Macrosaccadic oscillations (MSOs) are large to and fro saccadic intrusions (hypermetric saccades) which may occur around the fixation point, in that they straddle and overshoot fixation without foveation of the target. MSOs take the eye off target by an amplitude of 5°–15° and return after an intersaccadic interval of 70–150 ms.
MSOs are usually induced by a gaze shift, but may occur during attempted fixation or even in darkness. Retinal slip following horizontal head impulses can also trigger MSOs.
The oscillations occur in bursts in which the saccadic amplitude increases and then decreases; eye movement recordings show a characteristic spindle shape.
Pathogenesis
Macrosaccadic oscillations occur from cerebellar lesions that alter the calibration of saccadic size, resulting in hypermetric primary and corrective saccades that oscillate around the desired eye position. MSO occurs with pontine or cerebellar lesions (eg, tumours, MS, stroke, paraneoplastic syndromes) that affect either the omnipause neurons or the fastigial nucleus input to premotor burst neurons.
Treatment
Memantine. 5 mg/d orally ; increase by 5 mg/wk to maximum daily dose of 20 mg (10 mg 2 times a day)
Case of compression of brainstem and cerebellum by epidermoid cyst of the 4th ventricle.
(vv)MS oscillations.mp4(tt)
From: Choi SY, Choi YJ, Choi JH, Choi KD. Teaching Video Neuro: Macrosaccadic oscillations induced by horizontal head impulses. Neurology. 2017;89(9):e116.
(vv)SWJMO.mp4(tt)
From: Gold D.Square wave jerks and macrosaccadic oscillations in a patient with a cerebellar tumor. Video. [Neuro-Ophthalmology Virtual Education Library: NOVEL Web Site]. 2018. Available at: https://collections.lib.utah.edu/ark:/87278/s6wm5qh3