The leakage of eight different
serum proteins and
immunoglobulins across the blood-nerve barrier (BNB) was studied by means of the
peroxidase-antiperoxidase method in hereditary and inflammatory neuropathies and graded semiquantitatively with respect to endoneurial staining intensity and distribution. These data were compared with the degree of alterations of the myelinated nerve fibre population evaluated by morphometric analysis. Our series of 18 human sural nerve biopsies included seven hereditary neuropathies (three
HMSN I, two
HMSN II, two tomaculous neuropathies), nine inflammatory neuropathies (seven
polyneuritis, two hypertrophic
neuritis) and two normal controls. In
HMSN II and in
tomaculous neuropathy there was no enhanced endoneurial staining for
serum proteins despite of a severe nerve fibre loss, whereas in
HMSN I a rise of
serum proteins of small and moderate molecular size like
albumin and
IgG was demonstrated in the endoneurial space indicating an impaired BNB function. Qualitative changes of the BNB with leakage also of high molecular weight
proteins were observed in
polyneuritis and hypertrophic
neuritis, irrespective of the degree of nerve fibre changes. Our results show that fibre loss and alteration of the BNB are not correlated. The unselective leakage of
serum proteins through the BNB appears to be a characteristic change in inflammatory neuropathies leading to proteinous
edema. With regard to the subperineurial accentuation of the endoneurial
edema it will be discussed that the vascular diffusion barrier is more fragile than the perineurial diffusion barrier.