Hello! Welcome on HCM! I read carefully your question and understand your concern. You should know that the main tests for this disorder are the electroneurography and spinal tap, followed by the exam of the cerebrospinal fluid. Other tests to consider are blood work to exclude any other systemic conditions (complete blood count, sedimentation rate, ANA, ANCA, Rheumatoid factor, genetic testing for Charcot Marie Tooth disease, etc.). Anyway, treatment with IVG can help distinguish between the other causes of neuropathy. So, if you have already performed some blood lab tests, an electroneurography and a spinal tap, I would strongly encourage you to start IVG therapy. Hope you will find this answer helpful! Best wishes, Dr. Aida