Tremor is a rhythmic unintended muscle contraction inducing to shaking movements in different parts of the body mostly the hands, but can occur as well in the head, the legs, vocal cords and rarely the torso, causing problems of holding utensils, writing and singing among others. Characteristically it is getting worse during stress or strong emotions. Tremor is very often misinterpreted as a symptom of withdrawal in substance abuse.
Tremor affects both males and females of all races, ethnic backgrounds and ages. It is embarrassing and usually not a symptom of a life-threatening disease. Tremor may occur in frequent spells for seconds or lasting constant.
It is caused by a problem in the basal ganglia, an area of grey matter at the base of the forebrain. Tremor can occur on its own or be a symptom associated with other neurological diseases as Stroke, Multiple Sclerosis or Parkinson’s Disease.
Certain medication as asthma medication containing theophylline or corticosteroids or neuroleptics can trigger.
Overactive thyroid, liver or kidney failure, mercury poisoning, anxiety or panic are other possible reasons.
Differentiation is basically depending on the current activation state of the muscle. Resting tremor occurs while the muscle is relaxed, such as in Parkinson’s disease or action tremor appears with voluntary movements such as:
- Postural tremor occurs when a person maintains a position against gravity, such as holding the arms outstretched.
- Kinetic tremor is associated with any voluntary movement, such as moving the wrists up and down or closing and opening the eyes.
- Intention tremor is produced with purposeful movement toward a target, such as lifting a finger to touch the nose with worsening by getting closer to the target.
- Task-specific tremor only appears when performing highly-skilled, goal-oriented tasks such as handwriting or speaking.
- Isometric tremor occurs during a voluntary muscle contraction that is not accompanied by any movement such as holding a heavy book or a dumbbell in the same position.
Classification is as well done by appearance, cause or origin. There are more than 20 types of tremor known. The most common forms include:
It shows up in all healthy individuals as human phenomenon, not considered a disease. It is characterized by a fine shaking of both hands rarely visible.
Enhanced physiologic tremor
Enhancement emerge by reaction to certain drugs, alcohol withdrawal, or medical conditions including an overactive thyroid and hypoglycaemia. It is usually reversible once the cause is corrected.
It is the most common movement disorder worsening by aging. The reason is unknown, although often associated with hypertension and in 50 % it occurs in more than one family member thought to be caused by a genetic risk factor. Distinctive is the appearance in both hands during action and resting. Additional symptoms may include the head (e.g., a “yes” or “no” motion) or the voice.
It occurs within dystonia — a movement disorder where overactive muscles resulting in abnormal “jerky” or irregular body postures due to forceful muscle spasms or cramps. By touching the affected body part or muscle severity of the tremor may be reduced.
It appears within a damage to the cerebellum. It is a slow, high-amplitude (easily visible) tremor of the limbs at the end of a motion e.g. such as trying to press a button.
Psychogenic or functional tremor
It manifests abruptly at all body parts increasing in times of stress and decreasing when distracted. It is often associated with depression or post-traumatic stress disorder (PTSD).
It includes shaking in one or both hands at rest. It may also affect the chin, lips, face, and legs. The tremor may initially appear in only one limb or on just one side of the body.
It is a rare disorder characterized by rapid muscle contractions in the legs that occur when standing associated with feelings of unsteadiness or imbalance, causing immediately attempt to sit or walk.
Diagnosis starts by taking an extensive medical history addressing your symptoms, the trigger factors, the duration and the frequency, work environment, social habits, toxic exposure, risk of infectious diseases and family history of neurological disease. Check of vital signs such as blood pressure and pulse, followed by a proper physical examination with focus whether the tremor occurs at rest or action, the location and the appearance, balance, muscle stiffness and speech should give a first differential diagnosis. Additional tests such as laboratory tests, Electromyography (EMG), Nerve Conduction Studies (NCS) and imaging of brain are sometimes recommended investigations for ruling out symptomatic reasons.
Treatment depends on the underlying reason. If tremor is due to a thyroid malfunction, the tremor will improve or even resolve with treatment of thyroid malfunction. Also, if tremor is caused by medication, discontinuing the tremor-causing drug may reduce or eliminate this tremor.
Other treatment options include medication as Beta-blocking drugs, anti-seizure medications, Parkinson’s disease medications. In rare cases surgeries such as deep brain stimulation (DBS) or thalamotomy can help.
Lifestyle modifications as avoiding tremor-inducing substances such as caffeine and other medication and physical therapy for coordination and balancing improvement are advisable.