thiamylal and Pain

In an attempt to clarify the neurochemical background of central post-stroke pain and to undertake a pharmacological analysis, the basic pharmacological characteristics of this intractable pain syndrome were investigated by the morphine, thiamylal and ketamine tests. In addition, the correlation between the pharmacological characteristics and the effects of chronic motor cortex stimulation therapy was examined. The study employed 39 central post-stroke pain patients who had intractable hemibody pain associated with dysesthesias, and radiologically demonstrated lesions in the thalamic area (thalamic pain, n = 25) or suprathalamic area (suprathalamic pain, n = 14). The pharmacological evaluations showed that definite pain reduction occurred in eight of the 39 cases (20.5%) by the morphine test, in 22 of the 39 cases (56.4%) by the thiamylal test, and in 11 of 23 cases (47.8%) by the ketamine test. Based on these pharmacological assessments, there was no obvious difference between thalamic and suprathalamic pain. A comparison of the long-term follow-up results of chronic motor cortex stimulation therapy revealed that thiamylal and ketamine-sensitive and morphine-resistant cases displayed long-lasting pain reduction with chronic motor cortex stimulation therapy, whereas the remaining cases did not show good results. We conclude that pharmacological classification of central post-stroke pain by the morphine, thiamylal and ketamine tests could be useful for predicting the effects of chronic motor cortex stimulation therapy. It has recently been suggested that excitatory amino acids may be involved in the development of central post-stroke pain. However, the fact that only 23 of the present 39 cases (59.0%) of thalamic and suprathalamic pain were sensitive to the thiamylal or ketamine test reflects the complex pharmacological background and the difficulties associated with treating central post-stroke pain.

Topics: Adult; Aged; Analgesics, Opioid; Anesthetics; Cerebrovascular Disorders; Female; Humans; Ketamine; Linear Models; Male; Middle Aged; Morphine; Motor Cortex; Pain; Stimulation, Chemical; Syndrome; Thalamus; Thiamylal

In humans, peripheral somatosensory information converges upon dorsal horn neurons in the spinal cord, which can be recorded from the dorsal epidural space as spinal cord potentials (SCPs) following segmental dorsal root stimulation (SS) employing epidural catheter electrodes. Antidromic action potentials and descending inhibition from the dorsolateral funiculus may contribute to SCPs following dorsal column stimulation (DCS). Effects of thiamylal (2.5-7.5 mg/kg, i.v.) on SCPs evoked by independent DCS or SS were compared with those evoked by simultaneous DCS and SS (DCS/SS). DCS- and SS-evoked SCPs recorded from the lumbar enlargement consisted of a sharp negative (N) followed by a slow positive (P) potential. Thiamylal induced dose-dependent increases in amplitude and duration of both N and P potentials evoked by DCS and SS, whether the responses were summed or evoked simultaneously. In awake subjects, N and P potentials produced by simultaneous DCS/SS were significantly smaller than the sum of independent responses. Thiamylal anesthesia antagonized this inhibition; responses to simultaneous DCS/SS were larger than the sum of independent responses. These results suggest that in wakefulness DCS inhibits dorsal horn neuron activity in the lumbar spinal cord, while thiamylal antagonizes DCS-induced inhibition in dose-dependent fashion.

Topics: Action Potentials; Adolescent; Afferent Pathways; Anesthetics, Intravenous; Child; Dose-Response Relationship, Drug; Electric Stimulation Therapy; Electrodes; Electrophysiology; Epidural Space; Evoked Potentials, Somatosensory; Female; Humans; Lumbar Vertebrae; Male; Neural Inhibition; Pain; Posterior Horn Cells; Spinal Cord; Spinal Nerve Roots; Thiamylal; Wakefulness

Topics: Abscess; Anesthesia, General; Animals; Arthritis; Castration; Corynebacterium Infections; Female; Goats; Haemonchiasis; Keratoconjunctivitis; Lymphadenitis; Male; Mastitis; Pain; Pre-Eclampsia; Pregnancy; Skin Diseases, Infectious; Thiamylal; Urinary Calculi

Topics: Adolescent; Adult; Anesthesia, Intravenous; Animals; Autonomic Nervous System; Body Temperature; Child; Electric Stimulation; Electrocoagulation; Electroencephalography; Epilepsy, Temporal Lobe; Female; Globus Pallidus; Humans; Male; Middle Aged; Pain; Parkinson Disease; Plethysmography; Pulse; Respiration; Stereotaxic Techniques; Sweating; Telencephalon; Thalamus; Thiamylal