**4. Demographic and clinical characteristics**

The comparison of demographic and clinical characteristics between series of pusher patients is complicated not only because of the several selection criteria discussed above but also due to the differences among the designs of the studies. Nevertheless, we summarized some demographic and clinical characteristics that have been published so far (table 2).

Pusher behavior has been found more frequently in older patients (table 2). More recently, Barbieri et al. found a correlation between age and perception of posture in healthy subjects (Barbieri et al., 2009). If the internal model of verticality is less robust in elderly people, it would be possible that this population could be more vulnerable to present PB. Though, the incidence of strokes is much greater in old than in young adults. It remains unclear the influence of the deterioration of postural control related to aging on the development of PB. Moreover, there is no investigation about the occurrence of PB in children with an acute encephalic lesion.

New Insights for a Better Understanding

**Male %**

**Age (mean±SD)**

71 (39-81)■ 68 (38-89)# Median (range)

68,5 (38-81) Median (range)

63 (51-79) Median (range)

70 (41-88) Median (range)

**Whole Sample (pusher patients)**

al. (2000) 46 (23) 60,87%\*\*

al. (2002) 23 (12) 66,6%

(2004) 8 (8) 100%

et al. (2006) 25 (15) 80%\*\*

al. (2005) 40 (14) 57,14%\*\* 66,1±7,5■

et al. (2006) 45 (21) 80,95%\*\* 68±9,4■

al (2008) 86 (6) 66,67%\*\* 62,67±11,33\*

(2008) 72 (36) 52,77%\*\* 74,6±9,1■

(2009) 19 (9) 66,66%\*\* 67,8±6,1 <sup>α</sup>

evaluation of pusher patients in published literature.

**Author (year)** 

Pedersen et

Karnath et

Karnath et

Pérennou et

Karnath et

Broetz et al.

Danells et

Santos-Pontelli et al. (2004)

Saj et al.

Karnath et

Pontelli et

Johannsen

Johannsen

Johannsen

Pérrenou et

Babyar et al.

Honoré et al

Ticini et al.

damaged patients. <sup>β</sup>

■

of the Pusher Behavior: From Clinical to Neuroimaging Features 245

**Right encephalic lesion %** 

al. (1996) 327 (34) 47,1% 75±7,6 52,9%\*\* NA NA 40% / 27,3% 47,1%

al. (2000) 10 (5) 40%\*\* 73,6±4,56\*\* 100% 100% 100% 100% 0%

al. (2002) 14 (3) 66,67%\*\* 52,67±5,03\*\* 100%\*\* 100%\*\* 100%\*\* 100% NA

al. (2004) 62 (39) 59% 69 (NA) 59% 82%▲ 56% 62% NA

(2005) 17 (5) 40%\*\* 69±6,6\*\* 100% NA NA 80% NA

al. (2005) 9 (9) 55,50%\*\* 71,8±5,9 55,50%\*\* 100%\*\* 66,6%\*\* 33,30%\*\* NA

67,8±8,3# 52,3%\*\* 91%■

et al. (2006) 25 (9) 66,67%\*\* 69,7±13 88,88%\*\* 100% NA 88% 0%

(2009) 18 (3) 33,3%\*\* 66,3±6,7 100% NA NA 100% NA

NA= not available.\*Data informed by the authors. \*\*Calculated from the data available in the reference.

Right brain damaged patients. #Left brain damaged patients. ▲Severe hemiparesis. <sup>α</sup>

Table 2. Overview of demographic and clinical characteristics observed on the first

Extra-thalamic brain damaged patients.

63,9±9,7# 64,28%\*\* 100% 89%■

100%#

72,5±8,5# 58,33%\*\* NA NA 0%■\*\*

64,5±16,6 <sup>β</sup> 66,6%\*\* 100% NA 100%■\*\*

530 (8) 62,5% 65,4±12,32\*\* 75%\* 87,5%▲\*\* 50%\*\* 75%\*\* 25%\*

**Paresis % Sensory** 

65,2% 100% 80%■

**deficit %** 

62%#

80%#

86,6%\*\* 100% NA 73% 7%

73%■ 90%#

\* 83,30%\*\* NA NA NA NA

75%\*\* 100% 58% 67%■

75% 100% 71% 83%■

**Neglect / Anosognosia Aphasia** 

> 80%■ 0%#

> > 0%#

0%#

67%■ 0%#

100%■ 10%#

27,77%#\*\*

7%■ 100%#

0%■ 100%#

0%■ 50%#

0%■ 60%°

0%■ 80%#

73,33%■\*\* 0%\*\*

0%#\*\* 33,3%\*\*

Thalamic brain


SCP= Scale for Contraversive Pushing. NA= not available. SD= Standard Deviation \*All stroke patients admitted in study period. \*\*Patients without lower extremity paresis on admission, with early death or early recovery were excluded. ¥ At least one point in each criterion. + More than 0 in each criterion.

Table 1. Dependent factors for the incidence of pusher behavior. PB= Pusher Behavior.

**Assessment Cutoff Inci-**

PB presence considered if 'pushing were present in any posture'.

SCP = 3

PB presence considered if both criteria were present.


