Clinical Pearls from an Unusual Case of Vertigo

Case Study: Cough-Induced Vertigo

Dr. Esmonde: Alright, let’s dive into your slides. There’s no need to reinvent the wheel. Your patient case is wonderfully described in the article. It’s about a 76-year-old male with a seven-month history of vertigo, particularly triggered by coughing and lasting about a minute. He also experienced milder dizziness when bending forward, sitting up from lying down, and moving his head around, which lasted only seconds. He reported horizontal oscillopsia, which most people describe as double vision, during these episodes. He didn’t report any prolonged symptoms, which we usually associate with migraine or Meniere’s. Did I capture that correctly?

Dr. Walter: Yes, that’s correct. He didn’t have diplopia. With coughing, he’d experience oscillopsia, feeling like his visual world would take off. He felt unstable but had no diplopia. Any general activity caused some imbalance, but coughing specifically triggered strong vertigo attacks.

Dr. Esmonde: Understood. And you also reported no history of falls, no other positional vertigo except what’s described, no acute hearing loss, no tinnitus, and autophony. We’re listening for pattern recognition here, right, Dr. Walter?

Dr. Walter: Exactly. He had symptoms of superior canal dehiscence but mainly cough-induced dizziness, which makes that less likely. It’s important to ask patients about cochlear involvement. In his case, there was no associated acute hearing loss or tinnitus with his dizziness. We should also ask about fullness, autophony, ear pain, infection, and otorrhea (discharge from the ear). In vestibular therapy, it’s crucial to ask about the health of the cochlea to help with differential diagnosis.

Dr. Esmonde: Right, since they are closely related. The patient had seen physical therapists who didn’t feel they could help with vestibular rehab and were concerned about possible superior canal dehiscence, considering imaging. Can you talk through that?

Dr. Walter: Yes, this was an outside therapist, not part of our team. The main concern was the patient experiencing vertigo when coughing, so vestibular rehab didn’t seem helpful. One of the initial thoughts was superior canal dehiscence. For imaging, you want a temporal bone CT with very fine cuts. An MRI of the brain can suggest dehiscence but isn’t as good as CT for bony defects. Unfortunately, the primary care initially ordered an MRI, which wasn’t optimal. The MRI suggested no canal dehiscence but mentioned getting a temporal bone CT if it was a chief concern. The MRI report was normal, but we didn’t see the actual image, just the report.

Dr. Esmonde: Could this MRI have shown something like a vestibular schwannoma, or would it need to be ordered differently?

Dr. Walter: This MRI was ordered to visualize a vestibular schwannoma optimally. You need contrast for this. Many ER patients with vertigo get MRIs without contrast, which isn’t sensitive for schwannomas. The MRI should focus on the internal auditory canal (IAC). An IAC-focused MRI gives more concentrated images near the eighth nerve, which is crucial for schwannomas. In this case, the MRI was ordered correctly but didn’t show anything abnormal.

Dr. Esmonde: Got it. Sometimes reconciling image reports with clinical findings can be challenging, especially when suspecting cerebellar degeneration. The MRI might be normal, but clinical findings suggest otherwise. It can be difficult.

Dr. Walter: Absolutely. A good vestibular exam can sometimes be more sensitive than an MRI. MRIs are not always the definitive answer. I’ve had cases where the MRI missed central involvement initially, but my assessment picked it up. New tools like infrared goggles give us more insight into the patient’s nervous and vestibular systems, sometimes capturing impairments before imaging can.

Dr. Esmonde: Agreed. We must balance our assessments and use our best judgment. Speaking of imaging, can you elaborate on the follow-up CT?

Dr. Walter: We had a follow-up CT of the temporal bone, which we trust more for ruling in or out superior canal dehiscence. It was read as normal. This is important because CTs underread bone. If bone is present, the patient doesn’t have the disorder. However, close to 10% of CTs on non-dizzy individuals can look like canal dehiscence. A normal CT rules out the disorder, but if the CT suggests dehiscence, we need the right history and special tests to confirm. In this case, the CT ruled it out.

Dr. Esmonde: Right, if someone has clear signs of posterior canal BPPV and treatment resolves their dizziness, even if imaging suggests dehiscence, I wouldn’t counsel them to see a surgeon. We must consider the entire picture. Is that your stance?

Dr. Walter: Exactly. If the history doesn’t fit, and symptoms aren’t bothersome enough to consider surgery, we shouldn’t rush into it. Superior canal dehiscence surgery involves significant procedures, like brain lifting. If patients aren’t willing to undergo such treatment, they might not need a detailed workup unless they want a specific diagnosis.

