume in the vestibular cortex, bilateral hippocampus, visual cortices and the cerebellum.
Within the DDRC vestibular rehabilitation has only been routinely undertaken for people diagnosed with IEDS since 2021. As complete recovery is seen in only about 30% of cases [9]; this suggests that there may be a cohort of patients with residual vestibular symptoms. In surveys of the aural and vestibular effects of diving, including those conducted by the DDRC, 79% (of 790 respondents) have reported aural related problems after learning to dive. Of those with reported problems 46% did not seek any medical advice and 39% specifically reported dizziness / vertigo. In total this suggests that at least 14% of all divers may have undiagnosed vestibular problems that could benefit from vestibular rehabilitation. A case review highlights that since 1999 there have been 79 cases of clinically diagnosed IEDS at the DDRC. Therefore, there is a need to assess and provide rehabilitation support to people with past IEDS and potentially in the future a larger cohort of divers with previously undiagnosed symptoms.
This study plans to:
undertake a prospective observational study where people with acute onset IEDS are followed up. This will include the current battery of clinical and laboratory (rotary) tests but also additional optional clinical and physiological testing (Vestibular Evoked Myogenic Potentials VEMPs), imaging (Diffusor Tensor Imaging DTI and functional Magnetic Resonance Imaging f MRI) and semis-structured interviews in the acute (1-14 days) and chronic (3 months and 12 months) stage.
We will also:
undertake a retrospective cross-sectional study of people who have previously been managed for IEDS by the DDRC. Here we will undertake the same battery of tests as for the prospective study which includes measures of potential risk factors and patient reported outcome measures. We will also take this opportunity to explore people's symptoms post IEDS and their views on future rehabilitation trials. In those with remaining vestibular symptoms and signs we will provide advice on vestibular rehabilitation by qualified personnel with follow up as required. We will compare our data to a cohort of healthy controls of a similar age and gender distribution.
- Conditions
- Decompression Sickness
- Keywords
- vestibular, inner ear
- Medical subject headings
- Decompression Sickness
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Prospective Cohort | Divers admitted with suspected IEDS | |
| Retrospective Cohort | Divers diagnosed with Inner ear decompression sickness (IEDS) at Deep Diving Research Centre within past 10 years |
What is being measured
The primary outcome is the main question the study is designed to answer.
Side of peripheral vestibular damage: Prospective cohort
Side (left or right) of vestibular dysfunction as determine by video head impulse test (v HIT) testing
Measured: T0=baseline within 24 hours of IEDS in the prospective cohort
Site of peripheral vestibular damage: Prospective cohort
Site of dysfunction: semi-circular canals affected as determine by v HIT testing. One or a combination of Horizontal, anterior or posterior canals.
Measured: T0=baseline within 24 hours of IEDS in the prospective cohort
Extent of peripheral vestibular damage: Prospective cohort
VOR gain (unit less) as measured by v HIT at T0 (Range 0-1 higher values are better outcome)
Measured: T0=baseline within 24 hours of IEDS in the prospective cohort
Side of peripheral vestibular damage: Retrospective cohort
Side (left or right) of vestibular dysfunction as determine by video head impulse test (v HIT) testing
Measured: 1 time point: 0-10 years post injury
Site of peripheral vestibular damage:Retrospective cohort
Site of dysfunction: semi-circular canals affected as determine by v HIT testing.One or a combination of Horizontal, anterior or posterior canals.
Measured: 1 time point: 0-10 years post injury
Extent of peripheral vestibular damage:Retrospective cohort
VOR gain (unit less) at T0 (Range 0-1 higher values are better outcome)
Measured: 1 time point: 0-10 years post injury
Secondary outcomes (21)
VOR gain v HIT: Prospective Study
Change from baseline (T0) in VOR gain assessed through V HIT test . Gain is unit less and range from 0-1 where higher values indicate a better clinical outcome.
Measured: 7-10 days , 3 months and 12 months post injury
VOR gain: Prospective Study
Change from baseline (T0) in VOR gain assessed through sinusoidal rotation in the dark . Gain is unit less and range from 0-1 where higher values indicate a better clinical outcome.
