By Palanisamy Vijayanand
In the treatment of radicular pain, there have been IDET’s (Intradiscal electrothermal therapy), Biacuplasties, Annuloplasties, Nucleoplasties, Dekompressors, Laser diskectomies, MILD (minimally invasive lumbar decompression) etc, which have come and gone. We’ve even had ozone injections into the intervertebral disc, and diesel, and coconut oil, and… Yes, you get the gist. Medicine’s inventiveness in the treatment of radicular pain, even when we knew it to be devoid of any evidence whatsoever, seems boundless. On the contrary – like when everything looks like a nail for a person with a hammer – when the pain is from pancreas, whether it is pancreatic cancer or chronic pancreatitis, there is only coeliac neurolysis. And when the treatment doesn’t work, the pain specialist goes around shaking all the trees and hoping that some dollop of wisdom would fall out. A new study published provides just that – a dollop of wisdom, albeit a small, tantalizing and an oblique one – on why coeliac neurolysis may not be effective on all pancreatic pains. It also challenges the conventional wisdom, one that has been parroted for decades, that pancreatic tumours are excruciatingly painful in the last stages of life.
In their study, D’Haese and colleagues systematically recorded pain patterns in all pancreatic diseases, and correlated them with clinico-pathological data by collecting pancreatic tissue samples from more than a thousand patients who underwent resection for pancreatic diseases. First up, they found that pancreatic pain depicts different facets and patterns of abdominal pain sensation according to the respective pancreatic disorder and does not allow a unification of the term pancreatic pain. Only 51% of patients with pancreatic adenocarcinoma suffered from pain, but when pain was reported it served as an indicator of poor prognosis. Patients with serous cystadenoma were almost pain free, and so were neuroendocrine neoplasias (64% pain free) and ampullary carcinoma (61% pain free). In comparison, 80% of patients with chronic pancreatitis and 80% of patients with mucous cystadenoma had at least mild pain. It was also evident that pancreatic pain was very distinct and much more frequent and severe in chronic pancreatitis when compared to pancreatic cancer.
In addition, they found that the most frequent tumour site was the head of pancreas, with serous and mucous cystadenomas found more commonly in the body and tail. Tumour localization influenced pain sensation independent of tumour histology, wherein 51% vs. 39% vs. 42% (head, body and tail) had no pain, compared to 35% vs. 44% vs. 43% (head, body and tail) with mild pain. The tumour with moderate to severe pain was more commonly located in the body of the pancreas. Ampullary carcinoma (due to its location) and chronic pancreatitis (due to widespread inflammation) were excluded from this analysis. The additional presence of diabetes did not have any effect on pancreatic pain sensation in chronic pancreatitis. There was no significant difference between malignant and benign tumours in the no pain category (49.2% vs. 47.6%), but severe pain was more common in malignant tumours (14.4% vs. 6.7%). Tumour grading and staging did not show any significant correlation to pain sensation in all of the analysed pancreatic cancer cases. The number of lymph nodes and/or the number of metastases did not influence the existence or severity of pancreatic pain in pancreatic cancer patients. The survival of pancreatic cancer patients, however, was significantly influenced by pain.
Pain patterns in pancreatic diseases turned out to be very diverse and were mainly dependent on tumour type, anatomic localization and dignity (benign or malignant). From basic sciences research they point out the fact that while the pain due to pancreatic cancer, due to neural infiltration within and outside the pancreas, might be due to pancreatic neuropathy; the pain due to chronic pancreatitis might be due by visceral inflammation. It serves as a pointer to the possible reason why coeliac neurolysis in pancreatic cancer has a better efficacy compared with chronic pancreatitis. Concluding, they propose that, ‘Abdominal pain sensation in pancreatic diseases should therefore be observed and documented much more carefully since they may be used as an additional diagnostic tool to estimate pancreatic tumor dignity and patient’s prognosis.’ As an extension, one could also propose that the efforts at pain palliation in pancreatic diseases need to consider the aetiology and influences that caused the pain to be insufferable as assiduously as they confront the pain itself, if not more so.