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Sensation Elicited by Mechanical Stimuli to the Oropharyngeal Mucosa
Auris' Nasus' Larynx (Tokyo) 11, 37-42 (1984)
SENSATION ELICITED BY MECHANICAL STIMULI TO THE OROPHARYNGEAL MUCOSA Mikikazu YAMAGIWA, M. D., Haruki FUKUO, M. D., Yasuo SAKAKURA, M. D., and Yasuro MIYOSHI, M. D. Department of Otolaryngology, Mie University School of Medicine, Mie, Japan
An inaccurate localization of the site of stimulus, a higher two-point threshold for touch than those at lower lip or soft palate mucosae, and reference of touch sensation to the submaxillary cervical region following mechanical stimuli to the posterior oropharyngeal wall or lateral pharyngeal band were observed in the present study on otolaryngologists, medical students and patients with abnormal sensations in the throat. These results indicated that not only the somatic but also the visceral nervous system might contribute to the elicitation of sensation from the oropharyngeal structures behind the soft palate. It has been described that stimulation of the lateral pharyngeal band or, if it is absent, along the lateral pharyngeal wall behind the posterior pillar, results in referred sensation in the submaxillary cervical region of the same side (PASTORE, 1953). Patients' failure to localize the foreign body in the oropharnyx may be an example of this law. Fish bones most occasionally lodge in the palatine tonsil. The patient, however, seldom localizes the foreign body and only complains of the pain which seems to come from the lower neck. Such a phenomenon in patients suggested that the sensation elicited by mechanical stimuli to the pharyngeal mucosa might be alike to the visceral sensation, rather than the superficial or cutaneous one. The first aim of the present study was to investigate the unreferred sensation in the pharyngeal mucosa by measuring the accuracy of localization and the twopoint threshold for touch. The second goal was to analyse the modality of the reference of sensation following a mechanical stimulation of the pharyngeal mucosa for elucidating the referred sensation from that area. MATERIAL AND METHOD
The investigation was carried out on 44 otolaryngologists (37 males and 7 Received for publication June 6, 1983 37
38
M. YAMAGIWA, H. FUKUO, Y. SAKAKURA, and Y. MIYOSHI
females, 25 to 60 years of age), 50 medical students (47 males and 3 females, 24 to 34 years of age) and 46 patients with abnormal sensation, such as a lump or itchy feeling, in the throat (21 males and 35 females, 17 to 69 years of age). Investigation of unreferred sensation. The left lateral pharyngeal band or, if it was absent, the lateral pharyngeal wall behind the posterior pillar was stimulated mechanically with a cotton tipped applicator at the level of uppermost of the left palatine tonsil. The otolaryngologists were ordered to mark the site stimulated on the schematic drawing of the oropharnyx, as shown in Fig. I. Since otolaryngologists are well acquainted with the anatomy of the pharynx and its neighboring structures, they are the most suitable subjects for the study of localization. On 23 of the medical students and 30 of the patients, the two-point threshold for touch was examined at the posterior oropharyngeal wall, forehead skin, lower lip mucosa and soft palate mucosa by simultaneously applying the two blunt points of a bayonet forceps parallel with the horizontal level of the body. The distance between two points of forceps was locked up and those with distances of 5, 10, 15, 20 and 25 mm were used for measuring. The smallest distance between points at which they were still perceived by subjects as two separate contacts was defined as the two-point threshold. Investigation of referred sensation. All subjects were ordered to point by finger to the site in the cervical or other region where the touch sensation referred after a mechanical stimulation of the lateral pharyngeal band or wall in the manner described above. RESULTS
Unreferred sensation . A. Localization. The stimulated points in the pharynx localized by the otolaryngologists were shown in Fig. I. Of 44 subjects, 10 (23 %) including 2 (5 %) individuals who pointed to the stimulated site in a great accuracy localized the site (3-B area in Fig. 1) almost accurately. Though there were no subjects who mistook the stimulated side, most subjects tended to localize the site in the posterior pharyngeal wall below the site of stimulus. The accuracy of the localization of the site of stimulus did not correlate with the years spent by each individual as an otolaryngologist. B. Two-point threshold. Regional differences of the two-point threshold for touch obtained from the 53 subjects were shown in Table 1. In a preliminary experiment, it was clarified in a majority of subjects that the threshold at the posterior oropharyngeal wall was higher than 25 mm, and the distance between both lateral pharyngeal bands was slightly longer than 25 mm. Therefore, only the forceps with 25 mm in distance between two points were used for the measurement of threshold at the posterior oropharyngeal wall. As shown in Table I, the two-point threshold at the posterior oropharyngeal wall was extremely higher
SENSATION IN THE OROPHARYNGEAL MUCOSA
39
A B
c Fig. I. Points (black dots) taken by 44 otolaryngologists as the site of stimulus after a mechanical stimulation of the left lateral pharyngeal band at the level as high as the uppermost portion of the ipsilateral palatine tonsil. Table I.
