[Electron microscopic findings in a polyneuropathy complicating panarteritis nodosa]

Electromicroscopial changes were observed in arterioles, nerves, and striated skeleton muscle cells in a case of clinically and histologically definite polyarteritis nodosa with polyneuropathy. Inflammatory infiltrates were found in and around arteriolar walls; motor nerves were partly demarkated and presynaptic motor endplates were degenerated. The myofibrills of skeleton muscle cells showed a disorganization that is regarded as the morphological substrate for the clinically observed muscular weakness in this case.