Tohoku J. Exp. Med., 1990, 161, Suppl., 21-27 Involuntary Movements OLAF B. PAULSON Department of Neurology, Rigshospitalet, 9 Blegdamsvej, DK-2100, Copenhagen, Denmark PAULSON, O.B. Involuntary Movements. Tohoku J. Exp. Med., 1990, 161, Suppl., 21-27•\Movements disorders are prominent symptoms in many neur- ological diseases, especially with affection of the basal nuclei. Several of these diseases have characteristic symptoms and signs, whereas clinical diagnosis is more difficult in other diseases. The various movement disorders, hypokinesia, hyper- kinetic syndrome, tremor etc. are defined and described, and clinical features of the various diseases were commented on.•\basal nuclei disease ; dyskinesia ; hyperkinetic syndromes ; hypokinesia ; involuntary movements Involuntary movements constitute a group of neurological symptoms of major significance. For the single patient the movement disorder may be disturbing and disabling. The symptoms are often characteristic leading to an accurate clinical diagnosis. In other instances diagnosis may be difficult. Movement disorders are seen with several neurological diseases, and especially with diseases of the basal nuclei. Comments on the terminology of lesions in the motor system The "classical" terms "pyramidal lesion" and "extrapyramidal lesion" are somewhat incorrect and misleading. Thus, a socalled "pyramidal lesion" with spastic paresis, hypertonia, increased tendon reflexes and extensive plantar response is not due to a pure lesion of the pyramidal tract but to a lesion of a group of pathways running close connection to the classical pyramidal pathway. A pure pyramidal lesion is very uncommon and would in fact give a different picture with facial palsy and extensive plantar response. The so-called "classical pyrami- dal lesion" therefore involves affection of both pyramidal and in its strict sense extrapyramidal structures. The "classical" term "extrapyramidal lesion" has been used synonymous to basal nuclei lesion. This seems not logic since other structures in the motor system could even as well be called extrapyramidal including the cerebellum and the above mentioned motor pathways. The terminology of lesions in the motor system need therefore to be revised. It is proposed that the term supranuclear motor lesion is used for the characteristic lesion of the motor descending (activating) system with symptoms of spastic paresis, increased tendon reflexes and extensive plantar response. The term 21 22 O.B. Paulson infranuclear / nuclear or peripheral lesion will then as ordinarily describe the facial paralysis seen in lesions of the peripheral motor neurons. The uncommon isolated lesion of the pyramidal tract with facial paralysis as mentioned above should be called an isolated lesion of the pyramidal tract itself . A lesion or disease in the basal nuclei should be called a basal nuclei lesion and the term •gextrapyramidal•h should be avoided. A cerebellar lesion is obviously still be called a cerebellar lesion. The anatomical structures in the basal nuclei are the telencephalic structures, the caudate nucleus, globus pallidus, putamen, and claustrum. Globus pallidus and putamen are together called the lentiform nucleus. Although anatomically related the amygelaloid body is here not considered as part of the basal nuclei because it physiologically relates more to the hippocampus and the limbic system. The diencephalic and mesencephalic structures, the subthalamic nucleus and substantia nigra are here considered part of the basal nuclei system since they physiologically are closely connected to the lentiform and caudate nuclei. Many pathways from the basal nuclei goes to the ventrolateral thalamic nucleus which from a physiological point of view also can be considered part of basal nuclei system. TABLE 1. Diseases with movement disorders Involuntary Movements 23 Diseases with movement disorders Several diseases are characterized by or accompanied by movement disorders (Table 1) and many of these affects the basal nuclei. The symptoms and signs seen with diseases of the basal nuclei are listed in Table 2. It appears that movements disorders are the most prominent symptoms in these diseases, and movement disorders are in fact primarily associated with diseases in the basal nuclei. It is characteristic for all movement disorders in basal nuclei diseases that they disappear during sleep and become more marked during emotional stress. Classification, definition and clinical features of movement disorders The different movement disorders are listed in Table 3. Hypokinesia is reduced motor activity. It can have the form of akinesia with reduced spontaneous motor activity despite normal strength and normal coordina- tions, e.g., the patient does not swing the arms when