Two point threshold for touch investigated at various sites in 53 subjects.
Sites Forehead skin Lower lip mucosa Soft palate mucosa Posterior oropharyngeal mucosa
Threshold (mm) ;:£5
10
15
20
25
4
19
15 1
6
6
3
51 31
19
2
14
39
25<
1
than those obtained at the other sites. Referred sensation It was a typical report by otolaryngologists that the touch sensation in the throat disappeared several seconds after the stimulation, and then the referred sensation in the anterior neck remained only for a few minutes, as shown in Fig. 2. Such referred sensation was localized by 40 otolaryngologists (91 %). Sixteen (40 %) of them localized the referred sensation between the hyoid bone and the superior cornu of the thyroid cartilage on the stimulated side. In 3 subjects, the sensation referred far to the supraclavicular region. The distribution of referred sensation localized by medical students was shown in Fig. 3. Of 50 students, 40 (80 %) could localize the referred sensation. There were 3 students in whom the sensation referred to the left ear; the remaining 37 localized the sensation referred to the submaxillary cervical region of the same side. As well as otolaryngologists, most students (50 % of all) localized the sensation near the midline at the level between the hyoid bone and the superior cornu of the thyroid cartilage. They answered undoubtedly that the level of referred sensation should be at the same height as that of stimulus. Of 56 patients with abnormal sensation in the throat, 51 (91 %) localized the
40
M. YAMAGIWA, H. FUKUO, Y. SAKAKURA, and Y. MIYOSHl
Fig. 2. Referred points (black dots) of touch sensaticn obtained from 40 (91 %) of 44 otolaryngologists after a mechanical stimulation of the left lateral pharyngeal band in the manner described in the legend of Fig. 1.
,\
Hyoid bone
Thyroid gland
-----Fig. 3. Referred points (black dots) of touch sensation obtained from 40 (80%) of 50 medical students after a mechanical stimulation of the left lateral pharyngeal band in the manner described in the legend of Fig. I.
sensation referred to the cervical region of the same side. The area of referred sensation localized by patients appeared to be more confined, and 36 (64 %) patients localized the sensation over the superior cornu of the thyroid cartilage (Fig. 4). DISCUSSION
WEBER (1852) touched the skin with a pointer dipped in powder charcoal to mark the point stimulated. Then the subjects, with eyes closed throughout, tried to touch the same spot with another pointer. The measured discrepancy between the two marks gave the error of localization. WEBER'S technique, however, is of little utility for testing the localization on the oropharyngeal mucosa. With the
SENSATION IN THE OROPHARYNGEAL MUCOSA
41
Fig. 4. Referred points (black dots) of touch sensation obtained from 51 (91 %) of 56 patients with abnormal smsations in the throat after a mechanical stimulation of the left lateral pharyngeal band in the manner described in the legend of Fig. 1.
