**3. Incidence**

242 Neuroimaging for Clinicians – Combining Research and Practice

test sitting and standing, the patient is passively tilted 30° (15–20° for standing) towards his/her paretic side (contralesional tilt) and then brought back to vertical alignment. Scores are then based on any voluntary or reflex movements noted in trunks, arms or legs according to the angle from true vertical where the resistance starts. For example, the sitting scores are as follows: 0=no resistance; 1=resistance starts at 5° tilt before full vertical; 2=resistance starts at 10° tilt before full vertical; and 3 is scored if they sense true vertical between 30° and 10° (D'Aquila et al., 2004). Total scores range from 0 for those without resistance to a maximum score of 17. Patients scoring 2 or greater are considered to exhibit

Fig. 1. A patient with left brain damage and severe pusher behavior. Examiner stabilizes the paretic leg of the patient in order to evaluate PB sings in standing position. The absence of this stabilization makes the observation of the characteristics of the disorder significantly difficult. Also, the examiner should guarantee the presence of a surface besides the patient in standing position, in order to observe the behavior of ipsilesional arm/hand activity to

D`Aquila et al. (2004) analyzed the concurrent validity of the BLS with Fugl-Meyer Balance score, Functional Independence Measure and length of rehabilitation stay is moderate and the inter-rater reliability is very high. However, there are no available data about sensitivity, specificity, internal consistency and responsiveness for this scale. According to the authors, one of the weaknesses of the BLS is that the assessments are subjective and can be affected by both patient and therapist comfort and familiarity with the test protocol (D'Aquila et al., 2004). It could be difficult for untrained examiners to interpret the 5 or 10-degree increments from true vertical to determine the resistance to passive correction during functional activities. Nevertheless, this is the only scale that includes PB evaluation during supine

Another assessment of PB was proposed by Lafosse et al.11 based on Davies' criteria (Lafosse et al., 2005), including (a) the presence of an asymmetrical posture or the midline of the body towards the hemiplegic side, and (b) the presence of resistance against any attempt at passive correction of any of these postures across the midline of the body towards the 'non-affected' or ipsilesional side. A patient is classified as having PB if both criteria are present. No ordinal scale is specified in this analysis. Further differentiation is used with the help of a 4-point scale that is based on the number of postures (standing, sitting and/or lying) in which contraversive pushing is present as follows: a score of 0 indicated no PB, a score of 1 indicated PB when

search for contact with the surface and of achieving extension of the elbow.

PB (lateropulsion).

rolling and walking.

Among the studies that considered the PB according to Davies' description, the incidence of this disorder ranges from 1.5 % to 63 % of patients with acute encephalic lesions (Table 1) (Pedersen et al., 1996; Danells et al., 2004; Santos-Pontelli et al., 2004; Lafosse et al., 2005; Baccini et al., 2006). Pedersen et al. (Pedersen et al., 1996) found an incidence of 5.3 % of PB in all stroke patients who were admitted in study period and 10.4 % of patients without lower extremity paresis on admission, when early death or early recovery were excluded. Danells et al. (Danells et al., 2004) found a PB incidence of 23% and 63% among 65 stroke patients with moderate to severe hemiparesis depending on the assessment cutoff. We found 1.5 % of pusher patients among all neurological inpatients of an emergency hospital (Santos-Pontelli et al., 2004), and Lafosse et al. (Lafosse et al., 2005) found an incidence of 40 % of left-brain-damaged patients and 52% of right brain damaged patients at a rehabilitation center. More recently, Baccini and coworkers (Baccini et al., 2006) compared the incidence of the PB based on 4 different criteria: 3 different cutoffs of the SCP (SCP > 0; SCP≥ 1,75; SCP ≥ 3) and a clinical examination according to Davies' recommendations that focused on careful observation of patients while lying down, sitting, standing, weight transferring and walking (table 1).

The comparison of the reported frequencies of PB is very complicated due to the differences in the timing of the first post ictal evaluation, inclusion/exclusion criteria, characteristics of the institutions where patients were investigated, etiologies included in the screening and the assessments of PB and their cutoffs.

The post ictal timing of the first identification of PB is an important aspect for incidence analysis. PB may not be observed if the assessment is done in outpatients or after several weeks because of early resolution of the behavior. On the other hand, if the assessment is conducted too early, pusher behavior can appear as a fluctuated symptom. Therefore, the screening of this behavior should be conducted as soon as clinical conditions allow and repeated afterwards during several weeks after the ictus onset.
