Juvenile myasthenia gravis: a twenty-year experience.

OBJECTIVE: Juvenile myasthenia gravis (JMG) is an antibody-mediated autoimmune disorder of the neuromuscular junction, at the postsynaptic end plate. JMG presents with fluctuating skeletal muscle weakness and fatigue before the age of 18 years. Very frequently JMG presents with the involvement of the oculomotor muscles, with or without generalized involvement. METHODS: We performed a retrospective chart review of patients diagnosed with myasthenia in the pediatric neuromuscular clinics at UT Southwestern, between 1990 and 2010. Osserman classification and the response to therapy scale of Millichap and Dodge were used to compare each patient's severity of myasthenia and responsiveness to drugs before the surgery as a baseline and at the last visit, after thymectomy. RESULTS: Fifty-eight patients were included; 29 (50%) were African American, and 34 (58.6%) were female. Age of onset was 11 months to 17 years, and 38 patients (65%) presented as generalized myasthenia gravis. Forty-nine patients (84%) were acetylcholine receptor antibody (AchR-Ab) positive. Of the 32 to undergo thymectomy, 19 subjects (59%) experienced an improved response to B level on the Myasthenia Scale of Millichap and Dodge (good improvement, both objective and subjective, but continuation of drug therapy required in the same or lower dosage) and 75% experienced a drop in Osserman classification by at least 1. Of the 8 individuals who did not show improvement after thymectomy, 4 subjects (50%) underwent repeat thymectomy. They had initially less invasive fluoroscopic or thoracoscopic procedure. Thymic hyperplasia was found in 7 patients (21%) and thymoma in 2. CONCLUSIONS: Thymectomy was well tolerated by this group of children. There was clinical improvement after thymectomy in two thirds of the AchR-Ab-positive generalized myasthenia gravis patients. Thymic pathology was seen in less than one third of the patients who underwent thymectomy, with thymic hyperplasia being common. Further studies are necessary to determine whether thymectomy is indicated for all children with generalized JMG. More information about the immunologic, genetic, and molecular differences between patients may determine the best treatment for individual patients.

The PedsQL in pediatric patients with Duchenne muscular dystrophy: feasibility, reliability, and validity of the Pediatric Quality of Life Inventory Neuromuscular Module and Generic Core Scales.

OBJECTIVE: To evaluate the reliability and validity of the PedsQL 3.0 Neuromuscular Module (NMM) in assessing health-related quality of life in the Duchenne muscular dystrophy (DMD) population for use as a secondary outcome measure in phase III clinical trials. BACKGROUND: DMD is the most common genetic form of muscular dystrophy in childhood. Clinical trials are underway to evaluate modalities of treatment. The NMM was developed based on interviews of patients with DMD and spinal muscular atrophy. To determine the PedsQL reliability and validity, we administered the NMM to patients with DMD and their caregivers. DESIGN/METHODS: Boys 8 to 18 years old with DMD were recruited from a neuromuscular disease clinic. At baseline, the child and caregiver completed the NMM and the PedsQL 4.0 Generic Core Scales (GC). The NMM was repeated 2 to 6 weeks later. Reliability was assessed using Cronbach's coefficient alpha (internal consistency) and intraclass correlation (ICC) (test-retest consistency). Construct validity was assessed by comparing baseline child and caregiver NMM total scores with the GC Total Score, forced vital capacity, cardiac ejection fraction, and ambulatory status. RESULTS: Forty-four children and their caregivers completed the study. Internal consistency reliability of the total scale score of the NMM was demonstrated (Child alpha = 0.85; Caregiver alpha = 0.87). Test-retest reliability of the NMM was also demonstrated (Child ICC = 0.75, P = 0.001; Caregiver ICC = 0.85, P < 0.001). Validity of the total scale score of the NMM when compared with the GC Total Scale Score was supported (Child r (41) = 0.63, P < 0.001; Caregiver r (42) = 0.64, P < 0.001). Validity of the NMM compared with forced vital capacity was also supported (Child r (38) = 0.35, P = 0.032; Caregiver r (39) = 0.41, P = 0.01). The NMM parent-proxy-report and child self-report "About My Child's Neuromuscular Disease" scale was significantly related to wheelchair use (P < 0.008 and 0.016, respectively); the GC "Child Self-Report "Physical Health" scale was also significantly related to wheelchair use (P < 0.001). We were unable to conduct any analysis with ejection fraction because of the small number of children across all categories. CONCLUSIONS: The PedsQL NMM is a reliable measure of disease-specific health-related quality of life in the DMD population and may be used as an outcome measure in clinical trials.