Ciliospinal reflex response in cluster headache

Area of Science:

• Neurology
• Ophthalmology
• Pain Medicine

Background:

• The ciliospinal reflex (CSR) involves sympathetic nerves controlling pupillary dilation.
• Pupillary responses in cluster headache (CH) suggest sympathetic dysfunction.
• A subset of CH patients presents with Horner-like syndrome (miosis, ptosis).

Purpose of the Study:

• To investigate CSR in cluster headache patients.
• To determine if CSR abnormalities differentiate CH subgroups.
• To explore the role of sympathetic dysfunction in CH pathophysiology.

Main Methods:

• Studied CSR in 25 CH patients and controls.
• Assessed pupillary responses to phenylephrine and tyramine.
• Correlated CSR findings with clinical presentation, including Horner-like syndrome.

Main Results:

• CH patients with Horner-like syndrome had significantly reduced CSR on the symptomatic side compared to controls and CH patients without Horner-like syndrome.
• Reduced CSR was also observed on the non-symptomatic side in patients with Horner-like syndrome.
• 18/25 (72%) CH patients showed asymmetric CSR, often reduced on the symptomatic side.

Conclusions:

• Patients with Horner-like syndrome represent a distinct subgroup of cluster headache.
• The Horner-like syndrome in CH is linked to postganglionic sympathetic nerve dysfunction.
• Findings support the involvement of cephalic sympathetic nervous system dysfunction in cluster headache pathophysiology.