A case report of horner's syndrome presenting post bimaxillary osteotomy

Horner's syndrome develops as a result of disruption of the sympathetic nerve supply to the eye. This article will give an overview of the anatomy of the sympathetic nerve supply to the eye, its pathway and relations. An understanding of the anatomy helps to explain the clinical manifestations and multiple aetiologies of Horner's syndrome, which are described.

The sympathetic neurones supplying the eye have their origins in the hypothalamus. After they leave the hypothalamus they take a lengthy and convoluted pathway to the effector organs of the eye. Disruption of the nerve supply can occur at any point along the route, resulting in Horner's syndrome.

The first-order sympathetic neurones supplying the eye leave the hypothalamus, descend in the spinal cord and terminate at the level of C8-T2. Second-order pre-ganglionic fibres exit the spinal cord at T1 and enter the cervical sympathetic chain, where they are closely related to the pulmonary apex and subclavian artery. The fibres ascend through the sympathetic chain and synapse at the superior cervical ganglion at the level of C3-C4 and at the bifurcation of the common carotid artery. The third-order, post-ganglionic sympathetic fibres, responsible for pupil dilation, ascend with the internal carotid artery in the internal carotid nerve. This nerve forms a plexus alongside the internal carotid artery and passes with the artery through the carotid canal to enter the cranial cavity. They enter the cavernous sinus, located at the base of the skull in the middle cranial fossa. While passing through the cavernous sinus, the plexus gives off branches to the oculomotor and ophthalmic division of the trigeminal nerves, which also run through the cavernous sinus. These nerves run anteriorly close to the base of the skull in the middle cranial fossa and enter the orbit through the superior orbital fissure. The ophthalmic division of the trigeminal nerve branches into the nasociliary and long ciliary nerves, which supply the dilator pupillary muscle. The oculomotor nerve supplies the smooth muscle of the levator palpebrae superioris.