Negative Study Results
When an imaging study fails to demonstrate the expected pathology in relation to the clinical presentation, the clinician’s first step is to reexamine the study parameters, ideally with a neuroradiologist. Several questions to keep in mind are:
Were the appropriate studies performed, including required sequences and orientations?
Was the area of interest adequately imaged (Fig 2-15)?
Are the study results truly negative (Fig 2-16)?
Figure 2-15 Delayed diagnosis of a right cranial nerve (CN) III schwannoma. A, Initial MRI results were negative, but fine cuts through the cavernous sinus demonstrated asymmetry, with a slight nodule in the superior portion of the cavernous sinus on the right. B, This area became bright following administration of gadolinium contrast, which indicated the presence of a right CN III schwannoma (arrow).
(Courtesy of Steven A. Newman, MD.)
Figure 2-16 A 41-year-old woman was referred for progressive vision loss in the right eye. She had been told she had a swollen optic nerve on the right; her condition was diagnosed as a “mild form of multiple sclerosis.” Her visual acuity was 2/200 OD and 20/20 OS, with a right relative afferent pupillary defect. She had reportedly had 2 previous MRI scans, with negative results. A, A fundus photograph of the right optic nerve head demonstrates temporal pallor with optociliary shunt vessels. The patient was referred for a third MRI scan, but this study was misdirected for workup of “microvascular brainstem disease” and revealed no abnormalities. B, A sagittal MRI scan taken through the orbit shows an abnormal optic nerve sheath appearance consistent with an optic nerve sheath meningioma (arrow). The arrowhead points to the plaque portion of the meningioma.
(Part A courtesy of Steven A. Newman, MD; part B courtesy of Eric Eggenberger, DO.)
Even if the ophthalmologist cannot personally review the studies, speaking directly with the radiologist may prevent certain lesions from being overlooked and can provide the clinical information required to enhance the radiographic report’s accuracy and usefulness.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.