Phenomena of Dystonia                                 Standard Approach to Examination of Dystonia        

Examination of Dystonic Tremor                     Examination of Spasmodic Dystonia                Examination of Cervical Dystonia

Three important aspects of dystonia should be highlighted before delineating the details of the clinical examination:

1. Abnormal Physiology

With respect to examination findings, it is appropriate to highlight two areas of abnormal physiology found in dystonia; both are likely to depend on an inbalance between excitatory and inhibitory circuits because of defective inhibitory mechanisms operating at various levels of the central nervous system¹:

• The presence of sustained simultaneous co-contraction of agonist and antagonist muscles (which can be triggered or worsened by task-specific actions and relieved by some sensory tricks)
• An excess of movement with loss of selectivity, and with involvement of adjacent or distant muscles (“overflow”).

2. Variability of Phasic Dystonic Movements

An important clinical feature of dystonia, which makes for a challenging differential diagnosis with potential confusion with other movement disorders, is the variable speed of phasic dystonic movements.  These features have to be looked for in all movement disorders, either fast or slow, especially when the immediate impression is that of a tremor, tic, chorea, or myoclonus. Phasic dystonic movements include:

• Rapid and jerky movements, resembling myoclonus or tics
• Slow (athetoid dystonia) movements
• Rhythmic (dystonic tremor)

3. Progression of dystonia with time²:

• Dystonic movements are frequently worsened during voluntary movement (action dystonia), and idiopathic dystonia commonly begins with a specific action, ie action dystonia. 
• In some cases, as the dystonic condition progresses, less specific action of the leg affected by dystonia may activate dystonia (eg, when tapping the floor).
• With further evolution of underlying dystonia, action in other parts of the body can induce dystonic movements of the involved leg, a state referred to as overflow.
• With further deterioration, dystonia may be present even at rest. Eventually the limb may go into sustained posturing.

 

 

 

From: Martino D, Espay AJ, Fasano A, Morgante F. Disorders of Movement: A Guide to Diagnosis and Treatment. Berlin-Heidelberg: Springer; 2016

 

Phenomenological features of dystonia.

1. Dystonia is related to voluntary movement:

• Dystonia and dystonic postures are often triggered or worsened by attempts at voluntary movement or posture, and are associated with the phenomenon of overflow.
• Movements are often sustained at their peak, and dystonic movements often resemble a spasm.
• The presence of abnormal postures that are superimposed upon, or substitute for voluntary movements, is a characteristic feature of dystonia³.
• Dystonia is typically influenced by voluntarily maintained posture, as in antigravity support.
• At an extreme of its relationship to voluntary movement, dystonia may only be present with specific voluntary actions.
• Speed of contractions of dystonic movements may be slow or rapid, but at the peak of movement, it is sustained⁴.

2. Dystonia is position sensitive:

• Consequently it is important to examine for features of dystonia by careful inspection of the arms during posture holding and batwing positions (arms flexed at the elbows and the forearms pronated with the fingers held near the nose).
• Dystonic features may be brought out by asking the patient to hold the arms extended in front of their body for 30–60 seconds. In this setting, dystonic thumb flexion and other dystonic postures may be seen.
• In addition, the patient should slowly rotate the outstretched arms from pronation to supination, since this may show a position-specific tremor, indicating an underlying dystonic tremor.
   

3. Presence of a null point:

• Certain positions may be associated with lessening, or virtual disappearance of the dystonia or tremor, termed a null point. For example, when the body part is positioned in the maximum direction of the movement (eg turning the head to the right in right laterocollis)⁵.
• Limbs may be passively positioned by the examiner in search for a “null point” as well. Common positions include extreme pronation, supination, flexion and extension of the wrists.
• Lessening of movements or detecting a null point may be sought by asking the patients to adopt their preferred posture (usually opposite to the direction of movement).
   

4. Dystonia has directionality:

• After a large or moderate sized movement, the abnormal dystonic posture will tend to lessen gradually to a preferred position (usually opposite to the direction of movement).
• Usually, dystonic tremor increases in amplitude when moving away from the usual direction of the dystonic contractions, and tends to show much greater right-left asymmetry than essential tremor.
• In patients with dystonic tremor of the head, the head tends to be pulled in one direction and released back in the other direction, rather than for the head to rotate symmetrically around a central vertical axis. As the patient moves their head from right to left, there may be clear asymmetry of tremor.
   

