Thymus gland tumor can make a myasthenic crisis more likely

Thymoma almost three times more common in those with crisis, report finds

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Having a thymoma, or a tumor in the thymus gland, can make a severe complication of myasthenia gravis (MG) — known as a myasthenic crisis — more likely, a Turkish study suggests.

“We found that thymoma increased the risk of developing a myasthenic crisis, and also increased the risk of multiple crises,” the researchers wrote, with the likelihood of a crisis nearly three times higher.

The study, “Occurrence and severity of myasthenic crisis in an unselected Turkish cohort of patients with myasthenia gravis,” was published as a brief research report in Frontiers in Neurology.

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Myasthenic crisis can affect muscles responsible for breathing, swallowing

MG is an autoimmune disease wherein self-reactive antibodies impair the normal communication between nerves and muscles, resulting in weakness and fatigue that can affect any muscles involved in voluntary movement.

A myasthenic crisis is marked by a sudden worsening in MG symptoms. The muscles responsible for breathing and swallowing can weaken, leading to severe problems that require hospitalization.

Researchers in Turkey reviewed the medical records of people with MG to better understand a myasthenic crisis, including what precedes them, how they can be predicted, and what treatments work best for patients having them.

The study included 95 adults (53 women, 42 men) with generalized MG, a form of the disease that’s usually more severe and that tends to start in the muscles controlling eye and eyelid movements, and that gradually spreads to others. All had been followed from 2011 to 2021 at an Istanbul hospital.

Patients had a mean age of 52.6, with women on average some 12 years younger than men (48.9 vs. 61.5). During the 10-year observation period, 12 patients (13%) had at least one myasthenic crisis.

Five (42%) of these people also had another health condition. Four had high blood pressure, one had chronic tuberculosis (a bacterial infection that usually attacks the lungs), and one had a laryngeal carcinoma, a tumor in the voice box. Among patients without a crisis, 54 or 65% also had comorbidities ranging from cancers to infections and heart disease.

Link seen between a thymoma and myasthenic crisis

A thymoma was almost three times more common among those who had a myasthenic crisis than those who did not (58.3% vs. 21.5%).

It’s believed that abnormalities in the thymus gland, an organ in the upper chest that’s part of the immune system, may be involved in producing MG-driving antibodies.

In the 12 patients with at least one myasthenic crisis, 11 (92%) had a previous surgery to remove the thymus gland, known as a thymectomy. Seven of the surgeries removed a thymoma.

Seven patients had more than one myasthenic crisis. In five, early symptoms affected their bulbar muscles, those in the head and neck involved in speaking, swallowing, and chewing. Four had a thymoma.

While thymoma considerably increased the risk of one or more myasthenic crises, a “thymectomy did not seem to reduce this risk in thymoma patients,” the researchers wrote.

Two patients were given an MG diagnosis during a myasthenic crisis. One had double vision for two months and a mild upper respiratory tract infection right before the crisis. The other had rapidly worsening difficulty swallowing and breathing. Both had anti-AChR antibodies, the most common type of MG-causing antibody.

Ten out of a total of 18 myasthenia crisis episodes occurred during the summer.

“Myasthenic crises were more common in the summer months,” the researchers wrote.

Nine patients were taking immunosuppressants and 11 were using anticholinesterases, which help improve muscle strength. Four were taking corticosteroids in daily doses of 20 to 80 mg, and five took 100 mg of the immunosuppressant azathioprine every day.

In all 18 myasthenic crisis episodes, patients were treated with intravenous immunoglobulin (IVIG). No satisfactory recovery was achieved in three cases, and plasmapheresis was performed after two weeks.

“In these cases, we preferred to administer plasmapheresis rather than repeat IVIG, taking into account the IVIG half-life and the complete lack of clinical response,” the researchers wrote.

Proper management of a patient’s crisis can lead to good outcomes

Anticholinesterase and azathioprine doses were increased after 10 crisis episodes, and four patients were started on rituximab after their second myasthenic crisis.

The minimum hospital stay was five days and the maximum 60 days (about two months). Five patients were admitted to the intensive care unit, where they stayed for up to 55 days.

With proper management, including individualized and active immunosuppressive treatment and intensive care, positive crisis outcomes are possible for people with generalized MG, the researchers said.

“Early access to intensive care with active and individualized immunosuppression, combined with treatment of complications [like infections], provides a good outcome for myasthenic crisis,” they wrote.

Such care “is especially important in high-risk MG patients: those with a thymoma and those who have previously experienced myasthenic crisis,” the researchers added.