Dr. Esmonde: Benefits versus risks. We always have to keep that in mind, for sure. All right, so then the patient saw a neuro-ophthalmologist. Can you briefly speak to that?

Dr. Walter: Yeah, he saw a neuro-ophthalmologist in our system that we work with a lot. He couldn’t find a central cause for the patient’s complaints. So, a central workup was not yielding any results. He still thought it could be superior canal dehiscence, even though the imaging didn’t show it, but we talked about that being a possibility. He referred the patient to us at that point for further investigation, suspecting it was not from central nervous system disease.

Dr. Esmonde: Got it. All right. So, here we have a report. Do you want to talk through this?

Dr. Walter: Yeah. So, this is an audiogram. It’s a test we frequently do at our balance center. It’s very common unless the patient has straightforward BPPV, where it might not be necessary. This test screens a patient’s auditory function. On the viewer’s left is the right ear plotted in red with round symbols. Remember your Rs. On your right is the left ear plotted. The solid line going across horizontally is a normative line. You can see this patient’s hearing is not normal at almost every frequency, indicating a mild to moderate sensory neural hearing loss. The first term indicates hearing performance in the low frequencies, and the second term indicates hearing performance in the high frequencies. For example, a note might say hearing is normal to profound loss on the right side, which means hearing in low frequencies is in the normative range, but in high frequencies, there is a profound loss. The hearing loss shown here is very common for someone who is 76, gradually worsening in the higher frequencies. His word recognition scores at the bottom of the report were not asymmetric. So, he has hearing loss, but it doesn’t appear to be in a disease-related pattern.

With superior canal dehiscence, air scores are diminished because sound waves entering the ear split, with some going through the dehiscence, resulting in reduced sensitivity to sounds in the environment. Bone scores can be superhuman, meaning the patient hears exceptionally well when the skull is vibrated but not environmental sounds. We look for this split in superior canal dehiscence cases, and it’s not present in this patient, further affirming it’s unlikely to be superior canal dehiscence.

Dr. Esmonde: Not looking like it. All right, so we had some calorics here. Can you summarize this?

Dr. Walter: Sure. Calorics should usually be done with water to minimize technical errors. This subject had a substantial right-side caloric weakness. When we do a caloric test, we indirectly heat or cool the fluid in the horizontal semicircular canal, causing excitation or inhibition. We measure the velocity of the slow phase of their nystagmus, reflecting vestibular function. This patient had a 51% weakness on his right side, well above the normal limit, indicating reduced function on the right side.

Dr. Esmonde: And this is testing the horizontal canal, correct?

Dr. Walter: Absolutely, and the superior vestibular nerve. It shows you’re not getting a great signal from that canal and nerve to the brainstem, indicating hypofunction.

Dr. Esmonde: There we go. 51% weaker, as you said. Perfect. So, outside VNG completed, 20% asymmetry reported.

Dr. Walter: The teaching point is similar tests are often not done with high quality. Our caloric was done not long after that one, but we were suspicious of the tracings’ quality, so we repeated it. It’s frustrating because what’s worse than no information is wrong information. Sometimes we have to repeat testing on patients.

Dr. Esmonde: Right, that’s tough. All right, VEMPS, not attainable.

Dr. Walter: It’s unusual, but in some geriatric subjects, especially those with a lot of adipose tissue in the neck or trouble holding their head up, we sometimes can’t attain responses. This testing is helpful to identify superior canal dehiscence, where patients almost always have abnormal VEMP testing, which this patient did not.

Dr. Esmonde: Got it. So, they did look at some ear situations. Anything revealing here or normal?

Dr. Walter: This reinforces what we saw in the audiogram. His Weber test was normal, implying grossly symmetric hearing without conductive loss. A simple test for superior canal dehiscence is the Weber test, where a tuning fork is placed on the external ear and then the mastoid. Patients with superior canal dehiscence will hear bone better than air. In a normal ear, air is heard better than bone. Another test is placing a tuning fork on the great toe or patella, and the vibration often emanates to the involved ear with superior canal dehiscence.

Dr. Esmonde: Right. I always tell patients to see an ENT for a full workup. If I’m wrong, fine.

Dr. Walter: If you don’t have a tuning fork, have your patient hum. If a patient with right-side hearing loss hums and feels it emanates to the side with hearing loss, they probably have a conductive loss. If it emanates to the contralateral ear, they likely have a sensorineural loss. It’s a useful telemedicine tip.

