Hyperkinetic Movement Disorder

Original Editor - Muskan Rastogi Top Contributors - Muskan Rastogi and Kim Jackson

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Introduction

Hyperkinetic movement disorders also referred to as Dyskinesias are characterized by abnormal, often repetitive, involuntary movements overlapped to normal motor activity. Its 5 major types are Tremors, Chorea, Dystonia, Myoclonus and Tics.

Etiology

Common etiologies seen in Hyperkinetic Movement Disorders-

1. Genetic abnormalities
2. Neurodegenerative diseases
3. Structural lesions
4. Infection
5. Drugs
6. Psychogenic problems
7. Others

Pathophysiology

Among all HMDs there appears to be decreased neural firing rates in the inhibitory output nuclei of the basal ganglia leading to a subsequent disinhibition of thalamocortical activity. Sensory abnormalities may also have a role.

Cardinal Features

Hyperkinetic movement disorders can be grouped according to distinct cardinal features, which can be described in terms of

• Time
• Space distribution
• Body state’s impact.

Sub- features

Rhythmicity

A rhythmic movement repeats over time at a fixed interval of time. If the movement can be defined with a frequency during an observation period, it has a regular rhythm (e.g., essential tremor, parkinsonian tremor), if the movement repeats with a more complex temporal pattern, it has an irregular rhythm (e.g., cortical myoclonus), and finally, if the movement repeats over time at no fixed interval of time, it is arrhythmic (e.g., chorea, athetosis, ballism, tics, akathitic movements).

Speed

The second temporal item is the speed of the movement . It can be very fast, such as in myoclonus or hemifacial spasm, fast las in ballism or tics, intermediate as in chorea and tremors, or slow as in athetosis or akathitic movements.

Duration of the Muscular Contraction

Finally, in terms of the time spectrum, we need to describe the duration of the muscular contraction and the duration of the whole movement . The duration of the muscular contraction can be sustained or not. A sustained muscular contraction is fixed and doesn’t change during time, unlike the non-sustained muscular contraction.

Duration of the Movement

The duration of the movement can be defined as paroxysmal, if the movement repeats with a sudden recurrence (e.g., paroxysmal dyskinesia, paroxysmal ataxia); continual, if the movement repeats over and over again without a sudden recurrence (e.g., ballism, chorea), or continuous, if the movement continues without stopping (e.g., abdominal dyskinesias).

Body Distribution

According to space characteristics, we can classify hyperkinetic movements according to body distribution, i.e., the body part involved in the involuntary movement. Dystonia can be classified as :

• Focal: 1 body part is affected
• Segmental: 2 contiguous body parts are affected
• Multifocal: 2 non-contiguous body parts are affected
• Hemi -dystonia: Ipsilateral arm and leg are involved
• Generalized: 3 body parts are affected, including the trunk and 2 other sites; with or without leg involvement

Muscular Pattern

Another important space feature is the muscular pattern activated in dystonia . In patterned movement, the involuntary movements involve the same group of muscles in a repetitive way.

Amplitude

Finally, in terms of space characteristics, it is important to define the amplitude of the movement: large (e.g., ballism), medium (e.g., chorea), or small (e.g., tremor).

Body State’s Impact

The last main feature needed to classify a hyperkinetic movement is the impact of body state on the movement. Can the involuntary movement be modified by a voluntary movement? Is it suppressible? Is it modified by wakefulness?

Action Rule

First, we need to evaluate the action rule. Some movements are present only during rest. For example, paradoxical dystonia can be present at rest and disappear during action. Some movements are present during voluntary movement only. In this case, the involuntary movement can be triggered by a general movement of a body part (action dystonia, paroxysmal kinesigenic dystonia) or need a specific task to be triggered (task-specific dystonia) .Other movements are present during both rest and voluntary movement.

Suppressibility

Another important feature is suppressibility. We need to detect if the movement is totally or partially voluntary suppressible (e.g., stereotypies, tics, akathitic movements), or if it is not suppressible (e.g., myoclonus).

Wakefulness

Finally, we need to understand the relationship between movement and wakefulness, e.g., if it is present while awake or sleeping. Some movements appear during sleep only (e.g., REM sleep behavior disorder, periodic movements in sleep), or persist during sleep (e.g., spinal myoclonus, myokimia, moving toes) and others are present only while awake.

Below is Chart representing Cardinal features of hyperkinetic disorder in detail.

Classification

There are 5 types of tremors

1. Tremors
2. Chorea
3. Dystonia
4. Myoclonus
5. Tics

Assessment

Things that are need to be assessed

• Gait and Balance for fall prevention
• Functional tasks
• Speech and cognition
• Dysphagia
• Mental Health (behavior/affective state)

Management

Management of Chorea

Management of Dystonia

Management of Tremor

Management of Tics

Management of Myoclonus