Stereotactic and functional neurosurgery
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Stereotact Funct Neurosurg · Jan 1994
Comparative StudyAnalgesic action of acute and chronic intraspinally administered opiate and alpha 2-adrenergic agonists in chronic neuropathic pain.
Intrathecal (IT) administration of opiate analgesics has become a popular method of pain control in patients with pain of both malignant and nonmalignant origin. Therapeutic efficacy for nonmalignant pain states might be improved by having a broader range of available pharmacologic agents for intrathecal administration. Toward this aim, we have applied a new model of neuropathic pain in the rat to evaluate the relative analgesic efficacy and potential cross tolerance of both acutely and chronically administered IT morphine (MS) and tizanidine (TZ), an alpha 2-adrenergic agonist. ⋯ The animals rapidly became tolerant to these agents so that by day 4, neither drug had an analgesic effect. No significant cross tolerance between MS and TZ was observed. Thus, both IT MS and TZ are analgesic in experimental chronic neuropathic pain.(ABSTRACT TRUNCATED AT 400 WORDS)
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Stereotact Funct Neurosurg · Jan 1994
An experimental animal model of spinal cord stimulation for pain.
In spite of the routine usage of spinal cord stimulation (SCS) as treatment of chronic pain, there is an insufficient understanding of the mechanisms underlying its effect. The method was originally developed as a spin-off from experiments demonstrating the inhibitory control of nociceptive signals by the activation of large afferent fibers, and on the basis of these findings the gate-control theory was advanced. Later experiments showed that stimulation of the dorsal columns can inhibit the relay of nociceptive impulses to second-order neurons in the dorsal horn. ⋯ SCS was applied at the approximate level of Th-XII during 10-20 min and produced a marked augmentation of the stimulus threshold. This abnormally high threshold was not normalized until 30-60 min after the end of SCS. In awake animals SCS was applied via an implanted spinal electrode and the effect on behavior changes associated with mononeuropathy was studied.(ABSTRACT TRUNCATED AT 250 WORDS)