Dr. Esmonde: Awesome tips. All right, other exams. Ocular motor looks good. They had a horizontal nystagmus in the dark or with visual fixation removed. Can you review this?

Dr. Walter: Sure. This patient had left-beating nystagmus without fixation, regardless of gaze direction. It was third-degree nystagmus, meaning it was present in all three positions: left, center, and right gaze. This indicates a peripheral issue because it’s unidirectional and only present with fixation denied. Nystagmus typically beats towards the more neural active ear. This, combined with caloric testing, indicates right-side hypofunction.

Dr. Esmonde: Indeed, good. Same with the mastoid vibration. We won’t dig into that today, but it’s a great way to get more information. Using a tool that vibrates at 100 Hz behind the mastoid can induce nystagmus. It’s a useful but not standalone test.

Dr. Walter: This isn’t our case, but normal mastoid vibration usually shows left beats on the left side and right beats on the right side. This is an example of normal mastoid vibration, similar to a warm water caloric test.

Dr. Esmonde: Go ahead, tell us about this one, Dr. Walter.

Dr. Walter: In this subject with unilateral vestibular loss, the vibration induces left beats on both sides, indicating right-side vestibular loss. This quick test requires minimal equipment but is reliable. Our subject failed this test, supporting the diagnosis of unilateral vestibular loss.

Dr. Esmonde: Indeed, good point. You just discussed mastoid vibration. I’d love to do a whole journal club on this because I think it has great value. While it doesn’t provide all the answers, that’s true of almost any test, so I’m fine with that. I appreciate having more information, especially objective data. Patient reports can be very helpful, but sometimes they aren’t due to various reasons like inconsistent feelings or language barriers.

Dr. Walter: One quick point on this test that makes it helpful for clinicians to realize: if you had vestibular hypofunction in 1978 or last week, you’ll flunk it either way. It’s a defect that, as long as the hypofunction is there, doesn’t go away over time. Even though a patient can functionally compensate from a unilateral vestibular loss and feel like they’re functioning better, this test will often remain abnormal throughout their life. It’s not like spontaneous nystagmus, which can diminish over time from a unilateral loss; abnormal mastoid vibration doesn’t resolve over time.

Dr. Esmonde: And the horizontal head shake test can resolve in a good percentage of folks as well.

Dr. Walter: Yes, the impulse test looks a lot better over time too, as patients learn to compensate because they have covert saccades in their head movements. Patients have various ways of hiding their defect from the clinician, but here’s the key with mastoid vibration.

Dr. Esmonde: Knowing that it’s old helps me. Even if it turns out they have something else, I’m not surprised. For instance, if they end up with BPPV on that side more often or have persistent postural perceptual dizziness, I suspect it could have been kicked off by this. We’re looking at different concurrent issues that could contribute to the problem.

With balance assessment, the patient had moderate findings, consistent with someone with a lateral vestibular issue. I love using the loaded Dix-Hallpike, which has been very helpful. In this case, the patient was looking great, with no issues indicating possible BPPV, which is one less thing to worry about for now. Third window testing, like Valsalva, open-closed glottis, and Tullio’s type assessment, were negative.

Dr. Walter: Those are all third window tests that should be done with video infrared goggles on, or you would miss it. They were all negative, which reinforces the CT being negative. So, we can pretty much rule out superior canal dehiscence for this patient.

Dr. Esmonde: Right, exactly. The symptoms sounded a little like it, which was fair to suspect initially, but at this point, we’re not there.

Dr. Walter: This video shows our actual patient, who is going to cough for you. This was before COVID. Watch what happens after he coughs. This is the second time he did it that day, so it was a little harder to trigger, but keep watching. After the forceful cough, watch closely. There’s vigorous nystagmus predominantly beating to his right, with a slight downward component. If he was on his feet, he would struggle to function. A teaching point here is that it didn’t occur while he coughed but after.

With superior canal dehiscence, the nystagmus we see is never as robust as this and occurs while you cough, not after. The nystagmus was beating towards what we thought was the paretic ear, indicating an irritative nystagmus beating towards the ear with diminished function.

Dr. Esmonde: Right. Usually, right-beating nystagmus suggests left hypofunction. However, in rare situations, an irritation can cause nystagmus towards the more active side. Can you elaborate on this?

