A CASE OF HYPERPNEUMATIZATION OF THE TEMPORAL BONE PRESENTING WITH VERTIGO

Yoko Ohta, Mamoru Suzuki, Koji Otsuka, Yasuo Ogawa

Department of Otolaryngology, Tokyo Medical University, Tokyo, Japan

Introduction

Vertigo is a common symptom encountered in the clinical practice of otolaryngology. There are many causes of vertigo, but it can be difficult to determine the exact etiology. We encountered a case of hyperpneumati-zation of the temporal bone and surrounding bones which caused thinning of the superior semicircular bony canal. Hyperpneumatization of the temporal bone is a rare condition which induces a variety of symptoms, such as headache, the development of a palpable mass in the occipital region,1 a feeling of fullness in the temporal region,2 and conductive hearing loss.3 Reports concerning vertigo induced by hyperpneumatization of the temporal bone are very scarce. We suspected that the vertigo in the present case was possibly due to the thinning of the superior semicircular bony canal, mimicking superior semicircular canal dehiscence (SSCD) syndrome.

Case report

A 60-year-old woman visited our clinic in March 2011 because of vertigo after airplane take-off. The vertigo occurred a few minutes after take-off and lasted for about 30 minutes. She had experienced this vertigo in two out of three flights. Simultaneously, she had pain in her left lateral neck. There were no other ontological symptoms such as hearing loss or tinnitus. Occasionally, she felt dizzy when she inserted a finger into her left ear canal. She had no Tullio phenomenon. Her past medical history was unremarkable.

Clinical data

The patient was well oriented with normal gait. Physical examination revealed intact tympanic membranes. There were no abnormal neurologic findings. Crepitation was observed in her left neck on a Valsalva maneuver.

Neuro-otological findings

Audiometry on the first visit revealed an average air-bone gap of 15 dB in the left low-tone frequencies (Fig. 1), but there was no air-bone gap in other occasions. Tympanometry was performed twice and both tests revealed Type A for the right ear and the peak shift to the positive pressure for the left ear (Fig. 2). A Eustachian tube test revealed bilateral stenosis. There was no nystagmus on the gaze or positional test. A fistula sign test applying positive and negative pressure into the ear canal was negative. The stabilometry findings were normal. The cervical vestibular-evoked myogenic potential (cVEMP) was hyporesponsive on the left side.

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Fig. 1. An audiogram of the first consultation showed an average air-bone gap of 15 dB in the left low tone frequencies.

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Fig. 2. Tympanometry revealed a Type A tympanogram for the right ear; on the left side, the peak had shifted to the positive pressure side (arrow).

Imaging findings

Computed tomography of the temporal bone revealed hyperpneumatization of the left temporal bone and surrounding bones extending to the sphenoidal sinus and atlanto-occipital joint. The bony wall of the left posterior cranial fossa was extremely thin. Air was noted in the left neck muscles (Fig. 3 a-c). Furthermore, there were well-developed air cells above the left superior semicircular canal (SSC), indicating SSCD (Fig. 4).

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Fig. 3a. Computed tomography showed the hyperpneumatized left temporal bone extending into the petrous apex (arrows).

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Fig. 3c. Air space in the left neck (closed arrow). A pneumatized atlas bone (open arrow) was observed.

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Fig. 3b. The hyperpneumatization extended into the sphenoidal sinus and atlanto-occipital joint (open arrow). Thinning of the posterior cranial fossa bone was observed (closed arrow).

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Fig. 4. The hyperpneumatized cells above the left superior semicircular canal. SSCD was suspected (closed arrow).

We diagnosed the condition as hyperpneumatization of the temporal bone and possible SSCD, which induced vertigo at the time of take-off. We advised her in April 2011 to take difenidol hydrochloride and diphen-hydramine salicylate, which successfully treated her vertigo. However, despite the successful control of her vertigo, her left lateral neck pain remained. She makes it a practice to take both drugs before each take-off.

Discussion

Hyperpneumatization of the temporal bone is a rare condition with either congenital or acquired etiology. The former is caused by excessive bone resorption during pneumatization or persistent embryological synchondro-sis.4 The latter is known as the ‘ball-valve effect’: the air enters the middle ear through the Eustachian tube as nasopharyngeal pressure rises during swallowing, coughing or sneezing. This air then becomes trapped by a ball-valve mechanism, which allows the air to enter but not to leave, resulting in hyperpneumatization.5

In the present case, we assumed that the hyperpneumatization of the temporal bone and surrounding bones was caused by both congenital and acquired etiologies. The stenosis of the patient’s left Eustachian tube may have induced the ball-valve effect. Hyperpneumatization then developed above the left SSC, which eroded the canal and resulted in dehiscence.

