Ocular MG symptoms can be eased with immunosuppressants: Study
Medical records of 135 MG patients were reviewed as part of analysis
Immunosuppressive therapies, administered with or without acetylcholinesterase inhibitors, helped ease symptoms of ocular myasthenia gravis (MG), according to an analysis of medical records from several hospitals in Japan.
Although treatment was associated with favorable outcomes, some symptoms persisted in more than half the treated patients. Still, immunotherapy, including corticosteroids, may benefit patients with ocular MG, researchers noted in “Immunotherapy for ocular myasthenia gravis: an observational study in Japan,” which was published in Therapeutic Advances in Neurological Disorders.
In MG, the immune system mistakenly attacks components of the neuromuscular junction, where nerves connect with the muscles they control. Symptoms may be limited to the eyes and eyelid muscles — called ocular MG — or they can be more severe and widespread, and affect many muscles, including those that control breathing. This is called generalized MG (gMG).
Ocular MG is generally considered a mild disease, but patients with eye-only involvement are typically treated the same way as generalized symptoms are. There is limited documentation about real-world clinical treatment and outcomes in those with ocular MG, however.
In this study, researchers examined how 135 ocular MG patients (67 men, 68 women) were treated at eight different clinical centers in Japan. Patients were a mean age of 58.7 and had been living with MG for 14.3 years, on average.
Treatments and outcomes for ocular MG
A total of 120 patients (88.9%) were treated with acetylcholinesterase inhibitors, such as pyridostigmine (sold as Mestinon), a recommended first-line therapy for MG designed to improve nerve-muscle communication and muscle strength.
Among them, 78 (57.8%) received further treatment with one or more immunotherapies, primarily oral prednisolone. Of the 15 (11.1%) who didn’t receive acetylcholinesterase inhibitors, 12 (8.9%) were treated with one or more immunosuppressive therapies. Overall, 90 received immunotherapy, 45 didn’t.
Intravenous (into-the-vein) methylprednisolone was administered to 37 patients, while calcineurin inhibitors were also used frequently. Intravenous immunoglobulin treatment and plasma exchange were used in four patients to ease their eye symptoms. A thymectomy, surgery to remove the thymus gland and used as a long-term MG treatment, was performed on 11 patients.
Outcome data showed eight of the 135 patients (6.0%) achieved complete stable remission (CSR), defined as having no signs or symptoms of MG and no longer requiring treatment. Six of them received short-term treatment with acetylcholinesterase inhibitors and two improved spontaneously without treatment.
Another 45 (33.3%) reached pharmacologic remission/minimal manifestation (PR/MM), defined as a state of remission or having no symptoms that affect daily function after some form of treatment is received.
A total of 72 (53.3%) people were ranked as improved, meaning their symptoms eased, but remained. A lack of response or worsening of symptoms (unchanged/worse, U/W) occurred in 10 cases (7.4%). Symptoms persisted even after treatment in 82 patients (60.7%).
Blood tests showed the levels of antibodies targeting the acetylcholine receptor — the most common MG-causing antibodies — were significantly lower in those who achieved CSR than in unresponsive patients.
Among the 90 patients who received immunotherapy, none achieved CSR, while 35 reached PR/MM, and 53 improved. There were two U/W cases. Of the 45 patients who didn’t receive any immunotherapy, eight reached CSR, 10 PR/MM, 20 improved, and eight were U/W.
The proportion of patients showing a lack of response (U/W) was significantly lower in those treated with immunotherapy than in those who weren’t (2.2% vs. 17.8%).
All the patients treated with intravenous methylprednisolone responded, as did those treated with calcineurin inhibitors, intravenous immunoglobulin, or plasma exchange. After thymectomy, seven patients reached PR/MM and four improved.
Age of onset for ocular MG and treatment outcomes
None of the 24 patients diagnosed with juvenile-onset ocular MG (disease onset before age 15) achieved CSR. At the same time, six were unresponsive, “representing a higher proportion than that in other age groups.”
Outcomes were markedly better in the 67 late-onset patients (disease onset at age 50 or older) than in the early-onset group (disease onset before age 49), with seven reaching CSR, 58 showing improvements (PR/MM and improved), and two being unresponsive.
The treatments varied between hospitals, with some preferring immunotherapy, while others used intravenous methylprednisolone or calcineurin inhibitors more often. Data showed a larger proportion of ocular MG patients at each medical center significantly correlated with more frequent use of immunotherapy for eye-only disease. The use of corticosteroids also followed this pattern.
“The overall prognosis for patients with [ocular MG] was good in our study; however, the outcomes of some patients, especially those who did not receive immunotherapy was unfavorable,” the researchers wrote. “Immunotherapy appears to be beneficial for patients with [ocular MG].”
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