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C. SOMATOTOPIC FREQUENCY MAPPING AND ISOFREQUENCY COLUMNS

C. SOMATOTOPIC FREQUENCY MAPPING AND ISOFREQUENCY COLUMNS

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Affected hand:

behind mirror



Unaffected hand:

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)

%

100

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0



% or

mm



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Control

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Post



Control 50

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Lum/Prof



ROM



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Neural

Tensio n



Physical Performance



%



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Graph



Stereog



Sensory Discrimination

(% high=good; mm low=good)



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Control

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Post



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Motor

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Time for

Mot Acc



Motor Control

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

parameters.

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



© 2005 by Taylor & Francis Group.



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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



© 2005 by Taylor & Francis Group.



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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



© 2005 by Taylor & Francis Group.



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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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