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Hyperdeviation associated with isolated unilateral abducens palsy.

M L Slavin
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Abstract

Sixteen patients with isolated unilateral abducens palsy were found to have an associated hyperdeviation (HD) in peripheral gaze on Maddox rod examination. In four patients, the chief complaint was vertical as well as horizontal diplopia. Vertical ductions were normal in each case and the maximal HD ranged from 8 to 16 prism diopters (PD) in 10 of 16 patients (62.5%) and from 4 to 7 PD in 6 of 16 patients (37.5%). In ten cases, an HD in primary as well as peripheral gaze was detected. The magnitude of HD did not correlate with the degree of abduction defect, and the HD was maximal to the side of the paretic lateral rectus muscle in 14 of 16 cases, with 2 cases greatest on direct lateral gaze; 6 cases, lateral upgaze; and 6 cases, lateral downgaze. The Bielschowsky head tilt test was positive in 1 of 14 cases, and the double Maddox rod test showed the absence of cyclodeviation in 10 of 12 cases tested. A variable HD was present in six cases. In two cases, up and downshooting of the paretic eye, respectively, was noted on attempted abduction. The HD diminished in synchrony with abduction improvement. Mechanical factors and vertical substitution movements may explain the HD.

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Abducens NerveAdultAgedDiplopiaFemaleHumansMaleMiddle AgedOphthalmoplegiaStrabismusComparative StudyJournal Article

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BibTeXRIS

M L Slavin. 1989. Hyperdeviation associated with isolated unilateral abducens palsy.. https://doi.org/10.1016/s0161-6420(89)32865-x

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PubMed2006

Modulation of corticospinal excitability by paired associative stimulation: reproducibility of effects and intraindividual reliability.

OBJECTIVE: Electrical stimulation of the median nerve followed by a magnetic pulse on the primary motor cortex (M1) is effective to cause an increase in the amplitude of motor evoked potential (MEP) registered in the target muscle with the interstimulus interval (ISI) at 25ms (paired associative stimulation, PAS). The aim of this study is to evaluate the reproducibility of PAS with ISI 25 (PAS25), assessed in two separate sessions. Intraindividual reliability of TMS measures was also evaluated. METHODS: Motor threshold of abductor pollicis brevis (APB), assessed at rest, and MEP amplitude of APB and abductor digiti minimi (ADM) were assessed before and after PAS25 in 18 healthy volunteers (nine males and nine females). RESULTS: Data showed a significant increase of MEP amplitude in the target muscle (APB) after PAS25 and a reproducibility of group effect in the two sessions, as assessed by ANOVA, but a lack of intraindividual reliability, as assessed by intraclass correlation coefficients (ICC). CONCLUSIONS: The results underline the reproducibility of mean effects and the need to be careful when comparing the same subject on different days. SIGNIFICANCE: Electrical stimulation of the median nerve followed by a magnetic pulse delivered on M1 after 25ms causes a reproducible increase in MEP amplitude, without showing an acceptable intraindividual reliability.

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