Denny-Brown's views on the pathophysiology of dystonia.

We review Denny-Brown's hypotheses on the mechanisms underlying motor behavior and his views on how dysfunction in these mechanisms can result in dystonia. His formulations were based upon clinical observations of patients with diseases of the central nervous system and on monkeys with surgically-induced lesions of structures affected by diseases in his patients. Denny-Brown viewed dystonia as resulting from an imbalance of reflex responses to natural stimulation, both tonically and phasically. The evidence for this view came from demonstration of alterations of dystonic postures by natural vestibular, cutaneous, proprioceptive and visual stimuli. His formulations remain highly useful to clinicians faced with a bewildering variety of postural and movement disorders.