1. The “Guitar Pick” Sign: An expanding repertoire of orbital pathology Vincent Dam MD, Joel Stein MD, PhD, Suyash Mohan MD Department of Radiology Perelman School of Medicine at the University of Pennsylvania Control #: 1751, Poster #: EE-12

2. Disclosures Vincent Dam, MD: No disclosures Joel Stein, MD, PhD: No disclosures Suyash Mohan, MD: No disclosures

3. Purpose Posterior globe tenting, the “guitar pick” sign, has been associated with acute and often permanent visual impairment. The finding is usually seen in the context of orbital trauma and other acute inflammatory pathologies.

4. Guitar pick Axial image of an orbital CT in a patient with ocular trauma and left retrobulbar hemorrhage (not shown) with posterior tenting of the left globe.

5. Few cases to date have been reported in association with progressive infiltrating neoplasm. Our case serves to expand the clinical context in which the “guitar pick” sign can be seen. Purpose

6. Case Report A 61-year-old man with locally advanced sinonasal adenoid cystic carcinoma and resultant left eye blindness presented to outpatient clinic with acute right eye blindness of 12 hours duration. The patient was transferred to the emergency department where an unenhanced maxillofacial CT was obtained followed by an MRI.

7. 11/2014 9/2014 Axial (a) & coronal (b) maxillofacial CT demonstrate extensive infiltrating neoplasm involving the sinonasal cavity with bilateral intraorbital extension (yellow arrows) and resultant bilateral "guitar pick" signs (red arrows). Comparison to prior sinus CT from 9/2014, axial and coronal planes (c & d), demonstrates 11/2014 findings are new and likely correspond to acute symptomatology. a b c d

8. MRI orbits: Axial & coronal post contrast T1 weighted images corroborate CT findings with extensive infiltrating neoplasm involving the sinonasal cavity with bilateral intraorbital extension (yellow arrows). Notice, “guitar pick” signs are manifested in the bilateral globes, more conspicuous on the left (red arrows). 11/2014

9. Treatment & Follow-up Based on the imaging findings, the patient was admitted and given a course of high dose corticosteroids as well as targeted radiation. Right eye vision returned after treatment. MRI of the orbits 1 month later demonstrated improved left and resolution of right posterior orbital tenting.

10. 11/2014 12/2014 Follow up axial (a) & coronal (b) post contrast T1 weighted MRI shows marked decrease in tumor extent with corresponding resolution of bilateral posterior globe tenting. This is compared to the MRI obtained at the time of the patient’s acute presentation (c & d). a b cd

11. Summary In addition to prior reports, the guitar pick sign can be seen with infiltrative neoplasms on both CT and MR imaging modalities and corresponds to acute visual impairment. Prompt medical intervention is essential and can prevent permanent visual damage.

12. References Dalley RW, Robertson WD, Rootman J. Globe tenting: a sign of increased orbital tension. AJNR Am J Neuroradiol 1989:10(1):181-6. Hrach CJ, Quint DJ. Globe tenting as a result of head trauma. AJNR Am J Neuroradiol 1997:18(5):980-2. Theoret J, Sanz GE, Matero D, et al. The “guitar pick” sign: a novel sign of retrobulbar hemorrhage. CJEM Can J Emerg Med Care 2011:13(3):162-4.