Ischia S, Finco G, Gottin L Benedini B, Lonati G Polati E* Institute of Anesthesiology and Intensive Care, Pain Relief Center,
University of Verona , Italy
*Institute of Anesthesiology and Intensive Care, University ofUdine, Italy

INTRODUCTION

Cancer related pain can be adequately treated in most patients using relatively simple measures such as the regular administration of non opioid or opioid analgesics (1,2) The remaining patients, especially those with neurogemc or incident type pain, are less responsive to these measures and may require more aggressive approaches, such as neuromvasive (spinal administration of opioids and/or local anesthetics) or neuroablative procedures (3 5)]

At the present percutaneous cervical cordotomy (PCC) rapresents the most important neuroablative technique in cancer pain treatment Its aim is to interrupt the spmo-thalamic tract, the most prominent ascendmg mciceptive pathway m the spinal cord PCC is performed at latero cervical level, between Cl C2, where the fibers of the lateral spmo-thalamic tract are closely compacted in the anterolatersal quadrant of the spinal cord, and present a precise somatotopy When PCC is correctly performed, it must achieve a deep pinch analgesia controlateral to the lesion and a Claude Bernard Homer syndrome ipsilateral to the lesion Differently from pharmacological therapy it proved to abolish unilateral neurogemc or incident type nociceptive cancer pain up to death in a high percentage of patient(6 8)

Since we lack prospective, randomized studies comparing neuromvasive versus neuroablative procedures in the management of refractory cancer pain, it is important to provide the outcome predictors of the different procedures for the identification of patients at risk/benefit for the specific treatment In this study we attempt to identify the outcome predictors of PCC on the basis of a prospective analysis of the last 200 PCCs performed at our Pain Relief Center

METHODS

A group of 200 cancer pain patients (137 males and 63 females mean age 60 9 years) were treated with unilateral PCC in our Pain Relief Center The inclusion criteria were the following neurogemc pain, incident pain, cancer pain poorly responsive to opioid therapy (9) In this patient population we studied the outcome of PCC and we assessed if there were any outcome predictors The mdipendent variable tested as a predictor of deep pinch analgesia was the pain site, whereas the mdipendent variables tested as predictors of pain relief were age, gender, the time interval between onset of pain and performance of PCC, pain site, pain intensity pain characteristics (incident versus non incident-type pain) and pain mechanism (neurogemc versus non neurogemc pain) The mdipendent variables we took into account for mortality and morbidity were pain site, the presence of preoperative respiratory failure and the performance status Statistical analysis was earned out by means of Kaplan Meier survival curves Cox proportional hazard regression analysis and Fisher's exact test

PCC was performed according to the technique introduced by Mullan (10) and modified later by Rosomoff (11), in an awake and collaborating patient using only atrophme e v as premedication The pilot needle (18 gauge) introduced between Cl C2, must be placed in the subarachnoid space, immediately above the dentate ligament (subarachnoid target) Then we proceed with myelography using 1 ml of lipophilic contrast medium emulsified in 4 ml of cerebrospmal fluid By fluoroscopy we control the correct position of the pilot needle that must be aligned with the sector of the spinal cord were the lesion has to be made (spmo thalamic tract in the antero lateral quadrant only few millimeters above the dentate ligament) Only at this point we introduce the electrode, and proceed with motory and sensitive stimulations The correct position of the electrode is confirmed by the omolateral rhythmic contraction of small portions of trapezius and stemocleidomastoid muscles during the motor stimulations and by the evocation of controlateral thermic sensations Tetanic contractions of the ipsilateral muscles (hand and foot) indicate involvement of pyramidal fibres (electrode situated in excessively dorsal position and thus necessitating repositioning) Finally we proceed with the lesion by radiofrequency

All the patients undergone PCC were directly observed in our hospital for 1 week After discharge regular follow up was conducted up to death in all patients

