"Movement disorders lecture:- A movement disorder impairs the regulation of voluntary motor activity without directly affecting strength, sensation or cerebellar function."
The video clip below may take a few moments to appear
This video illustrates a disorder known as pseudoathetosis.
Pseudoathetosis consists of abnormal writhing movements, usually of the fingers, caused by a failure of joint position sense (proprioception)and indicates disruption of the proprioceptive pathway, from the peripheral nerves to the parietal cortex of the brain. Paradoxically, eye closure may decrease the amount of movement as the visual information or cues probably trigger corrective movements which return the limb to the desired "baseline" allowing a new phase of involuntary drift before a subsequent corrective phase occurs.
It may be mistaken for choreoathetosis, however, these abnormal movements are relatively constant irrespective of whether the eyes are open or closed and occur in the absence of proprioceptive loss.
Hemipseudaoathetosis refers to pseudoathetosis on one side of the body ,usually the upper limb and is most commonly caused by a lesion affecting the cuneate tract or cuneate nucleus in the cervical spine or lower brainstem (medulla) respectively as was the case in this patient with hemipseudoathetosis on the left.
Gotkine M, Gomori JM (2007). "Hemipseudoathetosis due to a hemorrhage at the cervicomedullary junction". Neurology 69 (15): 1551.
Slide 2: What is a Movement disorder? “ A disorder which impairs the regulation of voluntary motor activity without directly affecting strength, sensation or cerebellar function ” • Sometimes also known as “ extrapyramidal disorders” • Many neurologists restrict the term “ extrapyramidal” to refer only to Parkinsonism
Slide 3: Types of abnormal movement • Myoclonus • Ballismus • Chorea • Athetosis • Dystonia • Tics • Tremor ( discussed elsewhere )Movement disorders lectureSlide 4: Myoclonus •“ sudden, brief, shock-like involuntary movements” • May be caused by active muscle contraction - positive myoclonus • May be caused by inhibition of ongoing muscle activity - negative myoclonus ( eg. Asterixis ) • Generalised - widespread throughout body • Focal / segmental – restricted to particular part of bodyMovement disorders lectureSlide 5: Generalised myoclonus • Physiologic - Nocturnal ( usually on falling asleep ) - Hiccups • Essential - Occurs in the absence of other abnormality - Benign and sometimes inherited • Epileptic - Demonstrable cortical source • Symptomatic i.e secondary to disease process - Neurodegenerative eg. Wilson’s disease - Infectious e.g CJD, Viral encephalitis - Toxic e.g. penicillin, antidepressants - Metabolic - anoxic brain damage - hypoglycemia - hepatic failure ( “ asterixis” ) - renal failure - hyponatremia….. And others
Slide 6: Segmental Myoclonus • Can arise from lesions anywhere in the CNS • Can arise from many of the processes that can cause generalised myoclonus • Example is “palatal myoclonus” which arises due to any lesion that interrupts pathway between red nucleus, cerebellum and olivary nucleus.
Slide 7: Treatment of Myoclonus • Valproic acid is drug of choice • May respond to benzodiazepines e.g. clonazepam
Slide 8: Ballismus, Chorea, Athotosis and Dystonia These should NOT be thought of as separate entities amenable to specific definition but rather as a SPECTRUM of movements that blend into one-another WHY?
Slide 9: Because…….. • They often co-exist • Even neurologists may often not be able to agree as to how a particular movement should be classified! • They often ( with some notable exceptions ) have the same significance in terms of aetiology.
Slide 10: The spectrum Ballismus Chorea Athetosis Dystonia Movements become - Less violent / explosive / jerky - Smoother and more flowing - More sustained They differ from tics in that they cannot be suppressed by voluntary control
Slide 11: Ballismus • Violent “flinging” movement of entire limb • Almost always unilateral and therefore use term “ HEMIBALLISMUS” • Involves proximal musculature and is sometimes thought of as a “ proximal unilateral chorea ” • Usually due to a CVA in contralateral subthalamic nucleus
Slide 12: Chorea ( “dance” in Greek) • Rapid irregular muscle jerks • May affect limbs, head, face and tongue • In the limbs chorea refers more to distal movements ( as proximal movements usually called ballismus) • Patients often attempt to conceal involuntary movements by superimposing voluntary movements onto them e.g. an involuntary movement of arm towards face may be adapted to look-like an attempt to look at watch
Slide 13: Athetosis “ changeable” in Greek • Slow, flowing, often twisting movements • Occurs mainly distally ( hands, fingers) • Can also affect face and tongue • Often use term “ choreoathetosis ” due to overlap between syndromes ( chorea referring to less smooth , more jerky movements)Movement disorders lectureSlide 14: Dystonia • “ condition in which the patient assumes a sustained, abnormal posture or limb position” • Due to co-contraction of agonist and antagonist muscles in part of body • Can be thought of as an athetoid movement that “gets stuck” for a period of time; thus, a patient with choreoathetosis may perform an involuntary movement in which his hand and fingers are twisted behind his head. He may hold this position for a few moments before his hand moves back in front of his body. • The part of the movement when the limb was held, unmoving, in an abnormal position would be considered a dystonia ( may occur alone).