technique used in the present study, the accuracy of localization in that area can be measured on individuals who are well acquainted with pharyngeal anatomy. In the present study, the otolaryngologists tended to take the stimulated site lower than that of the stimulus. It was not possible to say that they could point to the stimulated site with sufficient accuracy. Even if the same experiment could be carried out on ordinary persons who were not acquainted with pharyngeal anatomy, a similar result might be obtained. Therefore, the possibility that the localization at the oropharyngeal mucosae behind the soft palate is not accurate must be admitted. Regional variation in two-point threshold for touch was observed among other sites of the body. Even in the oropharyngeal structures, such variation was observed: namely, the two-point threshold at the posterior oropharyngeal wall was greatly higher than that at the soft palate mucosa. WEINSTEIN (1968) found a high correlation between the two-point threshold and the accuracy of localization. It was therefore presumable that the somatic nerve system contributing to the superficial sensation might not participate so much in the pharyngeal structures behind the soft palate. On the other hand, the reference of sensation was attractive. It occurred in a majority of all subjects and was not affected by subjects' knowledge of the head and neck anatomy. Impulses arising in visceral structures may give rise to pain localized in more superficial structures of the body, often those at a considerable distance from the disturbed organ. Such pain is said to be referred (RUCH, 1979). It is well recognized clinically that the referred pain from the heart in the case of angina pectoris seems to come from the chest and from a thin strip along the inner aspect of the upper arm. The reference of sensation following the stimulation of oropharyngeal mucosa may occur in a similar neurophysiological process to the referred visceral pain (SELZER and SPENCER, 1969).
42
M. YAMAGlWA, H. FUKUO, Y. SAKAKURA, and Y. MIYOSHl
From the present study, it is concluded that not only a somatic sensation but also a visceral one might occur following a mechanical stimulation to the posterior oropharyngeal wall. REFERENCES PASTORE, P. N.: Neurologic disorders of the pharynx. In The pharynx (HoJlender, A. R., ed.), The Year Book Publishers, Chicago, 1953. RucH, T. C.: Pathophysiology of pain. In Physiology and Biophysics (Ruch, T. c., and Patton, H. D., eds.), Saunders, Philadelphia, 1979. SELZER, M., and SPENCER, W. A.: Convergence of visceral and cutaneous afferent pathways in the lumbar spinal cord. Brain Res. 14: 331-348, 1969. WEBER, cited from RucH, T. c.: Somatic sensation: Receptors and their axons. In Physiology and Biophysics (Ruch, T. c., and Patton, H. D., eds.), Saunders, Philadelphia, 1979. WEINSTEIN, S.: Intensive and extensive aspects of tactile sensitivity as a function of body part, sex, and laterality. In The Skin Senses (Kenshalo, D. R., ed.), Charles C. Thomas, Springfield, 1968.
Request reprints from:
Dr. M. Yamagiwa, Departmen' of Otolaryngology, Mie University School of Medicine, 2-174 Edobashi, Tsu 514, Mie, Japan
SENSATION ELICITED BY MECHANICAL STIMULI TO THE OROPHARYNGEAL MUCOSA Mikikazu YAMAGIWA, M. D., Haruki FUKUO, M. D., Yasuo SAKAKURA, M. D., and Yasuro MIYOSHI, M. D. Department of Otolaryngology, Mie University School of Medicine, Mie, Japan
An inaccurate localization of the site of stimulus, a higher two-point threshold for touch than those at lower lip or soft palate mucosae, and reference of touch sensation to the submaxillary cervical region following mechanical stimuli to the posterior oropharyngeal wall or lateral pharyngeal band were observed in the present study on otolaryngologists, medical students and patients with abnormal sensations in the throat. These results indicated that not only the somatic but also the visceral nervous system might contribute to the elicitation of sensation from the oropharyngeal structures behind the soft palate. It has been described that stimulation of the lateral pharyngeal band or, if it is absent, along the lateral pharyngeal wall behind the posterior pillar, results in referred sensation in the submaxillary cervical region of the same side (PASTORE, 1953). Patients' failure to localize the foreign body in the oropharnyx may be an example of this law. Fish bones most occasionally lodge in the palatine tonsil. The patient, however, seldom localizes the foreign body and only complains of the pain which seems to come from the lower neck. Such a phenomenon in patients suggested that the sensation elicited by mechanical stimuli to the pharyngeal mucosa might be alike to the visceral sensation, rather than the superficial or cutaneous one. The first aim of the present study was to investigate the unreferred sensation in the pharyngeal mucosa by measuring the accuracy of localization and the twopoint threshold for touch. The second goal was to analyse the modality of the reference of sensation following a mechanical stimulation of the pharyngeal mucosa for elucidating the referred sensation from that area. MATERIAL AND METHOD
