Thigh and Leg Muscle MRI Findings in GNE Myopathy

Abstract

Background: Muscle MRI protocols have been developed to assess muscle involvement in a wide variety of muscular dystrophies. Different muscular dystrophies can involve muscle groups in characteristic patterns. These patterns can be identified in muscle MRI in the form of fatty infiltration. Objective: This study was conducted to add the existing knowledge of muscle MRI in GNE myopathy and evaluate the correlation of muscular involvement with different gene mutations. Methods: The MRI scans of the 18 GNE patients were analyzed retrospectively. Cluster analysis was done for grouping the muscles and patients. Results: The four muscles with the highest fat infiltration were adductor magnus, tibialis anterior, semitendinosus, and semimembranosus. Furthermore, three clusters of muscle involvement were found, including cluster 1, typical muscle involvement indicating muscles with the highest infiltration: extensor digitorum longus, gracilis, biceps femoris, soleus, gastrocnemius medial, adductor longus, tibialis anterior, adductor magnus, semimembranosus, semitendinosus; cluster 2, less typical muscle involvement indicating muscles with intermediate fat infiltration, peroneus longus, gastrocnemius lateral, and minimal fat infiltration in most of the patients, i.e., tibialis posterior; and cluster 3, atypical muscle involvement with low-fat infiltration: rectus femoris, sartorius, vastus intermedius, vastus medialis, and vastus lateralis. Conclusions: This study found three clusters of muscle involvement and three groups of patients among GNE patients. Hamstring muscles and the anterior compartment of the lower leg were the muscles with the highest fat infiltration. Moreover, a weak genotype-muscle MRI association was found in which tibialis posterior was more involved in patients with the most frequent mutation, i.e., C.2228T > C (p.M743T) mutation; however, this finding may be related to longer disease duration.

Clinical-pathological features and muscle imaging findings in 36 Chinese patients with rimmed vacuolar myopathies: case series study and review of literature

“…Muscle scans of patients with SQSTM1/TIA1 mutations revealed fatty replacement in the adductor magnus and vastus lateralis of the thighs and the tibialis anterior and medial gastrocnemius of the lower limbs (21). Patients with GNE myopathy have a similar pattern of muscle involvement as patients with OPDM, with predominant involvement of soleus and gastrocnemius medialis even in the early stages (27,30). However, some differences were observed: in GNE myopathy, the tibialis anterior dysfunction and vastus lateralis are spared, whereas, in OPDM, the long head of the biceps femoris, popliteus, and the short head of the biceps femoris are relatively spared (28).…”

Advances in understanding of the natural history, mechanism, extra‐muscular manifestations and treatment of GNE myopathy

“…While the hamstring muscles and anterior compartment of the lower leg are preferentially affected, the quadriceps muscles typically remain strong, even later on when a wheelchair is required. [2][3][4][5] Ankle-foot orthoses help patients to walk and maintain their balance and are often used for 3-9 years from disease onset onwards. 3,4 Disease progression is variable but often leads to loss of ambulation by 10-15 years after onset.…”

“…Muscle weakness gradually progresses to the proximal limb and truncal muscles, and patients experience difficulties climbing stairs, rising from a sitting position, walking, raising the hands, and lifting the neck. While the hamstring muscles and anterior compartment of the lower leg are preferentially affected, the quadriceps muscles typically remain strong, even later on when a wheelchair is required 2‐5 . Ankle‐foot orthoses help patients to walk and maintain their balance and are often used for 3‐9 years from disease onset onwards 3,4 .…”

“…GNE myopathy has an estimated worldwide prevalence of 1/1 000 000 (Orphanet; https://www.orpha.net/consor/cgi-bin/index.php) but is more common in Persian and Japanese populations 1 . It is an adult‐onset progressive myopathy which typically starts with foot drop and uniquely spares quadriceps until the late stage 2‐5 . Rimmed vacuoles are frequently be found in atrophic fibers of affected muscles 1 .…”

“…1 It is an adultonset progressive myopathy which typically starts with foot drop and uniquely spares quadriceps until the late stage. [2][3][4][5] Rimmed vacuoles are frequently be found in atrophic fibers of affected muscles. 1 Model mice studies have led to the better understanding of molecular mechanism and multiple clinical trials.…”