Case for Quantitative Evaluation

Introduction: Evaluation of the visual pathways includes a combination of psychophysical testing, physiologic testing, and anatomic testing. There is a tendency to prefer the last two because they were objective, instead of subjective. It is important to note that while objective findings are useful, they do not completely obviate the importance of physiologic studies, and even for that matter, psychophysical testing.

Case Report: This 64-year-old patient was seen in June of 2019 complaining of progressive diplopia. In 2006, an MRI scan showed a large parasellar lesion that prompted a transsphenoidal surgery in April of 2006 which demonstrated, surprisingly, an oncocytoma. She underwent a second transsphenoidal surgery in November of 2006 and a craniotomy in May of 2007, and then a third transsphenoidal surgery in September of 2014. The peripheral core was treated in 2007 with Cyber Knife. In 2014, she received proton therapy.

In June of 2019, visual acuity was 20/25 and 20/25. Visual fields demonstrated superior > inferior arcuate defect on the right and minimal diffuse depression on the left. Motility was abnormal with limitation in depression > elevation on the right and an exodeviation increasing on left gaze, compatible with a partial right-III nerve palsy. She had evidence of elevation of the right upper lid with attempt at down gaze to the left, suggesting aberrant regeneration. Quantitative motility testing with the Hess screen confirmed marked limitation of vertical gaze on the right compatible with the presumed aberrant regeneration of III.

Following cataract surgery OS, visual acuity was 20/30 and 20/20. She continues to have arcuate visual field changes worse on the right than the left. Palpebral fissures were 6/7.5 again with lid hang up on attempt at down gaze to the left. The most interesting aspect was the Hess screen now demonstrated definite worsening of vertical gaze on the right side.

The findings here indicate that in spite of three transsphenoidal procedures, a craniotomy, radiation with cyper knife, and proton beam, and grade-III nerve palsy with aberrant regeneration continued to progress.

Discussion: This case emphasizes the importance of looking at all aspects of evaluation. Looking at the CT scan alone did demonstrate the effect of previous surgery and radiation therapy, but the Hess screen, which quantitates relative ocular motility clearly demonstrated progression, in spite of the lack of other changes. This clearly indicates the importance of evaluation in a quantitative fashion, not just of the anatomy and physiology, but also of the psychophysics.

Conclusion:

1. The advent of CT and later of MRI scan has dramatically improved our ability to look at the anatomy of the afferent and efferent visual pathways.

2. Quantitative assessment of ocular motility may show evidence of change even when MRI does not.

3. Looking at all aspects of evaluation may contribute to our ability to detect progression of skull base lesions.

4. All tests can be identified as either qualitative (is there a defect) or quantitated (how much of a defect).

Publication History

Article published online:
12 February 2021