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C. SOMATOTOPIC FREQUENCY MAPPING AND ISOFREQUENCY COLUMNS
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in front of mirror
Right hand looks like left in mirror
FIGURE 11.6 Sensorimotor Mirror Training. While the subject looked at the mirror image
of the affected side, sensory and motor tasks were formed to provide positive feedback and
facilitate normal performance.
practice tasks such as: 1. the hand feeling normal; 2. the hand playing the instrument
normally and easily with appropriate speed and accuracy; 3. using eating utensils
normally; 4. writing without excessive gripping on the pen and moving the pen from
the elbow-shoulder; 5. doing detailed hand work; and 6. completing fine motor tasks.
Each subject was also encouraged to make a video of someone playing their instrument or doing tasks that they could view and imagine themselves doing the task.
As sensory processing skills improved, they were also asked to practice, small,
independent, isolated movements of the uninvolved and involved digits. If they
returned to instrumental play, they were asked to begin with new music.
This was a pre-experimental single group, prepost test study design with 12
subjects with FHd that participated in a controlled sensorimotor training program
for 6 months. All scores were reported descriptively and prepost test differences
were tested for significance using the paired Wilcoxon Test or the Paired t Test
depending on whether the dependent variables were ordinal or ratio scales.
a. Study Findings
All patients improved significantly on all parameters of clinical performance (25%
to 80%), bringing the performance of musculoskeletal parameters, sensory discrimination and fine motor control to the level of normal subjects. Task specific motor
control increased to 94%. All but two subjects returned to their previous work.
However, none gained 100% control of the hand. Rather, they still had to be careful
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Change: Pre Post Treatment (n=12)
(% high=good; mm low=good)
FIGURE 11.7 Summary of Change in Clinical Performance Following Sensorimotor Training for Patients with Focal Hand Dystonia. Post training, the subjects with FHd improved
their performance in all sensory and motor areas, matching their performance to controls in
all performance areas except accuracy on the Motor Accuracy Test where they required twice
a much time as normal subjects. Motor control on the target task improved to 85% of normal.
how they performed the target task Some no longer were playing professionally and
others were able to return to performance. (Figure 11.7).
3. Experiment III: Three Case Studies
The purpose of this study was to determine the effect of learning based sensorimotor
training on change in structure and clinical function in patients with FHd. Three
musicians were referred from the Peter Ostwald Health Program for Performing
Artists, University of California, San Francisco to participate in the study. Ten healthy
age matched controls served as reference norms for magnetoencephalography and
30 additional healthy subjects served as reference norms for the clinical performance
Two subjects lived outside the United States (#1 and #2) and the third was from
the San Francisco Bay Area (#3). All of the subjects agreed to participate in at least
8 weeks of physical therapy. All of the subjects had been diagnosed with FHd by a
neurologist approximately one year prior to this current intervention study.
All of the patients were otherwise healthy except for the complaints of painless,
uncontrollable curling of digits four and five (D4–D5) on the left hand when they
played their instrument. All indicated that the fifth digit excessively curled or
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extended and it was hard to lift D4. All three subjects noticed that it was more
difficult to control D4 and D5 when D3 was pressing down. All of the subjects were
completely independent in personal care and household management, and were well
integrated into the community. They all participated to some extent in fitness programs. One subject played for the symphony and was out on medical disability, one
subject played for a travelling performance group but was working at a desk job
when physical therapy was initiated, and the third subject was a full time music
student who was home for two quarters and was working part time as a waitress.
All subjects participated in measurements pre and post treatment including
magnetoencephalography and clinical testing as described in Experiments I and II22
(Byl et al., 2000c).19
Subject # 1 participated in supervised treatment for 12 weeks [two 6 week
sessions], subject #2 participated daily for two weeks and Subject # 3 participated
for 17 weeks). Consequently, the total period of treatment as well as the number of
visits with a physical therapist varied across subjects (23 visits for subject #1, 19
visits for subject # 2, and 23 visits for subject #3).
At baseline, somatosensory evoked responses were similar on the right and left
sides for controls except the spread of the digits on the dominant hand were greater
than the nondominant hand on the z-axis. On both hands, the order and location of
the digits on the z-axes followed a predictable pattern with D2-D5 progressing from
inferior to superior. For the subjects with FHd, both the amplitude and the spread
of the digits on the x,y, and z axes were reduced on the affected side compared to
the unaffected side and the digits were not sequentially organized from inferior to
superior for D1-D5 on the z axis on either side. Compared to controls, the FHd
subjects had a shorter SEF latency, the neuronal burst was higher on the affected
and unaffected sides for subjects #1 and #3, and the amplitude was lower in the
early phase (30–70 msec) for subjects #2 and # 3. The location of the hand representation on the x, y, and z axes were different for FHd subjects and controls.
Bilaterally, the spread of the digits on the x, y, and z-axes was greater for the subjects
with FHd (who were all musicians) than the controls.
