The Chronic Acalculous Symptomatic Hyperkinetic (CASPER) Gallbladder or "The Excitable Gallbladder"

In this Invited Review, we provide an update on "Gallbladder Hyperkinesia" for medical and lay audiences. The Chronic Acalculous Symptomatic hyPERkinetic (CASPER) gallbladder can be considered the opposite of the Chronic Acalculous Symptomatic hyPOkinetic (CASPO) gallbladder. Just as the CASPO gallbladder could be typified as "the lazy gallbladder," the CASPER gallbladder would correspond to "the excitable gallbladder." Symptomatic gallbladder hyperkinesia has three essential features: a) biliary symptoms, b) no gallstones on ultrasound (acalculous), and c) an unusually elevated gallbladder ejection fraction on HIDA scan. Although gallbladder hypokinesia is recognized in standard medical textbooks, gallbladder hyperkinesia is a relatively unknown condition that has begun gaining appreciation in the 21^st century. Here, we distill detailed clinical information about gallbladder hyperkinesia garnered over the past five years after we independently identified gallbladder hyperkinesia as a novel entity at the University of Iowa Gallbladder Dysfunction Clinic in 2018. We discuss potential cut-off levels for the gallbladder ejection fraction on cholescintigraphy for a diagnosis of gallbladder hyperkinesia, pending confirmation by future statistical studies. We summarize the differential diagnosis and common investigations used in approaching a patient with suspected gallbladder hyperkinesia, and emphasize that it is a diagnosis of exclusion. We present a 12-point checklist for the symptoms and signs of CASPER gallbladders. We explain the deviations of this 12-point checklist from the Rome IV Criteria for functional gallbladder disorders. We review the literature written on gallbladder hyperkinesia over the past two decades and summarize observations of several clinicians from various geographical regions. We underline the problems associated with trying to complete a prospective, randomized, controlled study to validate the indication for cholecystectomy in patients experiencing substantial symptoms from gallbladder hyperkinesia. We point out the role played by internet-based social media platforms in bringing together patients with gallbladder hyperkinesia and surgeons that recognize the condition.