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 neurological 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, hyperkinetic 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 pyramidal 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 coordinations, 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 movements can have several forms which often overlaps each other. It is although still advantageous to distinguish between the different syndromes. TABLE 2. 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 movement 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 characteristically 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 comprising 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 tries to fix an object with e.g., to put a finger on the tip of his nose. Other more common types of cerebellar, tremor have less intention character and cerebellar tremor may even be predominantly of static nature. Parkinsonian tremor is a rather slow (5 cps) coarse resting tremor which ordinarily disappears or becomes less marked during movements. Fasciculations are spontaneous contraction in a bundle of muscle fibers ordinary from one motor unit. They can be seen with nearly all diseases affecting, the distal motor neurons, and are especially frequent in diseases of the anterior horn cells such as amyotrophic lateral sclerosis. In these instances reduced muscle strength and muscular wasting are also present. Fasciculation may also be a quite benign phenomenon and if no other symptoms are present fasciculations are essentially always benign. Myokymia are spontaneous brief contractions in groups of muscle fibers with a tendency to a continuous displacement of the phase of contraction giving the surface an undulating character, slower than in fasciculations. Myokymia may be considered as a condition with continuous fasciculations. Myokymia are most often benign and can be seen with fatigue. They can also be seen with metabolic disturbances and in the face with lesions in the brain stem. Spasm is a more longlasting involuntary contraction of a muscle or a muscle group. Spasm may be seen with several diseases, e.g., in muscle contractions due to pain, in decerebrated rigidity due to a lesion in the central nervous system, in spasmodic torticollis, in writers and other gprofessional h cramp, in hemifacial spasm, and in tetany with low plasma-calcium. In tetany the spasms are characterized by flexion in elbows, hand and the fingers proximal joints, but extension of the fingers middle and distal joints. Flexion is also present the legs and the feet are in plantar flexion. In spasmodic torticollis the patients continuously twist the head to one side and the contralateral sternocleid muscle will be hypertrophic with spasm. Other neck muscles are also involved. Spasmodic torticollis can often be considered as part of a dystonic movement disorder
26 O.B. Paulson probably due to a disease in the basal nuclei. In other cases torticollis seems to be part of a psychogenic syndrome. Writers cramp is a condition with cramp in the muscle used when writing which is provoked by attempt to or brief writing. It often occurs in patients who in their work (professionally) have to write and some patients then learn to write with the other hand. This condition and similar cramps in other muscle groups used in other professions have been called gprofessional cramps h. Their pathogenesis remains unknown. Pharmacological aspects There is a fine balance between different neurotransmitter system in the normal basal nuclei. Only the most important systems, the dopaminergic and the cholinergic system will be considered here. Degeneration of the cholinergic system occurs typically in Huntington's chorea and leads to hyperkinesia. Contrary degeneration of the dopaminergic system as it typically occurs in Parkinson's disease leads to hypokinesia. Thus, the imbalance between the cholinergic and dopaminergic system in the basal nuclei is of major significance for movement disorders. The disturbance of the cholinergic-dopaminergic neurotransmitter balance gives the rational for the treatment of Parkinson's disease with anticholinergica or with the more effective L-DOPA. L-DOPA can pass across the blood-brain barrier, it is thereafter transformed to dopamin which is blood-brain barrier impermeable. The balance between the cholinergic and the dopaminergic system in the basal ganglia also explains why overtreatment of Parkinson's disease with L-DOPA may induce hyperkinesia and why treatment with neuroleptic drugs (dopamin-blockers) may induce parkinsonian symptoms. General consideration and some therapeutical aspects From the above description of the various movement disorders it is obvious that the clinical picture is often characteristic and may lead to a correct clinical diagnosis. But in other instances the clinical picture will be uncharacteristic and diagnosis becomes difficult. This may not only be the case in the early stage of a disease but also later in its course. Some movement disorders will not resemble previous seen syndromes and remains unclassified. An guncharacteristic h clinical picture is often seen in Wilson's disease. The early symptoms may indicate a disease in the basal nuclei with tremor, rigidity and hyperkinetic movement which may be quite bizarre. The early symptoms may also be of cerebellar nature with marked intention tremor, but simultaneously there is most often a slight dystonia, especially in the face. In still other cases the early symptoms are of cognitive type with dementia or psychosis. Furthermore the first symptoms may be those of liver affection. Essentially all patients with Wilson's disease and neurological symptoms have a Kayser-Fleischer ring in the cornea, however, especially in patients with brown eyes split lamp examination
Involuntary Movements 27 may be necessary to reveal it. In most diseases with movement disorders only symptomatic treatment can be offered to the patient. In these instances an early diagnosis, although reassuring for the patients is not essential for the therapeutic outcome. In other instances early diagnosis is, however, crucial for the prognosis. In Wilson's disease early diagnosis is important because the pathologic cooper deposit in the organism can be removed by penicillamin treatment and thereby progression of the disease can be stopped and partial remission may even occur. In Huntington's chorea early diagnosis may be essential for genetic considerations.