--as slow, chronic progression, it does happen (it certainly did to me--full-body over hours/days with burning pain but no motor symptoms).

Very often, after the initial rush of horrible symptoms, the condition settles down. But often there's been major nerve damage, and recovery is not complete, but partial and patchy. Weird symptoms may persist for years, and even healing of nerves, as the growth cones fight their ways through tissue and attempt to reconnect to their afferents, can cause weird parasthetic symptoms--pain, tingles, fasiculations.

These may become less prominent in time, but never completely leave, and one may be prone to flares in times of sickness or stress--it's been estimated, for example, that about half of all people who are stricken with Guillain-Barre syndrome, one of the most well-documented acute onset demyelinating neuropathies, while recovering much function over weeks/months, still have residual symptoms or dysfunction years later, to varying degrees.

Most clinical reports of acute onset neuropathy end with the prognosis of "slow, partial recovery"--how slow and how partial depend on lots of individual factors. One should try to maximize the condtions for nerve healing with appropriate diet, supplementation, and exercise to tolerance.