The diagnostic considerations of an inflammatory brainstem disease and its symptoms are shown in 22 cases. The diagnosis based on a topodiagnostic decision and the demonstration of an inflammatory genesis. The topodiagnosis has to take into consideration that a symptom can be caused by both a central lesion as well as a peripheral nerve lesion. Electrophysiological methods (EEG, Nerve conduction velocity, reflex studies and evoked potentials) were of only minor use in these decisions. The somatosensory evoked potentials demonstrated 5 central lesions and were far more useful than the other methods. The CCT demonstrated a brainstem lesion in one case. In fifty percent of the cases, symptoms caused by both peripheral and central nerve lesions were demonstrated. Thus, there is no clear border between a brainstem encephalitis and a peripheral neuropathy (Fisher-Syndrome or Guillain-Barré-Syndrome). The inflammatory genesis was proven by CSF in 12 cases. An inflammatory disease was supported in the other cases through the exclusion of another genesis by means of CCT, NMR, Doppler sonography, angiography and an observation of the course of the illness.