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 synd rome consists of miosis, ptosis, apparent enophthalmos, anhidrosis, and vas cular 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 Ame rican surgeons published the first accurate, detailed report of oculosympat hetic 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 n ot serendipitous, as one of the authors had previously worked in the labora tory 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) betwee n 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 supe riorly through the first thoracic and inferior cervical ganglia, which are frequently fused together and termed the stellate ganglion. The stellate ga nglion lies posterior to the origin of the vertebral artery. The second-ord er neurons continue through the ansa subclavia, a loop anterior to the subc lavian artery that connects the stellate and middle cervical ganglia, and t erminate in the superior cervical ganglion. The superior cervical ganglion is located at the level of C2 in the posterior carotid sheath. The third-or der neurons exit the superior cervical ganglion and ascend along the course of the internal and external carotid arteries. Ophthalmic branches enter t he superior orbital fissure and innervate the levator palpebrae superioris muscle and the dilator pupillae muscle.