Aktuelle Neurologie 2007; 34 - V156
DOI: 10.1055/s-2007-987527

„Central pain generator“ arises from partially preserved spinothalamic tract neurons

G Wasner 1, D Burton 1, B Lee 1, S Engel 1, E McLachlan 1
  • 1Kiel; Sydney, AUS

Central pain following lesions within the central nervous system is the most excrutiating and most difficult type of neuropathic pain to treat. Abnormal neuronal activity following spinothalamic tract damage is suggested to be the underlying pain mechanism. The origin of this 'central pain generator' as well as the role of the central pain pathway is unclear, since the same deficits in spinothalamic tract function were found in patients with and without pain. In the present study central pain patients with complete spinal cord lesion were investigated in the skin area, in which pain was perceived. Spinothalamic tract function was tested by heating and cooling the skin before and after sensitization of peripheral afferents via topical application of transient receptor potential agonists capsaicin and menthol. Sensitization was performed to increase sensitivity of thermal stimuli to detect even minor remaining spinothalamic tract pathways. 8/12 patients perceived stimulus-evoked sensations indicating partial preservation of spinothalamic tract neurons in the majority of pain patients. Further, thermally-evoked sensations mimiced individual central pain characteristics indicating that the remaining pathways are involved in maintaining the pain. No sensation was induced in matched pain-free patients. We concluded that partially preserved spinothalamic tract neurons serve as the 'central pain generator'.

Supported by the Alexander von Humboldt-Foundation (Germany) and the Spinal Injury Research Centre of the Prince of Wales Medical Research Institute (Sydney, Australia)