The investigation was carried out on 44 otolaryngologists (37 males and 7 Received for publication June 6, 1983 37
38
M. YAMAGIWA, H. FUKUO, Y. SAKAKURA, and Y. MIYOSHI
females, 25 to 60 years of age), 50 medical students (47 males and 3 females, 24 to 34 years of age) and 46 patients with abnormal sensation, such as a lump or itchy feeling, in the throat (21 males and 35 females, 17 to 69 years of age). Investigation of unreferred sensation. The left lateral pharyngeal band or, if it was absent, the lateral pharyngeal wall behind the posterior pillar was stimulated mechanically with a cotton tipped applicator at the level of uppermost of the left palatine tonsil. The otolaryngologists were ordered to mark the site stimulated on the schematic drawing of the oropharnyx, as shown in Fig. I. Since otolaryngologists are well acquainted with the anatomy of the pharynx and its neighboring structures, they are the most suitable subjects for the study of localization. On 23 of the medical students and 30 of the patients, the two-point threshold for touch was examined at the posterior oropharyngeal wall, forehead skin, lower lip mucosa and soft palate mucosa by simultaneously applying the two blunt points of a bayonet forceps parallel with the horizontal level of the body. The distance between two points of forceps was locked up and those with distances of 5, 10, 15, 20 and 25 mm were used for measuring. The smallest distance between points at which they were still perceived by subjects as two separate contacts was defined as the two-point threshold. Investigation of referred sensation. All subjects were ordered to point by finger to the site in the cervical or other region where the touch sensation referred after a mechanical stimulation of the lateral pharyngeal band or wall in the manner described above. RESULTS
Unreferred sensation . A. Localization. The stimulated points in the pharynx localized by the otolaryngologists were shown in Fig. I. Of 44 subjects, 10 (23 %) including 2 (5 %) individuals who pointed to the stimulated site in a great accuracy localized the site (3-B area in Fig. 1) almost accurately. Though there were no subjects who mistook the stimulated side, most subjects tended to localize the site in the posterior pharyngeal wall below the site of stimulus. The accuracy of the localization of the site of stimulus did not correlate with the years spent by each individual as an otolaryngologist. B. Two-point threshold. Regional differences of the two-point threshold for touch obtained from the 53 subjects were shown in Table 1. In a preliminary experiment, it was clarified in a majority of subjects that the threshold at the posterior oropharyngeal wall was higher than 25 mm, and the distance between both lateral pharyngeal bands was slightly longer than 25 mm. Therefore, only the forceps with 25 mm in distance between two points were used for the measurement of threshold at the posterior oropharyngeal wall. As shown in Table I, the two-point threshold at the posterior oropharyngeal wall was extremely higher
SENSATION IN THE OROPHARYNGEAL MUCOSA
39
A B
c Fig. I. Points (black dots) taken by 44 otolaryngologists as the site of stimulus after a mechanical stimulation of the left lateral pharyngeal band at the level as high as the uppermost portion of the ipsilateral palatine tonsil. Table I.
Two point threshold for touch investigated at various sites in 53 subjects.
Sites Forehead skin Lower lip mucosa Soft palate mucosa Posterior oropharyngeal mucosa
Threshold (mm) ;:£5
10
15
20
25
4
19
15 1
6
6
3
51 31
19
2
14
39
25<
1
than those obtained at the other sites. Referred sensation It was a typical report by otolaryngologists that the touch sensation in the throat disappeared several seconds after the stimulation, and then the referred sensation in the anterior neck remained only for a few minutes, as shown in Fig. 2. Such referred sensation was localized by 40 otolaryngologists (91 %). Sixteen (40 %) of them localized the referred sensation between the hyoid bone and the superior cornu of the thyroid cartilage on the stimulated side. In 3 subjects, the sensation referred far to the supraclavicular region. The distribution of referred sensation localized by medical students was shown in Fig. 3. Of 50 students, 40 (80 %) could localize the referred sensation. There were 3 students in whom the sensation referred to the left ear; the remaining 37 localized the sensation referred to the submaxillary cervical region of the same side. As well as otolaryngologists, most students (50 % of all) localized the sensation near the midline at the level between the hyoid bone and the superior cornu of the thyroid cartilage. They answered undoubtedly that the level of referred sensation should be at the same height as that of stimulus. Of 56 patients with abnormal sensation in the throat, 51 (91 %) localized the
40
M. YAMAGIWA, H. FUKUO, Y. SAKAKURA, and Y. MIYOSHl
Fig. 2. Referred points (black dots) of touch sensaticn obtained from 40 (91 %) of 44 otolaryngologists after a mechanical stimulation of the left lateral pharyngeal band in the manner described in the legend of Fig. 1.
