Tremor

Original Editor - Muskan Rastogi Top Contributors - Muskan Rastogi and Lucinda hampton

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Introduction

Tremor may be an involuntary movement that is rhythmic (i.e., regularly recurrent) and oscillatory (i.e., rotating around a central plane). Tremor has its own rich clinical phenomenology and various ways of classification. It is a Hyperkinetic Movement Disorder.

Pathophysiology

Tremor's Pathophysiology is still a debatable topic. The researchers have been unable to identify a particular cause for tremors due to the complex nature of the condition. A hypothesis given in a 2014 article the pathogenesis of both classic tremor and essential tremor is hypothesized to be caused by cerebello–thalamo– cortical network. The distinction appears to be in how this network is activated to oscillate. In classic tremor, the setting is the stability of a body part where an abnormal beta rhythm synchronizes the basal ganglia and in a mechanism still to be elucidated triggers the cerebellar network. In essential tremor, the irregularity appears to be in the cerebellar network itself, and dysfunction of the motor controller for generating an action sets off the oscillation.

Classification

Types of tremor

• Rest tremor: Its frequency is between 4 and 6 Hz. This variant of tremor can be diminished or resolved with movements or antigravity position and usually aggravated by with stress and agitation. Tremor at rest origins from any dysfunction of basal ganglia (especially substantia nigra) (25-29).

• Action tremor: Action tremors are started or exacerbated by movements. There are four subtypes of action tremor:

1. Kinetic tremor: Can occur with any voluntary movement and are uniform in nature.
2. Intention tremor: Worsens with the end of targeted movements. This kind of tremor can be due to cerebellar dysfunctions.
3. Isometric tremor: Produced by additive force against fixed target.
4. Postural tremor: Seen when maintaining a body part in a constant immobile position and is due to Cerebello-Olivary system dysfunction.

• Rubral tremor: Also called as Holmes or midbrain tremor. This type is determined by coarse, large amplitude and low-frequency irregular jerky movements. It is usually nonprogressive but may be very disabling. Any structural or functional abnormality in midbrain and thalamus can cause this type of tremor.
• Physiologic tremor: The normal motor oscillations in humans can be enhanced or exacerbated with some situational challenges such as; excitement, fatigue, and caffeine consumption which is called Physiologic tremors.
• Psychogenic tremor: Is an acute onset, nonprogressive tremor that is due to any underling psychiatric condition.
• Essential Tremor: It usually presents as a bilateral postural (6 to 12 Hz) tremor of the hands, followed by a kinetic and resting component.

Examination

The approach to the patient involves taking medical history which is followed by a neurologic examination.

Medical History

The first set of questions should be aimed to distinguish whether the tremor is occurring at action or at rest.

The best is to begin with an initial question that is open-ended (e.g., “Can you tell me about your tremor?” or “What type of tremor do you have?” or “When do you notice tremor?”).

After this question, try to ask more specific questions, such as “Does your hand shake when you are writing?” or “Does your hand shake when you are trying to eat something?” .It is asked so as to certain whether the tremor is an action tremor or a resting tremor.

This is then followed by additional questions that extracts information from the patient on the following items:

• Body areas that seem to be shaking (e.g., arms, head, voice)
• Limb positions that show on the tremor and, conversely, those that seem to lessen it.
• Age at which tremor began
• How the tremor has changed over the years
• Presence of any other involuntary movements
• Presence of other neurologic symptoms besides from tremor
• Is there any pulling sensations or discomfort in the body part that is shaking?
• The medications used by patient that seem to produce or exacerbate tremor
• Dietary factors that exacerbate tremor (e.g., coffee and other forms of caffeine)
• Symptoms of thyroid diseases (e.g., weight loss, heat intolerance)
• Family history of “shaking” or tremor (e.g., the presence of affected first-degree relatives is often reported by patients with essential tremor, among whom the pattern of inheritance may resemble that of an autosomal dominant disease)

Neurological Examination

A detailed and focused neurologic examination should be performed.

First, the healthcare professional should ask the patient to raise arms against gravity, with the palms down in front and then in the wing-beat position with the hands facing one another in the midline.

If a postural tremor is present during sustained arm extension, the examiner should assess the following:

• Is the tremor is regularly recurrent and oscillatory
• What all joints are involved (e.g., elbow, wrist, metacarpophalangeal joints) and in what directions (e.g., for the wrist, flexion-extension, pronation-supination)
• Is the tremor in each arm is synchronous with that of the other arm (i.e., in phase or out of phase)
• Is the tremor is of a reemergent quality (i.e., initially absent and the time it takes to emerge)

Next, the examiner should attempt to elicit kinetic tremor. Thus, the examiner may ask the patient to perform

The finger-nose-finger maneuver

• Pour water between cups
• Draw spirals
• Write a sentence.

Also, the examiner should assess the following items:

• Does the tremor have an intentional component (ie, does the tremor worsen as the limb approaches a target [eg, during the finger-nose-finger maneuver])?
• Are dystonic movements or postures present (eg, do some of the fingers flex, extend, or twist during the finger-nose-finger maneuver)?
• What is the relative severity of the kinetic tremor that is being observed to that which was observed during sustained posture (above)?

Further, the examiner should assess whether there is any tremor at rest in the patient’s arms or legs. Tremor at rest in the arms can be assessed while the patient is seated, standing, walking, and lying down. Resting tremor in the legs can be assessed while the patient is seated or lying down. In addition, tremor while standing (i.e., orthostatic tremor) may be assessed while the patient is standing in a stationary position.

Finally, the examiner may assess for tremor in the head (i.e., neck) (while the patient is seated and lying down), jaw (with the patient’s mouth closed and then with the mouth held open), facial muscles (e.g., forehead, cheek), chin, tongue, and voice (during sustained phonation and during speech).

Diagnosis

The history and physical examination are first used to establish whether the main type of tremor is an action tremor (i.e., postural, kinetic, or intention tremor) or a tremor at rest.

Physiotherapy Management

Goals of management

Strengthen the muscles

Improve Balance