Gait Abnormalities in Late-Onset Pompe Disease (LOPD) — Gower’s Sign

  Pompe disease is a progressive and potentially life-threatening genetic neuromuscular disorder. When symptoms present in individuals one year of age and older the disease is most often referred to as late-onset Pompe disease or LOPD. LOPD is characterized by progressive weakness in the trunk and proximal muscles as well as the group of muscles surrounding the pelvis. This may affect a person’s mobility, making it difficult to walk, climb stairs, stand up from a chair, and reach overhead. Weakness in the diaphragm and other respiratory muscles also cause progressive respiratory disease. Since LOPD presents as a spectrum of symptoms that can mimic other neuromuscular disorders, a diagnosis can often be delayed and difficult. One of the visible symptoms of LOPD is difficulty rising from a seated position, which is characterized by core muscle weakness and the reliance on upper body strength to push oneself up. The following videos were created using motion capture technology of actual patients diagnosed with LOPD. Some patients with Pompe disease may be more severely affected or have a longer disease duration. Brian is a 44-year old man with severe LOPD. As with many affected people, weakness in the pelvic girdle and proximal muscles makes it difficult for Brian to rise from a seated position. Brian is only able to stand when using the armrests for support. He overcompensates for weak core muscles by using his upper body strength to push against the armrests and raise himself to a standing position. Notice how he then swings his pelvis forward to straighten out his body as he stands. He also positions his feet against the chair legs to provide stability in standing. This is Susan, a 50-year old woman who has LOPD. Susan is more severely affected. Weakness in her proximal muscles and pelvic girdle makes it challenging for Susan to stand from a seated position, typical of a person with LOPD. Patients often overcompensate for weak core muscles by using their upper body for support when rising from a seated position. When seated in a chair without armrests, Susan struggles to stand. She rocks her body slightly and uses her arms to push off her thighs in order to gain momentum to stand with her feet in a wide position for stability, then bringing them together. When seated in a chair with armrests, Susan is able to use her upper body strength to push against the armrests and raise herself more quickly to a standing position, while also bracing her legs against the chair. This is Karen, an 18-year old woman with LOPD. Some patients, such as Karen, may be less-severely affected or have experienced a shorter disease duration when assessed. Upon first look, it appears that Karen has no difficulty rising from a chair with or without armrests. 

 

                             She does not need to rely on her upper body strength in order to stand in either scenario. However, you may notice that she leans forward and swings her body to compensate for the proximal weakness and takes a moment to regain her balance when rising from the chair without armrests. Weakness in core muscles can result in unsteadiness when support is not available. Robert is a 28-year old man with LOPD. Robert appears to be visibly healthy and asymptomatic as he is able to rise from a seated position without relying on armrests or upper body strength for support. Not all patients with LOPD will portray physical abnormalities characteristic of weak core muscles. Some patients may be less-severely affected or have experienced a shorter disease duration when assessed. So it’s important to take all symptoms into consideration, such as general muscle weakness, exercise intolerance, or shortness of breath. If you notice any of these characteristics in your patients, consider a GAA enzyme assay or genetic testing to test for Pompe disease.