,\
Hyoid bone
Thyroid gland
-----Fig. 3. Referred points (black dots) of touch sensation obtained from 40 (80%) of 50 medical students after a mechanical stimulation of the left lateral pharyngeal band in the manner described in the legend of Fig. I.
sensation referred to the cervical region of the same side. The area of referred sensation localized by patients appeared to be more confined, and 36 (64 %) patients localized the sensation over the superior cornu of the thyroid cartilage (Fig. 4). DISCUSSION
WEBER (1852) touched the skin with a pointer dipped in powder charcoal to mark the point stimulated. Then the subjects, with eyes closed throughout, tried to touch the same spot with another pointer. The measured discrepancy between the two marks gave the error of localization. WEBER'S technique, however, is of little utility for testing the localization on the oropharyngeal mucosa. With the
SENSATION IN THE OROPHARYNGEAL MUCOSA
41
Fig. 4. Referred points (black dots) of touch sensation obtained from 51 (91 %) of 56 patients with abnormal smsations in the throat after a mechanical stimulation of the left lateral pharyngeal band in the manner described in the legend of Fig. 1.
technique used in the present study, the accuracy of localization in that area can be measured on individuals who are well acquainted with pharyngeal anatomy. In the present study, the otolaryngologists tended to take the stimulated site lower than that of the stimulus. It was not possible to say that they could point to the stimulated site with sufficient accuracy. Even if the same experiment could be carried out on ordinary persons who were not acquainted with pharyngeal anatomy, a similar result might be obtained. Therefore, the possibility that the localization at the oropharyngeal mucosae behind the soft palate is not accurate must be admitted. Regional variation in two-point threshold for touch was observed among other sites of the body. Even in the oropharyngeal structures, such variation was observed: namely, the two-point threshold at the posterior oropharyngeal wall was greatly higher than that at the soft palate mucosa. WEINSTEIN (1968) found a high correlation between the two-point threshold and the accuracy of localization. It was therefore presumable that the somatic nerve system contributing to the superficial sensation might not participate so much in the pharyngeal structures behind the soft palate. On the other hand, the reference of sensation was attractive. It occurred in a majority of all subjects and was not affected by subjects' knowledge of the head and neck anatomy. Impulses arising in visceral structures may give rise to pain localized in more superficial structures of the body, often those at a considerable distance from the disturbed organ. Such pain is said to be referred (RUCH, 1979). It is well recognized clinically that the referred pain from the heart in the case of angina pectoris seems to come from the chest and from a thin strip along the inner aspect of the upper arm. The reference of sensation following the stimulation of oropharyngeal mucosa may occur in a similar neurophysiological process to the referred visceral pain (SELZER and SPENCER, 1969).
42
M. YAMAGlWA, H. FUKUO, Y. SAKAKURA, and Y. MIYOSHl
From the present study, it is concluded that not only a somatic sensation but also a visceral one might occur following a mechanical stimulation to the posterior oropharyngeal wall. REFERENCES PASTORE, P. N.: Neurologic disorders of the pharynx. In The pharynx (HoJlender, A. R., ed.), The Year Book Publishers, Chicago, 1953. RucH, T. C.: Pathophysiology of pain. In Physiology and Biophysics (Ruch, T. c., and Patton, H. D., eds.), Saunders, Philadelphia, 1979. SELZER, M., and SPENCER, W. A.: Convergence of visceral and cutaneous afferent pathways in the lumbar spinal cord. Brain Res. 14: 331-348, 1969. WEBER, cited from RucH, T. c.: Somatic sensation: Receptors and their axons. In Physiology and Biophysics (Ruch, T. c., and Patton, H. D., eds.), Saunders, Philadelphia, 1979. WEINSTEIN, S.: Intensive and extensive aspects of tactile sensitivity as a function of body part, sex, and laterality. In The Skin Senses (Kenshalo, D. R., ed.), Charles C. Thomas, Springfield, 1968.
Request reprints from:
Dr. M. Yamagiwa, Departmen' of Otolaryngology, Mie University School of Medicine, 2-174 Edobashi, Tsu 514, Mie, Japan