Measured: 7-10 days , 3 months and 12 months post injury
VOR Time constant:Prospective Study
Change from baseline (T0)in VOR time constant in response to a step rotation (initial 140°/s acceleration/deceleration and a 60°/s fixed-chair velocity) stimulus . Time constant (seconds) where a higher time constant is clinically better. Range 0-40s.
Measured: 7-10 days , 3 months and 12 months post injury
Patient reported outcome measure: Prospective Study
Change from baseline (T0) in PROM (patient reported outcome measure) vertigo severity scale.15 questions rated 0-4. Score range =0-60 where lower scores indicate a better clinical outcome
Measured: 7-10 days , 3 months and 12 months post injury
Clinical measure of walking: Prospective Study
Change from baseline (T0) in Dynamic Gait Assessment (DGA). Eight tasks scored 0-3. Total range = 0-24 with a higher score indicating better walking ability.
Measured: 7-10 days , 3 months and 12 months post injury
Clinical measure of balance: Prospective Study
Change from baseline (T0) in Clinical measures of balance sharpened Romberg (tandem stance). The length of time a person is able to stand in the eyes open, tandem stance position is recorded up to a maximum of 30 seconds.
Measured: 7-10 days , 3 months and 12 months post injury
Posturography: Prospective Study
Change from baseline (T0) in Postural sway quotient. Postural sway (mm/s) is measured via force plates. The ratio of the sway with eyes open and eyes closed is calculated (unitless ratio).
Measured: 7-10 days , 3 months and 12 months post injury
Perception of verticality: Prospective Study
Change from baseline (T0) in Rod and Disk test: The ability to orientate a line to vertical is assessed with / without visual distractors. The error from vertical is recorded in degrees. Outcomes range from 0-180 degrees where lower numbers indicate better verical perception.
Measured: 7-10 days , 3 months and 12 months post injury
Functional MRI response to an optokinetic stimulus: Prospective Study
Change from baseline (T0) in Regions of interest will also assess changes in activation with an optokinetic stimulus compared to rest in cortical and subcortical sites that process vestibular information namely the insulo-parietal cortex and hippocampus and sites that process other sensory information namely the visual cortex and somatosensory cortex
Measured: 7-10 days , 3 months and 12 months post injury
Vestibular Evoked myogenic Potentials latency: Prospective Study
Change from baseline (T0) in Galvanic and Auditory Vestibular Evoked myogenic Potentials (VEMPs) will be assessed and the latency of evoked responses measured in milliseconds.
Measured: 7-10 days , 3 months and 12 months post injury
Vestibular Evoked myogenic Potentials amplitude: Prospective Study
Change from baseline (T0) in Galvanic and Auditory Vestibular Evoked myogenic Potentials (VEMPs) will be assessed and the amplitude of evoked responses measured in millivolts.
Measured: 7-10 days , 3 months and 12 months post injury
VOR gain: Retrospective Study
VOR gain assessed through sinusoidal rotation in the dark . Gain is unit less and range from 0-1 where higher values indicate a better clinical outcome.
Measured: 7-10 days , 3 months and 12 months post injury
VOR Time constant: Retrospective Study
VOR time constant in response to a step rotation (initial 140°/s acceleration/deceleration and a 60°/s fixed-chair velocity) stimulus . Time constant (seconds) where a higher time constant is clinically better. Range 0-40s.
Measured: 1 time point: 0-10 years post injury
Patient reported outcome measure: Retrospective Study
PROM (patient reported outcome measure) vertigo severity scale.15 questions rated 0-4. Score range =0-60 where lower scores indicate a better clinical outcome
Measured: 1 time point: 0-10 years post injury
Clinical measure of walking: Retrospective Study
Dynamic Gait Assessment (DGA). Eight tasks scored 0-3. Total range = 0-24 with a higher score indicating better walking ability.
Measured: 1 time point: 0-10 years post injury
Clinical measure of balance: Retrospective Study
Clinical measures of balance sharpened Romberg (tandem stance). The length of time a person is able to stand in the eyes open, tandem stance position is recorded up to a maximum of 30 seconds.
Measured: 1 time point: 0-10 years post injury
Posturography: Retrospective Study
Postural sway quotient. Postural sway (mm/s) is measured via force plates. The ratio of the sway with eyes open and eyes closed is calculated (unitless ratio).
