Post-COVID-19 dizziness associated with a patulous eustachian tube

Summary

A frequently occurring symptom following COVID-19 is dizziness. Yet, the causes of post-COVID-19 dizziness are still largely unclear. This paper presents a case of a patient in his 40s who developed persistent dizziness after a SARS-CoV-2 infection. Dizziness only occurred during nasal respiration. Inspection of the tympanic membrane on respiration indicated a patulous eustachian tube (PET). Video-oculography showed a slight nystagmus during nasal respiration. Placement of a tympanostomy tube 6 months after the start of symptoms immediately resolved the dizziness, and nystagmus during nasal respiration was reduced. A few days after treatment, the patient developed ocular fatigue and pain associated with eye movement, which was diagnosed as vestibular asthenopia. These symptoms were largely resolved by subsequent treatment with vestibulo-visual rehabilitation. This case report indicates that post-COVID-19 dizziness can be associated with a PET, and in that case, it can be successfully treated by placement of a ventilation tube.

Background

A substantial subset of individuals infected with SARS-CoV-2 develop persistent, relapsing or new symptoms after infection. This postacute infection syndrome is referred to as long COVID or post-acute sequelae of COVID-19 (PASC). More than 200 long COVID symptoms have been documented, which can differ from person to person. A frequently occurring long COVID symptom is dizziness. Dizziness was first described as a common neurological symptom of acute COVID-19 in April 2020,¹ and subsequent studies indicated that approximately one-sixth of patients report this symptom.² In addition to being an acute COVID-19 symptom, dizziness is also a frequently occurring postacute symptom.³ Notably, in a study with 9764 long COVID patients, dizziness occurred in 62% of the cases and was identified as one of the hallmark symptoms that could be used for the development of a more specific long COVID disease definition.⁴

Similar to almost all other long COVID symptoms, the causes of post-COVID-19 dizziness are still largely unknown. Yet, for some other viral infections the cause of postinfection dizziness has been previously elucidated. Of particular interest for this case study is a previous case study of dizziness after an influenza infection.⁵ That report describes a patient who developed a one-sided patulous eustachian tube (PET) after influenza, which selectively caused nystagmus and dizziness during nasal respiration, but not when holding breath.⁵

In the present study, we encountered a patient who, after SARS-CoV-2 infection, developed similar symptoms, characterised by persistent dizziness on nasal respiration.

Case presentation

A male patient in his 40s developed persistent dizziness after having COVID-19 in March 2022 (dominant SARS-CoV-2 strain at that time in the Netherlands: Omicron BA subvariants). SARS-CoV-2 infection had been determined by qPCR by the Dutch Public Health Service. The patient suffered from mild symptoms such as fever for 3–4 days and did not require hospitalisation. The patient did not lose substantial weight during acute disease (weight loss is a known risk factor for the development of a PET⁶). Symptoms of dizziness had already emerged during the acute phase of the disease. He experienced vestibulo-visual symptoms during nasal breathing, especially during inspiration, which subsided when he held his breath and which were reduced when he switched to mouth breathing. No other triggers for dizziness were identified. There were no complaints of autophony or hearing other bodily sounds. While 1 week after infection all other COVID-19 symptoms subsided, the vestibulo-visual symptoms and mild sinusitis remained.

Investigations

4 weeks after infection, the patient went to the general practitioner, who excluded benign paroxysmal positional vertigo as a cause and provided nasal corticosteroids. Since symptoms did not subside, the patient was referred to the otorhinolaryngologist at the local hospital. A high-resolution CT scan demonstrated limited opacification of the maxillary sinuses, consistent with mild maxillary sinusitis. No abnormalities were seen of the inner ear and the bony confoundings of the semicircular canals were intact, for which the patient continued to use nasal corticosteroids. Audiometry was symmetrical and within normal range. MRI of the brain showed no aberrancies, but the neurologist at the local hospital observed a nystagmus (not further specified) and referred the patient for vestibular physiotherapy.

