hyperkinetic disorders

Types of Hyperkinetic Movements Chorea: refers to involuntary, irregular, purposeless, non-rhythmic, rapid, unsustained movements that seem to flow from one body part to another. They are unpredictable in timing, direction and distribution. Chorea involve random group of muscles.They can be partially suppressed and the patient can often camouflage some of the movements by incorporating them into semi-purposeful(quasipurposive) movements (termed ‘parakinesias’). Huntington's disease presents with chorea.

Athetosis: Here the involuntary movements are slow, writhing, continuous.

Ballismus :this constitutes large amplitude choreic movements of the proximal parts of the limbs causing flinging and flailing limb movements. Most frequently unilateral,The lesion is most likely in the contralateral subthalamic nucleus.

Athetosis, chorea, and ballism may represent a continuum of one type of hyperkinetic movement disorder and are sometimes combined (‘choreoathetosis’ or ‘chorea-ballism’).

Dystonia: refers to twisting movements, they are sustained at the peak of the movement;many a time progress to prolonged abnormal postures. Both agonist and antagonist muscles contract simultaneously to produce the twisted posture of the limb, neck or trunk. Dystonic movements repeatedly involve the same group of muscles.

Focal dystonia - a single body part is affect. Examples of focal dystonia include: blepharospasmspasmodic torticollis (cervical or neck dystonia), writer’s cramp (hand dystonia).
Segmental Dystonia: Involvement of 2 or more contiguous regions of the body .
Generalized dystonia: Involvement of the trunk, legs and other body parts.
Idiopathic torsional dystonia:Common among Ashkenazi Jews, autosomal dominant disorder (with reduced penetrance) that begins in childhood as a focal or segmental dystonia that later generalizes to the entire body. (dystonia of the eyelids), Focal dystonia can be treated by injecting the involved muscles with botulinum toxin.
Generalized dystonia can be treated by anticholinergic agents (benztropine, trihexyphenidyl), or muscle relaxants (clonazepam, baclofen).

Myoclonus: is a sudden, brief, shock-like jerk caused by a muscle contraction (positive myoclonus) or inhibition (negative myoclonus). The causes of myoclonus are quite diverse from epileptic syndromes, to drug side effects, metabolic disturbances, and CNS lesions. Unless the cause is readily identifiable, it often requires a laborious work-up.
Regardless of its etiology, mainstay symptomatic treatments are benzodiazepines (such as clonazepam) and valproic acid.

Restless legs syndrome: refers to the phenomenon of restless legs, where the patient describes an unpleasant, crawling sensation in the legs, particularly when sitting and relaxing in the evening which then disappear on walking. It is quite common, found in 10% of the general population in one study. It is mostly “idiopathic” but is found in increased frequency among parkinsonian patients and in patients with iron deficiency anemia. Sometimes, simply replacing with iron will provide relief. Otherwise, dopaminergic agents (such as dopamine agonists and levodopa) are the mainstay treatments of RLS. In refractory RLS, anti-epileptic agents (such as gabapentin), benzodiazepines and opiates can be used.

Tics: consist of abnormal movements (motor tics) or abnormal sounds (phonic tics). When both types of tics are present, and occurring under the age of 15, accompanied by obsessive compulsive features, the designation of Tourette syndrome is commonly applied. Tics frequently vary in severity over time and can have remissions and exacerbations. Motor and phonic tics can be simple or complex. Most of the time tics are repetitive. They can be suppressed temporarily but will need to be “released” at some point providing internal ‘relief’ to the patient until the next ‘urge’ is felt. Examples include: shoulder shrug, head jerk, blink, twitch of the nose, touching other people, head shaking with shoulder shrugging, kicking of the legs, obscene gesturing, grunting, throat clearing, etc. Dopamine receptor blocking agents (such as conventional antipsychotic agents), dopamine depleting agents (such as reserpine), clonazepam, and clonidine are used to symptomatically control tics.

Tremor: is an oscillatory, usually rhythmical and regular movement affecting one or more body parts, such as limbs, neck, tongue, chin or vocal cords. The rate, location, amplitude and constancy varies depending on the specific type of tremor. It is always helpful to determine whether a tremor is present at rest (resting tremor), with posture holding (postural tremor) or with action such as writing or pouring water (intention or kinetic tremor). Resting tremor, for example, while on its own is a hyperkinetic movement, is often part of a hypokinetic movement disorder: parkinsonism. When tremor occurs mostly with action or intention, the most common cause is Benign Essential Tremor—a non-progressive disorder which can either be hereditary (usually autosomal dominant) or sporadic. The tremor can sometimes be relieved by beta blockers (propranolol), primidone (an old anti-epileptic drug) or clonazepam.
When the tremor frequency is rapid and most prominent with posture holding, it can be a manifestation of “enhanced physiologic tremor”.
Remember the conditions that ‘enhance’ the silent tremor that is in all of us include: hyperthyroidism, anxiety, hypoglycemia, medications such as steroids and anti asthma agents such as terbutaline, albuterol, etc.