Muscle Ultrasound Findings in giant axonal neuropathy



Poster Number: V412


Abigail Potticary, BS, NINDS/NNDCS, Diana Bharucha - Goebel, MD, NINDS/DIR/CNP/NGB/NNDCS, Rotem Orbach, MD, NINDS/DIR/CNP/NGB/NNDCS, Gina Norato, ScM, NIH/NINDS, Dimah Saade, MD, NINDS/DIR/CNP/NGB/NNDCS, Gilberto Mike Averion, BSN, RN, NINDS/DIR/CNP/NGB/NNDCS, Sandra Donkervoort, MS, CGC, NINDS/DIR/CNP/NGB/NNDCS, Mina Jain, PT, MS, DSc, PCS, CC/OCMO/RMD/PTS, Melissa Waite, MSPT, CC/OCMO/RMD/PTS, Reghan Foley, MD, National Institutes of Health, Christopher Mendoza, NINDS/DIR/CNP/NGB/NNDCS, Joshua Todd, Phd, NINDS/DIR/CNP/OCD, Meghan McAnally, MD, NINDS/DIR/CNP/NGB, Tanya Lehky, MD, CAPT, MC, USPHS, NINDS, EMG, Carsten Bonnemann, MD, PhD, National Institutes of Health

Giant axonal neuropathy (GAN) is an ultrarare, autosomal recessive neurodegenerative disease that affects both the peripheral and central nervous systems with progressive sensorimotor neuropathy. Muscle ultrasound is a highly sensitive, real – time imaging tool that can be feasibly performed in young pediatric patients. We aim to evaluate a muscle ultrasound severity scoring system, the modified Heckmatt scale – a qualitative grading system of scores 0 – 3, shown as a composite sum score in individuals with GAN and to determine how it relates to other clinical and functional outcome measures. 
53 individuals with GAN were evaluated under an approved natural history study at the NIH. Of those, muscle ultrasound scoring was performed on imaging from 20 individuals (13 Female, 7 Male; ages 3 – 21 years old). Two individuals had repeat ultrasound studies, yielding 23 total studies. Unilateral transverse ultrasound images of eight muscle groups were utilized. Two muscle graders reviewed the images using the modified Heckmatt grading scale, and interrater reliability was determined using weighted Cohen’s Kappa (0.90). The composite modified Heckmatt score reflected neurogenic muscle changes, with a median score of 12.5, ranging from a score of 6 – 23 (normal reference = 0).  Lower extremity composite scores were higher than upper extremity scores, with a median value of 8, ranging from 5 – 12, reflecting the predominant neurogenic changes in the lower extremities. Additionally, lower extremity composite scores were significantly correlated with age, possibly representing disease progression (Pearson correlation test, two tailed pv = 0.0487). Further analysis compared composite scores for proximal versus distal muscle groups and motor function.  
Here we present data for a composite muscle ultrasound scoring system, emphasizing the potential of muscle ultrasound in studying disease progression for inherited neuropathies, supporting it as a feasible and easy to apply imaging biomarker.