Download Pancreatic stone, ERCP and ESWL – a case study and review

Pancreatic stone, ERCP and ESWL – a case study and review.
Abstract
Introduction
Pancreatic duct stones are found in 22 to 60 per cent of patients with chronic pancreatitis
(CP).1 The stones can lead to obstruction of the outflow of pancreatic secretions causing
increased intraductal pressure.
2
The pancreas is relatively noncompliant. Therefore the rise
in intraductal pressure can induce tissue hypertension and ischemia. This can be a major
factor causing pain in patients with CP.3 This hypothesis is supported by the observation
that symptoms may improve following pancreatic duct drainage.
4,5
Case Presentation
A 62 year old woman presented with persistent epigastric pain. Investigations revealed
calcifications within the main pancreatic duct and head of the gland. Treatment with
Endoscopic retrograde cholangiopancreatography (ERCP) and extracorporeal shock wave
lithotripsy (ESWL) achieved a good outcome.
Conclusion
Standard endoscopic removal of the stones proved impossible so treatment with ESWL was
undertaken. Following fragmentation, the calculi and fragments passed spontaneously or
were removed endoscopically. If pancreatic stones cannot be removed endoscopically, ESWL
should be considered prior to surgery.
1
Background
A 62 year old Caucasian woman presented with 4 months of persistent epigastric, central
abdominal and left iliac fossa pain. The pain radiated to the back and could be severe. There
was associated nausea, retching and anorexia with an unspecified amount of weight loss.
She had intermittent diarrhoea with previous constipation and pain in response to stress.
Past history included hysterectomy complicated by adhesions and bowel obstruction, rectal
bleeding and a right knee replacement. She had no personal or family history of
pancreatitis, dyslipidaemia or malignancy. She took one standard unit of alcohol daily and
paracetamol and a paracetamol-codeine phosphate compound for severe pain but no other
regular medications. Physical examination revealed moderate epigastric tenderness.There
was no guarding and no masses or organs were palpable.
Investigations showed CRP 93 mg/l (NR <5), total white cell count 11.3 x 10 9/l (neutrophils
8.7, monocytes 1.1) and amylase 74 u/l (NR 8-53). Liver function tests, amylase, CA 19-9,
CEA and IgG4 were all within normal reference range. She underwent upper and lower GI
endoscopy revealing mild reflux oesophagitis LA grade A and Helicobacter pylori associated
gastritis and mild sigmoid diverticular disease. Abdominal ultrasound showed calcified
stone/s within the head of the pancreas associated with main duct dilatation to 7mm. There
was no fluid collection or mass lesion. The liver, biliary tree and gallbladder were normal. CT
confirmed a 7mm stone within the main pancreatic duct in region of the neck with dilation
of the duct downstream from this (Figure 1). There was a cluster of calcification superiorly
within the pancreatic head.
Figure 1. CT scan - pancreas
2
Case
ERCP was performed 2 months after initial presentation (Figures 2, 3, 4). The pancreatic
duct was selectively cannulated with a sphincterotome followed by guidewire and found to
be mildly dilated to 7-8mm. The guidewire was obstructed at the neck, presumed to be
secondary to the stone (although the stone was not visualized). A pancreatic
sphincterotomy was performed and a 5fr 5cm length plastic removable stent was placed.
MRCP therefore performed (Figure 5) to further evaluate pancreatic duct anatomy. This
showed partial pancreas divisum and confirmed the stones. The pancreatic duct appeared to
be decompressed with calibre reduced to 5mm.
Figure 2. ERCP - pancreatogram
3
Figure 3. ERCP - normal major
ampulla
Figure 4. ERCP – plastic pancreatic
stent
4
Figure 5. MRCP
Figure 6
radiograph pre ESWL.
5
Abdominal
A surgical opinion was obtained and it was decided that pancreatic duct bypass and
resection were not to be pursued. Six weeks later, she underwent ESWL. This was
performed with a modern Dornier S II on Mobile Medical Technology’s lithotripsy bus. The
system is equipped with dual imaging modalities which permits fluoroscopy or ultrasound
localisation of stones. Fluoroscopy was used in this instance (Figure 7).
The shock rate was set to 1 Hz and the power increased from a minimum of 12kV to a
maximum of 15.1 kV. A rate of 1 Hz provides superior fragmentation.
6
During the
procedure, the patient lay on the lithotripter table in a prone right anterior oblique position.
Treatment was performed under conscious sedation, administered by a specialist
anaesthetist. Total duration of treatment was one hour and was well tolerated. The patient
stayed in hospital for 1 night to receive supportive care and was discharged well the
following morning. There were no complications.
Figure 7 ESWL – fluoroscopic localisation of stone
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A second ERCP was performed five days after ESWL (Figure 8). By this stage she had
already had reduction in pain. The pancreatic stent was removed with a snare and
pancreatic duct cannulated with a sphincterotome. A pancreatogram was obtained showing
dilatation of the main duct to 8mm, but complete filling to the tail. There was no stone,
stricture or obstruction evident. The duct was trawled with a 9mm extraction balloon
confirming a clear duct. A single pigtail stent 7fr 7cm length was then placed to ensure
drainage and reduce the risk of pancreatitis (Figure 9) associated with pancreatic
instrumentation. The pancreatic stent was removed 2 weeks later at upper GI endoscopy.