Measured: 1 time point: 0-10 years post injury
Perception of verticality: Retrospective Study
Rod and Disk test: The ability to orientate a line to vertical is assessed with / without visual distractors. The error from vertical is recorded in degrees. Outcomes range from 0-180 degrees where lower numbers indicate better verical perception.
Measured: 1 time point: 0-10 years post injury
Functional MRI response to an optokinetic stimulus: Retrospective Study
Regions of interest will also assess changes in activation with an optokinetic stimulus compared to rest in cortical and subcortical sites that process vestibular information namely the insulo-parietal cortex and hippocampus and sites that process other sensory information namely the visual cortex and somatosensory cortex
Measured: 1 time point: 0-10 years post injury
Vestibular Evoked myogenic Potentials latency: Retrospective Study
Galvanic and Auditory Vestibular Evoked myogenic Potentials (VEMPs) will be assessed and the latency of evoked responses measured in milliseconds.
Measured: 1 time point: 0-10 years post injury
Vestibular Evoked myogenic Potentials amplitude: Retrorospective Study
Galvanic and Auditory Vestibular Evoked myogenic Potentials (VEMPs) will be assessed and the amplitude of evoked responses measured in millivolts.
Measured: 1 time point: 0-10 years post injury
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Apr 2024
- Study startJun 2024 (estimated)
- Primary completionApr 2028 (estimated)
- Study completionSep 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (15)Papers the sponsor has linked to this study.
- Other trials for Decompression SicknessStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Other
- Enrolment
- 41 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Plymouth
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Jon Marsden, University of Plymouth
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06370897
- Sponsor's protocol ID
- 337421
- Status last verified
- May 2024
- First submitted
- 8 Apr 2024
- Last updated
- 13 May 2024
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Following study completion and publication of results anonymous data sets of clinical and laboratory outcome measures will be made available to other research teams on written request.
Publications
Gempp E, Louge P. Inner ear decompression sickness in scuba divers: a review of 115 cases. Eur Arch Otorhinolaryngol. 2013 May;270(6):1831-7. doi: 10.1007/s00405-012-2233-y. Epub 2012 Oct 26.
PubMed 23100085Tremolizzo L, Malpieri M, Ferrarese C, Appollonio I. Inner-ear decompression sickness: 'hubble-bubble' without brain trouble? Diving Hyperb Med. 2015 Jun;45(2):135-6.
PubMed 26165540Mitchell SJ, Doolette DJ. Pathophysiology of inner ear decompression sickness: potential role of the persistent foramen ovale. Diving Hyperb Med. 2015 Jun;45(2):105-10.
PubMed 26165533Landolt JP, Money KE, Topliff ED, Ackles KN, Johnson WH. Induced vestibular dysfunction in squirrel monkeys during rapid decompression. Acta Otolaryngol. 1980;90(1-2):125-9. doi: 10.3109/00016488009131707.
PubMed 6969520Landolt JP, Money KE, Topliff ED, Nicholas AD, Laufer J, Johnson WH. Pathophysiology of inner ear dysfunction in the squirrel monkey in rapid decompression. J Appl Physiol Respir Environ Exerc Physiol. 1980 Dec;49(6):1070-82. doi: 10.1152/jappl.1980.49.6.1070.
PubMed 6969248Kurata N, Kawashima Y, Ito T, Fujikawa T, Nishio A, Honda K, Kanai Y, Terasaki M, Endo I, Tsutsumi T. Advanced Magnetic Resonance Imaging Sheds Light on the Distinct Pathophysiology of Various Types of Acute Sensorineural Hearing Loss. Otol Neurotol. 2023 Aug 1;44(7):656-663. doi: 10.1097/MAO.0000000000003930. Epub 2023 Jun 29.
PubMed 37400150Song CI, Pogson JM, Andresen NS, Ward BK. MRI With Gadolinium as a Measure of Blood-Labyrinth Barrier Integrity in Patients With Inner Ear Symptoms: A Scoping Review. Front Neurol. 2021 May 20;12:662264. doi: 10.3389/fneur.2021.662264. eCollection 2021.
PubMed 34093410Vargas-Figueroa VM, Caceres-Chacon M, Labat EJ. Scuba Diving-Induced Inner-Ear Pathology: Imaging Findings of Superior Semicircular Canal and Tegmen Tympani Dehiscence. Am J Case Rep. 2024 Jan 2;25:e941558. doi: 10.12659/AJCR.941558.
