MOVEMENT DISORDERS

There are a somewhat bewildering array of movement disorders, but simply one can talk about disorders which cause excess movement, and those which cause diminished movement.

There is at times an overlap with psychiatric disturbances (Gilles de la Tourette), but it is a common error to assume that because a movement looks bizarre, or is difficult to explain, it is of functional origin: a cardinal rule is that most abnormal movements are genuine, however strange they may appear. Note that most movement disorders disappear during sleep.



ANATOMY

The striatum of the caudate nucleus and the putamen, projects to the globus pallidus and the substantia nigra: These latter two structures project to the thalamus, in an inhibitory manner, preventing excessive movement. The thalamus projects to motor areas of the cortex. This cortex in turn has excitatory projections to the striatum.

Another section of the substantia nigra projects to the striatum modulating its function: this is the projection which is altered in Parkinson's disease.

The globus pallidus is modulated by the subthalamic nucleus.

Blockade of dopamine receptors decreases movement; addition of dopamine increases movement.

In addition to projections from the substantia nigra of dopamine, there are extensive dopaminergic projections from the brainstem into the cortex and limbic system. Treatment of schizophrenia with phenothiazines is achieved with agents which block dopamine receptors and, as a side-effect, lead to a parkinsonian-like picture.



SYMPTOMS AND SIGNS

There is considerable overlap in the appearances of the various disorders of excessive movement, and dystonia, athetosis, chorea and hemiballismus merge into one another, when attempting to describe the clinical manifestations of a movement disorder. In addition, over a period of time, a movement disorder may progress from one manifestation to another: hemiballismus may, for example, progress to resemble chorea.

1. CHOREA

The movements involve distal muscles, as opposed to hemiballismus, which is proximal. In both conditions the purposeless movements are brisk, random (in both timing and distribution) and basically continuous.

The main difference is that chorea is often bilateral, hemiballismus is unilateral.

In chorea, the movements are often incorporated into voluntary movements, so that a movement of the arm can become a scratching behind the ear. Also, voluntary movements cannot be sustained: fluctuation in grip is "milkmaid's grip".

    Causes of Chorea

    1.1 Huntington's Chorea:
This is quite common in the Western Cape. It is an autosomal dominant condition and there are probably no spontaneous mutations and therefore, one makes the diagnosis in an isolated case with great reluctance. The genetic abnormality consists of an increase in terminal repeats of a single codon on chromosome 4

The condition may start in teenagers, when there is often rigidity, bradykinesia and seizures. In adults, one typically seas chorea, abnormal eye movements and dementia; the chorea may involve the limbs and the face (tongue protrusion, pouting). In the initial stages there is insight into the condition, the severe psychiatric disturbance is common, with suicide being no infrequent,

Investigation: CT scan may show generalised atrophy or atrophy of the caudate head

Treatment: Dopamine Blockers (Haloperidol)

    1.2 Sydenham's Chorea
Seen mostly in teenage girls, a third of whom will have rheumatic heart disease. Initially, the child is thought to be nervous or fidgety, but often becomes clumsy and then develops clear chorea of limbs and face. The chorea resolves, but may relapse over the next two years.

Investigation: Raised ASO tire, normal spinal fluid.

Treatment: Haloperidol (small doses). Penicillin prophylaxis

    1.3 Chorea associated with structural basal ganglia disease
This often occurs in patients with tuberculous meningitis, who have occlusion of the lenticulostriate arteries which are the arteries supplying the basal ganglia, arising from the middle cerebral and are involved by the basal meningitis which causes an arteritis and occlusion of the vessels.

    1.4 Chorea Gravidarum
Usually in first trimester in first pregnancy: resolves after delivery.

    1.5 Systemic Lupus Erythematosus

    1.6 Senile Idiopathic Chorea

    1.7 Chorea associated with thyrotoxicosis

2. HEMIBALLISMUS

Wild, large amplitude flinging movements of the arm and leg of one side of the body, typically so severe that the patient is unable to stand. This follows on infarction of the sub-thalamic nucleus and there is usually a history of hypertension of diabetes, or it may follow TB meningitis. The condition is treated with dopamine blockade and with time and treatment, the wild flinging movements lessen gradually and the appearance is then more choreiform.

