Horner's Syndrome results from injury to the nerve fibers that connect the eye and the brain. Symptoms include a droopy eye and a constricted pupil. The eyeball itself can sink a bit into its orbit, and the affected side of the face may perspire less than normal.
The nerve fibers involved don't travel directly from the brain to the eye but snake down the spinal cord to the chest and then back up the neck, through the skull and into the eye. The nerves can be impeded at any point along this meandering path, by any number of abnormalities including a tumor in the lung, brain, or spinal cord; a stroke, atherosclerosis or injury to the carotid artery; and even the vascular spasms that cause cluster headaches. Certain medications including some eye drops can also cause Horner's Syndrome. Very rarely, the syndrome can be present at birth.
There is no single treatment for this disorder. Instead, you need to investigate and deal with the underlying cause. This may involve tests including an MRI of the head, an ultrasound test to examine the carotid artery in the neck, a chest x-ray, a CT scan of the chest, blood tests, an angiogram and eye tests.
Once the problem is found, treating it may help. I would also recommend trying acupuncture, hypnosis, and an extract of Lion's Mane mushrooms (Hericium erinaceus), a medicinal mushroom believed to stimulate nerve growth. It is nontoxic. You can get Lion's Mane in extract-form from Fungi Perfecti (www.fungi.com). Follow the dosing directions on the product.
Andrew Weil, M.D.