Convergence nystagmus

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Abstract
Convergence and/or retraction nystagmus are rate symptoms with high localizing value in the area of the anterior sylvian aqueduct, the posterior wall of the third ventricle, and the tegmental areas of the midbrain. It is proposed that two related forms of convergence-retraction nystagmus be recognized, namely, the "paretic type," which is apparent only when the patient attempts to look in the direction of gaze that shows weakness and the "spontaneous type," which is not linked to any gaze movement, is more regular, more intense, and marked, and tends to persist during sleep. Histologic serial sections in a case of spontaneous convergence nystagmus due to an astrocytoma of the brain stem seem to implicate three areas, the lesions of which may be the necessary condition for the appearance of the symptom: the midline nuclei of the oculomotor complex, the superior colliculi, and the reticulate substance of the midbrain and pons. The striking clinical similarities to the so-called palatal myoclonus are emphasized. It is suggested that many rhythmic motor abnormalities of brain-stem origin may develop on a background of reticulate-substance lesions with superadded disorders in the individual cranial nerve nuclei.

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