Post traumatic brain injury. Riding a two-wheeler. Fell down on the left side of the face. Had a laceration on the temporal region. Uh, examination. Atrophy of the left eye. Not reacting. Uh, and, uh, I only literally left us download moment is there. And, uh, the facial, mild facial palsy on the left side present. But upward, uh, eye, upper word normal. Only deviation of angle of mouth and loss of nasolabial fold is present. Vastest sensations are normal. All other cranial nerves are normal. Where can be the most probable lesion present?
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post traumatic brain injury optic nerve palsy facial nerve UMN pattern temporal region lesion localization
It's not atrophy. Left titosis.
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You will not meiosis. It's dilated. And the pupil is not seen, not EOM, right side restricted.
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This is a perfect localization. Here is the complete analysis:
Lesion Localization: Left Ventromedial Midbrain (Weber Syndrome)
Reconstructed Clinical Signs
| Sign | Side | Structure Damaged |
|---|---|---|
| Ptosis | Left | CN III (levator palpebrae) |
| Dilated, non-reactive pupil | Left | CN III parasympathetic (Edinger-Westphal nucleus fascicle) |
| Restricted EOM (down and out) | Left | CN III motor fascicle |
| Lower facial palsy (forehead SPARED) | Left face / Right UMN | Corticobulbar tract crossing in cerebral peduncle |
Why This Is Weber Syndrome
The key principle is crossed neurological signs at the midbrain level:
-
The CN III fascicle exits the ventromedial midbrain (cerebral peduncle). A lesion here hits CN III before it exits the skull, causing ipsilateral (left) CN III palsy with:
- Ptosis (Müller + levator palpebrae denervation)
- Dilated, fixed pupil (parasympathetic Edinger-Westphal fibers run on the outside of CN III - maximally vulnerable to compression/trauma)
- "Down and out" eye (unopposed CN IV + CN VI)
-
The corticospinal and corticobulbar tracts run through the same cerebral peduncle and have not yet crossed. So a left peduncle lesion damages the left corticobulbar fibers heading to the right facial nucleus (lower face only, because upper face has bilateral cortical supply). This causes contralateral UMN lower facial palsy - which in this case is on the... left face.
Wait - the facial palsy is also on the LEFT. This means the corticobulbar involvement is right-sided, producing a left lower facial UMN palsy, meaning the lesion is in the right cerebral peduncle - OR -
Reconciling the laterality
Re-reading the case: the fall was on the left side, the ptosis and dilated pupil are left, the UMN facial palsy is also left (lower face only). This is actually the classic Weber pattern because:
- Ipsilateral CN III palsy (left) = lesion is on the left midbrain peduncle
- Contralateral UMN facial palsy = would normally be on the right...
BUT the patient's UMN facial sign is on the left (angle of mouth deviation left, left nasolabial fold lost). This means the facial palsy and the CN III palsy are on the same side (left), pointing instead to:
Revised - Most Probable Single Lesion: Left Cerebral Peduncle / Posterior Limb of Internal Capsule
Given the mechanism (head trauma, temporal blow) and all signs being ipsilateral:
- Left CN III palsy (ptosis + dilated pupil + EOM restriction)
- Left UMN facial palsy (forehead spared - corticobulbar)
- Normal taste, normal sensation
The most anatomically consistent single lesion is a traumatic contusion/hemorrhage at the left cerebral peduncle causing:
- Direct damage to the left CN III fascicle as it exits - giving ipsilateral CN III palsy
- Damage to left corticobulbar fibers which control the contralateral (right) facial nucleus lower face - but here the left facial lower palsy may reflect right peduncle involvement OR this could represent an uncal herniation pattern where:
Most Likely Final Answer: Uncal Herniation / CN III Compression at the Tentorial Edge
In the context of post-traumatic brain injury with a temporal blow, the single most probable and clinically important diagnosis is:
Left Temporal Lobe Contusion with Uncal Herniation
- The expanding left temporal hematoma/contusion pushes the uncus (medial temporal lobe) over the tentorial notch
- This compresses the left CN III as it runs along the tentorial edge - causing ipsilateral ptosis + dilated fixed pupil + EOM restriction (the parasympathetic fibers on the outside of CN III are hit first)
- As herniation progresses, it compresses the left cerebral peduncle - disrupting the corticobulbar tract to the right facial nucleus lower face
- The left UMN lower facial palsy (forehead spared) is the corticobulbar sign from the contralateral peduncle compression
This is the classic blown pupil of herniation - a neurosurgical emergency.
Summary Table
| Feature | Explanation |
|---|---|
| Left ptosis | Left CN III compression at tentorial notch |
| Left dilated, fixed pupil | Parasympathetic fibers of CN III (outermost, compressed first) |
| Left EOM restricted | CN III motor fascicle involvement |
| Left UMN lower facial palsy | Corticobulbar tract involvement (contralateral peduncle) |
| Forehead spared | UMN pattern - bilateral cortical supply to upper face |
| Normal taste, sensation | CN V, VII LMN, IX, X all intact |
| Mechanism | Left temporal blow → extradural/subdural hematoma → uncal herniation |
The single most probable lesion is a left temporal extradural or subdural hematoma causing transtentorial (uncal) herniation, compressing the left CN III at the tentorial edge and the left cerebral peduncle - a classic neurosurgical emergency requiring urgent CT head and decompression.
- Localization in Clinical Neurology, 8e (Weber Syndrome, Ventral CN III Fascicular Syndrome)
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