walking. It can also have the form of bradykinesia where all movements are performed solely, at a pathologically reduced velocity, e.g., the patient is extremely slow buttoning a button. Akinesia and bradykinesia is especially characteristic of Parkinson's disease. The hyperkinetic or dyskinetic syndromes characterized by involuntary move- ments can have several forms which often overlaps each other. It is although still advantageous to distinguish between the different syndromes. TABLE2. Symptoms of diseases in the basal nuclei TABLE 3. Movement disorders 24 O.B. Paulson Chorea are variable, irregular, rapid, jerking movements in the extremities or the face. Chorea is often accompanied by hypotonia. Chorea is typically seen in Huntington's chorea. Chorea may be unilateral (hemichorea). If unilateral chorea is especially pronounced in the proximal joints the movement abnormality is called hemiballism. This syndrome is most often due to a vascular lesion in the subthalamic nucleus. Athetosis are somewhat slower, twisting movements. One athetotic move- ment often continues in another. Athetosis is most pronounced in the face and distally in the extremities, and may be provoked if the patient try to keep the face and extremities quite or to perform finer skilled movements. It may not be easy to distinguish chorea and athetosis and chorea and athetosis may occur in the same patient. The term choreoathetosis is then often used. Athetosis is characteristi- cally seen in Huntington's chorea. A special form of athetosis with involuntary movements in the face is characteristic of tardive dyskinesia seen in some patients after many years treatment with neuroleptic drugs. Dystonia or torsion spasms can be described as persisted athetotic movements of the extremities, head or the truncus. It is sometimes induced by drugs and can be seen in Huntington's chorea. Myoclonus are one or a short series of jerks in a muscle group. It can occur with many diseases : In several types of epilepsy, associated with diseases of the basal nuclei, and in some diseases with diffuse affection of the brain such as subacute sclerosing panencephalitis, Creutzfeldt-Jacob's disease and some cases of metabolic encephalopathy. Myoclonus located to the palate and face may be seen with lesions near the fourth ventricle. Myoclonus can also be a quite benign "physiological phenomenon" as seen in sleep myoclonia where a normal person who is half asleep suddenly wakes up due to a myoclonic jerk. Tics are stereotype repetitive involuntary movements in one or a few muscle groups, often in the face or larynx, e.g., a brief cough. The pathogenesis is unknown, but seems often to be of psychogenic nature. In other instances tics accompany diseases affecting the basal nuclei. Gilles de la Tourette syndrome is a special most likely organic disease with tics that may have the character of brief swear-word and which may be most embarrassing for the patient. Other movement disorders, e.g., tremor and seizures are different from the above described irregular involuntary hyperkinetic syndromes. Seizures will not be described here. Tremor is a more or less regular, repeated and often continuous shaking of the head, hands, arms or legs. Tremor may be most marked at rest when relaxed (resting tremor), during static movements such as holding the arms outstretched (static tremor) or when trying to fix an object (intention tremor). Tremor is seen with several diseases and can be categorized in three main groups : One compris- ing the physiological tremor and the somewhat similar essential and thyrotoxic tremor ; one consisting of the cerebellar tremor and one consisting of the parkin- Involuntary Movements 25 sonian tremor. Physiologic tremor is of low amplitude and rather high frequency (8-12 cps). It occurs often at rest and may be aggravated by movements. Normally physiological tremor is absent, but may be provoked by extreme fatigue , in stress situations with activation of the sympathetic nervous system, and in all individuals following intravenous injection of epinephrine. Shivering may be considered as a special type of physiological tremor. Essential tremor is often familial and a little slower than the physiological. It is provoked by movements and characteristically the tremor most often disappears following the ingestion of a small amount of alcohol. Thyrotoxic tremor resembles the physiological, but is somewhat faster. Cerebellar tremor is especially pronounced with lesion of the dentate nucleus, of the other cerebellar roof nucleus or of the pathways through the superior cerebellar peduncle from these nuclei to the red nucleus in the mesencephalon. This type of cerebellar tremor is characterized by a crescendo like marked increase of its amplitude when the patient