Approach to diagnosis and
treatment of dystonia
Terence D. Sanger
University of Southern California
Dept. Biomedical Engineering, Child Neurology, Biokinesiology
Types of Dystonia
Hypertonic (stiff)
Hyperkinetic (too much movement)
Hypertonia: Resistance
to passive movement
• Spasticity: velocity-dependent,
asymmetric and/or a catch
• Dystonia: sustained or intermittent
muscle contractions cause twisting and
repetitive movements or abnormal
postures
Reflexes in Spasticity
Phasic
Tonic
Characterized by catch: Sudden ONSET determined
by position and velocity; not proportional.
Van Doornik
and Sanger,
2009
Tonic stretch reflexes maintain fixed
dystonic postures.
Hyperkinetic disorders:
Excess involuntary movement
Dystonia is defined as a movement disorder in
which involuntary sustained or intermittent muscle
contractions cause twisting and repetitive
movements, abnormal postures, or both.
Chorea is a random-appearing sequence of
movements or movement fragments with
continuously variable timing, duration, direction,
and anatomic location.
Athetosis is a continuous flowing or writhing
movements that prevent maintenance of a stable
posture.
Hyperkinetic Dystonia
Where does dystonia come
from?
We are not really sure
Best guess is often basal ganglia
How the Basal Ganglia Work
Motor command in the cortex...
... is amplified in basal ganglia...
...and sent back to the cortex.
Dopamine controls whether the
signal is increased or decreased.
Over time, dopamine “teaches”
the basal ganglia which signals
to increase and which to
decrease.
What goes wrong?
Too little dopamine, or injury to
basal ganglia, and the output
may be too much or too little.
Too little output -> Parkinsons
Too much output -> Dystonia
Involuntary and continual
activation of a region of cortex.
Long pulse trains to cortex trigger
stable multijoint postures
Graziano, Taylor, Moore 2002
What causes dystonia?
Inserted postures in dystonia...
... are caused by involuntary stimulation of motor cortex...
... by the basal ganglia (or anything else).
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•
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Approach to
Treatment
Etiology-specific:
treatment of underlying
disease
Anatomy-specific: treat
sensory, basal ganglia,
frontal, or cerebellar
origin
Nonspecific: reduce
stretch reflexes
Approach to
Treatment
•
Etiology-specific:
treatment of underlying
disease
For AHC: Flunarizine,
or treat underlying
genetic disorder.
•
Approach to
Treatment
Anatomy-specific: treat
sensory, basal ganglia,
frontal, or cerebellar
origin
Levodopa,
Trihexyphenidyl, DeepBrain Stimulation
•
•
•
•
Medicines for
Dystonia
Artane: takes months to work; may affect
attention; works in many types of dystonia
Sinemet: works quickly; naturally-occurring
neurotransmitter; only works if dopamine
deficit
Clonazepam: works for hyperkinetic
dystonia; can cause drowsiness and
drooling
Tetrabenazine: works only for chorea
Approach to
Treatment
•
Nonspecific: reduce
stretch reflexes
Baclofen, Intrathecal
Baclofen,
Benzodiazepines,
Botulinum Toxin
•
•
•
•
Medicines for stretch
reflexes
Baclofen: primarily for spasticity; may help
dystonia at high doses; may cause trunk and
neck weakness
Botox: localized to targeted muscles; effect
lasts 3 months; requires repeated injections
Tizanidine: probably no better than baclofen
Dantrolene: causes permanent changes to
muscle
Treatment
Often need a combination of treatments.
Botulinum toxin if only a small number of muscles are the
problem.
Trihexyphenidyl (Artane) and Levodopa (Sinemet) affect
the whole body.
Deep-brain stimulation
Wire in basal ganglia
blocks abnormal activity
and reduces excessive
stimulation of the motor
cortex.
Pacemaker is in the
chest. Can be
programmed externally.
Batteries last 2-5 years.
Taskforce on childhood
motor disorders
Multi-disciplinary
Funded by NIH
Consensus definitions and measurement technology
Conclusion
Treatments for dystonia target multiple
places in the chain from the disease to the
symptoms.
Need more research to find new treatments
that are less invasive.
Need to understand the details of dystonia
in AHC
short-term rescue treatment
prevention of progression