Lhermitte's Sign following VMAT-Based Head and Neck Radiation-Insights into Mechanism. PLoS One 2015;10(10):e0139448
Date
10/09/2015Pubmed ID
26448647Pubmed Central ID
PMC4598033DOI
10.1371/journal.pone.0139448Scopus ID
2-s2.0-84948661476 (requires institutional sign-in at Scopus site) 5 CitationsAbstract
PURPOSE/OBJECTIVES: We observed a number of patients who developed Lhermitte's sign (LS) following radiation to the head and neck (H/N), since instituting volumetric modulated arc therapy (VMAT). We aimed to investigate the incidence of LS following VMAT-based RT without chemotherapy, and determine the dosimetric parameters that predict its development. We explored whether the role of inhomogeneous dose distribution across the spinal cord, causing a "bath-and-shower" effect, explains this finding.
METHODS AND MATERIALS: From 1/20/2010-12/9/2013, we identified 33 consecutive patients receiving adjuvant RT using VMAT to the H/N without chemotherapy at our institution. Patients' treatment plans were analyzed for dosimetric parameters, including dose gradients along the anterior, posterior, right, and left quadrants at each cervical spine level. Institutional Review Board approval was obtained.
RESULTS: 5 out of 33 (15.2%) patients developed LS in our patient group, all of whom had RT to the ipsilateral neck only. LS patients had a steeper dose gradient between left and right quadrants across all cervical spine levels (repeated-measures ANOVA, p = 0.030). Within the unilateral treatment group, LS patients received a higher mean dose across all seven cervical spinal levels (repeated-measures ANOVA, p = 0.046). Dose gradients in the anterior-posterior direction and mean doses to the cord were not significant between LS and non-LS patients.
CONCLUSIONS: Dose gradients along the axial plane of the spinal cord may contribute to LS development; however, a threshold dose within the high dose region of the cord may still be required. This is the first clinical study to suggest that inhomogeneous dose distributions in the cord may be relevant in humans. Further investigation is warranted to determine treatment-planning parameters associated with development of LS.
Author List
Ko HC, Powers AR, Sheu RD, Kerns SL, Rosenstein BS, Krieger SC, Mourad WF, Hu KS, Gupta V, Bakst RLAuthor
Sarah L. Kerns PhD Associate Professor in the Radiation Oncology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AgedCarcinoma, Squamous Cell
Female
Head and Neck Neoplasms
Humans
Male
Middle Aged
Radiation Injuries
Radiometry
Radiotherapy Dosage
Radiotherapy, Intensity-Modulated
Spinal Cord
Tomography, X-Ray Computed