A 78-year-old female patient without vascular risk factors presented with sudden left eye deviation at awakening. Neither diplopia nor other symptoms were reported. On admission, left eye exotropia at primary gaze position and bilateral internuclear ophthalmoplegia (bINO) were found (figure 1A,B). Convergence in the near sight was impossible. Vertical conjugate gaze was flawless. Visual acuity was normal in both eyes. Cover–uncover test (see online supplementary video) was performed. Strabismus disappeared after 1 week.