PubMed 38163945Gempp E, Louge P, de Maistre S, Morvan JB, Vallee N, Blatteau JE. Initial Severity Scoring and Residual Deficit in Scuba Divers with Inner Ear Decompression Sickness. Aerosp Med Hum Perform. 2016 Aug;87(8):735-9. doi: 10.3357/AMHP.4535.2016.
PubMed 27634609Curthoys IS, Halmagyi GM. Vestibular compensation: a review of the oculomotor, neural, and clinical consequences of unilateral vestibular loss. J Vestib Res. 1995 Mar-Apr;5(2):67-107.
PubMed 7743004McDonnell MN, Hillier SL. Vestibular rehabilitation for unilateral peripheral vestibular dysfunction. Cochrane Database Syst Rev. 2015 Jan 13;1(1):CD005397. doi: 10.1002/14651858.CD005397.pub4.
PubMed 25581507Darlington CL, Smith PF. Molecular mechanisms of recovery from vestibular damage in mammals: recent advances. Prog Neurobiol. 2000 Oct;62(3):313-25. doi: 10.1016/s0301-0082(00)00002-2.
PubMed 10840152Bense S, Bartenstein P, Lochmann M, Schlindwein P, Brandt T, Dieterich M. Metabolic changes in vestibular and visual cortices in acute vestibular neuritis. Ann Neurol. 2004 Nov;56(5):624-30. doi: 10.1002/ana.20244.
PubMed 15449325Hong SK, Kim JH, Kim HJ, Lee HJ. Changes in the gray matter volume during compensation after vestibular neuritis: a longitudinal VBM study. Restor Neurol Neurosci. 2014;32(5):663-73. doi: 10.3233/RNN-140405.
PubMed 25096973Helmchen C, Klinkenstein J, Machner B, Rambold H, Mohr C, Sander T. Structural changes in the human brain following vestibular neuritis indicate central vestibular compensation. Ann N Y Acad Sci. 2009 May;1164:104-15. doi: 10.1111/j.1749-6632.2008.03745.x.
PubMed 19645887
Study at a glance
From the registry record, last updated by the sponsor on 13 May 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Prospective and Retrospective Observational Study of Symptoms and Mechanisms of Recovery in People With Inner Ear Decompression Sickness (IEDS)
- ClinicalTrials.gov ID
- NCT06370897
- Acronym / sponsor ID
- 337421
- Conditions
- Decompression Sickness
- Keywords
- vestibular, inner ear
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 41 participants (estimated)
- Lead sponsor
- University of PlymouthUniversity, hospital or other
- Study start
- Jun 2024 (estimated)
- Primary completion
- Apr 2028 (estimated)
- Study completion
- Sep 2028 (estimated)
- First posted
- 17 Apr 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Inner Ear Decompression sickness (IEDS) accounts for 20% of all types of decompression sickness (the bends) in divers. The condition commonly affects the peripheral vestibular system (inner ear). IEDS results in acute symptoms of dizzyness (vertigo) and imbalance. Even with the recommended treatment of hyperbaric oxygen therapy some people do not recovery fully. However, even in the presence of a permanent vestibular deficit many people can show a behavioural recovery where symptoms improve over time. Recovery can be aided by vestibular rehabilitation (VR) which is now routine for acute IEDS but was not provided before 2021, and is not widespread across the UK (United Kingdom) or world, meaning people may have a suboptimal recovery.
This project will investigate if and how people recover after an acute episode of IEDS and whether people who had IEDS in the past show changes in the central (brain) processing of vestibular function and in symptoms of dizziness, balance and posture.
This project has two main parts. Part one is a prospective observational study where people with an acute onset of IEDS are serially monitored while they are receiving hyperbaric treatment and VR over 10-14 days. Part two is a retrospective observational study where who have had IEDS in the past 15 years are re-assessed in a one-off session. The tests in both parts involve clinical tests and specialist eye movement recordings that assess vestibular function. We will also determine the site of any vestibular pathology by using selective stimulation of the vestibular end organ or nerve and assess whether there are any changes in how the structure and function of central vestibular pathways in the brain. In people with chronic IEDS with vestibular symptoms we will offer participants a course of VR over 12 weeks and assess whether this is associated with any improvement in symptoms.
