Value of the isolated tensor tympani muscle reflex elicited by electric lingual stimulation.

A bilateral reflex contraction of the isolated tensor tympani muscle has been obtained in man by bipolar electric stimulation of the edge of the tongue (DC generator). The avoidance of the elevated and variable body electric resistance and of the variable contact resistance from the hand to the ground plate, represents an appreciable improvement of this method in comparison with the unipolar method described in a earlier paper. A further improvement has also been achieved by applying the electric stimulus to one inferior aspect of the tongue near the floor of the mouth, nearer to the lingual nerve. An analysis has been subsequently conducted in normal subjects and in patients affected by pathologies of the tympano-ossicular system; otosclerosis, tympanosclerosis, unilateral complete suprastapedial facial paralysis, interrumption of the ossicular chain; in cases of interruption of the afferent arc: section of the unilateral lingual nerve; involvement of its central portion: cerebello-pontine angle tumour, brain stem tumour. A chiasma-like central nervous pattern is suggested.