Two classical signs of vertigo induced by external stimuli are seen in otology.
In this post, we will discuss:
Tullio Phenomenon, which is sound induced vertigo
Hennebert's Sign, which is pressure induced vertigo
Tullio Phenomenon
📌 Type of Sign
👉 Clinical Sign elicited by Sound stimulation.
🔍 What is the Sign?
Tullio Phenomenon refers to vertigo and nystagmus induced by loud sounds.
Seen In
1- Superior Semicircular Canal Dehiscence (Classical association)
2- Perilymph fistula
3- Meniere's disease (very rarely)
4- Cholesteatoma with labyrinthine fistula
5- Congenital syphilis
Features
Vertigo
Nystagmus
Imbalance
Nausea
🧠 Why Does it Occur?
Normally, sound stimulates only the cochlea.
In Tullio phenomenon, loud sound stimulates the cochlea and the vestibular system, producing vertigo and nystagmus.
⭐ The Third Window Effect
The key concept underlying Tullio phenomenon.
What is the third window effect? Describe it.
👨⚕️ Eponym
Named after Pietro Tullio, who described sound induced vestibular responses in experimental animals.
What are the features of superior semicircular canal dehiscence?
Hennebert's Sign
📌 Type of Sign
👉 Clinical Sign elicited during Vestibular examination.
🔍 What is the Sign?
Hennebert's Sign refers to vertigo and nystagmus produced by pressure changes in the external auditory canal, in the absence of a true labyrinthine fistula.
⭐ It is essentially a false positive fistula test.
🩺 How is it Elicited?
Pressure in the external auditory canal is changed by:
Pressing the tragus
Using Siegel's speculum
Seen In
1- Congenital syphilis (Classical example), due to a hypermobile stapes footplate
2- Meniere's disease, due to a fibrous band connecting the utricle to the macula
3- Superior semicircular canal dehiscence
🧠 Why Does it Occur?
Normally, the fistula test is positive only when there is an abnormal opening between the middle ear and inner ear.
In Hennebert's sign, there is no true bony fistula, but pressure is transmitted abnormally to the vestibular system due to an underlying pathology of the labyrinth.
👨⚕️ Eponym
Named after Hennebert, who described this positive fistula-like response without an actual fistula, especially in congenital syphilis.
Name the condition where you see a True positive fistula test.
Name the conditions where you see a False negative fistula test.
⭐ High Yield Rapid Revision Table
Feature
Tullio Phenomenon
Hennebert's Sign
Stimulus
Loud sound
Pressure change in the external auditory canal
Finding
Vertigo and nystagmus
Vertigo and nystagmus
Classical Condition
Superior semicircular canal dehiscence
Congenital syphilis
Mechanism
Third window effect
Abnormal transmission of pressure to the vestibular system without a true fistula
🧠 Viva Pearls
Tullio phenomenon is vertigo and nystagmus induced by loud sounds.
Tullio phenomenon is classically described in superior semicircular canal dehiscence.
Tullio phenomenon is also seen in perilymph fistula, Meniere's disease, cholesteatoma with labyrinthine fistula and congenital syphilis.
The third window effect is the key concept in Tullio phenomenon.
Hennebert's sign is vertigo and nystagmus on pressure change in the external auditory canal, without a true labyrinthine fistula.
Hennebert's sign is a false positive fistula test.
Hennebert's sign is classically seen in congenital syphilis, due to a hypermobile stapes footplate.
In Meniere's disease, Hennebert's sign is due to a fibrous band connecting the utricle to the macula.
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