doi: 10.2169/internalmedicine.6293-20
Intern Med 60: 2487-2490, 2021
http://internmed.jp

【 CASE REPORT 】

Macrosquare-wave Jerks Subsiding after Hydrocephalus
Treatment in a Thalamic Hemorrhage Patient
Kanta Tanaka 1, Daisuke Ando 2, Kenichi Irie 2,3, Masafumi Ihara 3 and Masatoshi Koga 2

Abstract:
A 54-year-old man suddenly developed impaired consciousness and left hemiplegia due to a right thalamic
hematoma. Emergent ventricular drainage for acute hydrocephalus improved the level of consciousness, but
macrosquare-wave jerks (MSWJ) consisting of a right-ward intrusive saccade and corrective saccade appeared. The MSWJ disappeared on day 2 when follow-up CT revealed improvement of hydrocephalus. However, on day 36, after ventricular drainage was clamped, the MSWJ reappeared. After ventriculoperitoneal
shunt, MSWJ again subsided. In this patient, hydrocephalus may have stretched the superior colliculus,
thereby decreasing activity of the fixation neurons and then omnipause neurons, and eventually resulting in
the reversible MSWJ.
Key words: intracerebral hemorrhage, hydrocephalus, macrosquare-wave jerks, superior colliculus, thalamus
(Intern Med 60: 2487-2490, 2021)
(DOI: 10.2169/internalmedicine.6293-20)

Introduction
Macrosquare-wave jerks (MSWJ) are rare, but have been
reported in multiple sclerosis and multiple system atrophy (1). We present the case of a patient with thalamic hemorrhage in whom MSWJ reproducibly disappeared after
treatment of hydrocephalus.

Case Report
A 54-year-old, right-handed man suddenly developed impaired consciousness and left hemiplegia. Glasgow Coma
Scale (GCS) score was 7 (E1V2M4). He showed right-ward
conjugate eye deviation that could be overcome with oculocephalic stimulation. The patient did not show anisocoria,
and pupillary light reflex was prompt on both sides. CT revealed a right thalamic hematoma measuring 3.3×2.0 cm
(estimated volume, 8.3 mL) with mesencephalic and intraventricular extension. Because acute hydrocephalus was evident, emergent ventricular drainage was performed. Level of
consciousness was improved the next day, with a GCS score
of 13 (E3V4M6). However, the presence of horizontal sac-

cadic eye movements was noted. The eye movement consisted of conjugate saccades that took the eyes away from
the fixation point toward the right and then returned them.
These saccadic movements could not be voluntarily suppressed by the patient. With eyes closed, these movements
were not observed through the eyelid. Skew deviation was
noted with hyperdeviation of the right eye without apparent
gaze palsies. The patient did not report oscillopsia. CT
showed that hydrocephalus was still apparent, but hematoma
had not expanded (Fig. 1A).
To elucidate details of the rhythm pattern for horizontal
saccades, video of the eye movements was analyzed using
motion analysis software (Kinovea, version 0.8.15; http://
www.kinovea.org) (2). This analysis revealed that eye oscillations occurred at a frequency of 2-3 Hz and that after taking the eyes off the fixation point, return occurred with a
median latency of 200 ms (range, 133-267 ms). The amplitude of horizontal saccades was estimated as >5° (Fig. 1B).
The eye movements were classified as MSWJ. On day 2 after onset, the abnormal saccades disappeared and follow-up
CT revealed improvement of hydrocephalus (Fig. 1C).
On day 36, after ventricular drainage was clamped, the
MSWJ reappeared without any apparent disturbance of con-

１

Division of Stroke Care Unit, National Cerebral and Cardiovascular Center, Japan, ２ Department of Cerebrovascular Medicine, National Cerebral
and Cardiovascular Center, Japan and ３ Department of Neurology, National Cerebral and Cardiovascular Center, Japan
Received: September 13, 2020; Accepted: January 14, 2021; Advance Publication by J-STAGE: March 1, 2021
Correspondence to Dr. Kanta Tanaka, tanaka19830311kanta@gmail.com

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DOI: 10.2169/internalmedicine.6293-20

