Horner's syndrome

Question 1

What is Horner’s syndrome?

Answer 1

Lesion in the SNS resulting in ipsilateral presentation in the eye

Question 2

What is the neuronal pathway in Horner’s syndrome?

Answer 2

1. First order neurones are in the hypothalamospinal tract
2. Second order neurones are pre-ganglionic, emerging from thoracic section (T1) of spinal cord to sympathetic chain ganglia just lateral to the spinal cord at the level of the ICA
3. Third order neurones are post-ganglionic and found at ICA. They travel to the effectors

Question 3

What are the causes of Horner’s syndrome? (x3 categories)

Answer 3

• FIRST ORDER NEURONE: SYRINGOMYELIA (cyst/cavity in spinal cord), MS, encephalitis, brain tumours, neurofibromatosis
• SECOND ORDER NEURONE: cervical rib, thyroid carcinoma, bronchogenic carcinoma (PANCOAST tumour), trauma at base of neck, thoracic aortic aneurysm
• THIRD ORDER NEURONE: CLUSTER HEADACHE, MIGRAINE, carotid artery DISSECTION, cavernous sinus thrombus, middle ear infection

Question 4

What are the signs and symptoms of Horner’s syndrome?

Answer 4

Miosis (constricted pupil), ptosis (droopy eyelid), anhidrosis (decreased sweating) and enophthalmos (inset eyeball). NOT exophthalmos.

Question 5

What are the investigations for Horner’s syndrome? (x3)

Answer 5

• COCAINE EYEDROPS: pupils will fail to dilate. Normally, cocaine blocks reuptake of NA resulting in mydriasis
• PAREDRINE TEST: hydroxyamphetamine is added to the eye causing NA release from third-order neurone leading to mydriasis. If the lesion is in the third-order neurone, this test will have a negative result
• There is no pharmacological test to differentiate between first and second order lesions, so must investigate first and second order aetiologies