It has been the general belief and part of the definition of "neuralgia" that in major trigeminal neuralgia no objective sensory disturbance is present. This experience holds true as long as we use pin and cotton wool as means of examination. But when graduated hairs or thorns and the electrical current are applied, we find that in about 25 per cent of our patients with trigeminal neuralgia who have not received any previous treatment the number of touch and pain points is reduced—penesthesia, penalgesia. We also note that the preserved points require a stimulus of greater strength and longer duration to produce a sensation—hypesthesia, hypalgesia. Such quantitative deviations of sensibility of the face are sometimes helpful in judging the operative chance for relief of pain in patients with a combination of typical and atypical features of trifacial neuralgia, as well as in determining the division of the fifth nerve primarily