The authors examined the British medical literature published in the 45-year-period following Parkinson's treatise on the shaking palsy to determine the number and type of references to the shaking palsy or paralysis agitans during this particular period. Several sources suggest that Parkinson's 1817 treatise on the shaking palsy received little immediate attention in his native country, England, and that not until 1861, in France, did Charcot began to elucidate the clinical features of this entity, separating it from other neurologic disorders (for example, multiple sclerosis). A review of the British medical literature from the 45-year-period 1817-1861 revealed a number of references to paralysis agitans, including those by Cooke (1820), Good (1824 and 1829), Elliotson (1827, 1829, 1830, 1831, and 1833), Gowry (1831), anonymous (1832), Todd (1833), Watson (1836), Gibson (1839), Hall (1838 and 1841), Thompson (1842), Graves (1843), Birkett (1853), Paget (1855), and Reynolds (1855). Many of these did not report new or personally observed cases, did not separate Parkinson's disease from other disease entities characterized by both "shaking" and "palsy" (for example, tonic-clonic seizures), or misattributed motor signs to dysfunction of the pyramidal system rather than an extrapyramidal system (that is, attributing bradykinesia or rigidity to weakness). Although there were several references to "shaking palsy" in the early- to mid-19th-century British medical literature, there were few original case reports of Parkinson's disease. This may have contributed to the fact that during this period little was added to the original observations made by Parkinson in 1817. In particular, the separation of bradykinesia and weakness did not become apparent until later work by the French.