No abstract

A patient with Horner syndrome from internal carotid artery dissection initially had a false negative hydroxyamphetamine test. Two months later, the ophthalmic signs had disappeared but the hydroxyamphetamine test was positive. This case illustrates that hydroxyamphetamine testing may be falsely negative in acute Horner syndrome because norepinephrine stores in oculosympathetic postganglionic terminals have not yet been depleted. However, the hydroxyamphetamine test may be positive even after the ophthalmic signs of Horner syndrome have disappeared.

We present two cases of posterior ocular staphylomas in axial myopia. CT findings of an enlarged globe with focal posterior bulging and scleral-uveal rim thinning appear to be specific for this diagnosis.

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Magnetic resonance imaging (MRI) can visualize the extent of corpus callosotomy performed for medically intractable epilepsy not amenable to focal surgery. Five patients underwent complete callosotomy and one an anterior callosotomy, aged 19 to 24 years, 21 to 53 months (prior to scanning). T1 images showed complete absence of the callosal shadow in five cases and visualization of the genu and splenium in the sixth case. T2-weighted pulse sequence spin-echo MRI showed intense image throughout the region of the entire callosum in the two cases with the longest postoperative course. The two middle cases showed intense T2 signal from the splenium, and the two latest showed no increase in T2 signal. We believe the increase in T2 signal in the transected callosum may represent an in vivo example of anisomorphic gliosis. T1 images demonstrate the anatomic extent of transection, while T2 images demonstrate the chemical and pathophysiologic sequence of transection. Thus, MRI is the imaging test of choice to evaluate callosotomy patients.