Horner Syndrome
🔑 Key concept
- Oculosympathetic
pathway lesion
- Classic
triad:
- Miosis
- Ptosis
(mild)
- Anhidrosis
- ต้องคิดตั้งแต่ benign →
life-threatening (carotid dissection)
🧬 Neuroanatomy
(high-yield)
3-neuron pathway:
1. First-order (central)
- Hypothalamus
→ C8–T2
2. Second-order
(preganglionic)
- spinal
cord → lung apex → superior cervical ganglion
3. Third-order
(postganglionic)
- carotid
artery → cavernous
sinus → eye
👁️ Clinical features
✔️ Key signs
- Miosis
- Ptosis
(<2 mm)
- Dilation
lag (สำคัญ)
- anisocoria
เด่นในที่มืด
✔️ Additional signs
- “upside-down
ptosis” (lower lid elevation)
- ±
anhidrosis
- ±
conjunctival injection / nasal congestion
🔍 Localization clues (สำคัญมาก)
🔴 First-order (central)
- brainstem
/ spinal cord lesion
- signs:
- ataxia,
weakness, sensory deficit
- example:
- Wallenberg
syndrome
🟣 Second-order
(preganglionic)
- lung
apex / brachial plexus
- clues:
- arm
pain / shoulder pain
- example:
- Pancoast
tumor
🔵 Third-order
(postganglionic)
- carotid
artery / cavernous sinus
- clues:
- neck
pain / headache
- ± CN
VI palsy
👉 Anhidrosis มักไม่มี
⚠️ Red flags (critical)
- Acute
Horner + neck pain →
carotid dissection until proven otherwise
- risk
stroke สูงในไม่กี่วัน
🧠 Common causes
Adults
|
Location |
Causes |
|
Central |
stroke, tumor, MS |
|
Preganglionic |
tumor lung apex, trauma |
|
Postganglionic |
carotid dissection,
cluster headache |
Children
- birth
trauma
- neuroblastoma
(ต้อง rule out)
🧪 Diagnosis
✔️ Bedside
- anisocoria
↑ in dark
- dilation
lag
✔️ Pharmacologic test
- Apraclonidine
- Horner
→ reversal of
anisocoria
- Cocaine
(alternative)
❗ Important
- acute
suspected dissection
👉 ไม่ต้องรอ test → imaging ทันที
🧠 Imaging strategy
|
Scenario |
Investigation |
|
Brainstem signs |
MRI brain |
|
Neck pain |
CTA/MRA carotid (urgent) |
|
Arm pain |
CT chest (lung apex) |
|
No clue |
image entire pathway |
⚖️ Differential diagnosis
- CN
III palsy (ptosis + mydriasis)
- physiologic
anisocoria
- pharmacologic
miosis
📈 Prognosis
- ขึ้นกับ cause
- carotid
dissection → high
stroke risk early
🧾 Clinical pearls
- anisocoria
↑ in dark → small pupil abnormal
- ptosis
mild (ต่างจาก CN III)
- dilation
lag = clue สำคัญ
- painful
Horner → vascular
emergency
🧠 One-line summary
👉 “Miosis + mild
ptosis + anisocoria worse in dark →
think Horner; if painful →
carotid dissection until proven otherwise”
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