Spasmus nutans-like nystagmus is often associated with underlying ocular, intracranial, or systemic abnormalities.

BACKGROUND: There is uncertainty as to whether spasmus nutans (SN) is an isolated idiopathic entity or whether there are underlying conditions that could cause or be associated with the nystagmus. We undertook this study to determine the frequency of ocular, intracranial, and systemic conditions in patients with nystagmus having characteristics of SN. METHODS: We performed a chart review of 22 consecutive patients examined from 2000 through 2005 at the Dean McGee Eye Institute and Children' Hospital of Oklahoma with nystagmus consistent with SN. We collected information related to gender, age at presentation and age at final visit, visual acuity, refractive error, laterality of nystagmus, presence of head nodding and torticollis, pattern of strabismus, neuroimaging and electroretinography results, and other associated clinical findings. RESULTS: Visual acuity was reduced in 75% of eyes at presentation and 58% of eyes at last visit. Eight patients had significant refractive error. Seven patients had strabismus. Two patients had chiasmal gliomas. Four patients had cone or rod/cone dystrophy. Only three patients had no associated ocular, intracranial, or systemic conditions. CONCLUSIONS: A substantial proportion of patients presenting with SN-like nystagmus have important underlying ocular, intracranial, or systemic abnormalities that may require evaluation and management.

The effects of caffeine on the inducibility of atrial fibrillation.

INTRODUCTION: There is widespread belief that caffeine consumption is linked to atrial arrhythmias; however, there is a relative lack of systematic evidence to support the assertion. The purpose of this study was to investigate whether caffeine, in doses equivalent to daily use in the general population, alter the propensity for atrial fibrillation (AF) in an experimental model comparing normal and simulated predisposition to AF. METHODS AND MATERIAL: Caffeine (caffeine Na benzoate, 50:50 mixture) was administered intravenously at 1, 3, and 5 mg/kg doses in dogs producing serum levels of 2 to 4, 5 to 7, and 8 to 10 microg/mL. To simulate focal AF, premature stimulation from the right superior pulmonary vein was delivered at 2x, 4x, and 10x threshold at a rate of 180/min (S(1)-S(2) = 330 milliseconds) without and then with low-level stimulation of ganglionated plexi (GP) at the entrance of the right superior pulmonary vein. The window of vulnerability (WOV), a measure of the propensity for AF inducibility, was determined by the longest coupling interval of the premature beat (S(1)-S(2)) minus the shortest S(1)-S(2), which induced AF. The cumulative WOV is the sum of the individually determined WOV. RESULTS: At each serum level of caffeine, the cumulative WOV was lower without rather than with GP stimulation compared with control. The cumulative WOV for both the stimulated, that is, predisposed to AF, and nonstimulated, that is, normal groups, exhibited a significantly lower average as compared with that exhibited by the control group (P