Tuan H. Vu, MD - Generalized Myasthenia Gravis Across Serological Subtypes: Challenges in Diagnosis and Treatment Personalization

To illustrate

our understanding today, we'll talk about this patient, Vicky.

She's a 48-year-old woman with a 14-month history of progressive fluctuating right cytotosis worsening toward the end of the day.

She also has difficulty chewing tough foods and bilateral proximal arm weakness.

She has been seen by another neurologist and had a negative ACHR antibody titer.

And her repetitive nerve stimulation study was somewhat equivocal and not clearly diagnostic.

She has not been diagnosed or treated.

So which of the following diagnostic steps is the most appropriate to establish a diagnosis and guide treatment planning? So the options are do a brain MRI with contrast, lumbar puncture, and neuro-ophthalmological referral.

Order musk antibodies and LRP4 antibodies plus single fiber EMG.

Repeat the ACHR antibody using cell-based technology, CT of the chest, and initiate empiric periodostate mean.

or do a muscle biopsy and brought genetic testing panel for congenital myasthenic syndromes.

And of course, there's always the option of I'm not sure.

So in this particular case, I probably would do the MUS antibody and LRP4 testing and single fiber EMG.

The first case, the brain MRI will contrast looking for perhaps brain stem lesion is probably not the first choice because of the fluctuating nature of her condition.

And in addition to the fact that it's been going on 14 months and any lesions there would likely be progressive and would cause additional problems.

Repeating ACHR antibodies along with CT of the chest and initiate empiric pyrostigmine is not an unreasonable option.

And definitely the CT of the chest if you suspect MG would be the right choice because of the potential for thymoma in about 10% of the cases.

At age 48, with symptom onset around age 47, congenital myosinatic syndromes would be less likely, so that would not be a good option.

So we can argue about repeat ACHR antibodies with cell-based assay or check the other two antibodies.

Either way is okay, but in my case, I would select for musk and LRP4 and single-fiber EMG.