Introduction

Abstract

In 1891, Ludwig Edinger, a German professor of neurology and founder of modern comparative neuroanatomy (see biography in [1]), challenging the prevailing opinion of the day, introduced the concept of centrally arising pains. The patient was Frau R. (Mrs. R.), aged 48, who developed heftige Schmerzen und deutliche Hyperaesthesie in den gelaehmten Gliedern (violent pains and clear-cut hyperesthesia in the paretic limbs: right arm and leg), Wegen der furchtbaren Schmerzen Suicidium 1888 (due to the terrible pains, suicide 1888). She was morphium (opioid) unresponsive. At autopsy, a thalamic infarction was found. In 1895, Wallenberg described facial pains following medullary stroke. In the first decade of the twentieth century, French neurologists Dejerine and Roussy introduced the concept of the syndrome thalamique which at times also included spontaneous pain. In 1911, Head and Holmes concluded that thalamic pain depends on the destruction of the posterior part of the external thalamic nucleus and provided the first—and still unparalleled—quantitative description of the associated somatosensory alterations. During World War I, several observations on “thalamic pains” following spinal cord war lesions were published, as previously done—but only descriptively—during the US Civil War in the 1860s. The term central pain (CP) was first used in the English literature by Behan in 1914. By the early 1930s, it was clear that lesions at any level of the CNS could be accompanied by CP. Despite these observations, the term thalamic syndrome became synonymous with CP. In 1969 Cassinari and Pagni, by studying iatrogenic “pure” lesions giving rise to CP, reached the conclusion that the essential lesion was damage to the pain-conveying spinothalamoparietal tract. Also, they observed how operations that interrupt the pain-relaying pathways in order to allay pain may themselves originate CP (sometimes more severe than the pain that led to the operation). The genesis of CP was finally revealed in 1994 by Canavero, Pagni’s pupil (Fig. 1.1; see [2] for complete historical survey).