RESULTS

Immediately atter PCC we obtained an adequate level of deep pinch analgesia in 195/200 patients (97 5%) and such "anatomic" result lasted up to death As regards the pain relief, 160/200 patients (80%) were completely pain free on the treated side up to death In fact, in the time course of the disease up to death 35/200 patients (17 5%) developed pain on the treated side in spite of the presence of a deep pinch analgesia This was due to the occurrence ofaneurophatic non nociceptive pain The Kaplan-Meier survival analysis shows that the expected probability of mantammg deep pinch analgesia 6 months after PCC is 97%, while the expected probability of pain relief at the same time interval is 74% The reason ot this difference is due to the occurrence of a neuropathic non nociceptive pain in the treated side (35/200 patients, 17 5%) Among the variables tested as predictors of pain relief by means of Cox model, the only one significant is the neurogenic mechanism of pain In fact the presence of a preoperative neurogenic pain mechanism is the main predictive factor of the occurrence of a neuropathic non nociceptive pain after PCC The Kaplan Meier survival analysis confirms this finding In fact the cumulative probability of pain relief 6 months after PCC falls from 90% in patients with non neurogenic pain mechanism before PCC, to 61% in patients with a preoperative neurogenic pain mechanism As regards mortality, 4/200 patients (2%) died within the first week postoperatively (operative mortality) Permanent morbidity consisted in motor dysfunctions (16/200 patients, 8%) and bladder dysfunctions (10/200 patients, 5%) The presence of a preoperative respiratory failure (Pa02< 60 mmHg) and a Kamotsky index lower than 50 are the two main predictors of patient mortality while there are no predictors of patients morbidity

DISCUSSION AND CONCLUSIONS

The results of this study confirm that in patients with refractory cancer pain PCC provides a deep pinch analgesia up to death on the treated side in a very high percentage of cases (97%) and that the incidence of pain in presence of a stable deep pinch analgesia (neuropathic non nociceptive pain ) is relatively low (17 5%) Moreover the presence of a neurogenic pain mechanism before PCC is the main predictors of its occurrence Finally, the mortality rate can be lowered by a careful patient selection taking its main predictors (preoperative respiratory failure and low Kamotsky index) into account

Therefore unilateral PCC by abolishing all types ol nociceptive pain up to death on the treated side in a very high percentage of patients with a low morbidity and a very low mortality rate. proves a very effective tool in the management of cancer pain, particularly of the refractory type even if the preoperative presence ot a neurogenic pain mechanism reduces its long term effectiveness

References

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SUPERIOR HYPOGASTRIC PLEXUS BLOCK FOR PELVIC CANCER PAIN

 Youn-Woo Lee. Duck Mi Yoon.
Department of Anesthesiology, Pain Clinic. Yonsei University College of Medicine, C.P.O.Box 8044, Seoul, Korea

Aim of Investigation: To investigate the effects of superior hypogastric plexus block(SHPB) for pelvic pain in cancer patients.

Methods: Twenty eight patients with gynecological, colorectal, or genitourinary cancer who suffered from intractable pelvic pain were treated with neurolytic SHPB. We approached with bilateral interdiscal method under the fluoroscopic guide. Ten ml of dehydrated alcohol was injected at each site. Pain score(visual analog scale;VAS) and daily doses of opioids were checked perioperatively.

Results: Fourteen of the 28 patients (50%) had excellent pain relief effects (VAS < 30 of 100), five patients (18%) had good (30 <VAS< 70), nine patients (32%) had poor (70 <VAS< 90) effects. Most of the poor result cases were with extensive retroperitoneal neoplastic involvement and with high dose of opioids before neurolytic block.

Conclusion: Neurolytic SHPB is one of effective pain relief method for pelvic cancer pain patients.And it will be more effective when try to earlier than end stage of cancer conditions.

Pain in Europe III. EFIC 2000, Nice, France, September 26-29, 2000. Abstracts book, p. 115, 297.