Two children with tremor

A right-handed 14-year-old boy was referred to a neurologist for an outpatient evaluation of tremor. The boy was previously healthy and not taking any medications. Developmental milestones were achieved within the appropriate norms. There was a family history of tremor in the boy's mother and maternal uncle. The mother reported that her tremor lessened following the consumption of alcohol. The parents first noticed the tremor in their son when he was about six years old. The tremor occurred mainly during voluntary activity, such as writing, eating soup with a spoon, drinking from a cup and using his hands for small skilled movements. The tremor affected both arms and was worse on the right side. His head, voice and legs were unaffected. The tremor was worse when he was physically tired (e.g., after heavy lifting) or nervous (e.g., public speaking). Over the years, the tremor has worsened slightly and has become a source of embarrassment to him. Tremors are classified as rest or action tremors depending on the circumstances under which they occur.3 Rest tremor occurs when a limb is relaxed and supported against gravity (e.g., a hand rested on a table). It is often augmented by mental stress and attenuates with action. Most tremors are action tremors, which occur with voluntary muscle contractions. They can be further subdivided into postural, isometric, kinetic or task-specific tremors. A postural tremor is observed while maintaining a position against gravity. An isometric tremor occurs when muscles contract against rigid stationary objects. A kinetic tremor occurs during voluntary muscle contraction; kinetic tremor is considered "simple" when it occurs during non-target-directed movements (e.g., flexion or extension at wrist) and "intentional" when it is target-directed (e.g., finger-to-nose test). Task-specific tremor occurs only during highly skilled activities (Box 1).1,5 Essential tremor develops insidiously and progresses slowly, presenting as a postural tremor involving both hands and arms in 95% of patients, although asymmetry may be present. It may appear as early as two years of age but often starts in late childhood or adolescence. Children with essential tremor often have a family history of the same.6 The common clinical presentation is the gradual onset of postural tremor over several years that involves both hands and arms and is occasionally associated with tremor of the head or voice. Leg tremor rarely occurs in essential tremor, but it ca