Detailed description
Decompression sickness after diving can occur following a rapid ascent. Here, nitrogen, absorbed by the body when breathing compressed air at depth, comes out of solution and forms microbubbles in the blood. Inner ear decompression sickness (IEDS) accounts for approximately 20% of all cases of decompression sickness. The vestibular system is involved in ~85% cases of IEDS resulting in symptoms of vertigo, nausea, vomiting and unsteadiness with hearing loss and tinnitus.
The strong association of IEDS with a patent foramen ovale (50-73% of cases) suggests that a shunted venous gas embolism causes damage to the vestibular apparatus, which is particularly vulnerable due to its low perfusion and thus slow inert gas washout, compared to the cochlea and other brain structures. It is hypothesised that the nitrogen bubbles within the blood vessels trigger an inflammatory reaction in the endothelium with a coagulation cascade that leads to hypoxic injury and/or that there is direct damage to the membranous labyrinth. Animal models of rapid decompression suggest that it can cause a haemorrhage within the labyrinth with ectopic bone growth and fibrosis occurring over the next month. Advances in the imaging of the inner ear using a gadolinium-based contrast agent (GBCA) allow us to explore structural changes in human divers. Imaging can also help to differentially diagnose another potential cause of diving induced dizziness, superior structural dehiscence syndrome
Decompression sickness and the subsequent inflammatory response requires emergency treatment using with hyperbaric oxygen. The effects of hyperbaric therapy and rehabilitation are not uniform across participants, factors affecting recovery include a high clinical score on admission and a delay in hyperbaric recompression of over 6 hours. Complete recovery is seen in only about 30% of cases. Previous studies have highlighted that people who do not fully recover can have a variety of symptoms that can affect work, hobbies and well-being. These include feelings of instability in some situations (working at a height and with movement) and imbalance in the dark or when changing position.
In people with permanent vestibular pathology, symptoms can still improve due to central adaptive processes within the brain termed vestibular compensation. Clinical studies in other types of peripheral vestibular dysfunction show that it is possible to facilitate the compensation process and symptom recovery through vestibular rehabilitation. Early access to vestibular rehabilitation is now routine practice at the Diving Diseases Research Centre (DDRC) where patients are treated in the South-West UK. This is coupled to diagnosis and monitoring of vestibular function using objective laboratory tests (rotary testing) and clinical tests.
Animal studies highlight the mechanisms underlying vestibular compensation following a peripheral nerve lesion. These focus on changes in the interconnections between brainstem nuclei (e.g. vestibular nuclei) and the cerebellum and re-weighting of the relative importance of multi-sensory sensory inputs. Human studies in chronic peripheral dysfunction also suggest there are recovery-related changes in cortical areas that normally process vestibular information over time. Functional changes in the acute stages include an increase in contralesional activity in the parietoinsular vestibular cortex as well as interlinked subcortical areas (posterolateral thalamus, anterior cingulate gyrus, pontomesencephalic brainstem, hippocampus) with a decrease in activity was seen in the visual, somatosensory and auditory cortices. Structural changes over the first 3 months post lesion include increases in grey matter volume in the vestibular cortex, bilateral hippocampus, visual cortices and the cerebellum.
Within the DDRC vestibular rehabilitation has only been routinely undertaken for people diagnosed with IEDS since 2021. As complete recovery is seen in only about 30% of cases [9]; this suggests that there may be a cohort of patients with residual vestibular symptoms. In surveys of the aural and vestibular effects of diving, including those conducted by the DDRC, 79% (of 790 respondents) have reported aural related problems after learning to dive. Of those with reported problems 46% did not seek any medical advice and 39% specifically reported dizziness / vertigo. In total this suggests that at least 14% of all divers may have undiagnosed vestibular problems that could benefit from vestibular rehabilitation. A case review highlights that since 1999 there have been 79 cases of clinically diagnosed IEDS at the DDRC. Therefore, there is a need to assess and provide rehabilitation support to people with past IEDS and potentially in the future a larger cohort of divers with previously undiagnosed symptoms.
