Parkinsonian gait is the type of gait exhibited by patients suffering from
Parkinson's disease. This disorder is caused by a deficiency of dopamine in
the basal ganglia circuit leading to motor deficits. Gait is one of the most
affected motor characteristics of this disorder although symptoms of
Parkinson's disease are varied. Parkinsonian gait is characterized by
small shuffling steps and a general slowness of movement, or even the total
loss of movement in the extreme cases. Patients with PD demonstrate reduced
stride length and walking speed during free ambulation while double support
duration and cadence rate are increased. The patient has difficulty starting, but
also has difficulty stopping after starting. This is due to muscle
hypertonicity. Abnormal gait characteristics
Patients with Parkinson's disease exhibit gait characteristics that are
markedly different from normal gait. While the list of abnormal gait
characteristics given below is the most discussed, it is certainly not
exhaustive. = Heel to toe characteristics =
Whereas in normal gait, the heel strikes the ground before the toes, in
Parkinsonian gait, motion is characterised by flat foot strike or
less often and in the more advanced stages of the disease by toe-to-heel
walking. In addition, PD patients have reduced foot lifting during the swing
phase of gait, which produces smaller clearance between the toes and the
ground. Patients with Parkinson's disease have
reduced impact at heel strike and this mechanism has been found to be related
to the disease severity with impact decreasing as the disease progresses.
Also, Parkinson patients show a trend towards higher relative loads in the
forefoot regions combined with a load shift towards medial foot areas. This
load shift is believed to help in compensating for postural imbalance. The
intra-individual variability in foot strike pattern is found to be
surprisingly lower in PD patients compared with normal people.
= Vertical ground reaction force = In normal gait, the vertical ground
reaction force plot has two peaks – one when the foot strikes the ground and the
second peak is caused by push-off force from the ground. The shape of the
vertical GRF signal is abnormal in PD. In the earlier stages of the disease,
reduced forces are found for heel contact and the push-off phase
resembling that of elderly subjects. In the more advanced stages of the disorder
where gait is characterized by small shuffling steps, PD patients show only
one narrow peak in the vertical GRF signal.
= Falls and freezing of gait = Falls and freezing of gait are two
episodic phenomena that are common in Parkinsonian gait. Falls and freezing of
gait in PD are generally thought to be closely intertwined for several reasons,
most importantly : both symptoms are common in the advanced stages of the
disease and are less common in the earlier stages, with freezing of gait
leading to falls in many instances. Both symptoms often respond poorly and
sometimes paradoxically to treatment with dopaminergic medication, perhaps
pointing to a common underlying pathophysiology.
Freezing of Gait: Freezing of Gait is typically a transient episode – lasting
less than a minute, in which gait is halted and the patient complains that
his/her feet are glued to the ground. When the patient overcomes the block,
walking can be performed relatively smoothly. The most common form of FOG is
'start hesitation' followed in frequency by 'turning hesitation' FOG can also be
experienced in narrow or tight quarters such as a doorway, whilst adjusting
one’s steps when reaching a destination, and in stressful situations such as when
the telephone or the doorbell rings or when the elevator door opens. As the
disease progresses, FOG can appear spontaneously even in an open runway
space. Falls: Falls, like FOG are rare in the
earlier stages of the disorder and becomes more frequent as the disease
progresses. Falls result mainly due to sudden changes in posture, in particular
turning movements of the trunk, or attempts to perform more than one
activity simultaneously with walking or balancing. Falls are also common during
transfers, such as rising from a chair or bed. PD patients fall mostly forward
and about 20% fall laterally. = Postural sway =
Postural instability in upright stance is common in end-stage PD and
compromises the ability to maintain balance during everyday tasks such as
walking, turning and standing up from sitting. An inability to adequately
balance the body's center of mass over the base of support combined with
inflexibility in body movements causes patients with advanced PD to fall.
Whereas postural sway in normal stance usually increases in patients with
balance disorders arising from stroke, head injury and cerebellar ataxia it is
often reduced in patients with PD. The reason for this because in PD the
problem appears to be a lack of flexibility in shifting postural
responses. This inflexibility increases the tendency to fall in these patients.
= Electromyographic studies = Electromyographic studies of the leg
muscles in PD patients have shown an extreme reduction in the activation of
the tibialis anterior muscle in the early stance and in the early and late
swing phases, and a reduction in triceps surae muscle bursting at push-off. The
quadriceps and hamstring muscles on the other hand, show prolonged activation in
the stance phase of gait. This implies that PD patients have higher passive
stiffness of ankle joints, show larger background EMG activity and more
co-contraction of leg muscles in stance. Stiffer joints lead to abnormal postural
sway in the PD patients. Gait improvement strategies
= Drugs = The most widely used form of treatment
is L-dopa in various forms. L-dopa is able to pass the blood–brain barrier as
a prodrug and is decarboxylated in the brain to the neurotransmitter dopamine
by the enzyme aromatic-L-amino-acid decarboxylase. In this way, L-DOPA can
replace some of the deficit in dopamine seen in Parkinsonism. Due to feedback
inhibition, L-dopa results in a reduction in the endogenous formation of
L-dopa, and so eventually becomes counterproductive.
Effect on gait parameters: The stride length and the kinematic parameters
related to the energy are Dopa-sensitive. Temporal parameters,
related to rhythm, are Dopa-resistant. Effect on falls and freezing of gait:
Levodopa treatment decreases the frequency and the akinetic type of FOG,
with a tendency for shorter FOG episodes. Results indicate that this is
primarily because L-dopa increases the threshold for FOG to occur but the
fundamental pathophysiology for FOG did not change. It has also been shown that
other dopamine agonists like ropinirole, pramipexole and pergolide that have a
strong affinity to D2 receptors increase the frequency of FOGs.
