Space occupying lesions of cranial nerves in calves with facial paralysis.

Clinical and pathological data of a recently discovered neurological disorder in young calves were studied. The symptoms were those of a paralysis of the nervus facialis and a dysfunction of the nervus vestibulocochlearis. Macroscopically, space occupying lesions were found at the roots of these two cranial nerves and in some cases further on their course into the os petrosum. On histological examination, these legions contained multiple nodules with mainly histiocytic cells, some plasma cells and multinucleated giant cells. Around these nodules, dense bands of connective tissue with fusocellular fibroblasts, some plasma cells and small blood capillaries were present. The nodular lesions were usually in close contact with the nerve. Ultrastructurally, a variety of cells, predominantly histiocytes and some plasma cells, were seen next to Schwann cells which contained degenerating axons.