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Clinical Consultation

Symptom: Dizziness with Atmospheric Changes

Lee, Ariel; Abouzari, Mehdi MD, PhD; Djalilian, Hamid MD

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doi: 10.1097/01.HJ.0000719812.50617.36
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A 53-year old woman presented with a history of dizziness in low atmospheric pressure and bilateral superior canal dehiscence. She reported having balance and cognitive issues during thunderstorms or cloudy weather or when traveling to the mountains. She also reported getting headaches and right ear fullness. She underwent repair surgery of a previous bilateral superior and posterior canal dehiscence surgery and bilateral perilymphatic fistula repair. Results of her microscopic ear exam, ocular and cervical vestibular evoked myogenic potential (VEMP) test, and video head impulse test (vHIT) were normal. A previous audiogram showed normal to mild bilateral hearing loss (Fig. 1). Previous magnetic resonance imaging (MRI) showed no abnormalities. CT from post-surgery showed good repair of superior canal dehiscence.

Figure 1
Figure 1:
Audiogram of the patient on presentation. Audiology, surgery.
Figure 2
Figure 2:
(A) Poschl view (parallel to the superior canal) CT of the right temporal bone at the level of the superior canal showing the membranous superior canal (short black arrows) to be covered by bone cement (short white arrows). The canal has been narrowed in one area (dotted black arrow). (B) Poschl view (parallel to superior canal) CT of the left temporal bone showing the membranous superior canal (short black arrows) to be covered by bone cement (white) all around. Audiology, surgery.
Figure 3
Figure 3:
(A) Stenver view (parallel to the posterior canal) CT of the right temporal bone at the level of the posterior canal showing the bony posterior canal (short black arrows) to be intact and abutting the bone cement (short white arrows). (B) Stenver view (parallel to the posterior canal) CT of the left temporal bone showing the intact bony posterior canal (short black arrows) to be separated by some mucosa (grey) from the bone cement (white). Audiology, surgery.
Figure 4
Figure 4:
Figure 4. Coronal (parallel to face) CT of temporal bones before all surgeries at the level of the superior canal showing bilaterally dehiscent superior canal.
Figure 5
Figure 5:
Figure 5. Axial (horizontal) CT of temporal bones before all surgeries at the level of the posterior canal showing bilaterally intact posterior canals.

Diagnosis: Vestibular Migraine

When faced with a patient who has pressure-sensitive dizziness, clinicians can make a differential diagnosis that includes superior, posterior, or horizontal canal dehiscence, perilymphatic fistula, cochlear carotid dehiscence (BMJ Case Rep. 2019 Jul 17;12(7):e229773), cochlear facial nerve dehiscence (Front Neurol. 2019;10:1281), enlarged vestibular aqueduct, and migraine. The best method to evaluate canal dehiscence is to obtain a CT scan of the temporal bones. With any unusual type of vertigo, an MRI should be obtained to evaluate for an acoustic neuroma or other intracranial pathologies. Audiologic testing such as audiogram, fistula test, videonystagmography (VNG), VHIT, and VEMP can help in identifying and ruling out some of these conditions.

In the case of this patient, the first thing to evaluate is the superior and posterior canal dehiscences and whether the previous repair is holding up and in place. The patient's CT scan showed that the bone overlying the two superior canals was intact. The right superior canal repair with hydroxyapatite bone cement appeared to have encroached into the canal (Fig. 2). Evaluation of the posterior canal repair also showed no dehiscence (Fig. 3). In fact, it showed no posterior canal dehiscence, and the bone cement was placed over an intact posterior semicircular canal.

VHIT showed that the right superior canal remained open, and the VEMP test showed normal bilateral thresholds and normal amplitudes, indicating no canal dehiscence was likely present. Further evaluation of the cochlear and vestibule on the CT scan failed to reveal signs of carotid or facial nerve dehiscence with the cochlea or an enlarged vestibular aqueduct. With a normal MRI, the patient's problem appeared to be more complex. The patient brought over 100 pages of medical records documenting the opinion of eight other neurotologists in the U.S., some of whom had recommended surgery for perilymph fistula. The patient had a previous lumbar puncture, which found normal cerebrospinal fluid pressure.

In general, the diagnosis of a dizzy patient is primarily based on the patient's medical history. Examination and diagnostic testing help to confirm or rule out items on the differential diagnosis. As such, ot is critical to take a detailed patient history.

After a more detailed evaluation of the patient's medical history, including her original CT scan of the temporal bones prior to all her surgical procedures (Figs. 4, 5), we found no evidence of posterior canal dehiscence but found bilateral superior canal dehiscence.

