SEESAW NYSTAGMUS

Timothy C. Hain, MD • Page last modified: August 1, 2022

There are basically two variants of the interestingly named "seesaw" nystagmus. Seesaw and "hemi-seesaw". This boils down to pendular and jerk, but for some reason, instead of following the usual rules of naming things by "pendular" or "jerk", it was named "seesaw" and "hemi-seesaw".

In the "Seesaw" ("pendular" variety), the eyes move as if they are on opposite ends of a seesaw. This is found mainly in visual disorders. We are OK with this name.

In the "hemi-seesaw", the eyes move for a half cycle in a similar way, and then they jerk back. This is mainly found in central vestibular disorders. The same eye movement is also often labeled as a jerk torsional nystagmus.

This has resulted in a literature about the same things, indexed under two different names. Hm. We will use the nomenclature of "Seesaw" for the pendular variant, and "central torsional jerk nystagmus" for the jerk variant.

Pendular Seesaw.

Halmagi and Hoyt (1991) reported a pendular seesaw from a unilateral midbrain lesion. This is unusual.

Halmagyi reported later in 1994 on "jerk" see-saw" from unilateral lesions of the midbrain, or in other words, the same location but a different eye moement pattern.

Barton et al (1995) reported on a woman with bitemporal hemianopia who developed prief periods of seesaw after a blink.

Leitch et al (1996) reported seesaw in a person with no optic chiasm. Dell'Osso and Daroff (1998) agreed that seesaw is present in both humans and dogs with achiasma. Apkarian and Bour (2001) also reported on a patient with achiasma. Rudich and Lesser (2009) reported on a similar patient with septo-optic dysplasia. Prakash et al (2010) reported another case.

Pal et al (2020) reported a case caused by a craniopharyngioma. Saluja reported a similar case (2020).

May and Truxal (1997) reported a case of nystagmus of the blind that was seesaw. Jeong et al (2009) reported a similar case. They also noted PAN, which is a reasonable association as it is likely also related in lack of escape from feedback control.

Rambold et al (1998) reported on a patient with congenital nystagmus that had a pendular seesaw pattern.

Eggenberger (2002) reported a case in brain injury with bitemporal hemianopsia. Similarly, Moura et al (2006) reported a case of seesaw in a giant pituitary adnenoma (with bitemporal hemianopia of course). Similarly, Yat-Ming Woo et al (2018) reported another patient.

Kim et al (2019) reported on the effect of convergence, fixation, and static head tilt on the pendular variety and suggested that it was removed (even though one was from visual issues and the other had platybasia). This is a little difficult to figure out.

 

So as a summary, pendular seesaw seems to be almost always associated with visual loss, often bitemporal hemianopia.

Central Jerk torsional nystagmus-- Hemi-seesaw.

Central torsional spontaneous nystagmus (Jerk type) is usually associated with lesions of either the medulla or the cerebellar peduncles (Leigh and Zee, 1995, 2015). The upper lesion may be in pathways that are going to the INC. There are also some reports from lesions between the midbrain and medulla (i.e. pons), presumably from interruption of ascending vestibular pathways.

Medullary jerk torsional nystagmus

The lateral medullary syndrome is reported to cause torsional nystagmus(Jeong et al., 2017, Morrow and Sharpe, 1988). Lopez et al (Lopez et al., 1992) reported 35 cases of torsional nystagmus, and reported MRI lesions often occurred in the area of the contralateral vestibular nucleus. Thus in theory, medullary lesion associated torsional jerk nystagmus should be a central vestibular nystagmus. While this is said to be the most common type, we have not seen this often in our otoneurology clinic setting.

Choi et al (2004) reported "hemi-seesaw" in a medial medullary infarction. Kahn and Leuck (2013) reported another case. Lee et al (2014) discussed medial medullary and suggested that there was initially a torsional-upbeat that converted into a "hemi-seesaw".

Pontine jerk torsional nystagmus

Choi et al (2009) reported a case of a lesion in the pons. Oh et al (2005) made a similar report. Gong (2012) reported yet another case with INO. The case of Cakir et al (2014), with INO, is presumably another case of this.

 

Midbrain jerk torsion nystagmus.

In midbrain lesions, the nystagmus is related to the drivers for torsion in the ocular motor nucleus (i.e. III) and related structures such as the interstitial nucleus of Cajal. Small amounts of jerk torsional nystagmus may last for years. In midbrain lesions, vertical saccades are often slowed. (Helmchen et al, 2002).

Below is a short movie of mixed jerk torsion and shimmering pendular

Midbrain vascular malformation Thalamic vascular malformation
Midbrain Vascular malformation in patient with nystagmus shown above. Thalamic portion of same vascular malformation

In the case illustrated in the movie above, there was a large thalamic/midbrain vascular malformation combined with a vertical tropia, a torsional nystagmus (fast phases up and to the right), and a shimmering nystagmus resembing that of spasmus nutans. This was associated with strong vertigo. Voluntary vertical saccades were not possible but the vertical VOR was functional. There was no palatal myoclonus.

Many of these patients with thalamic vascular lesions have a similar torsional jerk nystagmus. We have not previously seen a shimmering nystagmus like this in this context.

Other reports include that of Kanter et al (1987) with "see-saw" nystagmus in the right interstitial nucleus of Cajal (in the midbrain).

Halmagyi reported in 1994 on "jerk" see-saw" from unilateral lesions of the midbrain,which he suggested was due to a lesion in the INC (as did Kanter et al, but 17 years earlier).

Man and Fu reported a case combining convergence retraction nystagmus with see-saw. This was from a paramedian thalamomesencephalic infarct.

Lee and Kim reported a case in the midbrain again. (2018)

Rizvi et al (2018) reported acase of paraneoplastic seesaw, attributed to the midbrain. There sere superimposed saccadic oscillations.

Rare causes of jerk torsion

Jerk torsion also occurs in Migraine, in other brainstem lesions that affect the pathways for the vertical semicircular canals, and occasionally in lesions of the cerebellar nodulus such as in Medulloblastoma cases. In the most common entity, migraine, it is very weak and just barely observable even with the higher-resolution (focussed) video goggles.

Treatment:

Little has been written about specific treatment of either type of seesaw. See the "pendular nystagmus" page however for attempts to treat the pendular variant.

Regarding treatment of the central vestibular nystagmus, medications that suppress central vestibular pathways would seem logical, or medicaitons that increase cerebellar activity (perhaps 4AP). Baclofen (which reduces velocity storage) would seem worth trying, as would gaba agonists (such as benzodiazepines). Gabapentin is a generally useful drug for nystagmus and also would seem reasonable to try.

References