Diagnosis: CIDP vs Nitrous Oxide abuse

Hello everyone-

Our adult son (20's) developed peripheral neuropathy, resulting in several days of hospitalization some months ago. The usual blood work, MRI's, EMG, CSF fluid tests, etc. High CSF protein, MRI's neg. Discharged without a firm diagnosis, as his condition worsened and he ended up in a wheelchair due to inability to walk, a new neurologist diagnosed CIDP.

Shortly after diagnosis, but before any IVIG, we (and the docs) learned that he'd been using Nitrous Oxide heavily as a recreational drug (he had denied drug use to the docs during testing). He'd used before and after hospitalization. These are also called whip-its-- it's the drug that Demi Moore recently overdosed on. Increasingly popular among teens and young adults here in the US, although I understand that it's been popular for some time elsewhere (many of the medical cases report teens and young adults in Australia and New Zealand).

Regular heavy use of N2O blocks the ability of the user to process vitamin B-12, resulting in a B-12 deficiency that can cause nerve demylination resulting in peripheral neuropathy, similar to that seen in CIDP patients. In our son's case, he also had some temporary loss of cognitive function-- mostly memory and searching for words-- due to the N2O.

Our son had been supplementing with oral B-12 shortly before hospitalization, causing his serum B-12 levels to actually be elevated, although his body wasn't able to properly process the B-12 in the blood (other blood work such as elevated MCV supported B-12 deficiency). This masked an obvious diagnosis initially.

He's improving over the past 7 weeks since stopping the N2O, and taking heavy doses of methyl B-12 sublingually. He's gone from wheelchair, to walker, to cane. Neurologist still thinks CIDP may also be involved, but son is holding off on the IVIG treatments for now, to see whether he'll have full recovery in a reasonable time, with no relapse.

So-- to my point. Have any of you dealt with this differential diagnosis issue between CIDP and N2O? I also wanted to make sure everyone was aware of the increasing problem of recreational use of N2O, and it's serious side effects that mimic those of CIDP.