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Table 1 Abnormal movement categories and their pathological origin listed in alphabetical order

From: Abnormal movements in critical care patients with brain injury: a diagnostic approach

Abnormal movement Definition Pathophysiological origin
Chorea Involuntary, purposeless, nonrhythmic, non-sustained movements that flow from one body part to the other Poorly understood. Could be due to loss of normal pallidal inhibitory input
Hemiballismus: a severe form of chorea, is characterized by vigorous irregular high amplitude movements on one side of the body Hemiballismus happens secondary to injury of the subthalamic nucleus
Clonus Rhythmic involuntary muscular contractions and relaxations Upper motor neuron injury and its descending pathways
Dystonia Sustained twisting movements that are often frequent and progresses to prolonged abnormal postures Basal ganglia. Abnormalities are also seen in the cortex and reduction in spinal cord and brainstem inhibition
Myoclonus Sudden, brief involuntary movements which may be caused by muscle contractions (positive myoclonus) Widespread origin depending on the injury or type: cortical, subcortical (basal ganglia), brainstem or spinal cord in segmental myoclonus
Asterixis is considered a negative myoclonus secondary to sudden loss of tone
NCSE Unilateral eye deviation, lip smacking, automatisms and some movements of the fingers Cortical in origin
Paroxysmal posturing Involuntary flexor or extensor posturing on one side or bilateral spontaneously or with pain. Opisthotonus posturing refers to hyperextension of the neck and back “arching position” Damage above the red nucleus (flexion posturing) or below (extensor posturing) Midbrain injury or tetanus (opisthotonus)
Shivering High frequency involuntary muscular contractions involving one group or more of muscles Thermoregulatory (due to hypothermia) or non-thermoregulatory (not well understood)
Tics Abnormal movements (motor) or sounds (phonic) which can be simple muscle jerks or complex when they consist of sequential movements in different parts of the body May be related to abnormalities in the basal ganglia
Tremor Oscillatory rhythmic movement that affects one or more parts of the body Likely related to the presence of central oscillator in the basal ganglia or cerebellum
  1. Description and pathophysiology of various categories of abnormal movements that may be seen in intensive care unit patients. NCSE non-convulsive status epilepticus