5. Dystonia is patterned and relatively stereotyped.  In children, foot inversion, wrist ulnar deviation, or lordotic trunk postures are particularly common³.

• The movements usually have a patterned and repetitive nature, and are consistent and predictable since they involve the same group of muscles, as opposed to chorea, where movements are random.
• The movement is predictable, as it involves one or more body regions.
• Contractions have a consistent direction, or result in a consistent posture.
• It should also be noted that there may be multiple dystonic postures in the same patient, so that different dystonic postures may be combined³.
   

6. Dystonia involves specific locations. 

These regions may be involved individually (focal dystonias) or in different combinations (segmental, multifocal, or generalized dystonias). Body distribution may change over time, typically with progression to previously uninvolved sites.

• The upper or lower cranial region
• The cervical region
• The larynx
• The trunk
• The upper limbs
• The lower limbs.
   

7. Dystonia is associated with abnormal postures.

• Muscle contractions may be continuous, forcing limbs and trunk into sustained postures but they may also be discontinuous and irregular.
• A body part is flexed or twisted along its longitudinal axis. Slowness and clumsiness carrying out skilled movements are associated with sensations of rigidity and pulling in the affected part⁶.
• Postural changes may be spasmodic or tonic, dynamic or fixed, or any combination.
• Abnormal postures tend to occur at intervals determined by voluntary movement and can be sustained for variable lengths of time. Relaxation may be impaired so that the dystonic posture may be maintained well beyond the end of the voluntary movement which triggered it³.
• In spasticity, the severity of the abnormal posturing tends to be constant throughout the gait cycle, whereas dystonic posturing often varies. For example, in a dystonic gait, the ankle might be inverted during the early swing phase but then normalize or even become everted just before the stance phase⁷.
• Dystonic stiffness and posturing of the legs can improve significantly or may even be absent during different walking tasks, such as walking backwards, walking heel to toe, or running, whereas a spastic gait does not change significantly according to task⁷.

 

8. Dystonia is associated with phasic movements. Phasic dystonia can mimic many other movement disorders (eg tremor, tics).  In the case of obvious underlying abnormal posturing, the clue that the associated phasic movement is dystonic is that it occurs in the same part of the body⁷. However, if phasic dystonia dominates, then there may be only subtle, stereotyped, abnormal posturing in the body part(s) affected by the involuntary movements that provides the clue to its dystonic origin. The patient needs to be instructed to allow the involuntary movement to occur freely, because voluntary compensatory postures or movements can be misleading. For example, a latent abnormal posture underlying tremor-dominant cervical dystonia often can be revealed by asking the patient to relax with eyes closed and let the head drift where it feels most comfortable, revealing underlying torticollis or other dystonia.  These phasic movements may appear to be:

• Rapid and jerky, resembling myoclonus or tics
• Slow (athetoid dystonia)
• Rhythmic (dystonic tremor), which typically has the following characteristics:
  • The dystonic tremor is diminished at the “null point”, and has the quality of being induced by head or body movement in a particular direction.
  • Dystonic tremor may be difficult to distinguish from essential tremor.
  • Dystonic tremor is often more irregular in timing and amplitude than is non-dystonic tremor, since the underlying muscle bursts are irregular in duration and amplitude. 
     

9. Dystonia may have abnormalities in tone.

• In dystonia, resting hypertonia is relatively uncommon and, when present, tends to be variable³.
• Some patients with task specific dystonia may show additional increased tone, reduced arm swing and effortful repetitive movements in the involved limb but without decrement of the amplitude of the movement (bradykinesia)⁵.
   

10. Dystonia is characterized by the presence of sensory tricks (Gestes antagonistes). 

• Sensory tricks are voluntary actions performed by patients that reduce or abolish the abnormal posture or the dystonic movement, usually by simple light touch.  They are usually simple movements directed to the body region affected by dystonia, and are not the exercise of force to overcome the dystonic movement. Typical examples include touching the lower face in cervical dystonia, touching the upper face in blepharospasm, or putting a toothpick in the mouth in oromandibular dystonia. Patients should always be asked if they can do anything to suppress their abnormal movements because these tricks can be very odd and patients are sometimes reluctant to mention them⁸.

