Core imaging in adult hydrocephalus
Advances in neuroimaging have greatly improved the management of hydrocephalus. The various imaging modalities are useful in confirming the diagnosis, determining the etiology of hydrocephalus, providing intraoperative guidance, and improving the follow-up of patients who have undergone treatment including cerebrospinal fluid (CSF) shunting or endoscopic third ventriculostomy (ETV). The various imaging modalities that are utilized include: conventional X-rays; ultrasonography; computerized axial tomography (CT); magnetic resonance imaging (MRI); radionuclide shunt patency imaging. As systematically as possible, we will list for each modality their use in the preoperative, perioperative, and postoperative period. Conventional X-rays Conventional X-rays often are used to evaluate shunted patients as the entire shunt hardware can be visualized to assess the continuity of the shunt. However, as the majority of shunt malfunctions are unrelated to mechanical discontinuity, the majority of images obtained will demonstrate intact tubing; Lehnert et al. [1] found only 4% of shunt surveys to be abnormal in a series of 296 patients in the emergency room. Similarly, Griffey et al. [2] assessed the utility of shunt surveys in diagnosing shunt malfunctions in the emergency room in adult hydrocephalus patients and found a sensitivity of only 0.11 but a specificity of 0.98. A similar study in the pediatric population demonstrated a slightly higher sensitivity of 0.31 [3]. Conventional X-rays are also utilized to verify the shunt setting, because programmable shunt valves generally have radiopaque markers.