We considered that the pressure within the air cells increases after take-off and acts on the SSC through dehiscence, resulting in vertigo. The neck pain was also induced by an increased pressure transmitted into the subcutaneous tissue. The tympanogram curve that was observed to have shifted to the positive pressure side may also have been due to a higher pressure in the pneumatized space, rather than in the ear canal. Charbel et al. reported similar results by tympanometry, caused by a middle ear pressure rise with head rotation to one side.4

A series of symptoms induced by SSCD was first reported by Minor et al. as SSCD syndrome.6 Patients with SSCD syndrome exhibit symptoms of oscillopsia or vertigo induced by pressure or sound, because the absence of the bony layer covering the SSC creates a third window. Congenital dysostosis, trauma and bone erosion by cerebrospinal fluid pulsation may result in SSCD.7 SSCD increases the threshold of air conduction due to dispersed energy into the inner ear from the third window effect, and decreases the bone conduction threshold by amplified vibration transmitted to the temporal bone.8 This mechanism is possibly responsible for the air-bone gap across the low tone frequencies in the present case. However, the audiograms taken on other occasions showed no air-bone gap. This is possibly due to the positive pressure within the air cells that acts on the SSC, thus weakening the third window effect. Tullio phenomenon, positive fistula sign, and enhanced cVEMP are characteristics of SSCD syndrome. In the present case, Tullio phenomenon was absent, a fistula sign test was negative and the cVEMP was hyporesponsive. The positive pressure acting on the SSCD may also be responsible for suppressing these signs and VEMP enhancement.

Martin et al. reported the placement of a myringotomy tube for the treatment of hyperpneumatization. Tube placement reduces the air pressure in the pneumatized areas within the skull base and atlas, leading to ossification and new bone formation.1 In the present case, vertigo was controlled by the use of two anti-vertiginous drugs. Myringotomy tube insertion may also be an option for more secure treatment. The present patient had a risk of infection spreading into the hyperpneumatized air space. We advised her to be aware of the possible development of infection such as acute otitis media.

Conclusion

We encountered a case of a hyperpneumatized temporal bone and surrounding bones. Vertigo developed at the time of take-off in flight. Dehiscence of the SSC was the most likely cause of the vertigo.

Acknowledgements

We are indebted to Mr. Roderick J. Turner, Associate Professor Edward F. Barroga and Professor J. Patrick Barron, Chairman of the Department of International Medical Communications of Tokyo Medical University, for their editorial review of the English manuscript.

References

1.Martin ML, Bhargava R, Ashforth RA, Russell DB. Mastoid pneumocele causing atlanto-occipital pneumatization. AJNR 19(7):1231–1233, 1998

2.Rebol J, Munda A, Tos M. Hyperpneumatization of the temporal, occipital and parietal bones. Eur Arch Otorhinolaryngol 261:445–448, 2004

3.Levenson MJ, Ahuja G, Bergeron T. Spontaneous extracranial pneumatocele associated with mastoid hyperpneumatization. Arch Otolaryngol Head Neck Surg 115:107–108, 1989

4.Rameh C, Meller R, Magnan J. Mastoid hyperpneumatization with atlantoaxial fistulization presenting as head rotation-induced aural fullness. Otol Neurotol 30:936–938, 2009

5.Maier W, Fradis M, Scheremet R. Spontaneous otogenic pneumocephalus. Ann Otol Rhinol Laryngol 105(4):300–302, 1996

6.Minor LB, Solomon D, Zinreich JS, Zee DS. Sound- and/or pressure-induced vertigo due to bone dehiscence of the superior semicircular canal. Arch Otolaryngol Head Neck Surg 124(3):249–258, 1998

7.Carey JP, Minor LB, Nager GT. Dehiscence or thinning of bone overlying the superior semicircular canal in a temporal bone survey. Arch Otolaryngol Head Neck Surg 126:137–147, 2000

8.Minor LB. Clinical manifestations of superior semicircular canal dehiscence. Laryngoscope 115:1717–1727, 2005


Address for correspondence: Yoko Ohta, Department of Otolaryngology, Tokyo Medical University, 6–7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160–0023, Japan. yomayomayoko@hotmail.com

Cholesteatoma and Ear Surgery – An Update, pp. 249–253

Edited by Haruo Takahashi

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