Introduction. Les étiologies des troubles visuels après un traumatisme crânien sévère sont multiples : affection du système visuel propre, paralysie des nerfs oculomoteurs ou troubles oculomoteurs centraux. Nous rapportons le cas extraordinaire d’un patient qui se plaignait de troubles visuels depuis un traumatisme crânien sévère, survenu 30 ans auparavant et correspondant à un nystagmus purement rotatoire provoqué par le regard en bas. Observation. Il s’agissait d’un homme de 50 ans, qui avait subi à l’âge de 21 ans un traumatisme crânien sévère avec coma de 4 semaines. Il se plaignait depuis d’une vision floue et d’une diplopie intermittente, spécialement pendant la lecture. Une paralysie traumatique du nerf pathétique droit avait été diagnostiquée et deux fois opérée sans amélioration des symptômes. L’examen clinique montra un nystagmus purement rotatoire provoqué par le regard vers le bas. La solution thérapeutique consista en des lunettes de lecture bifocals avec une addition placée près de la position primaire du regard, et des prismes 6ˆ base vers le bas.

Introduction. Visual disturbances are common after severe head trauma. Some authors report 50p.cent of theses patients having damage to the visual system, ocular motor nerve palsies, or central eye movement disturbances. Visual disturbances influence prognosis and outcome of neurological rehabilitation, and, in most cases, diagnosis and treatment require interdisciplinary care. Case report. We report here a 50-year-old patient who suffered from severe head trauma at age 20. After coming out of a 4-week coma, he suffered visual disturbances such as blurred vision and diplopia. Visual acuity was 1.0 and the visual fields were intact. The symptoms remained unexplained for a long time. One year after the trauma, right trochlear palsy was diagnosed and surgical treatment was performed. However, the symptoms persisted, and one year later, a second operation was performed without changing the symptoms. During many years, prisms or refractive corrections were used to improve the visual disturbances, and finally, a psychiatric treatment was started. At age 40, the patient became presbyopic and his visual problems increased, especially for reading. When he was examined for the first time in our consultation, corrected visual acuity was 1.0 with a small hyperphoria of the right eye. During careful examination of the eye downgaze, a conjugate pure torsional nystagmus was observed, which disappeared in primary gaze position. Conclusion. Pure torsional nystagmus is difficult to diagnose, especially when it is provoked only by one gaze direction such as in our patient. As a sequel of the severe head trauma with brainstem contusion, this type of nystagmus is a rare form of central vestibular nystagmus, and may by modified by head rotation or suppressed by convergence. The “treatment” of the patient’s burred vision when reading was easy by ordering goggles with a near part placed near the primary gaze position and a 6ˆ base down prismatic correction. Reading was then possible without provoking torsional nystagmus.