3. DYSTONIA

This consists of abnormal fixed postures, which may be prolonged or fleeting, as a result of sustained muscle contractions. Any group of muscles in the body may be affected. If only one body part is affected, such as the arm or neck, the dystonia is focal. If a contiguous region of the body is involved, such as one arm and the trunk, it is called segmental, and if the whole body is involved, it is generalised.

Some movements are involuntary, others arise as excessive, unwanted concomitants to voluntary movements.

    3.1 Generalised torsion dystonia

This usually starts in childhood with torsion dystonia of the leg (involuntary plantar flexion and inversion of foot) and then spreads to arm and face over 10 years. The dystonia is often exacerbated by movement or speech. It may be autosomal dominant in inheritance and is seen more commonly in Ashkenazi Jews. Intelligence, motor and sensory findings are normal other than the abnormal movements.

    3.2 Focal Dystonia

    (i) Torticollis: In adults this is usually a focal or segmental dystonia; the head is tilted to one side, and there are often superimposed intermittent jerks. It can be extremely disabling and difficult to treat; anticholinergics are often used initially. Currently injections of Botulinum toxin into the contracting muscle gives relief, although the effect may last only a few months before having to be repeated.

    (ii) Cranial Dystonia:
        Blepharospasm: spasms of involuntary eye closure
        Hemifacial spasm: spasm of the side of the face
        Oromandibular Dystonia: spasms of muscles around the face, mouth and tongue.
        Laryngeal: forced spasm of laryngeal muscles.
        Treatment is as for torticollis,

(Note: Benign eyelid twitching: This is a very common intermittent fasciculation-like twitching of eyelid associated with fatigue and stress)

    (iii) Isolated focal dystonia related to work activities:

The best known of these is writer's cramp; it is a stiffness and slowness of the hand when writing. These are frequently abnormal postures of the fingers and wrist. It usually begins in the thirties. Patients may go on to develop difficulty with shaving or applying cosmetics (progressive writer's cramp). Numerous other examples of this form of focal dystonia occur, particularly in musicians and sportsmen. These are important causes of occupational disability.

    3.3 Secondary dystonia

This includes perinatal birth injury, toxins (manganese) and some forms of Huntington's chorea. The most important is Wilson's disease. This is an autosomal dominant condition, associated with damage to the basal ganglia and with cirrhosis, owing to deposition of excessive free copper.
            Diagnosis: Serum caeruloplasmin is decreased
            Serum copper is decreased (free copper is increased, but this is not usually measured).
            24 hour urinary copper excretion is increased. MRI of the brain shows typical basal ganglia lesions.
            Treatment: Is with penicillamine, which binds copper.

4. ATHETOSIS

This is closely related to dystonia. Seemingly random writhing movements of the distal extremity flow into one another, giving rise to complex postures. Typical causes are perinatal birth injury and kernicterus in children and basal ganglia infarction in adults.

Sensory athetosis gives rise to a similar clinical appearance, but occurs as a result of difficulty maintaining posture because of the absence of proprioception.

5. DYSKINESIA

This refers to choreiform movements in specific circumstances.

    5.1 Tardive Dyskinesia

This develops in patients who have been taking neuroleptics/phenothiazines for months or years. The movements are to be distinguished from the parkinsonian like picture of reduced activity which is a common side-effect of phenothiazine. Typically in tardive dyskinesia there are: (1) chewing and sucking movements or the mouth and tongue (oro-bucco-lingual dyskinesia). (2)  thrusting movements of the pelvis, and (3) motor restlessness (also called akathisia). This may respond to increased dopamine blockade or to withdrawal of the phenothiazine, but is frequently hard to treat.

