5 Movement and Neurodegenerative Disorders 5.1 Approach to Movement Disorders 5.1.1 Approach to Abnormal Movements Ref: Davidson Ch26, Neurology in Practice Ch8, JC23, JC Teaching clinic, Maudsley’s guidelines Ch2 Movement disorders are divided into: □ Hyperkinetic disorders: tremor, chorea/choreoathetosis, tics, ballismus, myoclonus, dystonia, stiff-person syndrome □ Hypokinetic disorders: Parkinsonism, catatonia Note that functional movement disorders (common) may mimic any syndrome patterns A. Tremor Tremor: alternating contractions of antagonistic muscle groups causing involuntary rhythmic oscillation of body parts Types of tremor: □ Rest tremor: occurs in supported body parts w/o ms activation Test: observe with body part supported, ↑by mov’t in other body parts and ↓by its own mov’t □ Postural tremor: occurs when maintaining certain posture Test: observe by extending UL horizontally, pointing at objects, sitting erect w/o support, standing, protruding tongue □ Kinetic tremor: occurs during voluntary movement → Simple kinetic tremor: tremor roughly the same throughout course of a voluntary movement → Intention tremor: crescendo increase as affected body part approaches its target → Task-specific tremor: occurs during specific task, eg. primary writing tremor
Example Features Comments - Low-amplitude, high frequency (10-12Hz) tremor - Not evident in normal circumstances - Exacerbation of physiologic tremor Physiological - Postural tremor, occurs upon maintaining posture is the commonest cause of action - Symmetrical and distal in distribution tremor tremor - Should seek a primary medical - ↑ by anxiety, emotional stress, drugs (eg. β2-agonist and other catecholaminergic drugs, lithium, antidepressants), cause first in action tremor alcohol/opioid withdrawal, thyrotoxicosis, fever
- Variable amplitude, high-frequency (8-10Hz) tremor - Prev 300/100k (up to 5%) - 30-70% FHx +ve, AD inheritance Essential - Postural and kinetic tremor, NOT at rest - Typically affects bilateral arms (not LL) and head - Usually a/w insidious onset tremor - May be alleviated by alcohol but not ↑ by caffeine - Mx: propranolol, primidone, benzodiazepine (1st line), DBS of - NOT a/w other Parkinsonian and cerebellar features ventromedial nucleus of thalamus
- Coarse, low-frequency (3-4Hz) tremor - May be first manifestation of Parkinsonian - Resting tremor, dampened during volition idiopathic PD - Typically starts at unilateral UL and spread to other limbs - Anticholinergics may be used as tremor - Classically described as ‘pill-rolling’ tremor initial Tx in tremor-dominant PD in - Associated with rigidity and bradykinesia young pt
Cerebellar - Coarse, low-frequency (4-6Hz) tremor - Intention tremor, maximal approaching end of movement / tremor - Associated with other cerebellar features
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B. Choreiform Movements Chorea: sudden, unpredictable quasipurposive involuntary fidgety/jerky movement □ ↑ by voluntary movement, stress, anxiety; ↓ during sleep Athetosis: slower, coarser, more writhing movement, esp affecting distal parts of limbs □ Often occurs together with athetosis (choreoathetosis) Ballism: involuntary movement that are proximal and large amplitude with a flinging/kicking character □ Most often unilateral (hemiballism) □ Classically a/w contralateral subthalamic nucleus stroke