Pseudo-psychiatric symptoms of superior semicircular canal dehiscence syndrome

To the editor:

The superior semicircular canal dehiscence was first described by Minor et al¹ in 1998 as a condition in which the superior semicircular canal lacks a bony covering and has gained constantly increasing interest since its discovery.² The symptoms are varied but specific what is known as Minor syndrome or ‘third mobile window’ syndrome,³ as patients may experience autophony with abnormally loud sounds like footsteps, chewing, breathing, eye movement, echoing voice, distortion of environmental sounds and pulsatile tinnitus.

Based on radiologic temporal bone studies, the prevalence of superior semicircular canal dehiscence would reach approximately 0.8%.⁴ This high anatomical prevalence contrasts with the small number of patients referred to the ear, nose and throat (ENT) specialist. A large proportion of these anatomical dehiscence cases may remain asymptomatic. However, a significant proportion of patients may not be properly diagnosed even though they are symptomatic. Symptoms like tinnitus, autophony and hyperacusis in superior semicircular canal dehiscence may prompt patients to consult a psychiatrist and may be misinterpreted as psychiatric symptoms, such as auditory hallucinations.⁵ As in other somatic conditions, these symptoms can lead to a misdiagnosis of psychotic disorder, resulting in unnecessary prescription of antipsychotic medication and associated adverse effects.⁶ Patients may endure this for years before receiving an accurate diagnosis from an ENT specialist.^{7 8}

Patient testimonies from the French Minor Syndrome Association highlight the lack of knowledge among healthcare professionals, which often leads to misdiagnosis.⁹ Therefore, we urge psychiatrists to consider Minor syndrome when encountering patients with atypical symptoms associated with anxiety, depression or psychotic-like symptoms. In such cases, it is important to inquire about symptoms of ‘third mobile window’ syndrome, such as hyperacusis to bone-conducted sound, sound-induced or pressure-induced vertigo or pulsatile tinnitus. Patients presenting with any of these symptoms should be referred to an ENT specialist.¹⁰

Beyond the need for psychiatric differential diagnoses, comorbid psychiatric conditions can develop as Minor syndrome progresses. Similar to other somatic conditions that impair quality of life, delayed diagnosis and inadequate treatment can lead to depression and even suicidality.⁵

A recent retrospective case–control study of a cohort of 210 patients with Minor syndrome revealed significantly higher rates of anxiety disorders (31.4%) and depressive disorders (22.9%) compared with controls.¹¹ Furthermore, members of the French Minor Syndrome Association reported that the impact of their symptoms, once diagnosed, prompted them to consult a psychiatrist.⁹ They developed anxiety, distress and depression due to the daily presence of these symptoms, resulting in lifestyle changes, such as avoiding sports, avoiding noisy places and reducing speech.

Patient testimonials from the French Minor Syndrome Association underscore the disabling nature of these symptoms. For example, one patient had to stop dancing because the sound of her heels echoed in her skull, another had to quit his job as a truck driver due to sound sensitivity and a third stopped attending rock concerts for the same reason. Additionally, one patient reported an increase in pulsatile tinnitus following sexual intercourse. These testimonials highlight how these symptoms can be pervasive in patients’ daily lives and impact their quality of life. The association also conducted a survey to collect descriptive statistics about the syndrome’s impact. Among 110 respondents, 18.2% reported suicidal thoughts due to the symptomatic impact of the syndrome. The association’s board members also reported that two members took their own lives in recent years.

Early diagnosis is critical to mitigate the psychological and psychiatric burden of Minor syndrome. Recent data also suggests that proactive psychological and psychiatric support can reduce distress in populations with chronic, debilitating organic conditions.^{12 13} Moreover, there is evidence supporting that surgical treatment for Minor syndrome can alleviate both its specific symptoms and associated depressive symptoms and other neurobehavioural functional impairments.¹⁴

The primary objective of this letter is to raise awareness of the superior semicircular canal dehiscence syndrome within the psychiatric community, as these patients often experience medical uncertainty⁷ and may, in their search for answers, be referred to a psychiatrist. Additionally, patients with Minor syndrome require close monitoring due to their increased risk of developing psychiatric conditions such as depression and suicidality.^{5 9 11}

Apart from the previously mentioned case report and some testimonies, this issue has not yet been studied in this field. Investigating psychiatric diagnosis, psychoactive medication use and psychological symptoms in a prospective cohort of patients with superior semicircular canal dehiscence could provide valuable insights. Such research could help elucidate the mechanism underlying the association between superior semicircular canal dehiscence and psychiatric complications, identify risk factors and explore strategies to mitigate the psychological impact of the syndrome.

Biography

Quentin Legois, MSc, is a physiotherapist specialising in vestibular rehabilitation. He graduated from HELD (Haute École Libre de Bruxelles) in 2019 and has been working in the ENT department of Pr. Deguine, MD. PhD at the Toulouse University Hospital in France since 2022. After obtaining his Master’s degree in Neurosciences at UCL (Université Catholique de Louvain, Belgium), he is now a PhD student in Neurosciences at Toulouse Paul Sabatier University under the supervision of Prof. Mathieu Marx, MD. PhD, an oto-neurosurgeon. His PhD research focuses on an affection of the inner ear called superior semicircular canal dehiscence syndrome, with a particular emphasis on the role of electrophysiological tests in evaluating the symptomatic impact. His dissertation is titled “The Interest of Electrophysiological Explorations in Assessing the Symptomatic Impact of Superior Semicircular Canal Dehiscence”. He is affiliated with Toulouse Paul Sabatier University and the CerCo research laboratory (UMR5549). In addition to this objective work, he is also investigating the atypical symptoms of this syndrome, which can resemble those of psychiatric disorders. In collaboration with Valentin Raymond, MD, he plans to explore this aspect experimentally in future studies. Their aim is to highlight the pseudo-psychiatric symptoms of the syndrome, as well as its psychological impact on patients, including depression and suicide attempts.