Since vestibular physiotherapy did not attenuate the dizziness, 6 months after infection, the patient was referred to our University Medical Centre. In the left ear, otomicroscopy showed medial and lateral excursions of the tympanic membrane during nasal breathing and in the same rhythm as the respiratory rate, which is pathognomonic for a PET. Vestibular assessment (using videonystagmography) showed no abnormalities on the Dix-Hallpike test, Supine roll test, Head impulse test, Smooth pursuit test and the Optokinetic nystagmus test. However, with the latter two tests, the patient became nauseous. There was no spontaneous nystagmus with fixation. Rotational testing (including fixation suppression) also showed no abnormalities. Caloric testing showed that both horizontal canals of the vestibular organ were functioning where there was an asymmetry in the response (left side 20% less responsive compared with right side), which was still within the normal range. Figure 1 shows both oral (figure 1a) and nasal (figure 1b) respiration, the eye movements in horizontal (red) and vertical (blue) direction are shown as a function of time. A slight nystagmus to the left is visible in both conditions of about 0.7°/s in size and frequency comparable with that reported in the case report of Kitajima et al.⁵ All measurements were carried out 1 hour before placement of the tympanostomy tube in the left ear. 1 hour after the placement, a subset of the vestibular tests was repeated. This time, no nausea occurred with the smooth pursuit test and the optokinetic nystagmus test. Figure 1 shows that the size of the nystagmus during both oral (figure 1c) and nasal (figure 1d) respiration was reduced to about 0.4°/s.

Figure 1. Nystagmus was reduced after placement of tympanostomy tube. Eye movements (degrees) as a function of time (seconds). The red line indicates horizontal eye movements and the blue line indicates vertical eye movements. Panel (a) and (b) display the eye movements before placement of a tympanostomy tube with oral and nasal respiration, respectively. Panel (c) and (d) display the eye movements directly after placement of a tympanostomy tube with oral and nasal respiration, respectively.

Differential diagnosis

Dizziness following a SARS-CoV-2 infection can arise from a variety of causes. Dizziness is a frequently described symptom of long COVID, but is usually one of the multiple symptoms and is rarely seen as the sole symptom of long COVID. Dysautonomia, including postural orthostatic tachycardia syndrome (POTS), can lead to dizziness on standing due to abnormal heart rate and blood pressure regulation, but the patient did not experience any POTS symptoms, and dizziness occurred irrespective of standing up or sitting.

Common causes of dizziness, such as benign paroxysmal positional vertigo and vestibular neuronitis, have already been excluded by medical history and examination. Medication side effects can sometimes also induce dizziness, but this seemed unlikely to be induced by nasal corticosteroids, also because dizziness presented weeks before the patient started taking medication. A CT scan ruled out the presence of a third window anomaly, and the patient’s symptoms were not consistent with those typically associated with third window syndromes such as superior semicircular canal dehiscence. Also, there were no signs of a perilymphatic fistula, except for the dizziness that was associated with changes in middle ear pressure.

A potential cause of dizziness in this patient came from the diagnosed PET and the observation that dizziness was only present on nasal respiration. The highly specific presentation of vestibulo-visual symptoms triggered by nasal respiration, but not by oral respiration or breath-holding, made this case stand out as a unique set of complaints, with the exception of the previously mentioned case report.⁵

Treatment

6 months after the start of the symptoms, we placed a tympanostomy tube to nullify movement of the tympanic membrane on nasal respiration. The ventilation tube immediately resolved patient-reported dizziness. In addition, nystagmus was reduced in size (figure 1).

In the days following the initial treatment, the patient developed ocular fatigue and pain associated with eye movement. These symptoms frequently occur after a period of vestibular dysfunction. The disorder results from inadequate integration of afferent visual and vestibular input and is known as vestibular asthenopia.⁷ These symptoms were largely resolved by subsequent treatment with vestibulo-visual rehabilitation as previously described,^{7 8} which was executed between 9 and 17 months after the start of symptoms. Several eye movement parameters strongly improved. For vergence movements, progress was recorded in terms of latency, regularity and endurance. For saccades, progress was recorded in terms of latency and conjugation (figure 2).