Slide 15: Examples of focal dystonias • Blepharospasm: - involuntary forceful closure of eyes • Torticollis: - Tendency of neck to twist to one side. • Writer’s cramp: - Dystonic posturing of arm when hand used to perform specific tasks e.g. writing, playing pianoMovement disorders lectureSlide 16: Botulinum toxin • Derived from Clostridium botulinum • Prevents pre-synaptic release of Ach vesicles and therefore blocks neuro- muscular junction transmission • May be injected selectively into muscles responsible for focal dystonias, allowing relief for up to several months • Requires expertise; can cause more extensive paralysis than intended.
Slide 18: Hereditary • Huntington’s disease • Wilson’s disease • Neuroacanthocytosis • Hereditary dystonias - idiopathic torsion dystonia - dopa - responsive dystoniaMovement disorders lectureSlide 19: Wilson’s disease • Autosomal recessive defect of copper excretion in which there is defective copper-binding to ceruloplasmin • Leads to copper deposition in: - liver causing cirrhosis - brain ( especially basal ganglia ) leading to movement disorders and other abnormalities - Cornea leading to the appearance of rusty brown “ Kayser-Fleischer rings” around cornea (usually only seen with slit-lamp). • Diagnosis is via low serum ceruloplasmin, increased urinary Cu, liver biopsy ( excessive Cu) and brain MRI changes • Although it is rare it is very important to think-of and diagnose as it is TREATABLE:- Penicillamine is given to chelate the copper and promote excretion.
Slide 20: Idiopathic torsion dystonia • Hereditary and sporadic forms • Variable inheritence • High incidence in Ashkenazi Jews • Onset may be in childhood / adulthood • Affects limbs, trunk, neck, face • Trial of L-dopa usually initiated • Level of disability variable
Slide 21: Dopa-responsive dystonia • Autosomal dominant inheritence • Onset usually in childhood • Girls more severely affected • Some parkinsonian features - rigidity - bradykinesia Low levels of L-Dopa very effectiveMovement disorders lectureSlide 22: Drug-induced • Drugs acting on dopaminergic system - Antiparkinsonian - Antipsychotic • Lithium • Phenytoin • Oral contraceptives
Slide 23: Secondary to medical disorders (A SHEEP) • Anoxic brain damage ( post – CPR ) • Systemic lupus erythematosis • Hepatic failure • Endocrine - Thyrotoxicosis - Addisons • Electrolyte - Low Ca, Mg, - High Na • Polycythemia rubra vera
Slide 24: Sydenham’s chorea • Mainly children / adolescents • Complication of previous group A streptococcal infection • Usually no recent history of infection • Acute / subacute onset • May have behavioural problems • Usually remits spontaneouslyMovement disorders lectureSlide 25: Chorea gravidarum • Chorea of any cause that begins in pregnancy • May represent recurrence of Sydenham’s chorea. • Most commonly associated with anti- phospholipid syndrome +/- SLE • Usually resolves spontaneously
Slide 26: Tics • Recurrent, sterotyped abnormal movements • May be suppressed voluntarily or with distraction • Voluntary suppression leads to anxiety and a build-up of internal unrest. • Worsen under stress
Slide 27: Movement disorders lecture Summary • Movement disorders are often difficult to define precisely, but have similar differential diagnoses. • They are often a manifestation of a more widespread neurological or internal medical problem. • Other than the specific treatments mentioned, most details of therapy are beyond the scope of this course. • In some cases treatment includes treatment of underlying cause e.g. Wilson’s disease
Slide 28: Movement disorders lecture Submitted to AskTheNeurologist.Com in 2007 Author Anon.