This study plans to:
undertake a prospective observational study where people with acute onset IEDS are followed up. This will include the current battery of clinical and laboratory (rotary) tests but also additional optional clinical and physiological testing (Vestibular Evoked Myogenic Potentials VEMPs), imaging (Diffusor Tensor Imaging DTI and functional Magnetic Resonance Imaging f MRI) and semis-structured interviews in the acute (1-14 days) and chronic (3 months and 12 months) stage.
We will also:
undertake a retrospective cross-sectional study of people who have previously been managed for IEDS by the DDRC. Here we will undertake the same battery of tests as for the prospective study which includes measures of potential risk factors and patient reported outcome measures. We will also take this opportunity to explore people's symptoms post IEDS and their views on future rehabilitation trials. In those with remaining vestibular symptoms and signs we will provide advice on vestibular rehabilitation by qualified personnel with follow up as required. We will compare our data to a cohort of healthy controls of a similar age and gender distribution.
Study design
- Observational model
- Cohort
- Time perspective
- Other
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Prospective Cohort | – | –Divers admitted with suspected IEDS |
| Retrospective Cohort | – | –Divers diagnosed with Inner ear decompression sickness (IEDS) at Deep Diving Research Centre within past 10 years |
Who may qualify
- Ages
- 18 to 85 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Population: Divers Exposure: Dive resulting in IEDS symptoms
Key inclusion criteria (3 listed)
- Divers admitted with suspected IEDS
- Divers diagnosed with IEDS at DDRC within past 10 years
- Adults over 18 years
Key exclusion criteria (7 listed)
- Medically unstable
- Unstable orthopaedic deficits
- We will include all co-morbidities as these could affect prognosis and recovery following IEDS.
- Normative data will be gathered on an age matched group. There will be at least 10 participants for each decade (<30yrs ,30-40yrs, 40-50 yrs,50-60yrs,60-70 yr.)
- Neurological, sensory or orthopaedic conditions that could affect balance.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Side of peripheral vestibular damage: Prospective cohort
Time frame: T0=baseline within 24 hours of IEDS in the prospective cohort
Side (left or right) of vestibular dysfunction as determine by video head impulse test (v HIT) testing
Site of peripheral vestibular damage: Prospective cohort
Time frame: T0=baseline within 24 hours of IEDS in the prospective cohort
Site of dysfunction: semi-circular canals affected as determine by v HIT testing. One or a combination of Horizontal, anterior or posterior canals.
Extent of peripheral vestibular damage: Prospective cohort
Time frame: T0=baseline within 24 hours of IEDS in the prospective cohort
VOR gain (unit less) as measured by v HIT at T0 (Range 0-1 higher values are better outcome)
Side of peripheral vestibular damage: Retrospective cohort
Time frame: 1 time point: 0-10 years post injury
Side (left or right) of vestibular dysfunction as determine by video head impulse test (v HIT) testing
Site of peripheral vestibular damage:Retrospective cohort
Time frame: 1 time point: 0-10 years post injury
Site of dysfunction: semi-circular canals affected as determine by v HIT testing.One or a combination of Horizontal, anterior or posterior canals.
Extent of peripheral vestibular damage:Retrospective cohort
Time frame: 1 time point: 0-10 years post injury
VOR gain (unit less) at T0 (Range 0-1 higher values are better outcome)
21 secondary outcomes
VOR gain v HIT: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
VOR gain: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
VOR Time constant:Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Patient reported outcome measure: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Clinical measure of walking: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Clinical measure of balance: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Posturography: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Perception of verticality: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Functional MRI response to an optokinetic stimulus: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Vestibular Evoked myogenic Potentials latency: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
Vestibular Evoked myogenic Potentials amplitude: Prospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
VOR gain: Retrospective Study
Time frame: 7-10 days , 3 months and 12 months post injury
VOR Time constant: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Patient reported outcome measure: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Clinical measure of walking: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Clinical measure of balance: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Posturography: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Perception of verticality: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Functional MRI response to an optokinetic stimulus: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Vestibular Evoked myogenic Potentials latency: Retrospective Study
Time frame: 1 time point: 0-10 years post injury
Vestibular Evoked myogenic Potentials amplitude: Retrorospective Study
Time frame: 1 time point: 0-10 years post injury
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 May 2024.
