Profiles of neuromuscular diseases. Limb-girdle syndromes

Sixty-six individuals with Limb-Girdle Syndrome (LGS) were evaluated over a 10-yr period and classified into three types: 19 severe autosomal recessive muscular dystrophy of childhood (ARMDC), alternatively referred to by some as SCARMD, 18 autosomal dominant late onset (ADLO), and 29 pelvifemoral (PF) individuals. ARMDC subjects showed the greatest weakness, 2.5 +/- 1.0, mean Manual Muscle Test (MMT) grade for all muscles combined, and the only significant progression of loss of strength, -0.59 MMT unit decline per decade. Strength loss in ADLO and PF types was about the same, 3.7 +/- 0.7 and 4.0 +/- 0.7 grades, respectively. Quantitative strength measurements in ADLO and PF types were more sensitive than MMTs, showing losses of 30-40% strength in muscle groups with MMT grades of 4 or higher. All three types showed greater proximal and lower extremity weakness but usually no difference between flexor and extensor strength. There was a high percentage (44%) of mild very slowly progressive scoliosis in ARMDC, but spine deformity was unusual in ADLO and PF (11%) LGS. Contractures were few, slowly progressive, and usually mild in severity in all types, although more frequent in ARMDC. There also was a low frequency of severe restrictive lung disease in all types (10%) but a high percentage of electrocardiogram abnormalities (62-73%). The most common electrocardiogram abnormalities were increased R/S ratio in V1 and infranodal conduction defects. Intellectual and cognitive functions were within normal limits. Mobility and extremity function reflected the strength differences between the ARMDC and other types of LGS. Eight-five percent of ARMDC individuals relied on a wheelchair for all or part of their mobility, and all were unable to complete timed motor performance tests within the 99th percentile range for controls.