Dr. Walter: Trust your caloric and mastoid vibration tests for localization. They are reliable indicators of hypofunction. However, other tests, like hyperventilation, can also cause nystagmus. When a subject with hypofunction hyperventilates, they can get nystagmus that beats to their healthy ear due to increased nerve conduction velocity. In diseases like multiple sclerosis or vestibular schwannomas, hyperventilation can cause irritative nystagmus towards the diseased ear, which tends to be more violent.

In this patient’s case, I had him hyperventilate twice, but he didn’t show irritative nystagmus, suggesting it’s not a hyperventilation phenomenon. We considered a third window, but it wasn’t time-locked to pressure, and the cough increased intracranial pressure, possibly compressing his eighth nerve.

Dr. Esmonde: Good. We’re going to play one more video.

Dr. Walter: This is a patient with a vestibular schwannoma, unknown at the time. When he hyperventilates, you see robust left-beating nystagmus, indicating an irritative nystagmus because the tumor was on the left side. Interestingly, his first MRI was negative, but the second showed the tumor. He had exertional dizziness, a red flag for therapists. If a patient has exertional vertigo, it should be investigated further.

Dr. Esmonde: Right. Not to be confused with post-concussion dizziness, which could be dysautonomia. It’s essential to do our testing to sort out what we’re dealing with.

Dr. Walter: If your patient has strong nystagmus evoked by hyperventilation, they need to see an otologist or neurotologist and get an MRI because it could indicate a vestibular schwannoma. If they have exertional dizziness without nystagmus, it might be more related to a concussion.

Dr. Esmonde: Exactly. This patient had coughing that potentially increased intracranial pressure, leading to transient neural irritation on the right side, acting like a hypofunction side but showing right-beat nystagmus with coughing. Is that an accurate summary?

Dr. Walter: Absolutely. We suspect a lesion on the right but want to see the actual MRI film. We reviewed the MRI, and it showed a right-sided vestibular schwannoma not initially recognized.

Dr. Esmonde: So, monitoring over time, two months after the initial visit, the severity of symptoms increased, and there was a dizziness-associated motor vehicle accident.

Dr. Walter: Yes, the patient had a car accident from cough-induced vertigo but didn’t have severe injuries. Vestibular function impairment is a safety issue that needs to be addressed.

Dr. Esmonde: The patient tried stereotactic radiation therapy, resulting in complete hearing loss in the right ear, but the cough-induced dizziness went away. He was happier being deaf in that ear, having stability despite the loss of hearing.

Dr. Esmonde: Right. So, key takeaways include that stimulus testing may need to be repeated due to variable quality. Another important point is that having a radiology report is not necessarily the final word. As clinicians, we should consider that when we receive these reports, even though we’re neither ordering them as physical therapists nor reading them in depth. We should not feel at the mercy of these reports but instead be willing to advocate. Experience definitely helps with this. I think, Dr. Walter, you could speak to this as well—the more you see in your clinical exams, the more you notice when things aren’t adding up, right?

Dr. Walter: Yes, I’ve been fortunate to work closely with the physicians at our center. Through experience and repetition, I’ve become comfortable screening temporal bone CTs and MRIs for issues. As you become a more experienced therapist, getting comfortable with at least screening through imaging can help expedite a patient’s course of care. We are not radiologists, but it’s beneficial to view those images and have an idea of what you’re looking at, especially if you have concerns.

Dr. Esmonde: Absolutely. This can be challenging depending on your team and geography, and the doctors in your area. Whenever possible, build good relationships and communication with neurologists, ENTs, and audiologists. Advocate for second opinions when necessary to cover all bases for patients whose conditions don’t match up or cause more concern.

Dr. Walter: I love vestibular rehab, especially in a setting where I can easily consult with an otology PA or neuro-otologist. This multidisciplinary approach provides more answers and makes the process more efficient. If you’re not in such a setting, you have to advocate for your patient to pursue those services, even if it’s less efficient. I prefer quick answers and a multidisciplinary clinic setting suits my personality better.

Dr. Esmonde: For those with fewer resources, telehealth is an option. Patients can have their images reviewed by an experienced specialist remotely, or they can travel to larger medical centers for specialized care. While general ENTs can catch these issues, it’s often more effective to see a specialist for difficult cases.

Dr. Walter: If you’re dealing with a case like this, I would recommend referring the patient to an ENT who specializes. Many patients with superior canal dehiscence, for example, have already seen a general ENT without resolution. Experienced otologists or neuro-otologists are better equipped to diagnose these conditions. It might be worth the extra effort to see a specialist for quicker and more accurate answers.