Dear Editor-in-Chief,
Balint-Holmes’ syndrome (BHS) is a neuropsychological condition related to bilateral
lesions in the parieto-occipital cortex, characterized by simultanagnosia, ocular
apraxia, and optic ataxia [1, 2]. Simultanagnosia is the inability to detect multiple
visually presented objects (dorsal type) and to recognize the individual parts of
a multipart object (ventral type). Ocular apraxia is an impairment in saccade initiation
and visual pursuit, despite unrestricted ocular movements. Optic ataxia is the difficulty
in performing movements directed to visual objects, in the absence of primary sensory
and motor disorders.
BHS has been described mainly after cerebrovascular events, but also in relation to
HIV encephalopathy, carbon monoxide poisoning, or posterior cortical atrophy [1, 2].
Here we report a patient showing BHS following bilateral parieto-occipital damage
due to a stroke after SARS-CoV-2 infection.
A 55-year-old male teacher, with systemic arterial hypertension under pharmacological
treatment (ramipril and amlodipine) and mild hypercholesterolemia, suddenly developed
fever, cough, dyspnea, ageusia, and anosmia in March 2020. After detection of SARS-CoV-2
viral nucleic acid by a nasopharyngeal swab, the diagnosis of coronavirus disease
2019 (COVID-19) was made. In a few days, the patient was admitted to intensive care
unit for worsening of respiratory distress.
At discharge from intensive care unit, one month later (April 16, 2020), DG presented
with tetraplegia and vision loss. A magnetic resonance scan showed temporo-parieto-occipital
cortico-subcortical lesions in the right hemisphere and parieto-occipital cortico-subcortical
lesions in the left hemisphere (Fig. 1) which were compatible with a bilateral stroke
in the territory of the inferior division of the middle cerebral artery.
Fig. 1
Axial brain T1-MR scan showing the wide right temporo-parietal and the left parietal
lesions
When the patient was transferred to a rehabilitation unit (May 2020), he was alert
and cooperative, and showed mild bilateral hyposthenia with hyporeflexia, mild tactile
sensory loss, and left homonymous hemianopia. The neuropsychological examination at
bedside revealed left spatial neglect (Fig. 2a) associated with word finding difficulties
and mild executive dysfunction.
Fig. 2
a Patient’s performance in a line cancellation test. b Percentage of correct responses
in a task to assess optic ataxia: the patient was asked to reach for a visually displayed
object in the left (LF), right (RF), or central (C) visual fields by using his left
(LH) or right (RH) hand. c Left, percentage of correct response in a task to assess
dorsal simultanagnosia: the patient had to look for a visually presented object in
the left or right visual fields, or two objects displayed simultaneously at the center.
Right, ventral simultanagnosia: images containing both local features (parts) and
global features (the whole) were shown to the patient (e.g., a large letter “G” formed
by small letters “E,” or a big square whose sides were made by small circles); the
response corresponds to the local or global features reported by the patient. d Percentage
of correct responses in two tasks assessing gaze apraxia: left, static test—an object
was presented in four possible locations (left, right, up, down); the patient had
to move the eyes toward the object with no head movement. Right, dynamic test—an object
was slowly moved by the experimenter from left to center (LC), center to left (CL),
center to right (CR), or right to center (RC) on the horizontal axis; the patient
had to follow the object with his eyes with no head movements
When required to reach for visually displayed objects, the patient revealed marked
impairments, mainly in reaching for objects located in his left visual field with
his left and right hands, and in his right field with his left hand (Fig. 2b). This
behavior was consistent with the classical descriptions of optic ataxia [2].
The patients also showed obvious impairments in the visual perception domain, as he
failed to recognize large silhouettes made up of small parts; moreover, on some occasions,
the patient could not identify two objects simultaneously presented in his central
visual field (Fig. 2c). These findings demonstrated the presence of both ventral and
(to a small degree) dorsal simultanagnosia, combined with left visual hemineglect.
The clinical picture was also characterized by impairments in static and dynamic tests
assessing the ability to direct gaze toward specific targets. The patient proved to
be unable to move his eyes toward statically presented objects, particularly left-located
objects, without making concurrent head movements; moreover, he could not gaze at
an object slowly moving along the horizontal axis (Fig. 2d). These tasks thus revealed
severely impaired saccade initiation and visual pursuit (ocular apraxia).
All these clinical characteristics constitute the full-blown picture and are pathognomonic
of BHS, closely resembling the original descriptions by Balint, with a main involvement
of peripheral visual fields and of the left-hand movements in peripheral vision [2].
To our knowledge, this is the first case report of BHS following bilateral parieto-temporo-occipital
stroke correlated with SARS-CoV-2 cerebral vasculopathy.
As several studies demonstrated that SARS-CoV-2 infection can affect the central nervous
system [3–5], we could consider it as a likely causal factor in DG. Presence of vascular
risk factors in our patient is consistent with recent evidence suggesting that acute
cerebrovascular events related to COVID-19 are more frequent in patients with severe
respiratory distress and common cardiovascular risk factors [3]. Ageusia and anosmia
are further relevant signs of nervous system involvement in SARS-CoV-2 infection [4].
The exact pathophysiological mechanisms of the association between SARS-CoV-2 and
stroke have to be fully comprehended [3–5]. Literature suggests that such an association
could be mediated by misdirected immune response inducing coagulopathy and vasoconstriction.
Systemic inflammation and the potential direct action of the virus may cause endothelial
dysfunction, resulting in a hypercoagulable state and consequent ischemic strokes
[3].
Our observations are in line with recent studies on the impact of SARS-CoV-2 infection
on the central nervous system. As distribution of strokes related to COVID-19 has
not been analyzed yet, our report underlines that they can determine even quite rare
neurological syndromes, such as BHS, for which SARS-CoV-2 infection might represent
a possible risk factor.