When a clinician hears a complaint of pressure-induced vertigo, the first thing they think of is a perilymphatic fistula. After that, third window abnormalities such as canal or cochlear dehiscence or vestibular aqueduct enlargement are often considered. The patient had undergone perilymphatic fistula repair eight years before presentation. Had the patient had a continuous fistula for eight years, it would be highly unlikely that she would have an essentially normal audiogram. Therefore, it was unlikely that the patient had perilymphatic fistula for eight years with no hearing loss on either side. Then, we had to consider a canal dehiscence. With a normal CT scan showing a bone covering the superior canal dehiscence and a normal bone overlying the posterior canals, cochlea, and horizontal canals, the likelihood of a third window abnormality is low. Further evidence for this is based on a normal audiogram as well as VEMP and VHIT testing.

Vestibular migraine is a frequently missed cause of pressure-induced vertigo. Approximately 40 percent of patients with migraine headaches are sensitive to atmospheric pressure changes. These patients develop headaches with low atmospheric pressure such as cloudy, rainy, snowy, and windy conditions. These patients may state that they can predict a thunderstorm. Oftentimes, patients mistake this relationship between atmospheric pressure changes and their headaches as a relationship between allergy and sinus headaches. The same phenomenon as seen in vertigo. Many patients with vestibular migraine are sensitive to atmospheric pressure changes, with low atmospheric pressure often leading to vestibular symptoms. These patients may suffer from headaches, aural fullness, neck stiffness, among others. A more detailed look at this patient's medical history revealed that she had a lifelong history of right-sided headaches and that in the past 10 years, she has been suffering from right-sided ear pressure sensation that occurred intermittently and lasted for days at a time. She also suffered from unilateral neck stiffness and headaches on the same side. She had been treated with migraine preventative medications but never at doses that are needed for complete control. Of note, the patient did not take any proper dietary and lifestyle precautions.

Treatment of vestibular migraine requires controlling triggers that are primarily related to diet (certain foods, dehydration, hunger), poor sleep (frequent wake-ups, sleep apnea, shifting sleep schedule, reduced sleep, or sleeping too much), stress, hormonal changes (perimenstrual or perimenopausal), and overstimulation (light, sound, motion, visual motion, reduced atmospheric pressure, smells). Magnesium and riboflavin supplementation and migraine prophylactic medications (if necessary) are also given to patients. However, prescribing medications alone often leads to unsuccessful treatment.

This patient was insistent that she had a perilymphatic fistula. Convincing her otherwise was not successful. One easy way to rule out a perilymph fistula is to perform an intratympanic blood patch (Otolaryngol Head Neck Surg. 2009 Aug;141[2]:294-5.), which could be done in the clinic. This can help rule out perilymphatic fistula if there is no improvement of symptoms for at least a few days. Perilymphatic fistula repair using an intra-tympanic blood patch is very successful since the blood will temporarily plug the area of the fistula providing symptom relief. The blood causes an inflammatory reaction that results in the closure of the fistula.

In a patient with significant pressure-sensitive vestibular migraine where the only identifiable trigger is low atmospheric pressure, an easy way to control the symptoms is to place a tympanostomy tube on the affected or both sides. A tympanostomy tube will remove the brain's ability to sense pressure changes and resolve pressure-induced vertigo symptoms in most pressure-sensitive patients. In this patient, an intratympanic blood patch procedure failed to improve the symptoms. She had bilateral tympanostomy tubes, and was started on the dietary and lifestyle changes as well as magnesium and riboflavin supplements to help control the symptoms.

BONUS ONLINE VIDEOS: VISUAL DIAGNOSIS

Read this month's Clinical Consultation case, then watch the accompanying videos from Hamid R. Djalilian, MD, to review the patient's imaging for yourself.

  • Video 1. Poschl view (parallel to the superior canal) CT of right temporal bone showing the anatomy of the superior canal and membranous narrowing post-surgery.
  • Video 2. Coronal (parallel to face) CT of the right temporal bone showing the anatomy of the posterior and horizontal canals postoperatively.
  • Video 3. Poschl view (parallel to the superior canal) CT of the left temporal bone showing the anatomy of the superior canal post-surgery.
  • Video 4. Coronal (parallel to face) CT of the left temporal bone showing the anatomy of the posterior and horizontal canals postoperatively.
  • Video 5. Coronal (parallel to face) CT of the temporal bones showing the bilaterally dehiscent superior canals before all surgeries.
  • Video 6. Axial (horizontal) CT of the temporal bones showing the bilaterally intact posterior canals before all surgeries.

Watch the patient videos online at thehearingjournal.com.

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