Brachial plexopathy can cause Horner’s syndrome because it disrupts the sympathetic nerve pathways, specifically at the C8 and T1 levels, which are involved in controlling eye and facial functions. This disruption leads to the characteristic symptoms of Horner’s syndrome, including drooping eyelid, constricted pupil, and decreased sweating on the affected side. 

Here’s a more detailed explanation:

• Brachial Plexopathy:This refers to any damage or injury to the brachial plexus, which is a network of nerves that originates from the spinal cord and extends down the arm.Â
• Sympathetic Nerve Pathway:The sympathetic nervous system is responsible for controlling involuntary functions like heart rate, pupil dilation, and sweating. A specific pathway connects the brain to the eye and facial region via the brachial plexus at the C8 and T1 levels.Â
• C8 and T1 Levels:These are the specific nerve roots within the brachial plexus that are involved in the sympathetic pathway.Â
• Disruption of the Pathway:Brachial plexopathy, particularly at the C8 and T1 levels, can disrupt this sympathetic nerve pathway.Â
• Horner’s Syndrome:This syndrome occurs due to damage or disruption to the sympathetic pathway. It is characterized by:
  • Ptosis (Drooping eyelid): Due to the disruption of the nerves that control the muscles that lift the eyelid.Â
  • Miosis (Constricted pupil): Because the nerves that dilate the pupil are affected.Â
  • Anhidrosis (Decreased sweating): The nerves that regulate sweating are disrupted.Â