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From bone metabolism to mega stones

From bone metabolism to treatment of ‘mega’ stones, Plenary Session 7, the concluding session of EAU18, tackled a range of issues in stone disease management such as developments in pathogenesis, interventional therapies, urinary stone prevention and diagnostic issues.

Chaired by Professors Thomas Knoll (DE) and Arnulf Stenzl (DE), the session opened with Prof. Jean-Philippe Haymann (FR) with a lecture on bone metabolism and stones. He discussed issues such as bone demineralisation, its links with renal tubular and intestinal disorders.

“No specific therapy is available for counteracting impaired bone metabolism,” said Haymann. “However, bone demineralisation prevention requires in most cases a normal calcium diet. And with regards treatment, management may include chlorothiazides, RankL inhibitors, citrates and bisphosphonate.

Prof. Kemal Sarica (TR) moderated a case-based debate which posed the query “How can we evaluate and treat the high-risk stone former?”. He presented the case of a young female with recurrent stones who has received several therapies such as percutaneous nephrolithotomy and laser uretereplithotripsy, amongst others.

Using specifics of the case, Prof. Giovanni Gambaro (IT) discussed the role of metabolic evaluation of stone patients and pointed out key points including the identifying secondary forms of nephrolithiasis, diagnosing idiophathic calcium nephrolithiasis, tailoring  preventive stone treatment and metabolic follow-up.

“Empiric prevention is more than sufficient,” said Prof. Thorsten Bach (DE) in response to the arguments of Gambaro. Bach underscored the role of diet and said increased fluid intake decreases recurrence rates by 50%, while decreasing soft-drink intake is beneficial. With regards increased fibre intake (while lowering animal protein) studies have shown that there is no difference when compared with control groups.

Bach also emphasized that modern neurology is highly effective in treating first stone and recurrence. “Independent of any biochemical measure and stone composition, endourology provides high stone-free rate and very low morbidity,” said Bach, adding: “In case of recurrence, go for endourology.”

Dr. Junichi Matsuzaki (JP) gave the Urological Association of Asia (UAA) lecture titled “Experience with ‘mega stones’ treatment,” and provided an overview of Endoscopic Combined IntraRenal Surgery (ECIRS), its role, the surgical techniques and his experience.

Matsuzaki noted the benefits of ECIRS such as less percutaneous access. Accurate puncture and dilation/extraction, less radiation exposure and less bleeding. On the other hand, the drawbacks include the need for two surgeons, necessity for more devices such as scopes and video monitor, and higher costs, amongst others.

He discussed his use of the modified Valdivia position (supine) which he said has the advantages of less positioning time, improve cardio-pulmonary functions, better fluid egress from kidney, and enables the surgeon to perform the procedure in a sitting position. The disadvantages of modified supine Valdivia position, however, are less room for manoeuvring, collecting system decompression, and possibility of positioning injury.

In his take-home messages, Matsuzaki said ECIRS is a treatment option for ‘mega’ stone and the modified Valdivia position is safe and efficient. “Ureteroscopic assistance makes puncture, dilation and extraction safer and easier,” he added.

The session continued with a debate regarding single-use flexible ureteroscopy where moderator Mr. Kenneth Anson (GB) posed the query “Is it ready to become standard?” to debaters Ass. Prof. Andreas Neisius (DE) taking the affirmative stand and Dr. Steeve Doizi (FR) taking the contra position.

“The LithoVue single use ureteroscope has superb optical capabilities, deflection and flow, making it a viable alternative to standard non-disposable fourth-generation flexible digital and fibre optic ureteroscopes,”said Neisus. Doizi opposed Neisus’ arguments saying that reusable and single-use flexible URS “are similar in numerous aspects.”

“Single-use flexible URS, is it ready to become the standard? Not yet,” said Doizi. The audience in a vote of 43% to 56%  took the side of Doizi.

The session continued with a case-based panel discussion, a debate on miniature percutaneous nephrolithotomy (PNL) and differences in guideline recommendations on urolithiasis from the EAU and the American Urological Association.

Article by Joel Vega