Traumatic and latrogenic Horner syndrome: Case reports and review of the literature

Oculosympathetic paresis, or Horner syndrome, results from any lesion that interrupts the neuronal pathways from the hypothalamus to the eye. The syndrome consists of miosis, ptosis, apparent enophthalmos, anhidrosis, and vascular dilatation ipsilateral to the lesion. This constellation of findings was first described in animals by the French physiologist Claude Bernard.(1) Johann Friedrich Horner (1831-1886), a Swiss ophthalmologist, is credited with the first complete description of this syndrome in humans in 1869.(2) However, in 1864, 5 years before Horner's eponymous description, three American surgeons published the first accurate, detailed report of oculosympathetic paresis.(3) When the three surgeons treated a young Civil War soldier who sustained a gunshot wound to the right neck, they observed right-sided miosis, ptosis, enophthalmos, and facial flushing. They correctly ascribed the phenomena to cervical sympathetic nerve injury. This observation was not serendipitous, as one of the authors had previously worked in the laboratory of Dr. Claude Bernard.(1) The sympathetic innervation of the eye consists of a three-"order" system (Fig. 1). The first-order neuron originates in the posterolateral nuclei of the hypothalamus. The efferent fibers descend through the tegmentum of the midbrain and pons and terminate in the ciliospinal center (of Budge) between C8 and T1. The second-order fibers exit the cord via the ventral roots of C8, T1, and T2 and ascend in the sympathetic chain. The fibers course superiorly through the first thoracic and inferior cervical ganglia, which are frequently fused together and termed the stellate ganglion. The stellate ganglion lies posterior to the origin of the vertebral artery. The second-order neurons continue through the ansa subclavia, a loop anterior to the subclavian artery that connects the stellate and middle cervical ganglia, and terminate in the superior cervical ganglion. The superior cervical ganglion is located at the level of C2 in the posterior carotid sheath. The third-order neurons exit the superior cervical ganglion and ascend along the course of the internal and external carotid arteries. Ophthalmic branches enter the superior orbital fissure and innervate the levator palpebrae superioris muscle and the dilator pupillae muscle.