RESUMO
BACKGROUND & OBJECTIVE: There is no perfect method to control cancer pain. It is reported that nucleus centromedianus thalami plays a crucial role in the analgesia of central nerve system. The authors conducted this study, based on rat experiments, together with the clinical treatment of more than 90 cases involving various cancer pains, to explore the pain-relieving effects after damaging nucleus centromedianus thalami. METHODS: Ten SD rats, whose nucleus centromedianus thalami were damaged by electrolysis, were chosen, and then measured the pain degree by applying electricity to stimulate the tails of the rats. Meanwhile, another 10 rats, whose nucleus centromedianus thalami were not damaged, were chosen as the control group, among whom the same operation procedure as the above mentioned was carried out. The range of pain scale of the rats was measured by the alteration of the electric intensity. A total of 90 cases of intractable cancer pain were treated, including 36 cases of lung cancer, 21 cases of nasopharyngeal carcinoma, 10 cases of intestinal cancer, 8 cases of cancer of pancreas, 8 cases of osteocarcinoma, 4 cases of carcinoma of kidney, 3 cases of hepatocarcinoma. The brain stereotactic technique was used to damage the nucleus centromedianus thalami with radiofrequency coagulation lesions. The 10-grade method recommended by WHO was used to rank pain degree. RESULTS: Pain scale of rats in the first group rose from 0.152+/-0.034 mA prior to the damage to 0.326+/-0.05 afterwards, with a significant difference (P< 0.001), while the pain scale of the control group dropped from 0.142+/-0.027 mA prior to the operation to 0.138+/-0.035 mA afterwards, with no remarkable difference (P > 0.05). To patients with cancer pain, the average pain grade in this study went above 7 scores, but dropped to 0-3 scores after operation, according to the 10 grade method by WHO. A life-long tracing observation indicted that cancer pain in 24 cases relapsed to varying degrees but below 5 scores, the rest of the patients were analgesic persistently, 3 cases among whom lasted for as long as 2 years. The incidence cases of operational complications were 15 of somnolence, 10 of urinary incontinence, 8 of divagation, and 3 of unilateral oculomotor paralysis. These complications released after symptomatic treatments. CONCLUSION: Nucleus centromedianus thalami damage is an effective way to relieve cancer pain, as well as the complications should be paid attention.