Figure 2. Vestibular asthenopia was successfully treated by vestibulo-visual rehabilitation. (A) Pretreatment: the patient showed very high latency for both convergence and divergence. (B) After treatment by vestibulo-visual rehabilitation (5 treatments in 3 days with REMOBI & AIDEAL double step) latency was within normal range for divergence and strongly reduced for convergence. The kinetics of vergence movements were much more regular and enduring after treatment. (C) Saccades have generally correct latencies, amplitudes and speeds, but show a high rate of dysconjugation before treatment. (D) The saccades are much more regular after treatment and no longer show dysconjugation.

Outcome and follow-up

When the patient suffered from dizziness during the 6 months between start of symptoms and the placement of the ventilation tube, he had to work from home due to his complaints. He resumed his work on location directly after placement of the tube, but had difficulties working with computer screens. Working with computer screens strongly improved after the orthoptic vestibulo-visual exercises and he no longer experiences limitations for working.

The ventilation tube spontaneously released from the tympanic membrane after 20 months, which was accompanied by some bleeding. Inspection of the tympanic membrane on nasal respiration no longer showed fluctuations in the left ear, indicating spontaneous remission of the PET.

2 weeks after the release of the ventilation tube (December 2023), the patient got reinfected with SARS-CoV-2, but did not re-develop symptoms of dizziness.

Discussion

Similar to most long COVID symptoms, the causes of post-COVID-19 dizziness are still largely unknown. Research into the cause of post-COVID-19 dizziness is difficult because in patients it is often accompanied by a plethora of other symptoms, such as post-exertional malaise, POTS, palpitations and pain,^{4 9} all of which can themselves be linked to dizziness. The vestibular system, responsible for balance and spatial orientation, is a complex network integrating peripheral components—such as the inner ear structures—with central neural pathways in the brainstem, cerebellum and cerebral cortex. Disruption to any part of this system can lead to dizziness, vertigo or imbalance. It is likely that post-COVID-19 dizziness can stem from multiple underlying pathological processes. In this particular case report, dizziness was the only symptom, making it less likely to be a consequence of a complex syndrome. Although cases like these are rare, they could provide new insights into the pathophysiology of dizziness in postacute infection syndromes. Postinfection dizziness associated with a PET has been previously described by Kitajima et al.⁵ The current case report shows many similarities with this previous report from 2016. In both cases, dizziness was associated with a PET and triggered by a viral infection in a man around the age of 40 in the absence of any other symptoms. Similarly, dizziness specifically occurred during nasal respiration, coinciding with nystagmus. These findings suggest that influenza and SARS-CoV-2 can similarly contribute to the development of postinfection dizziness.

Although dizziness triggered by both SARS-CoV-2 and influenza coincided with a PET, the underlying mechanism of this is still unclear. In many cases, a PET is asymptomatic. Therefore, the vestibulo-visual symptoms observed in these patients likely involve an additional mechanism, where changes in middle ear pressure stimulate the vestibular system, leading to dizziness. If symptoms occur in the case of a PET, they usually involve autophony, hearing problems and/or tinnitus, but not dizziness.¹⁰ Previously, several possible mechanisms have been proposed to explain how a PET can affect inner ear function.⁵ For example, movement of the tympanic membrane could move the oval window, thereby affecting the inner ear via the ossicular chain.¹¹ In addition, pressure changes transmitted through the eustachian tube could be directly transferred to the thin round window membrane, which in turn affects the inner ear.⁵ However, if this were true, all people with a PET would experience vestibulo-visual symptoms on respiration.

Alternatively, the PET may have been present prior to the COVID-19 infection, with the infection introducing an additional mechanism that triggered the vestibulo-visual symptoms. In this scenario, the PET could be part of a cascade leading to these symptoms. While COVID-19 can affect the upper respiratory tract and induce mucosal swelling, it is less likely to directly cause the development of a PET. Upper respiratory tract infections (URTIs) typically do not result in mucosal atrophy, which is a potential cause of PET, and there is no established association between URTIs and PET. It is possible, however, that the inflammatory response caused by COVID-19 induced endolymphatic hydrops, thereby increasing the sensitivity of the vestibular system to changes in middle ear pressure and contributing to the dizziness. Nevertheless, the patient exhibited no other symptoms of endolymphatic hydrops, and no established link between Ménière’s disease and COVID-19 has been reported. Finally, a potential explanation for the induced dizziness could be stapes hypermobility.¹² Movement of the tympanic membrane on nasal respiration could allow a hypermobile stapes to transmit abnormal pressure changes from the middle ear to the inner ear fluids, disrupting the normal fluid dynamics and causing vestibular symptoms. A limitation of this study is that we could not ascertain that the PET was absent prior to SARS-CoV-2 infection. PET is frequently asymptomatic, and therefore it could have already been present before the symptoms occurred.

