peripheral polyneuropathy prognosisdemyelinating polyneuropathy prognosisaxonal polyneuropathy prognosisperipheral neuropathy prognosiscidp prognosisalcoholic neuropathy prognosissensory neuropathy prognosistoxic neuropathy prognosiscidp long term prognosisaxonal neuropathy prognosismultifocal motor neuropathy prognosissmall fiber neuropathy prognosis