Signs in Normal CT Temporal Bone | Ice Cream Cone Sign & Snake Eyes Sign
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Signs in Normal CT Temporal Bone
Two classical radiological signs are seen in a normal CT scan of the temporal bone. In this post, we will discuss:
- Ice Cream Cone Sign
- Snake Eyes Sign
Ice Cream Cone Sign
📌 Type of Sign
👉 Radiological Sign seen on Axial section of CT Temporal Bone.
🔍 What is the Sign?
Ice Cream Cone Sign refers to the normal configuration of the malleus head and the incus body seen on CT temporal bone.
It represents Normal middle ear anatomy.
| Part | Formed By |
|---|---|
| Scoop | Malleus head |
| Cone | Body of incus |
The space lateral to the malleus and incus is Prussak's space, also known as the Lateral epitympanic space.
What are the boundaries of Prussak's space?
🍦 Why is it Called Ice Cream Cone Sign?
The malleus head and body of incus together resemble an ice cream cone, hence the name Ice Cream Cone Sign.
⚠️ Clinical Significance
Loss of the Ice Cream Cone Sign suggests:
✅ Incudomalleolar disarticulation
What are the causes of incudomalleolar disarticulation?
What is the other ice cream sign seen in a pathological condition of the ear? And what is the reason behind it?
Snake Eyes Sign
📌 Type of Sign
👉 Radiological Sign seen on Coronal section of CT Temporal Bone.
📌 Also Known As
👉 Snail Eyes Sign
🔍 What is the Sign?
Snake Eyes Sign refers to two facial nerve segments appearing like the two eyes of a snake, superior to the cochlea.
The two "eyes" are formed by:
1- Proximal tympanic segment of facial nerve
2- Distal labyrinthine segment of facial nerve
What are the different segments of the facial nerve?
🧠 Clinical Significance
Helps in Identifying the course of the facial nerve.
🐍 Why is it Called Snake Eyes Sign?
The two facial nerve segments superior to the cochlea resemble the two eyes of a snake, hence the name Snake Eyes Sign.
⭐ High Yield Rapid Revision Table
| Sign | Type | Section on CT Temporal Bone | Formed By | Significance |
|---|---|---|---|---|
| Ice Cream Cone Sign | Radiological | Axial | Malleus head (scoop) and body of incus (cone) | Loss suggests incudomalleolar disarticulation |
| Snake Eyes Sign | Radiological | Coronal | Proximal tympanic and distal labyrinthine segments of facial nerve | Identification of facial nerve course |
🧠 Viva Pearls
- Ice Cream Cone Sign and Snake Eyes Sign are seen in a normal CT temporal bone.
- Ice Cream Cone Sign is seen in the axial section of CT temporal bone.
- In the Ice Cream Cone Sign, the malleus head forms the scoop and the body of incus forms the cone.
- Prussak's space is also known as the lateral epitympanic space.
- Loss of the Ice Cream Cone Sign suggests incudomalleolar disarticulation.
- Snake Eyes Sign is seen in the coronal section of CT temporal bone.
- Snake Eyes Sign is also known as Snail Eyes Sign.
- Snake Eyes Sign is formed by the proximal tympanic and distal labyrinthine segments of the facial nerve, superior to the cochlea.
- Snake Eyes Sign helps in identifying the course of the facial nerve.
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