Application of ultrasound for non-invasive first-line and follow-up diagnostic in patients with hydrocephalus

15/11/2019 to 15/11/2019

Objective: In neurosurgery a large number of pathologies is associated with increased intracranial pressure (ICP). ICP increase can be caused by hydrocephalus or idiopathic intracranial hypertension (IIH) or brain edema. Non-invasive diagnostic s to assess ICP and differentiate between hydrocephalus and other entities are needed in pediatric and adult patients. This study investigates the combined use of transorbital ultrasound measured optic nerve sheath diameter (ONSD) and transtemporal ultrasound based third ventricle diameter (TVD) to assess ICP and ventricular size in pediatric patients.
Methods: This prospective study includes 248 patients (median 7 years) diagnosed with hydrocephalus (53%), IIH (22%), tumor (8%) and other intracranial pathologies (17%). Binocular ONSD was measured transorbitally using a 12MHz linear probe. TVD was quantified with a transtemporal approach using a phased-array 1-4MHz transducer placed at the temporal window. All measurements were done with patient in supine position
Results: 148 patients presented increased ONSD (mean 5.9±0.6mm) and TVD (mean 7.86±5.86mm) and underwent ICP decreasing therapy. In 59 ONSD (5.9±0.6mm) was enlarged while TVD (3.97±2.39mm) was only marginally increased. In these cases further diagnostic procedures were recommended. 41 patients presented with normal ONSD (4.98±0.6mm) and normal to marginally increased TVD (4.25±3.58mm). Watch-and-wait was performed and none needed an intervention up to now. In 62 TVD was measured before/after hydrocephalus therapy and in 57 without intervention. The relative difference was higher in patients with therapy (31 ± 19.7%) than without (4.8± 4.2%), p<0.001. A change of > 7.65% is highly sensitive and specific for true and relevant ventricle enlargement (sensitivity 90.5%, specificity 87.5%, AUROC 0.939, OR 57)
Conclusion: Transorbital ultrasound ONSD is a reliable method to assess ICP and can be combined with transtemporal ultrasound beased TVD for identification of possible ICP increases. Changes of TVD over time can be used for diagnosis of clinically relevant ventricular enlargements in pediatric patients.