Tremors (Part one)

TREMORS are prolonged or continuous rhythmic involuntary movements of body parts (hands, feet, head, jaw, tongue, etc.), observed at rest or with activities. Like other involuntary movements, tremor is absent during sleep and the movement can be temporarily suppressed by the patient.

Tremors can occur in any age group including the newborn period. Neonates when picked up will have brief tremors and some stiffening of the extremities. In normal newborns, tremors may occur as part of a startle response to loud noise or sudden postural changes.

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This startle response in the newborn is known as Moro reflex described as a symmetrical tremulous uplifting of both upper extremities – the arms from the shoulders, the forearms from the elbows with flexion of the thumbs and extension of the fingers of both hands. The whole startle response or Moro reflex is like the act of doing an embracing motion.

Normally the response disappears after age 3-6 months. An abnormal startle response is considered if (a) it is absent, (b) not symmetrical or (c) if persistent after the age of 6 months which may indicate a nerve, bone or cerebral problems or abnormalities.

Moro reflex is one of the primitive reflexes in the newborn period. Primitive reflexes usually appear and disappear at certain periods of development. Absence or persistence of the reflex beyond the given developmental period is considered an abnormal function of the central nervous system (CNS).

The absence of the Moro reflex in the term newborn infant or persistence beyond the age of 6 months is an important sign of brain dysfunction. A vigorous cry usually follows the moro reflex. Absent, weak, high-pitched or excessive cry is considered abnormal.

Jitteriness is the most common involuntary movement in a healthy full term newborn, defined as rhythmic, fine to coarse tremors in the first 2 weeks of life. Jitteriness is considered abnormal if persistent beyond the second week of life which can be due to infection, intracranial bleeding, low blood sugar, low blood calcium or in infants with narcotic abstinence syndrome (from mothers who are drug users exposing their babies to the drug during pregnancy).

Jitteriness in the newborn may be confused with seizure disorder or convulsions. Unlike seizure, jitteriness is not accompanied by abnormalities of eye movements. It is often stimulus-sensitive and that the dominant feature of jitteriness are the rhythmic movements of tremors, not like the slow and/ or fast jerking spasms of muscles in seizures or convulsions.

Most children and adults have experienced tremors during moments of anxiety, fear, or fatigue. Such tremors are temporary and disappear without disturbance in other bodily functions. They do not cause parental or personal concerns and seldom are the phenomena brought to the attention of health care provider.
This type of tremors is also found in adults following the excessive use of alcohol, coffee or some colds or cough medications. Sometime tremors are constant, mostly annoying and cause impairment or difficulties in writing, eating, working or studying including disturbance in speech.

Traditionally, tremors are classified as either action tremors or tremors at rest. Action tremors are produced by voluntary muscle activity or contractions. Rest tremors occur when the affected body part is at rest.

1. Action tremors: are common in childhood mostly related to motor activities. They are divided into: (a) Physiologic, (b) Essential, (c) Cerebellar

(a) Physiologic Tremors: are benign postural tremors, most evident in the extremities held in fixed position against gravity. They are usually invisible to the naked eye. They can be made obvious by placing a piece of paper over the outstretched fingers. The tremor is not related to cardiac impulse or function. Frequency varies with age. It is much slower in the very young and faster in adolescence and young adults. There is no impairment of body function. Physiologic tremors maybe found in children with thyroid problems, low blood sugar, low blood calcium, or side effects of some drugs. Tremors often disappear once the cause is corrected or eliminated.

(b) Essential Tremors: They are most evident during active use of the affected muscle. It may involve the extremities, the head with nodding front to back movements or affecting the voice producing vocal tremors.

Essential tremor is one of the most common types of movement disorders. The incidence ranges from 4 to 40 per 1000 persons younger than 60 years of age. Onset and progression are often slow. About 50% of persons affected are not aware of the problem. Tremors maybe amplified with stress, fatigue, drugs or some voluntary activities such as writing, holding a cup and saucer. Rest, certain drugs and alcohol often decrease the tremors.

Essential tremor is a familial hereditary problem indicating similar type of tremors in other members of the family of earlier generations. Sometimes essential tremors are without family history of the problem. Although commonly evident during the second or third decade of life the tremors may manifest as early as the first decade. There are no abnormalities of intellectual capacity, speech or locomotion. It rarely impairs coordination but the tremor may cause embarrassment where coffee or tea or other beverages maybe spilled during parties or conferences or other social functions.

Reports have shown that the early manifestations of essential tremors are heralded by shivering or trembling attacks described as flexion movements of the head and extremities as if cold water was poured down the child’s back. During attacks, the child will stop walking and sometimes falls to the ground. These attacks usually begin in infancy (4-6 months of age), from few to a hundred a day often followed by several weeks without the attacks. The attacks may persist for several years and then decrease in the later part of the first decade (about 6-7 years of age) and disappears as the essential tremors become manifest.

It is seldom necessary to treat children with essential tremors. They are benign. However, parents and the child should be advised to avoid choosing artistic careers such as music, painting or architecture. (To be concluded next week).