Dyskinesia refers to a category of movement disorders that are characterized by involuntary muscle movements, including movements similar to tics or chorea and diminished voluntary movements. Dyskinesia can be anything from a slight tremor of the hands to an uncontrollable movement of the upper body or lower extremities. Discoordination can also occur internally especially with the respiratory muscles and it often goes unrecognized. Dyskinesia is a symptom of several medical disorders that are distinguished by their underlying cause. Types
Medication-induced dyskinesias
Acute dystonia is a sustained muscle contraction that sometimes appears soon after administration of antipsychotic medications. Any muscle in the body may be affected, including the jaw, tongue, throat, arms, or legs. When the throat muscles are involved, this type of dystonia is called an acute laryngospasm and is a medical emergency because it can impair breathing. Older antipsychotics such as Haloperidol or Fluphenazine are more likely to cause acute dystonia than newer agents. Giving high doses of antipsychotics by injection also increases the risk of developing acute dystonia.Methamphetamine, other amphetamines and dopaminergic stimulants including cocaine and pemoline can produce choreoathetoid dyskinesias; the prevalence, time-frame and prognosis are not well established. Amphetamines also cause a dramatic increase in choreoathetoid symptoms in patients with underlying chorea such as Sydenhams, Huntingtons, and Lupus.
The rate 
  
    
      
        
          Φ
          
            N
          
        
      
    
    {\displaystyle \Phi _{N}}
   at which a gas of molar mass 
  
    
      
        M
      
    
    {\displaystyle M}
   effuses (typically expressed as the number of molecules passing through the hole per second) is then

  
    
      
        
          Φ
          
            N
          
        
        =
        
          
            
              Δ
              P
              A
              
                N
                
                  A
                
              
            
            
              2
              π
              M
              R
              T
            
          
        
        .