2025 Poster Presentations
P116: WHAT YOU SEE IS NOT ALWAYS WHAT YOU GET: A CASE OF STRIKING DISCORDANCE IN NEUROVASCULAR COMPRESSION FOR TRIGEMINAL NEURALGIA BETWEEN PRE- AND INTRAOPERATIVE IMAGING
Maria Burritt, BS; Andrew Ghannad, BS; Dayna Sloane, BS; Ronak H Jani, MD; Atul Mallik, MD, PhD; Douglas E Anderson, MD; Loyola University Medical Center
Background: The gold standard treatment for classical trigeminal neuralgia (TN) is microvascular decompression (MVD), which relieves the trigeminal nerve of the constrictive and pulsatile neurovascular compression (NVC) provoking facial pain. Visualization of venous and/or arterial compression of the nerve is essential to understanding the nature of a patient’s TN and determining appropriate treatment.
Previous literature discusses the varied validity of magnetic resonance imaging (MRI) in predicting NVC of the trigeminal nerve, with some studies reporting success rates ranging from 54-97% in MRI visualization of compression and clinical features or sequence optimization. It has been shown that patients gain significant pain relief from MVD when compression is found preoperatively. However, when NVC remains undetected on imaging, physicians may overlook critical opportunities to provide surgical care to their patients. This case report details a striking disparity between detection of NVC in preoperative MRI and intraoperative photography.
A variety of high resolution 3D heavily T2-type weighted imaging, including steady state free precession (SSFP), constructive steady state interference (CISS), and modified T2 (T2 SPACE), are widely available and the standard sequence used to evaluate NVC. However, visualization of NVC of the trigeminal nerve on MRI can be complicated by the small size of the critical structures, potential positional differences from upright to prone, adjacent scarring or artifacts.
Case Presentation: Following CARE guidelines, the authors present a case of a 43 year old patient suffering from severe TN characterized by constant burning, sharp headaches, and pain in the V3 distribution. Providers at previous institutions reported no signs of gross abnormality or NVC along the trigeminal nerve using high resolution 0.8mm axial T2 FIESTA images and, resultantly, did not offer operative care.
The same MR examination was reviewed with additional reformations by an experienced radiologist and neurosurgeon who noted that the superior cerebellar artery passed near dorsal right cisternal trigeminal nerve, with possible abutment of the nerve but not at near the root entry zone, a nonspecific finding. The decision was made to proceed with MVD followed by microsurgical descending pontine tractotomy.
Results: Intraoperatively, numerous prominent arterial and venous structures contributed to multifocal vascular compression despite equivocal evidence of NVC on preoperative imaging. Upon intraoperative and review, some near artifactual or subthreshold structures may have been present on coronal reformations. In retrospect, post contrast T1 imaging was helpful for differentiation of arteries and veins. The microvascular decompression and descending pontine tractotomy were performed without complication. Upon discharge, the patient was pain free.
Conclusion: As in this case, it can be incredibly challenging to identify NVC from MR imaging alone. Techniques such as thin section post contrast imaging may be helpful for differentiating arteries and nerves, providing for more accurate visualizations. On re-examination, subthreshold observations not prospectively described in imaging appear to have correlated with more prominent intraoperative findings. These indications reveal that iterative review of preoperative imaging would support more thorough interpretations, further allowing patients to receive the best possible treatment options.