Note that neuroleptics can induce an acute dystonic reaction.

    5.2 Oro-facial dyskinesia

This is seen in elderly people, associated with wearing false teeth: after some years, some individuals will develop these chewing and lip-smacking movement.

    5.3 Dose-related to the ingestion of dopamine in Parkinson's disease

6. MYOCLONUS

This is a brief shock-like muscular contraction. It may be regular or arrhythmic. It may be focal, multifocal or generalised.

Myoclonus is a universal phenomenon: sleep starts typically, are small or massive myoclonic jerks occurring in drowsiness.

There are many causes of myoclonus:

    6.1 Patients of normal intellect

  1. Associated with Primary Generalised Epilepsies: this is seen in juvenile myoclonic epilepsy; typically the myoclonus occurs in the morning and patients complain of breaking cups at breakfast time.
  2. Periodic Leg Movements of Sleep: this is one cause of excess daytime sleepiness since recurrent jerks of the legs during sleep wake the patient (and usually the spouse).
  3. Exaggerated startle response: myoclonic jerks in response to sudden noise, etc.
    6.2 Patients with neurological disease
  1. Metabolic and toxic encephalopathies such as renal and hepatic failure and anoxic brain injury. (Asterixis is in fact the reverse of myoclonus, being a sudden focal loss of muscle tone).
  2. Prion dementias (Jakob-Creutzfeld disease) and rarely Alzheimer's disease.
  3. Subacute sclerosing panencephalitis
  4. Familial progressive myoclonic epilepsies: these include a wide range of storage diseases associated with enzyme deficiencies of the gangliosides, etc. etc.
7. TICS

Tics are quick, involuntary movements that are repetitive at irregular intervals. They are unique because they are not completely involuntary. Patients describe a psychic tension which builds up inside them and that is relieved by the movement. Thus the tics can be voluntarily suppressed for a period of time.

Patients can have single or multiple tics and may therefore resemble chorea or multifocal myoclonus.

  1. Commonest tic disorder is "transient tic of childhood".
  2. Gilles de la Tourette syndrome. This is a chronic, multiple tic disorder starting between 5 and 10 years, commoner in males. Vocal tics are frequent (grunting and barking noises) and coprolalia (swear words etc) is frequent. Treatment is with dopamine blockade.
8. TREMOR

Tremor is a universal phenomenon. The description of tremors often relies on an assessment of the tremor frequency: this is hard to judge with the naked eye. Physiological tremor occurs during muscle activity because of the twitches of the contracting muscle fibres are not "fused" together, producing a non-smooth movement.

    8.1 Enhanced physiological tremor

All tremors are exacerbated by the action of the sympathetic nervous system and physiological tremor is as well. This tremor is seen after hyperadrenergic states: administration of b -2 adrenergic agents, nervousness, thyrotoxicosis and alcohol withdrawal. Usually the aetiology of these tremors is obvious and it is short-lived.

    8.2 Essential-Familial tremor (Senile)

This is often (but not always) an autosomal dominant condition with a family history, tending to present at an earlier age in successive generations. It is a slowly progressive and permanent disorder. The amplitude increases in hyperadrenergic situations.

It is an action tremor occurring during activity and is of greater amplitude when reaching for a target. The tremor may involve the head, causing titubation (a side to side head tremor), and also often affects the voice. Responds to Beta-Blockers (Propanolol) or Primidone (Mysoline).

    8.3 Tremor with Parkinson's Disease

Typically this tremor is described as a rest tremor, since it occurs when the patient is sitting or lying. This is really a misnomer since if the muscles are completely relaxed, the tremor goes away. The tremor is an involuntary "pill-rolling" movement of the hands, jaw, face and legs. It is often asymmetrical. Tremor at rest is primarily a problem when trying to maintain position: drinking from a cup or reading the paper.

Like everybody else, patients with Parkinson's disease can have enhanced physiological tremor. They may also have essential-familial tremor.