Figure 1. (A) CT on day 1 after ventricular drainage. Hydrocephalus is still evident. The fourth
ventricle is filled with hematoma, but there is no hematoma extension into the cerebellar parenchyma.
(B) A plot of eye movements observed on day 1, demonstrating conjugate eye oscillations consisting of
a right-ward intrusive saccade and corrective saccade. To generate this plot, we analyzed video (MP4
format) at 30 frames per second using freeware motion analysis software (Kinovea). In the analysis,
the center of the pupil was tracked in every frame and distances from the initial fixation point were
recorded. Eye movement of 20 pixels corresponds with an amplitude of approximately 5°, according
to a trigonometric calculation based on the size of the eye ball on CT. Corrective saccades seem inaccurate, which may be due to hand movements during video recording or rotatory movements of the
patient’s head. (C) CT on day 2 with improved hydrocephalus. (D) After clamping the drainage, hydrocephalus exacerbated. (E) Three-dimensional fluid-attenuated inversion recovery imaging on day
36 shows the presence of subacute clots in the third and fourth ventricles. (F) Cerebral CT on day 40
shows improved hydrocephalus.

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DOI: 10.2169/internalmedicine.6293-20

Figure 2. A schematic illustration for possible mechanisms of reversible macrosquare-wave jerks
in the present case.

sciousness. CT revealed exacerbation of hydrocephalus
(Fig. 1D). MRI showed late subacute clots in the third and
fourth ventricles (Fig. 1E). A ventriculoperitoneal shunt was
placed on day 37 and MSWJ again disappeared on day 39.
Follow-up CT showed improvement of hydrocephalus
(Fig. 1F). At 6 months after onset, the modified Rankin
Scale score was 4 and no recurrence of hydrocephalus or
MSWJ was evident.

Discussion
Square-wave jerks are on the spectrum of saccadic intrusions and consist of: 1) a conjugate saccade away from the
fixation point; 2) maintenance of the eccentric eye position
for approximately 200 ms; and 3) return saccade back to the
initial position. Square-wave jerks with a large-amplitude
saccade typically >5° are called MSWJ (1). The characteristic feature in our patient was that MSWJ disappeared in association with improvement of hydrocephalus, and reappeared when hydrocephalus was exacerbated. Some leftward overshoots of the eye movements shown by motion
analysis might be attributable to hand movements during
video recording or rotatory movements of the patient’s head,
but suggest the possible coexistence of macrosaccadic oscillations.
For steady fixation, fixation neurons at the rostral pole of
the superior colliculus play an important role by exciting the
omnipause neuron located within the pontine raphe interpositus nucleus (3). In our patient, enlargement of the third
ventricle and cerebral aqueduct due to post-hemorrhagic obstruction at the fourth ventricular outlet foramina may have
stretched the superior colliculus, thereby decreasing activity
of the fixation neurons and then omnipause neurons, and

eventually resulting in development of the MSWJ (Fig. 2).
The reversible nature in our patient in response to treatment
of hydrocephalus also supports functional mechanisms rather
than destructive ones. Meanwhile, the superior colliculus
shows reciprocal connections with the mesencephalic reticular formation, and pharmacological inhibition of GABAergic
projections from the pars reticulata of the substantia nigra
leads to the generation of irrepressible saccadic intrusions (4, 5). Destructive lesions resulting from hematoma in
the midbrain might have promoted the development of
MSWJ in our patient. The thalamus also contributes the programming of saccades, and electrical stimulation of the internal medullary lamina elicits contralaterally directed saccades in monkeys (6). Right-ward direction of the intrusive
saccades in our patient might have been related to the rightsided thalamic lesion (7). The fastigial nuclei may also have
had association with the saccadic intrusions in our patient,
but CT showed no hematoma extension into the cerebellar
parenchyma (1). The lack of electrooculographic examination represents a key limitation. There is no reported data on
whether the rhythm pattern of MSWJ shown by motion
analysis software in our patient is equivalent to the pattern
on electrooculographic evaluation.
The authors state that they have no Conflict of Interest (COI).

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Ⓒ 2021 The Japanese Society of Internal Medicine
Intern Med 60: 2487-2490, 2021

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