• Alleviation of dystonia occurs immediately and affects both tonic and phasic components.
• Alleviation of dystonia occurs during the geste movement, usually soon after its start.

• Alleviation of dystonia may last for as long as the geste lasts, or slowly reverse spontaneously before its end.

`

From: Morgante F, Klein C. Dystonia. Continuum (Minneap Minn). 2013;19(5 Movement Disorders):1225-1241. doi:10.1212/01.CON.0000436154.08791.67 ¹³.

 

11. Dystonia is associated with Overflow: together with mirror dystonia, the presence of overflow may prove particularly helpful in cases of dystonia with mild or inconstant phenomenology.

• Overflow refers to the spread of involuntary activity to an unaffected (usually contiguous but also contralateral) body part distinct from the primary site of dystonia⁵.  In terms of localization of dystonia, this is therefore a dystonic contraction, which arises in one body segment but may spread to another segment. Overflow is usually ipsilateral, and when it spreads to the opposite limb is called contralateral overlow.  Overflow may be seen by inspection, or recorded with EMG, and commonly occurs at the peak of dystonic movements.
   

12. Dystonia is associated with Mirror dystonia:

• Mirror dystonia is a unilateral posture or movement with the same or similar characteristics to the patient’s dystonia (usually dystonic postures and some movements) that can be induced, usually in the more severely affected side, when contralateral movements or actions are performed by the homologous opposite, usually normal, body part.
• Specific task(s) which can elicit mirror dystonia may need to be identified to elicit mirror dystonia.  A typical example, observed in almost half of the patients with writer’s cramp, is mirror dystonia of the dominant hand while writing with the opposite unaffected hand.
• Ask the patient to perform repetitive hand tasks with each hand sequentially such as finger tapping, normal writing, or piano-like movements, rapid opening and closing of the hand, and hand pronation–supination; these should be performed at slow and fast speeds in the non-affected limb.
• Mirror dystonia may act as a guide for muscle selection for botulinum toxin injections.
   

13. Dystonia is associated with changes when writing

• Ask the patient to write sentence repetitively. When evaluating the writing task, make sure shirt sleeves are pulled up. Ideally, the feet are exposed as well.
• Ask the patient if (s) he feels tightness in the limb.
• In an affected limb, look for tight grip of the pen, unusual posturing of the hand that may progress as the patient continues to write, and involvement of more proximal muscles.
• Look for dystonic mirroring/overflow in another limb, and look for involuntary toe flexion, extension or foot inversion that would suggest dystonic overflow.

 

 

See also: Examination of Dystonic Tremor                Examination of Spasmodic Dystonia                    Examination of Cervical Dystonia

 

Head and neck	Observe the patient in resting position, with eyes open and with eyes closed. Observe the patient while performing voluntary movements: Open and close eyes tightly Open and close mouth Protrude tongue Count from 1 to 10 Vocalize a sustained high-pitch “e” Read a standardized passage Hold a brief conversation
Upper body (neck, shoulders, and arms)	Observe the patient in the resting position, both with eyes open and shut. Observe the patient while performing voluntary movements with the head: Turn the head to the right and to the left Turn the head up and down Tilt ear to shoulder on either side Observe the patient while performing voluntary movements with both arms, independently and together: Hold arms outstretched straight in front, with fingers spread apart: Bring prone arms to supine position Finger to nose, finger tapping Open and close fists Fingers extending toward each other but not touching (Batwing position) Repeat unilateral manoeuvres with eyes shut to detect mirroring. Observe subject while writing: “Today is a sunny day” 3 times While tracing a continuous line of cursive lower case “l”s without lifting pen from paper While drawing a spiral without the hand resting on paper Perform manoeuvres with either hand.
Lower body (trunk and legs)	Observe the patient in the resting position, with eyes open and with eyes shut. Observe the patient while performing voluntary leg movements: Rapid heel stomping on the floor Toe tapping with heel on floor Heel to toe taps. Perform manoeuvres on either side and alternating both legs
Full body in standing position	Observe the patient in the resting position, with eyes open and with eyes closed in the frontal, lateral and back views. Observe the patient while performing voluntary movements: walking forward and backward, away from and toward the examiner
Identify and document the gestes antagonistes and sensory tricks used by the patient	If necessary, perform EMG mapping to detect features of dystonia

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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