An 80 y.o. male with HT, CAD and ischemic cardiomyopathy comes in with a week of postitionaheadaches.

What do you notice?

Our patient had both pneumocephalus and chronic low density hygromas. He had a superior semicircular canal dehiscence with a defect in the tegmen tympani.  In simpler terms, a hole in the bony  top of the ear canal and a hole in the superior semicircular canal.

This dehiscence creates a “third” window in the ear which affects the fluid moving in the cochlea. Normally the oval window attached to the stapes, moves ” in” in response to vibration and the round window moves ” out” .  With a “ third” window, transmission of vibration can be intermittent with vibration transmitted into the cranial cavity or vestibular system.

The image above shows the position of a third “window” created at the superior semicircular canal which can occur congenitally, as a result of trauma or because of infection. A defect in the superior canal is estimated to occur in 1% of the population.

In addition to pneumocephalus and rhinorrhea.  A hole in the semicircular canal  can present with bizarre symptoms like:

Pulsatile tinnitus and vertigo triggered by noise

Balance problems triggered by noises or increased intracranial pressure as in sneezing, coughing or lifting heavy objects.

Osciliopsia- visual impairment where the environment appears to move to-and-fro with loud sounds or pressure in the ear canal. The eyes move up and down.

Rubbing sounds when the eyes move back and forth

Autophony- enhanced perception of your own voice, footsteps  and breathing.

Rhinorrhea caused by valsalva or coughing.

While surgery is recommended for symptomatic patients with a middle fossa cranial approach or transmastoid approach, often the defect  is managed conservatively as in our patient. He was treated with broad spectum antibiotics and his pneumocephalus improved.  He was discharged to a rehab facility.  

Mahendran S, Sunkaraneni V, Baguley D, Axon P. Superior semicircular canal dehiscence with a large tegmental defect. The Journal of Laryngology & Otology.2007, 121, 189-191

Crovetto, M, Whyte, J, Rodriguez, OM, Lecumberri, I, Martinez, C, Eléxpuru, J. Anatomo-radiological study of the superior semicircular canal dehiscence radiological considerations of superior and posterior semicircular canals. Eur J Radiol 2010;76:167–72

 Miner L, Solomon D, Zinreich J, et al. Sound and.or pressure induced vertigo due to bone dehiscence of the superior semicurcular canol. Arch Otolaryngol Head Neck surg 1998;124:240-58.