Use of A-scan Ultrasound and Optical Coherence Tomography to Differentiate Papilledema From Pseudopapilledema

Abstract

Significance Differentiating papilledema from pseudopapilledema reflecting tilted/crowded optic discs or disc drusen is critical but can be challenging. Our study suggests that SD-OCT peripapillary retinal nerve fiber layer thickness and retrobulbar optic nerve sheath diameter measured by A-scan ultrasound provide useful information when differentiating the two conditions. Purpose To evaluate the use of A-scan ultrasound and spectral-domain optical coherence tomography (OCT) retinal nerve fiber layer thickness (RNFL) thickness in differentiating papilledema associated with idiopathic intracranial hypertension from pseudopapilledema. Methods Retrospective cross-sectional analysis included 23 papilledema and 28 pseudopapilledema patients. Ultrasound-measured optic nerve sheath diameter (ONSD) at primary gaze, percent change in ONSD at lateral gaze (30° test), and peripapillary RNFLT were analyzed. Receiver operating characteristic (ROC) curves were constructed using one eye from each subject. Results Compared to pseudopapilledema, papilledema eyes showed larger mean ONSD (5.4 ± 0.6 vs 4.0 ± 0.3 mm, p < 0.0001), greater change(%) of ONSD at lateral gaze (22.4 ± 8.4 vs 2.8 ± 4.8, p < 0.0001), thicker RNFL (219.1 ± 104.6 vs 102.4 ± 20.1 μm, p< 0.0001). ONSD and 30° test had the greatest area under the ROC curve (AUC), 0.98 and 0.97, respectively; followed by inferior quadrant (0.90) and average RNFLT (0.87). All papilledema eyes with Frisén scale > II were accurately diagnosed by ONSD, 30° test or OCT. In mild papilledema (Frisén scale I&II, n = 15), AUC remained high for ONSD (0.95) and 30° test (0.93) but decreased to 0.61–0.71 for RNFLT. At 95% specificity, sensitivity (%) for ONSD, 30° test and RNFLT was 91.3, 91.3 and 56.5, respectively for the entire papilledema group; 80.0, 86.7 and 13.3 for the mild papilledema subgroup. Conclusions RNFL thickness can potentially be used to detect moderate to severe papilledema. A-scan may further assist differentiation of mild papilledema from pseudopapilledema.

Optische Kohärenztomografie bei Erkrankungen des zentralen Nervensystems

“…Bei milden Papillenschwellungen stellt sich oft die Frage, ob es sich um eine echte Papillenschwellung oder um eine Pseudoschwellung bei Drusen des Sehnervenkopfes handelt. Die OCT kann genutzt werden, dies zu differenzieren [146]. Aufgrund des schnellen Untersuchungsablaufs und der fehlenden Invasivität ist es auch bei Kindern dazu anwendbar [147].…”

Ultrasound Detection of Intracranial Hypertension in Brain Injuries

“…This technique was later utilized by Saenz et al ( 27 ), who also utilized the so called “30 degrees test” introduced by KC Ossoinig ( 7 , 8 ), and concluded that A-scan could assist differentiation of mild papilledema from pseudopapilledema ( 27 ).…”

“…This makes it much more suitable for measuring the ONSD because this technique shows easily discernible high reflective spikes from the interface between the arachnoid and subarachnoid fluid ( Figure 1 ). Unfortunately, in almost all the studies considered in this review, B-scan ultrasonography was used, and only Saenz et al used the standardized A-scan ( 27 ), which allows to perform the “30-degree test.”…”

Accuracy of machine learning for differentiation between optic neuropathies and pseudopapilledema

“…Although PPE is a benign condition, it should be differentiated from other optic neuropathies to reduce the need for unnecessary examination and to provide precise diagnosis, prognosis and therapeutic options to the patients. Recently, multi-modal imaging analysis including B-scan ultrasonography, fundus photography, autofluorescence, fluorescein angiography, and optical coherence tomography (OCT) have provided useful information for exact diagnosis of PPE [2–4]. However, the exact differentiation is still difficult.…”