Electronmicroscopic observation of the human facial nerve.

The facial nerves of Bell's palsy, Ramsay-Hunt's syndrome and traumatic facial palsy patients were studied using a transmission electron microscope. Changes were a proliferation of the collagen fibres, the degeneration of the Schwann cell, and a loosened or deteriorated myelin sheath. These changes differ considerably between individuals. Changes also vary in one subject. The cause and severity of the lesion, the duration of the palsy and the location of biopsy are possibly responsible for this phenomenon.