01/10/2025
Finding subsets and multidisciplinary approaches – lessons from the Australian experience.
For many decades, the scientific community has known MD is an expression of a family of disorders of distinct subsets, with a common pathologic substrate of endolymphatic hydrops, a dilation of parts of the space occupied by seemingly too much endolymph.
The main pathologic feature compared to non MD controls is ultrastructural damage to the endolymphatic sac and duct. Animal models, despite limitations, can replicate symptoms with a similar pathology seen in humans. But hydrops in and of itself does not imply a diagnoses as the movement, production, absorption, composition and volume of endolymph is a dynamic, not a static process.
The idea that subsets initiate and lead to chronic hydrops might seem revolutionary, but it’s not, nor is it radical or novel. Since 1920s, it’s been known inner ears are affected in dyslipidosis, atopy, altered metabolism, failure of pneumatisation of the temporal bone, the absence, narrowing or enlargement of the vestibular aqueduct, stenosis of auditory meatus and/or can be secondary to immunological, vascular and infectious processes and can be otosclerotic, drug and injury induced and much more. The complexity of the inner ear and MD’s symptom variability, heterogeneity, multifactorial and individual nature means one mechanism initiating hydrops in one person is rarely exactly same as the next. Despite all that’s known, this subset idea has yet to find widespread use in the global clinic. In fact, new technology and other surgical or medical “breakthroughs” in MD has never been limited to simplistic answers or one size fits all.
Doctor Wilmot noted in his early 1980s book on “MD and its management” referring to Harrison and Naftalin’s 1968 book of MD, “…it takes twenty years of study to have a basic understanding of MD.” Wilmot said, “…the problem is something akin to backache where a few cases are due to genuine disc pathology requiring expert diagnosis and treatment but in which the vast majority are due to a multiplicity of factors that each need careful assessment and evaluation. Those who believe all backache is due to disk involvement are as incorrect as those who believe that all patients with deafness tinnitus and vertigo have MD; similarly those who deny the existence of MD as an entity are as incorrect as those who are reluctant to believe in genuine disc pathology…it would appear therefore that the frequent and repeated failure of each new approach [surgical or otherwise] is due to a misunderstanding of the basic causes of the condition [in any one individual].
In 1995, the Australian federal government created a special task force of medical experts to develop a Statement of Principles (SoP) for MD. A SoP acts like a legal definition that helps determine who qualifies for medical test, benefits, disability pensions, and insurance claims, guiding interested doctors making diagnoses and recommending appropriate tests and treatments based upon the latest research for personal and individual diagnoses and treatments.
Professor Lindsay Wing was head of ENT at Hobart Royal Hospital for three decades. At Sydney University, taught ENTs anatomy and about subsets in MD which he first published in 1979. He used a unique method of taking a sample of mucus and blood and measuring immunological and cytokine bio-markers. Now, in 2025, subset approaches with additional genetics are being re-discovered and will hopefully re-emerge for today’s personal and individual diagnoses and treatments.
