Biomedical Engineering Reference
In-Depth Information
reaching therapy for chronic patients has been verified with Arm Guide (Colombo
et al.
, 2008). Kwakkel
et al
(Kwakkel
et al.
, 2008). did a systematic review and
meta-analyses on the effects of robot-assisted therapy on upper limb recovery
after stroke. Only randomized clinical trials were included in the review and ten
studies, involving 218 patients, were included in the synthesis. Meta-analysis,
using upper limb part of FM score as the parameter, showed a non-significant
heterogeneous summary effect size (SES) in terms of motor recovery. Sensitivity
analysis of studies involving only shoulder-elbow robotics demonstrated a signif-
icant homogeneous SES for motor recovery. No significant SES was observed for
functional ability (ADL), using FIM score as the parameter. The authors attribute
the failure to observe improvement in ADL to the improper choice of ADL scales.
Another review article by Prange
et al
(2006). reached very similar conclusions.
While the effects of rehabilitation with robots are mostly reported on motor
recovery and improvement in ADL in the past, we focused more on the abnormal
synergy. In the upper limbs, the abnormal synergies include the flexor synergy
(characterized by simultaneous shoulder abduction, elbow flexion, and forearm
supination) and the extensor synergy (characterized by simultaneous shoulder
adduction, elbow extension, and forearm pronation). At the initial stage of
stroke recovery, abnormal synergies of the affected limbs are facilitated in a
reflex level. After a period of treatment, abnormal synergies are broken down
and voluntary normal movements are facilitated. Quantification of abnormal
synergies can be used as an objective indicator of recovery. In recent studies,
quantitative assessment indices of abnormal synergies have been developed based
on kinematics, (Dipietro
et al.
, 2007; Micera
et al.
, 2005; Sukal
et al.
, 2007; Ellis
et al.
, 2008) kinetics (Dewald
et al.
, Beer
et al.
, 2004; Ellis
et al.
, 2005), EMG
(Gerachshenko
et al.
, 2008; Dewald
et al.
, 1995; Lum
et al.
, 2003), transcranial
magnetic stimulation(Schwerin
et al.
, 2008) and functional magnetic resonance
images during voluntary movements of stroke patients. Abnormal coactivation
of the elbow flexors with the shoulder abductors, extensors, external rotators,
elevators and retractors has been found in the affected limbs of stroke patients
(Dewald
et al.
, 2001; Ellis
et al.
, 2005; Dewald
et al.
, 1995; Lum
et al.
, 2003). Prior
to pronator contraction, corticomotor excitability of the antagonist biceps brachii
was increased post-stroke (Gerachshenko
et al.
, 2008). These studies focused on
observing the patient's abnormal synergies under static conditions. However,
most movements in daily activities are dynamic. Researchers have determined
that abnormal shoulder abductor/elbow flexor coupling limited stroke patients
from reaching out in the work area (Sukal
et al.
, 2007; Ellis
et al.
, 2008; Beer
et al.
,
2004). In addition, stroke patients exhibited high correlation between shoulder and
elbow angles during a circle-drawing task (Dipietro
et al.
, 2007) These studies have
demonstrated that abnormal synergies occurred during voluntary movements. In
addition, most of the studies have focused on the analysis of abnormal synergies
in proximal joints such as the shoulder and elbow rather than in distal joints.
We considered both the proximal and distal parts of the upper extremity at the
same time. In summary, the synthesized results concluded that the robots showed