Following the placement of a tympanostomy tube, the patient’s dizziness resolved immediately. While multiple studies have documented improvement of aural symptoms following tympanostomy tube insertion,13,15 the effect on specific PET-related symptoms was not detailed. A meta-analysis of these studies showed a 58% improvement in aural symptoms, while complications were rare.¹⁶ Specifically in patients with the sniff-type PET, tympanostomy tube placement can cause (transient) hyperacusis.^{13 15} However, vestibulo-visual symptoms, such as dizziness provoked by nasal respiration, have not been addressed in previous literature.

Although dizziness resolved after tube insertion, the patient subsequently developed vestibular asthenopia.⁷ Vestibular asthenopia is in many ways similar to the concepts of persistent postural-perceptual dizziness, visual vertigo or visual hyper-dependence, as it combines a set of highly visual symptoms resulting from an initial vestibular disorder, which can be explained by mechanisms that are currently well described.¹⁷ The vestibular disorder, which is the starting point of the pathophysiological process, triggers a series of cascading consequences in the processing of the visual signal from the retina to the integrative level. These consequences penalise binocularity, the quality of fixation, the kinetics of eye movements and the comfort of harmonious functional vision. They lead to visual fatigue, headaches, painful fixation, increased sensitivity to retinal slip, photophobia, neuro-vegetative reactions, reduced concentration and cognitive problems. The main explanation lies in the fact that the central weighting between the parvocellular and magnocellular visual pathways is no longer balanced; the magnocellular pathway becomes predominant to the detriment of the parvocellular pathway. This poor processing of the visual signal seems to persist over time if no specific treatment is offered. Fortunately, vestibulo-visual rehabilitation can largely resolve these problems.⁸

This reported case indicates that dizziness following COVID-19 infection can be related to PET dysfunction. While this is unlikely to explain the majority of cases of post-COVID-19 dizziness, where dizziness is often just one of many symptoms, it may provide an explanation for other post-COVID-19 cases in which dizziness is the only symptom. A PET is relatively easy to diagnose in suspected post-COVID-19 patients by assessing movement of the tympanic membrane on nasal respiration. Moreover, treatment is straightforward by placement of a tympanostomy tube. Yet, if the patient is treated long after onset, vestibular asthenopia can occur, which should be treated with specialised vestibulo-visual rehabilitation.

Patient’s perspective.

For me as a patient it was initially difficult to find proper medical care. I felt that knowledge on post-COVID symptoms was lacking, both for the GP and the doctors in the local hospital. When tests and examinations showed no aberrations they even told me ‘congratulations, you are healthy’. Looking back, I can identify three critical factors that ultimately led to identification and successful treatment of my symptoms. The first factor is perseverance, since I continued seeking medical care as long as I had symptoms, which was only possible because my symptoms were not completely debilitating. The second factor is my biomedical background that allowed me to identify potential causes in the medical literature myself, which ultimately I did. This critically depended on the existence of previous publications on dizziness and vestibular asthenopia, since without these precedents we probably would not have been able to discover this ourselves. The third factor is that because of my work I had access to doctors in academic and international hospitals, which were motivated to identify the unknown causes of my symptoms. While I have suffered from these symptoms for over a year, I realise full well that I was privileged by my biomedical background and access to academic medical care, which is something that many patients have to do without. As a patient, this health inequality concerns me, and is something that I hope will be addressed in the future.

Learning points.

• COVID-19 can trigger dizziness on nasal respiration associated with patulous eustachian tube (PET) dysfunction.

• Dizziness in patients with a PET, which selectively occurs during nasal respiration, can effectively be treated by placement of a tympanostomy tube.

• Delayed treatment with a tympanostomy tube can induce vestibular asthenopia, which can be treated with vestibulo-visual rehabilitation.