Dystonia and Tremor are common movement disorders that may exist independently or coexist. There are many commonalities between Dystonia and tremors. Isolated Tremor, Isolated Dystonia, and essential Tremor share the same phenomenological spectrum. If a patient with Dystonia shows no features of Tremor, it leads to diagnostic uncertainty.
Here is a guide to enlighten you with the prerequisite information regarding Dystonia vs. Tremor.
What is Tremor?
In clinical practice, Tremor is the most commonly encountered movement disorder. It involves the physiological rhythmic oscillation of a body part under certain conditions, including cold and fear. Such kind of involuntary rhythmic oscillation affects several body regions about a joint axis.
Age at onset
Adolescence (15–20 years) or late adulthood (50–70 years)
Classification of Tremor
On a broader scale, tremors are classified based on their origin.
1. Resting Tremor
This Tremor occurs in a body part that rests against gravity or a relaxing body part.
2. Action Tremor
This type of Tremor involves the voluntary contraction of a muscle.
According to statistical analysis, clinically detectable tremors are present among 96% of people.
The Primary Cause of Tremor
Relatively Symmetric displacement in either direction of the midpoint of the joint produced by synchronous or alternating contraction of the reciprocally innervated antagonistic and agonistic muscle is the primary cause of Tremor. Unfortunately, only a few patients with tremor disorder seek medical attention.
Mechanism behind Tremor
The pathophysiological mechanism and anatomical origin of tremors vary with the type of tremor disorder. There are rhythmical discharges controlled by feedforward and feedback loops in the neuronal network that ultimately generate the oscillations.
Virtually all pathological tremors involve cerebello-thalamocortical pathways.
Treatment of Tremor
Effective treatment for various tremor disorders involves impediment of the oscillations through applying high-frequency stimulations or stereotactic ablations to the ventrolateral thalamus.
Dystonia
Repetitive or abnormal posture and movements caused by intermittent or sustained muscle contraction are called dystonia movement disorder. Dystonic movements are usually patterned.
Classification of Dystonia
Here are the different types of Dystonia:
The body parts involved in Dystonia include the cervical region, the trunk, the upper or lower cranial region, the upper or lower limb, etc.
- If these body regions participate individually in Dystonia, it is called Focal Dystonia.
- However, various combinations of these territories lead to general, segmental, or multifocal Dystonia.
- Task-specific Dystonia This type is associated with particular activity or action such as writer’s cramp.
The Primary Cause of Dystonia
Voluntary actions associated with an overflow of muscle activation initiate or worsen Dystonia. In the wake of the current definition, it is clear that Tremor is a clinical feature of Dystonia that manifests during voluntary movements. However, it is tough to distinguish between isolated Dystonia and dystonic Tremor.
Age of Onset
Dystonia can occur at any age.
Physical signs of Dystonia
Here are some signs that are observed in patients with Dystonia.
Dystonic Postures
- Continuous muscle contractions may be persistent, forcing trunk and limbs into sustained postures (not available for laryngeal Dystonia or blepharospasm)
- A body part is twisted or flexed along its longitudinal axis
- Clumsiness and slowness for skilled movements are associated with the sensation of traction and rigidity in the affected body part.
Dystonic Movements
- Twisting and repetitive or patterned movements
- Tremor is the significant dystonic movement
Final Thoughts
All clinicians must remember that tremors and Dystonia mostly coexist. Therefore, vigilance is required during the diagnosis of isolated tremors as they may be present as incomplete phenomenology of Dystonia.
According to analysis, dystonic Tremor has a prevalence rate of 11% to 87%