- central pain
- Also known as thalamic pain, pseudothalamic pain, and *anaesthesia dolorosa. The term central pain is indebted to the Greek noun ken-tron (centre of a circle). It refers to the central nervous system as the originator of this type of pain. The term central pain was introduced into the English language in 1914 by the American surgeon Richard Joseph Behan (b. 1879). The concomitant concept, however, was introduced in or shortly before 1891 by the German neu-roanatomist Ludwig Edinger (1855-1918). Following various descriptions of pain arising in the context of bulbar lesions, spinal hemisec-tion, spinal trauma, and pons tumours - as rendered in the literature since 1811 - Edinger envisaged central entstehende Schmerzen (i.e. 'centrally mediated pains') as "caused by direct contact of injured tissue with the sensory path coursing in the internal capsule". According to the Italian pain specialists Sergio Canavero (b. 1964) and Vincenzo Bonicalzi (b. 1956), the use of the terms thalamic pain, pseudothalamic pain, and anaesthesia dolorosa as synonyms for central pain is not entirely correct. Today thala-mic pain is conceptualized as a specific form of central pain, whereas the term anaesthesia dolorosa only applies to central pain when there is an anaesthetic region caused by neurosurgical lesions. The term pseudothalamic pain has been discarded altogether. Today central pain is conceptualized as a somatosensory symptom due to a CNS lesion affecting a part of the spinothala-moparietal path. It is defined by the International Association for the Study ofPain (IASP) as "pain initiated or caused by a primary lesion or dysfunction of the central nervous system". Central pain can be complicated by other non-sensory symptoms such as * visual and * auditory hallucinations, vertigo, and cognitive or motor function abnormalities. Phenomenologically, it is characterized primarily by a segmentally distributed type of pain which is restricted to one or more body parts, such as the hemiface, one foot, one hand, a quadrant of the body, or the mouth and hand. In 40% of cases, the affected individual reports hemibody pain, with or without involvement of the face. The pain is described as having different qualities simultaneously. For example, there may be a burning pain in the leg and an aching pain in the face, or * dysaesthesia to the hemiface, and shooting pains to the limbs and trunk. Generally speaking, one type ofpain tends to be present continuously, while the other tends to be episodic in nature. The intensity ofthe pain can vary significantly, but it can be so unbearable that the affected individual may consider, or actually commit suicide. When central pain takes the form of an itch, it is referred to as central neuro-genic pruritis. Alternatively, central pain can also be characterized by an unpleasant sensation that is not pain or pruritis, and which the affected individual may find hard to describe. Pathophysio-logically, central pain is associated primarily with structural lesions affecting the spinothalamopari-etal path. Etiologically, it is associated primarily with stroke, neoplasms, and traumata. The notion of central pain should not be confused with pain syndromes such as * deafferentiation pain, * hyperalgesia, * hyperpathia, * causalgia, *topalgia, and * allodynia, or with the notions of *hallucinated pain and * hallucinated headache. The issue of whether pain can also be experienced in a hallucinated form is a knotty philosophical issue.ReferencesBehan, R.J. (1914). Pain: Its origin, conduction, perception and diagnostic significance. New York, NY: D. Appleton and Company.Canavero, S., Bonicalzi, V. (2007). Central pain syndrome. Pathophysiology, diagnosis and management. Cambridge: Cambridge University Press.Edinger, L. (1891). Giebt es central entstehende Schmerzen? Deutsche Zeitschrift für Nervenheilkunde, 1, 262-282.
Dictionary of Hallucinations. J.D. Blom. 2010.