Hi @fordsy
HNPP affects everyone a little differently. My son and I have some similar issues and some different from each other. About 90% of people with HNPP mostly just have numbness and an occasion limb going to sleep and for that reason, when most doctors read about it they think it's no big deal. However, the other 10% of people have severe, life changing issues from HNPP.

Since your grandson mostly seems to be dealing with muscle weakness, let's focus on that. My son and I both find stairs very challenging. I can make it up one or two flights and then my legs just completely stop working. I was told the muscles are no long receiving signals from the nerves.

If I read about myasthenia gravis, it describes the weakness portion of my challenges exactly. MG is caused by an autoimmune disorder that blocks the acetylcholine receptors at the neuromuscular junction preventing muscles from contracting and receiving nerve signals. The neurologist that did my nerve testing was a neuromuscular specialist (HNPP is a slowly progressing neuromuscular disorder) and advised me that HNPP was causing the same issue for me. We were focusing on my swallowing issues at the time. She recommended that I try Mestinon that is used to treat MG. When she explained everything to me, it made perfect sense that it might work. However, I have a lot of other issues including trouble metabolizing meds due to missing liver enzymes and almost every med I try gives me scary or even permanent life-changing side effects so I have a fear of meds based on my history. Mestinon can cause severe diarrhea and that's a deal-breaker for me. I was worried about other side effects as well so I never tried it. My son has never tried it. He has had a lot of bad experiences with neurologists and gave up on them. I do know someone with MG that takes Mestinon and apparently has no major side-effects from it. Also, sometimes side effects (especially GI) are only temporary until your body gets used to the med. So there is the hope for your grandson on the muscle weakness.

Mestinon helps the nerves and muscles communicate and is taken 2-4 times a day as needed. My neurologist wanted me to take it before meals to help with chewing and swallowing Maybe that would work for him and he'll be back to playing baseball and running up stairs. Catcher (squatting) and pitcher (repetitive motion) probably wouldn't be good positions with HNPP. I casually played softball for 3 years in my 20s, but we didn't practice much like a high school or travel ball team would so not much strain or repetition for my muscles.

In answer to your question, supplements and change of diet do not help me. Most supplements give me strong pins and needles all over my body obviously aggravating my HNPP, but that may also have to do with my metabolic issues. Again, everyone has a different experience with HNPP and with any meds.

I was tested for MG and came up negative. It might be worth having your grandson tested, but if they are sure he has HNPP then that causes similar issues so he probably doesn't have both. Please let me know if he tries Mestinon or anything else. Please feel free to message me privately with any specific questions. My son and I have so many issues from HNPP I could write a novel about our experiences that is too much for the public board.

In general, HNPP is aggravated by repetitive motions, stretching, pressure on a nerve (don't cross legs, lean on elbow, etc.) and challenging muscles can result in muscle fatigue. If I read a book or am texting, I have to put a couple pillows in my lap to rest my arms and the book/phone on the pillow. I can't hold them in the air very long at all. It's a demyelinating disorder (loss of myelin, the protective covering over nerves) so nerves can get damaged easily. I've been dealing with HNPP issues for 50 years and my son for 25 years, but we're still living our lives. Prayers for your grandson.