Effects on postural sway: Parkinson’s disease have abnormal postural sway in
stance and treatment with levodopa increases postural sway abnormalities.
During movement, it has been shown that early autonomic postural disturbances
are only partially corrected while the later occurring postural corrections are
not affected by dopamine. These results indicate that non-dopaminergic lesions
play a role in postural imbalance in PD patients.
= Auditory and visual cues = Basal ganglia dysfunctioning in PD,
causes it to stop acting as an internal cue for gait in Parkinson's patients.
Hence various external sensory cues like auditory and visual cues have been
developed to bypass the basal ganglia's cueing functions.
Visual cues: The visual cues are commonly transverse lines or rods on the
floor.Such cues have been shown to improve stride length and velocity in
Parkinsonian gait by substituting kinaesthetic feedback with visual
feedback for regulating movement amplitude. In addition gait initiation
has been shown to be significantly improved in PD patients compared with
auditory cues. Virtual reality glasses have also been developed recently to aid
walking in PD patients. Auditory cues: The auditory cues are
commonly rhythmic cues generated by a metronome or equivalent, sometimes
embedded in music, set at or slightly above the subject’s usual cadence.
Rhythmic auditory cues have been associated with increases in velocity
and cadence and sometimes stride after gait has been initiated. Auditory cues
have been shown to have little or no effect in gait initiation.
= Deep brain stimulation = Deep brain stimulation in the
pedunculopontine nucleus, a part of the brainstem involved in motor planning,
has been shown to improve gait function in patients with Parkinson's disease.
DBS in the subthalamic nucleus and the globus pallidus have also been shown to
have positive effects on gait abnormalities presented by Parkinson's
Disease patients. DBS in the STN has been reported to reduce freezing of gait
significantly at 1 and 2 year follow up. Contradictory results have been reported
on the effects on DBS on postural stability The results seem to be highly
location specific. The studies which do report positive effects suggest that the
effectiveness of DBS in improving postural stability is due to its ability
to affect non-dopaminergic pathways which are believed to cause postural
sway in PD patients. = Other treatments strategies =
Attention strategies: By consciously paying more attention to walking and
rehearsing each step before actually making it, PD patients have shown to
improve their gait. Sometimes, a companion walking alongside reminds the
patient to concentrate on gait or they create a visual cue to step over by
putting a foot in front of the person with PD over which the person must step.
This causes the patient to focus their attention on the stepping action, thus
making this a voluntary action and hence bypassing the faulty basal ganglia
pathway. Avoidance of dual tasks that require motor attention or cognitive
attention has also been shown to normalize gait in the PD patients.
Exercise: Physical therapy and exercise have been shown to have positive effects
on gait parameters in PD patients. Physiotherapists may help improve gait
by creating training programs to lengthen a patient's stride length,
broaden the base of support, improve the heel-toe gait pattern, straighten out a
patient's posture, and increase arm swing patterns.
Research has shown gait training combining an overhead harness with
walking on a treadmill has shown to improve both walking speed and stride
length. The harness assists the patient in maintaining an upright posture by
eliminating the need to use a mobility aid, a practice which normally promotes
a forward flexed posture. It is believed the activation of the central pattern
generator leads to the improvement in gait pattern.
Improving trunk flexibility, along with strengthening of the core muscles and
lower extremities has been associated with increased balance and an
improvement in gait pattern. Aerobic exercises such as tandem bicycling and
water aerobics are also crucial in improving strength and overall balance.
Due to PD’s progressive nature it is important to sustain an exercise routine
to maintain its benefits. Strategies such as using a vertical
walking pole can also help to improve upright postural alignment. The
therapist may also use tiles or footprints on the ground to improve foot
placement and widen the patient's base of support. Creative visualization of
walking with a more normalized gait pattern, and mentally rehearsing the
desired movement has also shown to be effective.
The patient should also be challenged by walking on a variety of surfaces such as
tile, carpet, grass, or foamed surfaces will also benefit the individual’s
progress towards normalizing their gait pattern.
Comparison with other gait disorders Subcortical arteriosclerotic
encephalopathy, also called lower-body parkinsonism, and cerebral ataxia are
two other gait disorders whose symptoms seem to closely resemble that of
Parkinson's. However, through regression analysis studies have revealed that in
Parkinson's, increasing the velocity of walking changes the stride length
linearly. However in SAE and cerebellar ataxia stride length had a
disproportionate contribution to increasing velocity, indicating that SAE
and cerebellar ataxia have common underlying mechanisms different from
those of Parkinson's. Socio-economic impact
Mobility issues associated with falls and freezing of gait have a devastating
impact in the lives of PD patients. Fear of falling in itself can have an
incapacitating effect in PD patients and can result in social seclusion leaving
patients largely isolated leading to depression. Immobility can also lead to
osteoporosis which in-turn facilitates future fracture development. This then
becomes a vicious circle with falls leading to immobility and immobility
facilitating future falls. Hip fractures from falls are the most common form of
fracture among PD patients. Fractures increase treatment costs associated with
health care expenditures in PD. Also, when gait is affected it often heralds
the onset of Lewy body dementia. References
External links Auditory Cues for Parkinson's
Visual Cues for Parkinson's Medfriendly: Festinating gait
About Physical Therapy GP Notebook