Pupillary symptoms of Holmes–Adie syndrome are thought to be the result of a viral or bacterial infection that causes inflammation and damage to neurons in the
ciliary ganglion, located in the posterior orbit, that provides
parasympathetic control of eye constriction. Additionally, patients with Holmes-Adie Syndrome can also experience problems with
autonomic control of the body. This second set of symptoms is caused by damage to the
dorsal root ganglia of the
spinal cord. Adie's pupil is supersensitive to
acetylcholine so a muscarinic agonist (e.g.
pilocarpine) whose dose would not be able to cause pupillary constriction in a normal patient, would cause it in a patient with Adie's Syndrome. The circuitry for the pupillary constriction does not descend below the upper midbrain, henceforth impaired pupillary constriction is extremely important to detect as it can be an early sign of brainstem herniation. ==Diagnosis==