EMG is nerve-muscle testing using small electrical signals. A particular type of EMG called repetitive stimulation can be seen to select muscles and evaluate for abnormalities that suggest MG. Single fiber EMG can also occasionally be used.
Blood tests can be obtained to evaluate for various ACh antibodies, including ACh binding antibody, ACh bloding antibody, or ACh modulating antibody. Some patients instead have antibodies to muscle specific kinase (MuSK). These patients may have more bulbar and neck/shoulder weakness and often have less of a fatigable nature to the weakness Voltage Gated Calcium Channel (VGCC) antibodies can be seen in a related condition called Lambert Eaton Myasthenic Syndrome (LEMS)
Occasional a medication called Tensilon (edrophonium) can be given to see if there is a change in weakness to suggest MG. This has largely been replaced by the above studies, as this medication can have significant side effects.
There are a variety of treatment options for MG. Often, the Neurologist can utilize multiple of these approaches to address the condition from various angles and optimize disease control.
IVIG is a product that contains pooled plasma from many donors. This is infused daily, typically over a 5 day period. The goal is that antibodies in the IVIG will bind to the problematic ACh receptor antibodies so they are neutralized. IVIG is about as effective at PLEX in treating MG crises. Symptoms usually improve within 1 week of IVIG and have relief for 4 to 8 weeks. Common side effects of IVIG can include chills, headache, or fever. Benadryl or Tylenol can help prevent these side effects. Other serious side effects such as stroke, renal failure, or aseptic meningitis are very rare.
A myasthenic crisis is a serious medical emergency, as it can lead to inability to breath due to diaphragm weakness or inability to swallow without aspiration due to weakness in the mouth and throat. At times, a person may need to be intubated and put on a ventilator until the crisis is resolved. Tube feeding may also need to replace eating by mouth. The medical team will also make sure to support blood pressure and evaluate for and correct any other underlying medical problem, such as an infection.
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