SCP SCP ≥ 3¥ 1,5%




side

scale)


Stroke 8±2 days SCP SCP > 0

**dence** 

5,3%\* 10,4%\*\*

63% 23%

40-52%



**Time of PB evaluation (mean±SD)** 

31,7 days (range=8-57 days)

Stroke 52,71±39,58

Stroke <=30

SCP= Scale for Contraversive Pushing. NA= not available. SD= Standard Deviation \*All stroke patients admitted in study period. \*\*Patients without lower extremity paresis on admission, with early death or early recovery were excluded. ¥ At least one point in each criterion. + More than 0 in each criterion.

Table 1. Dependent factors for the incidence of pusher behavior. PB= Pusher Behavior.

**Author (year)** 

Pedersen et al. (1996)

Danells et al. (2004)

> Santos-Pontelli et al. (2004)

Lafosse et al. (2005)

Baccini et al. (2008) 26 **Institution characteristics** 

Stroke Unit (acute care, workup and rehabilitation stages)

5 different acute care hospitals

Neurologica l Unit of an Emergency Hospital

> Rehabilitation Center

2 Inpatient rehabilitation hospitals

**Etiologies included for screening**

All acute neurologic diseases

Stroke NA


NA= not available.\*Data informed by the authors. \*\*Calculated from the data available in the reference. ■ Right brain damaged patients. #Left brain damaged patients. ▲Severe hemiparesis. <sup>α</sup> Thalamic brain damaged patients. <sup>β</sup> Extra-thalamic brain damaged patients.

Table 2. Overview of demographic and clinical characteristics observed on the first evaluation of pusher patients in published literature.

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hand.1b: with two hands.

2000b).

and SSA.

of the Pusher Behavior: From Clinical to Neuroimaging Features 247

patients' legs hanging freely, while Pérennou et al. used a plantar support (Perennou, D. A. et al., 2008). Additionally, Pérrenou et al. did not screen for neglect. The influence of the

1a 1b 2

3 4 1. SHV: determined by manipulation of a wooden or metal rod to the earth-vertical position with the patients' eyes closed: this is essentially driven by proprioceptive afferences (Sharpe, 2003). 1a: with one

2. SVV: assessed by the patients' verbal command to adjust a visible line in complete darkness. It depends only on vestibular information with the assistance of the visual cues, independent of the proprioceptors and truncal graviceptors when the subjects are positioned in alignment with Earth vertical (Anastasopoulos et al., 1997; Mittelstaedt, 1998; Trousselard et al., 2004; Lopez et al., 2011). 3. SPV: assessed with subjects seated on a tiltable chair that is capable of rotating in a particular plane and is immobilized by lateral stabilization to prevent postural reactions. The examiner asks the subjects to state, in absence of vision, when they feel their body as vertically oriented (Karnath et al., 2000b; Sharpe, 2003; Perennou, D. A. et al., 2008). The tilting velocity must be 1.5º/s to minimize semicircular canal stimulation (Sadeghi et al., 2007), and acoustic and vibration feedback should also be taken into account. This is determined essentially by interoceptive inputs (Mittelstaedt, 1998; Karnath et al.,

4. SSA: evaluated by asking the patient to point to the position they perceived as straight ahead and

Fig. 2. Methodology description and the sensorial systems involved with SHV, SVV, SPV

The SVV (with a haptic component) and the SSA was found to be tilted to the side of the lesion in patients with neglect without PB and tilted to the contralesional side in patients with neglect and PB (Saj et al., 2005; Honore et al., 2009). Nevertheless, the SVV with no haptic influence conducted in a representative sample of pusher patients with and without neglect did not reveal a tilt of this perception46. Unfortunately, none of the above studies performed a systematic evaluation of the vestibular system for review see (Eggers & Zee, 2003). Although the dysfunction of the vestibular system is not assumed to be involved with PB (Perennou, D., 2005; Pontelli et al., 2005), its evaluation became imperative to dissociate

represents an egocentric reference framework (Richard et al., 2004; Saj et al., 2006).

presence of plantar support or neglect on the measurement of the SPV is unknown.

A possible gender influence on the incidence of PB was initially suggested (Lafosse et al., 2005). Nevertheless, analysis of several studies performed in large samples of neurologic injured patients found no persistent gender predominance (Danells et al., 2004; Santos-Pontelli et al., 2004; Lafosse et al., 2005).

Paresis of the contralesional extremities seems to be more frequent and more severe in pusher patients than in control encephalic lesioned patients (Karnath et al., 2005). On the other hand, severe PB can occur despite mild degree of hemiparesis (Santos-Pontelli et al., 2007). This observation raises an interesting question: is hemiparesis necessary for the development of the pushing behavior? We reported a patient that the resolution of the contraversive pushing did not depend on the resolution of the hemiparesis (Santos-Pontelli et al., 2007). Therefore, it is possible that hemiparesis may be more properly considered a commonly associated symptom of PB rather than an essential component of the syndrome and its damaged graviceptive circuitry. Further studies involving patients with pusher syndrome controlled for the degree of hemiparesis may be necessary to clarify the impact of PB itself on long-term prognosis after neurologic conditions.
