Diagnostic efficacy of radionuclide scintigraphy in detecting lumboperitoneal shunt obstructions in idiopathic hydrocephalus and intracranial hypertension.

Background: This study aimed to evaluate the diagnostic effectiveness of radionuclide scintigraphy (RS) in detecting lumboperitoneal shunt (LPS) obstructions in patients with idiopathic normal pressure hydrocephalus (iNPH) and idiopathic intracranial hypertension (IIH).

Methods: We conducted a retrospective analysis of 44 patients who underwent LPS surgery between 2010 and 2020. Twenty-one patients were diagnosed with iNPH and 23 with IIH. Clinical symptoms, including gait disturbances, cognitive impairment, and urinary dysfunction for iNPH, and headaches and vision loss for IIH, were evaluated. Preoperative computed tomography/magnetic resonance imaging (MRI) scans assessed hydrocephalus indicators, and cerebrospinal fluid (CSF) opening pressure was measured through lumbar puncture. RS was performed using technetium-99m-diethylenetriaminepentaacetic acid, and findings were compared with surgical outcomes. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and concordance (kappa coefficient) were calculated to evaluate the diagnostic accuracy of RS.

Results: Of the 44 patients, 18 (40.9%) demonstrated total obstruction, 17 (38.6%) showed partial obstruction, and 9 (20.5%) had no obstruction on RS. All patients with total obstruction confirmed by RS had corresponding findings during surgery (PPV 100%). However, 10 of the 19 patients with partial or no obstruction on RS were found to have obstruction during surgery (NPV 47%). The kappa coefficient for total obstruction was 0.467 (P = 0.001), indicating good concordance between RS and surgical outcomes. Patients with lower CSF pressure, particularly those with iNPH, were more likely to experience false-negative RS results.

Conclusion: RS is a reliable tool for detecting total LPS obstructions, but its sensitivity for partial obstructions is limited. Extending imaging periods or integrating additional diagnostic tools such as MRI may improve detection accuracy, particularly in cases with low CSF pressure. Combining RS with clinical evaluations can reduce unnecessary shunt revisions and improve patient outcomes.