According to a recent article in the Myasthenia Gravis News, a team of doctors in Japan had been treating a man now aged sixty for multiple myeloma (MM). The doctors’ report stated that the patient was found to have an unusual form of myasthenia gravis (MG), a diagnosis that had never been previously reported in multiple myeloma patients and rarely found relative to other types of cancer.
MG is the result of an attack by the immune system on proteins located at the junction where the muscle cells and nerves interact.
This extremely unusual case began after the patient’s initial diagnosis of MM at the age of fifty-six. His first symptoms, which gave no clear indication of MG, were double vision plus weakness in his limbs and neck.
He was tested in a neurology clinic but showed no sign of antibodies against the primary cause of MG (acetylcholine receptors or AChRs). The patient was subsequently hospitalized.
Treatment for MM
As described in the BMC Neurology journal, in treating his MM, the patient was initially given bortezomib (Velcade) chemotherapy and the corticosteroid dexamethasone. As for maintenance therapy, a third drug, thalidomide, brand name Thalomid, was added.
It should be noted that because of infections and adverse events, the aforementioned treatment for MM had to be interrupted and modified several times.
Approximately ten percent of MG cases, including the case of the patient referenced in this article, are known to be caused by antibodies that target the muscle-specific tyrosine kinase (MuSK-MG).
The team reported that diagnosing this case was complicated by the cancer therapy that may have created a cover for the underlying symptoms of MG.
The doctors treated the patient’s MG with prednisolone, an anti-inflammatory steroid. The patient was able to leave the hospital within one month.
At discharge, the patient’s status was termed as “minimal” on the MGFA scale with fatigue and limb weakness cited on the release. In the final review, the researchers commented that the mechanism of the disease is still unclear, but they are of the opinion that an autoimmune disorder had been present prior to the discovery of MG.
Again, the researchers stated that the unusual circumstances surrounding the patient’s weakness in his limbs at age sixty without accompanying symptoms in the throat or face are not generally seen in MuSK-MG.
However, the team stressed a need to test MM patients fifty and older who have one or more similar MuSK-MG symptoms even if classic MuSK-MG symptoms are not present.