Horner’s Syndrome

Horner’s syndrome is a neurological condition characterized by a combination of signs resulting from disruption of sympathetic nerve pathways supplying the eye and surrounding structures. It can occur due to various underlying conditions affecting the sympathetic nervous system.

Signs of Horner’s Syndrome

Horner’s syndrome is typically identified by the following classic signs:

1. Ptosis: Drooping of the upper eyelid due to weakness of the levator palpebrae superioris muscle, which is innervated by sympathetic fibers.
2. Miosis: Constricted pupil resulting from unopposed parasympathetic activity. The affected pupil is smaller than the unaffected pupil.
3. Anhidrosis: Lack of sweating on the affected side of the face due to disruption of sympathetic innervation to sweat glands.
4. Enophthalmos: Slight sinking of the eyeball into the orbit, which may be perceived rather than actual.
5. Facial Flushing: In some cases, there may be flushing of the face on the affected side due to vasodilation from loss of sympathetic tone.

Central vs. Peripheral Horner’s Syndrome

Horner’s syndrome can be classified into central and peripheral types based on the location of the lesion affecting the sympathetic pathway.

Central Horner’s Syndrome

Location: The lesion occurs in the central nervous system, specifically in the hypothalamus, brainstem, or cervical spinal cord.

Causes:

• Stroke: Ischemic or hemorrhagic strokes affecting the brainstem.
• Tumors: Neoplasms in the region of the brainstem or cervical spine.
• Multiple Sclerosis: Demyelination affecting the sympathetic pathways.
• Syringomyelia: A cystic expansion within the spinal cord that can disrupt sympathetic fibers.

Signs: In addition to the classic signs of Horner’s syndrome, central lesions may present with other neurological deficits depending on the location of the lesion.

Peripheral Horner’s Syndrome

Location: The lesion occurs along the sympathetic pathway outside the central nervous system, typically affecting the preganglionic or postganglionic fibers.

Causes:

• Pancoast Tumor: A tumor at the apex of the lung that can invade surrounding structures, including sympathetic fibers.
• Trauma: Injury to the neck or upper chest that disrupts sympathetic pathways.
• Carotid Artery Dissection: Disruption of sympathetic fibers running along the carotid artery.
• Thyroid Surgery: Surgical manipulation or damage to sympathetic fibers during thyroidectomy.

Signs: Peripheral Horner’s syndrome typically presents with the classic triad of ptosis, miosis, and anhidrosis without additional neurological deficits.

Diagnosis 

Diagnosis

Diagnosis of Horner’s syndrome is primarily clinical, based on the characteristic signs. Additional tests may include:

• Pharmacologic Testing: Use of cocaine or apraclonidine drops can help confirm the diagnosis. In Horner’s syndrome, cocaine will not dilate the affected pupil, while apraclonidine may cause a paradoxical dilation due to denervation supersensitivity.
• Imaging Studies: MRI or CT scans may be performed to identify underlying causes, especially in cases of central Horner’s syndrome.

• Symptomatic Treatment: Addressing ptosis with surgical options if it significantly affects vision or aesthetics.