What Are the Different Types of Myasthenia Gravis?

Discussion Myasthenia gravis (MG) is a problem of the neuromuscular junction which causes muscle weakness. It can occur in all ages and have a range of symptoms from mild localized disease to mortality-threatening respiratory failure. MG occurs in 1.7-30 cases/million, with a prevalence of 77.7 cases/million. Pediatric patients comprise 10-15% of all patients with MG. In various Asian populations, the juvenile MG can be up to 50% of all of the MG cases. Fluctuations in muscle weakness is a hallmark of the disease. As a reminder, “[i]n normal synaptic transmission in the neuromuscular junction, the axon is depolarized and this depolarization travels to the axon terminal. Voltage-gated calcium channels open, leading to acetylcholine containing vesicles to fuse to the cell membrane. Acetylcholine is then released from synaptic vesicles into the synaptic cleft from the axon terminal. The acetylcholine travels across the synaptic cleft to the AChR [acetylcholine receptor] sites where binding causes sodium channels to open, depolarizing the motor end plate of the muscle fiber. Acetylcholinesterase degrades the acetylcholine, and the sodium channels close, allowing repolarization of the muscle fiber.” The diagnosis of MG is made by history of fatiguable weakness, clinical examination trying to fatigue muscles such as continuous upward gaze (patients worsen with this activity), physiological testing such as the Tensilon test (which has improved symptoms when the drug is...
Source: PediatricEducation.org - Category: Pediatrics Authors: Tags: Uncategorized Source Type: news