In general, the reference controls achieved comparable clinical performance
bilaterally and across digits except motor reaction time was slower for digits 4 and
5. The controls did have some postural asymmetry and indicated their health sometimes interfered with daily activities (scoring 89.6% out of a maximum score of
100% for functional independence). On the other hand, at baseline, the subjects with
FHd demonstrated reduced accuracy and slowing in sensory processing compared
to controls on both the affected and unaffected sides. On the motor performance
tests, subjects #1 and #3 performed with reduced motor accuracy on both sides with
prolonged processing time. On the affected side, Task Specific Motor Control Scores
were approximately 50% of that measured on the unaffected side. Subjects #2 and
#3 had limited finger spread between D3–D4 and D4–D5 on the affected side (25
degrees on the affected side compared to 35–45 degrees on the unaffected side).
Compared to controls, the subjects with FHd were more likely to have poor posture,
positive signs of neurovascular entrapment and decreased strength in the lumbricals
(on both sides). Two of the subjects with FHd also had limited shoulder internal
rotation bilaterally (45–55º). The subjects with FHd were not working at their usual
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jobs but they were independent in activities of daily living. They reported difficulty
with functional activities (ranging from 63–90% of maximum performance on the
functional independence test).
Based on magnetic source imaging, the controls did not change with retesting.
However, for the three subjects with FHd, there was a general increase in the spread
of the digits and the area of representation on the cortex on the trained side (larger
than control subjects). There was a decrease in the area of representation on the
unaffected side. The order of the digits (D1–D5) on the affected side approximated
an inferior to superior progression from D1 to D5, but they were still less orderly
than controls. The amplitude of the evoked somatosensory potential, integrated over
time, was increased and similar to controls on the affected side.
On the clinical tests, the subjects with FHd performed between 80–90% on the
target task. Motor reaction time did not change significantly on either the affected
or unaffected side but was similar to controls. The subjects with FHd improved in
motor accuracy 27–42%, performing at similar accuracy as controls, however, the
time needed to complete the task was still longer than controls. There were measurable improvements in accuracy on all of the sensory tests (25–50%), performing
similarly or better than controls. However, the time required to perform the tests
remained longer than controls for two of the subjects. (subjects #2 and # 3 required
66–197 seconds compared to 37 seconds for controls). The subjects also improved
their range of motion, strength, and posture, raising performance to the level of
controls. The FHd subjects also showed improvement in functional independence,
similar to controls.
III. SUMMARY OF INTERVENTION STRATEGIES
The consistency of the findings of somatosensory hand degradation with clear
objective improvement in clinical function and neural structure following learning
based sensory retraining strengthens the evidence in support of aberrant learning as
one etiology of FHd. It is important to examine the involved and uninvolved
limbs.12,13,16,31,60,95,113,142 (Charness and Hallett 1992,1993;27,28 Fry l986;43 Jankovic
and Shale l993;60 Chen and Hallett, 1998; McKenzie et al., 1997,2003;82 Norkin
1995;262 Leijinse 1991; Lockwood 2003;82 Sanger et al., 2000ab,120 2001;121 Tinazzi
et al., 2002; Wagner et al., 1974) In addition, voluntary fine motor control at the
target task should be videotaped and scored for quality and severity (Tubiana and
Chamagne, 1998)134 Some clinicians may be able to use computer technology (e.g.
MIDI) to objectively document abnormalities of timing and force45,59,105,142,143 (Pascual-Leone et al., 1995).59
The clinical studies suggest that the development of FHd is multifactorial. The
development of involuntary task-specific dystonic movements can develop under
conditions of aggressive, stressful, stereotypical, rapid, repetitive hand use interacting with anxiety, perfection, previous trauma, joint inflexibility or hypermobility,
imbalance of extrinsics intrinsics, poor posture, neurovascular entrapment, quick
motor reaction time, but slow and inaccurate sensory discrimination. Each individual
may present with unique physical characteristics, however for those with a history
of overuse, an etiology of aberrant learning should be considered. Thus, intervention
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strategies should be based on the principles of learning. A learning based sensorimotor strategy was associated with improvement in, physical performance, posture,
sensory discrimination, task specific motor control, and somatosensory organization
of the hand. However, performance was not 100% on the target task. Within the
system of health care constraints, intervention was only once a week, reinforced
with a self-guided home program. This may not be sufficiently intense to completely
normalize somatosensory structure and task specific performance.
Patients successfully rehabilitated confirm the necessity to stop the abnormal
movements which usually means not performing the target task. These individuals
also express the need for mentoring and guidance to maintain self esteem and stay
focused on sensorimotor retraining, while also integrating biomechanically safe hand
techniques, avoiding stereotypical, near simultaneous, alternating contractions of
agonists and antagonists or end-range motions. The potential for rewiring the brain
will necessitate the incorporation of new computerized learning models that are fun,
rewarded, repetitive, engaging and self initiated at home. Randomized clinical trials
across multiple centers are needed to continue to identify the risk factors for developing FHd but also the most efficient, effective learning-based retraining strategies.
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