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Y.-R. Chen, Y. J. Liao; Saccade Abnormality in Idiopathic Intracranial Hypertension. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1988.
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To characterize the horizontal saccade abnormality and to assess the effectiveness of acetazolamide in patients with idiopathic intracranial hypertension (IIH).
We recruited 13 consecutive patients with IIH regardless of symptoms of presentation for clinical assessment and eye movement recording at an academic institution over one year. Six patients had paired recordings that allowed intra-subject comparison of the efficacy of acetazolamide treatment. Binocular infrared oculography at 500 Hz was performed before and during acetazolamide treatment. Randomized, repetitive visual stimuli were presented with custom program written in Presentation. Data was analyzed with custom-written programs in MATLAB and IgorPro.
While most patients had no symptomatic binocular diplopia at presentation, those with clinically evident abduction abnormality exhibited small esophoria in primary gaze, which worsened at left or right gaze. Reflexive horizontal saccades showed bilateral or unilateral abduction deficits in the majority of patients with IIH. This was evident during the plateau phase of the saccade as well as in the initial dynamic overshoot. In 6 patients with paired recording, 83% had abduction deficits. The difference between the abducting and adducting eyes in 12 degree rightward saccades was 0.984 ± 0.202 deg, and for 12 degree leftward saccades, 0.809 ± 0.159 deg. Treatment with acetazolamide (1000-2000 mg per day) led to the rapid resolution of abduction deficit and ocular misalignment, with the average plateau difference of rightward saccade improving by 86% (0.134 ± 0.153 deg, n = 6, P = 0.0016), and the leftward saccade improving by 67% (0.267 ± 0.154 deg, n = 6, P = 0.0175). The amelioration of ocular mismatch during reflexive saccades occurred early, well before the resolution of papilledema.
Abduction deficit, most likely a result of cranial nerve VI dysfunction due to elevated intracranial pressure, occurred in more than 50% of patients with IIH, even in the absence of subjective binocular diplopia. This abnormality quickly resolved following acetazolamide treatment. Our study highlighted the utility of eye movement recording in assisting the diagnosis and monitoring of patients with IIH.
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