Neurosurgical treatment of cancer pain

Temporal Summation Predicts De Novo Contralateral Pain After Cordotomy in Patients With Refractory Cancer Pain

BACKGROUND

Percutaneous cervical cordotomy (PCC), which selectively interrupts ascending nociceptive pathways in the spinal cord, can mitigate severe refractory cancer pain. It has an impressive success rate, with most patients emerging pain-free. Aside from the usual complications of neurosurgical procedures, the risks of PCC include development of contralateral pain, which is less understood.

OBJECTIVE

To evaluate whether sensory and pain sensitivity, as measured by quantitative sensory testing (QST), are associated with PCC clinical outcomes.

METHODS

Fourteen palliative care cancer patients with severe chronic refractory pain limited mainly to one side of the body underwent comprehensive quantitative sensory testing assessment pre-PPC and post-PCC. They were also queried about maximal pain during the 24 h precordotomy (0-10 numerical pain scale).

RESULTS

All 14 patients reported reduced pain postcordotomy, with 7 reporting complete resolution. Four patients reported de novo contralateral pain. Reduced sensitivity in sensory and pain thresholds to heat and mechanical stimuli was recorded on the operated side (P = .028). Sensitivity to mechanical pressure increased on the unaffected side (P = .023), whereas other sensory thresholds were unchanged. The presurgical temporal summation values predicted postoperative contralateral pain (r = 0.582, P = .037).

CONCLUSION

The development of contralateral pain in patients postcordotomy for cancer pain might be due to central sensitization. Temporal summation could serve as a potential screening tool to identify those who are most likely at risk to develop contralateral pain. Analysis of PCC affords a unique opportunity to investigate how a specific lesion to the nociceptive system affects pain processes.

Stereotactic Radiofrequency Thalamotomy for Cancer Pain: A Systematic Review

Pain is a common occurrence in patients with cancer, which, in some cases, is not adequately controlled with medical analgesia. Thalamotomy is a treatment option in such circumstances, but synthesis of historical evidence and thalamic stratified data are lacking. We therefore sought to systematically review evidence supporting radiofrequency thalamotomy for intractable cancer pain. This review was performed using multiple electronic databases and a (PICO) patient/problem, intervention, comparison, outcome search with the terms "radiofrequency thalamotomy" and "cancer pain." Of 22 full-text studies assessed for eligibility, 14 were included for review. Articles were excluded in which radiofrequency ablation was not used, chronic implantation was used, or the study did not include patients with cancer pain. Thirteen case series and 1 case report were included. Thalamic targets included ventral posterior, central lateral, dorsomedial, centromedian, centromedian/parafascicular, centromedian and anterior pulvinar, pulvinar, limitans, suprageniculate and posterior nuclei. Patient characteristics, operative methods, lesioning parameters, patient follow-up, and outcomes were variably reported across the studies. Where relevant outcome data were available, 97% of patients experienced initial pain relief and 79% experienced significant lasting relief. Adverse events were typically transient. We conclude that radiofrequency thalamotomy for cancer pain is well tolerated and can produce significant relief from intractable cancer pain. No superiority of thalamic target could be determined.

Electrostimulation and neurosurgical measures in cancer pain

Neurosurgery for cancer pain may always be considered when the pain no longer responds to conservative treatment methods or only at the cost of undesirable side-effects. Almost all these operations that can be considered for the cancer patient can be performed percutaneously, without general anaesthesia, without loss of blood, and with short hospitalization. Chronic pain has to be differentiated according to whether it is somatogenic or neurogenic. For somatogenic pain (pain without any neurological deficit), intrathecal or intraventricular administration of morphine-like substances through an implanted drug delivery system is the most attractive method. The classical neurosurgical interruption of a tract conducting pain between the periphery and the cerebral integration centers is an almost obsolete method, and percutaneous cordotomy can only be discussed when the pain is strictly unilateral and the prognosis of the disease relatively favorable. For neurogenic pain (pain with sensory disturbances) the only method which can be helpful is electrical stimulation with an implanted neuropacemaker connected to an electrode in the dorsal columns of the cord or in the sensory thalamic nucleus (depending on the location of the pain), since morphine has at best only a poor analgesic effect on deafferentation pain.