Chronic post-surgical pain (CPSP) is not limited to major surgeries and can develop after smaller procedures such as hernia repairs. While nerve injury has traditionally been thought to be the culprit for CPSP, it is evident that nerve-sparing surgical techniques are not completely preventative. Regional analgesia and agents such as ketamine, gabapentinoids, and COX-2 inhibitors have also been found to decrease the risks of developing chronic pain to varying degrees. Yet, given the correlation of central sensitization with the development of chronic pain, it is reasonable to utilize aggressive multimodal analgesia whenever possible. Development of chronic pain is typically a result of peripheral and central sensitization, with CPSP being one of the most common presentations. Using minimally invasive surgical techniques may reduce the risk of CPSP. Regional anesthetic techniques and preemptive analgesia should also be utilized when appropriate to reduce the intensity and duration of acute post-operative pain, which has been correlated with higher incidences of chronic pain.
Moderate to severe pain occurs in many cancer patients during their clinical course and may stem from the primary pathology, metastasis, or as treatment side effects. Uncontrolled pain using conservative medical therapy can often lead to patient distress, loss of productivity, shorter life expectancy, longer hospital stays, and increase in healthcare utilization. Various publications shed light on strategies for conservative medical management for cancer pain and a few international publications have reviewed limited interventional data. Our multi-institutional working group was assembled to review and highlight the body of evidence that exists for opioid utilization for cancer pain, adjunct medication such as ketamine and methadone and interventional therapies. We discuss neurolysis via injections, neuromodulation including targeted drug delivery and spinal cord stimulation, vertebral tumor ablation and augmentation, radiotherapy and surgical techniques. In the United States, there is a significant variance in the interventional treatment of cancer pain based on fellowship training. As a first of its kind, this best practices and interventional guideline will offer evidenced-based recommendations for reducing pain and suffering associated with malignancy.
Purpose
We have observed a higher rate of Lhermitte's syndrome (LS) after chemo-IMRT of head and neck cancer than the published rates after conventional radiotherapy. We hypothesized that the inhomogeneous spinal cord dose distributions produced by IMRT caused a “bath and shower” effect, characterized by low doses in the vicinity of high doses, reducing spinal cord tolerance.
Methods and Materials
73 patients with squamous cell carcinoma of the oropharynx participated in a prospective study of IMRT concurrent with weekly carboplatin and taxol. 15 (21%) reported LS in at least 2 consecutive follow-up visits. Mean dose, maximum dose, partial (Vd) as well as the absolute volume (cc) of spinal cord receiving specified doses (≥10 Gy, 20 Gy, 30 Gy, 40 Gy), and the pattern of dose distributions at the “anatomical” (from the base of the skull to the aortic arch) and “plan-related” (from the top through the bottom of the PTV's) spinal cords were compared between LS and 34 non-LS patients.
Results
LS patients had significantly higher spinal cord mean doses, V30, V40, and volumes receiving ≥30 and ≥ 40 Gy compared to the non-LS patients (p < 0.05). Strongest predictors of LS were higher V40 and higher cord volumes receiving ≥40 Gy (p ≤ 0.007). There was no evidence of larger spinal cord volumes receiving low doses in the vicinity of higher doses (“bath and shower”) in LS compared to non-LS patients.
Conclusions
Greater mean dose, V30, V40, and cord volumes receiving ≥30 and ≥40 Gy characterized LS compared to non-LS patients. “Bath and shower” effects could not be validated in this study as a potential contributor to LS. The higher than expected rates of LS may be due to the specific concurrent chemotherapy agents, or to more accurate identification of LS in the setting of a prospective study.
The placement of thoracic epidural catheters is complicated by the layering of the vertebral lamina. Therefore, traditional blind palpation techniques require insertion of an epidural needle with likely contact of lamina with redirections into the epidural space. We discuss a safe and consistent technique using true real-time ultrasound visualization of the needle with a paramedian sagittal oblique view to improve the consistency of placing an epidural in the thoracic spine for postoperative analgesia. Successful epidural placement was achieved in every patient. All catheters were found to be effective for use in the postoperative phase.
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