Distinguishing postganglionic from preganglionic lesions. Studies in rabbits with surgically produced Horner's syndrome
B. Skarf and J. S. Czarnecki
It has been suggested that the pupillary response to hydroxyamphetamine
hydrobromide eyedrops will separate distal from proximal lesions of the
sympathetic pathway from the brain to the eye (the pupil fails to dilate in
postganglionic lesions). We studied the pupillary response to
hydroxyamphetamine in two groups of rabbits with surgically produced
Horner's syndrome. Rabbits in one group had postganglionic lesions. In all
animals, a miotic pupil developed ipsilateral to the surgical lesion, and
oculosympathetic paresis was confirmed in each by testing pupillary
response to topically applied cocaine. In rabbits with postganglionic
lesions, hydroxyamphetamine failed to dilate the miotic (Horner's) pupils
as well as it dilated the normal pupils, while in rabbits with
preganglionic lesions both miotic and normal pupils dilated equally.
Hydroxyamphetamine appears to be a diagnostically useful drug in Horner's
syndrome.
