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Other Movement Disorders

 

This article covers types of dyskinesia and their causes, with later focus on:

  • Drug-induced dyskinesias
  • Huntington's disease
  • Multi-system atrophy
  • Progressive supranuclear palsy

 

    Types of dyskinesia

    Dyskinesias are defined as abnormal involuntary movements. They include:

    1. Athetosis
    2. Chorea
    3. Hemiballismus
    4. Dystonias
    5. Myoclonus
    6. Tardive dyskinesia (see drug-induced dyskinesias)
    7. Tics
    8. Tremor (this is covered in another article)

     

        Athetosis and chorea

        Athetosis is characterised by slow, writhing movements, most commonly seen in the fingers and hands. It should be differentiated from pseudoathetosis, the 'piano-playing' movement of fingers, present in patients with deficits in proprioception. This phenomenon is elicited by asking the patient to hold their hands out in front of them with closed eyes.

         

        Chorea is characterised by rapid, jerky, 'dancelike' movements, most commonly in the limbs and head. Movements may appear semi-purposeful, and are not repetitive, but move fluidly to different parts of the body.

         

        These two dyskinesias often occur together as choreoathetosis.  Causes include:

        • IATROGENIC - medications for Parkinson's disease, epilepsy and schizophrenia
        • GENETIC - Huntington's disease (discussed further down)
        • DEVELOPMENTAL - cerebral palsy
        • AUTOIMMUNE - as a now rare complication of acute rheumatic fever, Sydenham's chorea, or as a symptom of SLE
        • HORMONAL - as an isolated symptom in pregnancy, or rarely as a side effect of theoral ontraceptive pill, hyperthyroidism
        • METABOLIC - sodium or glucose imbalance and vitamin B1/B12 deficiencies
        • VASCULAR - stroke
        • TUMOURS

         

        Hemiballismus

        Hemiballismus affects one side of the body, most commonly the arm. It is a sudden flinging movement that can often be problematic as objects may be unintentionally thrown, or the arm might hit other people/objects in the vicinity. Most commonly caused by subthalamic stroke.

         

         

        Dystonias

        Dystonias are spasmodic movements that may occur during intentional movement, either rhythmically (giving a repetitive appearance), or persistently (resulting in typical fixed postures). Focal dystonias may be responsive to treatment with botox. They may be :

         

        • In the neck such movements are called spasmodic torticollis
        • In the back they may result in a twisting scoliosis or an arched lordosis
        • In the eye, blepharospasm results in involuntary eye closure
        • Oromandibular dystonia affects the mouth, jaw, larynx and pharynx
        • Writer's cramp may appear in the hand

         

        These focal dystonias are usually acquired. In contrast, generalized dystonias are normally hereditary. Some can be treated with carbidopa.

         

        Spasmodic torticollis

        Myoclonus

        Rapid, sometimes repetitive, jerks of a muscle or group of muscles. Hiccoughs are a benign example, and people often experience myoclonus as they are falling asleep. Pathological manifestations include:

        • IATROGENIC - antihistamines, antidepressants, levodopa
        • METABOLIC - kidney or liver failure, hypo/hyperglycaemia
        • HYPOXIA  - Lance-Adams syndrome
        • INFECTION - viral encephalopathy
        • VASCULAR - stroke
        • TRAUMA
        • TUMOUR
        • NEUROLOGICAL DISEASES - epilepsy, MS, Parkinson's, Alzheimer's or CJD
        • IDIOPATHIC - essential myoclonus

         

          Tics

          Tics are rapid, repetitive, stereotyped movements. Patients may describe feeling an urge to do the tic, similar to an urge to sneeze, that can sometimes be supressed for short periods of time. However the urge usually becomes irresistable after several minutes, and the patient may feel momentary relief during and after performing the tic. 

           

          Simple tics include excessive blinking, grimacing,  A quarter of children develop tics at one point in their development that usually resolve within a year.

           

          Complex tics may be caused by Gilles de la Tourette syndrome. This may also include vocal tics, such as involuntary swearing.

           

          Drug-induced dyskinesias

          Neuroleptics (antipsychotics) can induce tardive dyskinesia. This is characterised by movements of the mouth such as chewing, lip-smacking and protrusion of the tongue. Extrapyramidal movements are also common side effects. These include rigidity, pill-rolling tremor, and bradykinesia (slowing of movement). Extrapyramidal movements induced by medication tend to be symmetrical, in contrast with Parkinson's disease where onset of tremor and rigidity is usually asymmetrical.

           

          Parkinson's medications such as levodopa can induce choreatic and athetoid movements. They may also induce myoclonus, as can antihistamines and tricyclic antidepressants.

           

           

          Huntington's disease

          This is an autosomal dominant, neurodegenerative disease affecting the basal ganglia. Onset is insidious, and usually between the ages of 35 and 50.

           

          Signs and symptoms

          The early signs and symptoms, which may persist for 10 years before onset of chorea, include:

          • Personality change
          • Mild psychosis
          • Apathy
          • Clumsiness
          •  Fidgeting and fleeting grimaces

           

          Core features are:

          • Chorea
          • Rigidity
          • Dementia
          • Seizures

          Dysarthria, dysphagia, myoclonus and tics are also common. Later in the disease chorea may be superseded by dystonia and parkinsonism.

          Management

          No known treatments are effective in slowing or stopping disease progress. Instead treatment is symptomatic:

          1. Chorea may respond to benzodiazepines and neuroleptics
          2. Psychosis should be treated with neuroleptics
          3. Depression should be treated with antidepressants, or in refractory cases ECT

          Genetic counselling is strongly recommended, as is the early arrangement of an advance directive.

          Most patients die within 13-15 years of disease onset.

           

          Parkinson-plus

          Though Parkinson's disease is the main form of parkinsonism, some other rarer diseases can also manifest with some or all of the triad of rigidity, tremor and bradykinesia:

            

          Multiple system atrophy (MSA)

          Extrapyramidal symptoms in this disease is mostly unresponsive to treatment. The tremor is generally not 'pill-rolling' as in parkinson's disease, and postural instability is often a core feature. Aside from extrapyramidal symptoms, this is characterised by changes in:

          1. THE AUTONOMIC SYSTEM. When this feature predominates, MSA is sometimes called Shy-Drager syndrome.

          • Postural hypotension (resulting in dizziness and syncope)
          • Urinary dysfunction
          • Impotence
          • Constipation

          2. THE CEREBELLUM

          • Ataxic gait
          • Ataxic dysarthria

           

          Progressive supranuclear palsy (PSP)

          This is characterised by:

          • Symmetric rigidity (greater proximally than distally) without cogwheeling
          • Neck hyperextension (dystonia)
          • Vertical gaze palsy
          • Postural instability
          • Dysarthria and dysphagia (pseudobulbar palsy)
          • Cognitive impairment

          It is unresponsive to therapy, and as suggested by the name, characterisd by progressive neurodegeneration.

           

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