- Background: PubMed 23100085Gempp E, Louge P. Inner ear decompression sickness in scuba divers: a review of 115 cases. Eur Arch Otorhinolaryngol. 2013 May;270(6):1831-7. doi: 10.1007/s00405-012-2233-y. Epub 2012 Oct 26.
- Background: PubMed 26165540Tremolizzo L, Malpieri M, Ferrarese C, Appollonio I. Inner-ear decompression sickness: 'hubble-bubble' without brain trouble? Diving Hyperb Med. 2015 Jun;45(2):135-6.
- Background: PubMed 26165533Mitchell SJ, Doolette DJ. Pathophysiology of inner ear decompression sickness: potential role of the persistent foramen ovale. Diving Hyperb Med. 2015 Jun;45(2):105-10.
- Background: PubMed 6969520Landolt JP, Money KE, Topliff ED, Ackles KN, Johnson WH. Induced vestibular dysfunction in squirrel monkeys during rapid decompression. Acta Otolaryngol. 1980;90(1-2):125-9. doi: 10.3109/00016488009131707.
- Background: PubMed 6969248Landolt JP, Money KE, Topliff ED, Nicholas AD, Laufer J, Johnson WH. Pathophysiology of inner ear dysfunction in the squirrel monkey in rapid decompression. J Appl Physiol Respir Environ Exerc Physiol. 1980 Dec;49(6):1070-82. doi: 10.1152/jappl.1980.49.6.1070.
- Background: PubMed 37400150Kurata N, Kawashima Y, Ito T, Fujikawa T, Nishio A, Honda K, Kanai Y, Terasaki M, Endo I, Tsutsumi T. Advanced Magnetic Resonance Imaging Sheds Light on the Distinct Pathophysiology of Various Types of Acute Sensorineural Hearing Loss. Otol Neurotol. 2023 Aug 1;44(7):656-663. doi: 10.1097/MAO.0000000000003930. Epub 2023 Jun 29.
- Background: PubMed 34093410Song CI, Pogson JM, Andresen NS, Ward BK. MRI With Gadolinium as a Measure of Blood-Labyrinth Barrier Integrity in Patients With Inner Ear Symptoms: A Scoping Review. Front Neurol. 2021 May 20;12:662264. doi: 10.3389/fneur.2021.662264. eCollection 2021.
- Background: PubMed 38163945Vargas-Figueroa VM, Caceres-Chacon M, Labat EJ. Scuba Diving-Induced Inner-Ear Pathology: Imaging Findings of Superior Semicircular Canal and Tegmen Tympani Dehiscence. Am J Case Rep. 2024 Jan 2;25:e941558. doi: 10.12659/AJCR.941558.
- Background: PubMed 27634609Gempp E, Louge P, de Maistre S, Morvan JB, Vallee N, Blatteau JE. Initial Severity Scoring and Residual Deficit in Scuba Divers with Inner Ear Decompression Sickness. Aerosp Med Hum Perform. 2016 Aug;87(8):735-9. doi: 10.3357/AMHP.4535.2016.
- Background: PubMed 7743004Curthoys IS, Halmagyi GM. Vestibular compensation: a review of the oculomotor, neural, and clinical consequences of unilateral vestibular loss. J Vestib Res. 1995 Mar-Apr;5(2):67-107.
- Background: PubMed 25581507McDonnell MN, Hillier SL. Vestibular rehabilitation for unilateral peripheral vestibular dysfunction. Cochrane Database Syst Rev. 2015 Jan 13;1(1):CD005397. doi: 10.1002/14651858.CD005397.pub4.
- Background: PubMed 10840152Darlington CL, Smith PF. Molecular mechanisms of recovery from vestibular damage in mammals: recent advances. Prog Neurobiol. 2000 Oct;62(3):313-25. doi: 10.1016/s0301-0082(00)00002-2.
- Individual participant dataSharing planned: Yes. Following study completion and publication of results anonymous data sets of clinical and laboratory outcome measures will be made available to other research teams on written request.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
The record lists no contact. Use the official record to reach the sponsor.
Questions about this trial
What is this clinical trial studying?
An observational study of Decompression Sickness, run by University of Plymouth.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 13 May 2024. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Side of peripheral vestibular damage: Prospective cohort (time frame: T0=baseline within 24 hours of IEDS in the prospective cohort). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06370897, which also lists 15 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 May 2024.