**5. Conclusion**

(3) premature bolus loss, (4) residue in oral cavity, and (5) oral transit time. On the other hand, measurements in the pharyngeal phase included (1) lift in the soft palate, (2) triggering of pharyngeal swallow, (3) epiglottic vallecula residue, (4) pyriform sinus residue, (5) pharyngeal transit time, and (6) aspiration. The relationship between total VF assessments in the oral phase and the threshold of electrical sensation showed a weak association with cerebral hemorrhage, cerebral contusion, amyotrophic lateral sclerosis and myasthenia gravis (Figure 4A). However, the relationship between total VF assessments in the pharyngeal phase and the threshold of electrical sensation had a strong association with these disorders (Figure 3B). On the other hand, a decrease in the electrical threshold of sensations following the treatment process was not observed in patients with amyotrophic lateral sclerosis or myasthenia gravis (black and

In summary, the criteria for evaluating recovery of the swallowing reflex may be covered by the electrical threshold of sensation on the soft palate, and acceptance of the electrical stimu‐ lation will produce a reduction in the bombing experience. Why dose the threshold of electrical sensation reflect recovery of the swallowing reflex? The reflex arc progresses as follows: receptor organ, afferent fiber, central nerve for the reflex, efferent fiber and effector organ. In particular, initiation of the swallowing reflex starts from the regions that induce swallowing (primarily the soft palate, posterior part of tongue, and posterior wall of the pharynx). VF assessments of the pharyngeal phase exhibited the swallowing reflex, and this reflex was initiated by stimulation of the regions that induce swallowing. We consider that the stimulation of these regions involves perception by sensory organs, and the swallowing reflex is then

**4.3. Relationship between electrical sensation and voluntary movement or reflex**

When we execute hand movements (especially during search behavior), we take notice of a keen sense in the fingers. Namely, our cutaneous sensation is excited before the execution of movements. This helps us to understand the inaccuracy and inadequacy of movements in patients with sensation disorders. In particular, when the patients with unilateral lingual nerve disease (e.g., secondary to sensory nerve damage during wisdom teeth extraction) are promoted to perform tongue protrusion, the tongue bends toward the diseased side. Further‐ more, monkeys with tactile agnosia after blocking of the first somatosensory cortex (SI) exhibit poor performance in gripping an object (Hikosaka et al.) [4]. Nelson [9] reported somatosen‐ sory neuronal activity in the SI prior to movement. These results indicate that sensory information in the SI is necessary for the initiation and preparatory of the start of movements. Based on these findings, it is understandable that the somatosensory information obtained prior to movement excites the facial, intraoral, and pharyngeal regions. Sessle et al. [10]. Sessle [11], Stohr and Petruch [12] and Stohr et al. [13] reported that a close relationship between the facial motor and sensory cortices is needed during facial and tongue movements. We assumed the presence of a relationship between electrical sensation and the recovery process based on our findings in the orofacial region. However, two patients in the present study (nos. 7 and 8, Table 2) exhibited no change with electrical stimulation treatment. Both of these patients had muscular atrophy, a degenerative disease. These results may suggest that progressive deterioration of the muscle and spinal cord make reconstruction difficult. On the other hand, although a close relationship between VF assessment of the pharyngeal phase and electrical

red lines of Figures Aa, Ab and B).

114 Seminars in Dysphagia

evoked by the sensory stimulation.

Although VF (videofluoroscopic examination of swallowing) is the best choice for the func‐ tional assessment of eating (mastication) and swallowing, we cannot avoid a bombing expe‐ rience. Therefore, we devised at new method to reduce the need for VF examination. The electrical threshold of sensation in centrally diseased sites of the orofacial region has long been examined in patients with stroke, head and neck tumor, external injury and other dis‐ orders following on the orofacial treatments. The results suggest a close relationship be‐ tween the electrical threshold of sensation and the recovery process. Many researchers have evaluated the results of VF assessments based on the Videofluorographic Examination of Swallowing Worksheet developed by Logemann (1993). We selected 11 applicable items used by many hospitals: bolus formation, tongue-to-palate contact, premature bolus loss, residue in oral cavity, and oral transit time in the oral phase; and lift in the soft palate, trig‐ gering of pharyngeal swallow, vallecular residue, pyriform sinus residue, pharyngeal transit time, and aspiration in pharyngeal phase. In particular, we considered that a higher sum in each phase might indicate a more serious condition. We also measured the electrical thresh‐ old of sensation on the soft palate when patients visited the hospital. Why is the threshold of electrical sensation reflected by recovery of the swallowing reflex?

In particular, VF assessments in the oral phase are related to voluntary masticatory move‐ ment, while those in the pharyngeal phase are related to the swallowing reflex. Initiation of swallowing reflex starts from the regions that induce swallowing (primarily the soft palate, posterior part of tongue, and posterior wall of the pharynx). We propose that electrical thresholds in the soft plate can be assessable as the function of swallowing reflex.
