Navigating Diagnostic Ambiguity in Palliative Pediatric Neuro-Oncology: A Conceptual Framework for Suspected Shunt Malfunction and Refractory Hyponatremia.

Management of suspected shunt malfunction in pediatric patients with terminal brain tumors presents a complex clinical and ethical dilemma. Differentiating mechanical shunt failure from disease progression or metabolic derangement is often radiographically indeterminate, while invasive diagnostics may conflict with palliative goals of care. We present the case of a five-year-old male with relapsed medulloblastoma and cerebrospinal fluid (CSF) dissemination who developed progressive ventriculomegaly and refractory hyponatremia (serum sodium nadir: 120 mEq/L). The clinical course was complicated by the overlap of potential etiologies: shunt failure, syndrome of inappropriate antidiuretic hormone secretion (SIADH) versus cerebral salt wasting (CSW), and terminal disease progression. This report details the diagnostic challenges encountered and proposes a conceptual framework for structuring clinical decision-making in the setting of diagnostic uncertainty. This framework prioritizes three parallel workstreams: (1) imaging trend analysis (emphasizing delta over static findings), (2) metabolic profiling (using osmolality to guide risk stratification), and (3) continuous goals-of-care realignment. In the palliative setting, definitive diagnosis of shunt failure is often unattainable. We suggest that, in selected palliative contexts, management may benefit from shifting away from the pursuit of diagnostic certainty toward a risk-adapted, goal-concordant approach.