Figure 8. ERCP - pancreatogram
Figure 9. ERCP – pancreatic stent
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At follow-up about five weeks after ESWL, abdominal pain and anorexia had resolved and
she was feeling stronger on a daily basis.
Discussion
It was initially thought that this patient’s symptoms represented a combination of gastrooesophageal reflux, Helicobacter gastritis and irritable bowel syndrome. Although she did
have these problems, her on-going epigastric pain and abnormal pancreas drew attention to
the pancreas. Despite evidence for chronic pancreatitis, there was no history of preceding
acute pancreatitis. It was assumed her pain and systemic symptoms arose from stone
obstruction of the main pancreatic duct. It was anticipated that there may be residual
fragments and a stricture following ESWL. However at the second ERCP the pancreatic duct
was mildly dilated with no other pathology present. The stone was very effectively treated
by ESWL. The patient is doing very well with need for further intervention. She is however
at increased risk of pancreatic cancer and on-going surveillance with tumour markers and
imaging is planned.
ERCP can be technically challenging and pancreatic endotherapy is usually performed by
advanced endoscopists only. Endoscopic stone removal alone can have limited success, due
to stone location, burden, and presence of strictures in the pancreatic duct.
7
In chronic
calcific pancreatitis, the main goals of therapy are to relieve pain by decompression of the
main pancreatic duct, primarily by removing stones or treating strictures. 8 Endoscopic
decompression has been shown to be effective in some nonrandomised studies.
9,10
Endoscopic stone extraction and duct decompression is limited by the size of the pancreatic
calculi and presence of strictures. ESWL overcomes the problem of the stone size by
fragmenting the stones and reducing the stone burden, therefore allowing endoscopic
clearance of the duct facilitates or spontaneous stone passage.
Focused shock waves administered during ESWL cause stone fragmentation. The
shockwaves propagate through the body with little dissipation of energy (and therefore
damage to tissues) due to the minimal difference in density of the soft tissues. At the stonetissue interface, the large difference in density, in addition to the concentration of numerous
shockwaves in a small area, produces a large dissipation of energy. Various mechanisms
(compressive and tensile forces, erosion, shearing, spalling, and cavitation), cause energy
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to overcome the tensile strength of the crystalline structure of the calculi, leading to
fragmentation. Repetition of this process eventually leads to pulverization of the calculi.11
Treatment of calculi by ESWL was first used for the treatment of kidney stones in 1980. 12
The technique has since been applied to gallstones
13
and pancreatic stones.
11
Current data suggest that ESWL is effective in complete duct clearance in up to 50% of
patients and in duct decompression and symptomatic improvement in up to 70% of
patients. Therefore ESWL should be considered a useful adjunct in the treatment of
pancreatic duct calculi.14,15
Choi and Kim review ESWL for pancreatic duct stones in patients with chronic pancreatitis
and find that ESWL is an effective and safe procedure for endoscopically irremovable main
pancreatic duct stones, and, in selected patients, ESWL alone may be effective.
16
Furthermore in the first meta-analysis evaluating ESWL with or without endoscopic therapy
in pancreatic duct clearance and symptom relief, seventeen studies published between 1989
and 2002 were reviewed. Results show that ESWL is useful in reducing the stone burden in
the main pancreatic duct and also for improvement of pain.
The effect of ESWL on pain relief is significant. The potential mechanism for this
improvement in pain is possibly due to main pancreatic duct decompression and relief of
obstruction by stone fragmentation. Failure to relieve pain can be due to incomplete stone
clearance, persistent strictures, or parenchymal pancreatic pain due to a diseased organ and
not related to ductal hypertension. All studies showed homogeneity suggesting similar effect
size irrespective of the combinations of therapy.
17
All studies were case series with a total
of 588 subjects. Outcomes of therapy are best studied in randomized, placebo controlled
trials. Meta-analyses typically include data from randomized controlled trials to calculate the
effect size. Unfortunately, there are no randomized trials of therapy for pancreatic duct
stones.
ESWL is an excellent therapeutic modality for large pancreatic calculi. The high efficacy,
non-invasive nature of the procedure, along with the low complication rate make it a
procedure of choice and can be offered as first-line therapy for selected patients with large
pancreatic and CBD calculi.
18-20
9
James M Hayes BSc (Hons). Medical Imaging Lecturer, Faculty of Health and Science, CPIT,
Christchurch. [email protected]
Steven L Ding MBChB FRACP. Consultant Gastroenterologist, Clinical senior lecturer
Christchurch Gastroenterology. [email protected]
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Abbreviations
CA 19-9
carbohydrate antigen
CEA
carcinoembryonic antigen
GI
gastrointestinal
Acknowledgements
To Dr Stu Gowland and Dr John Tuckey for their helpful comments on this paper.
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