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Functional Reconstruction for Unilateral Recurrent Laryngeal Nerve Paralysis Caused by Thyroid Cancer
Auris·Nasus·Larynx (Tokyo) 12 (Supp!. II) S 21O-S 216, 1985
FUNCTIONAL RECONSTRUCTION FOR UNILATERAL RECURRENT LARYNGEAL NERVE PARALYSIS CAUSED BY THYROID CANCER Fumihiko SATO, M.D. and Hitoshi SAITO, M.D. Department 0/ Otolaryngology, Fukui Medical School, Fukui, 910-11 Japan
Surgery for unilateral recurrent laryngeal nerve paralysis, which is caused by thyroid cancer, appearing within the past six months, should be aimed at improvement of the asymmetrical vocal cord and preservation of the stiffness and the mass of the vocal fold. To accomplish these aims, reconstructive surgery of the neuromuscular systems is available and it should be performed at the same time as thyroidectomy. Our surgical procedures for unilateral recurrent laryngeal nerve paralysis caused by thyroid cancer are reported along with some experimental investigations in dogs. Experimentally, muscle atrophy was prevented by neurorrhaphy or by free nerve grafting of the recurrent laryngeal nerve, although movement of the vocals cord was not recovered due to misdirected reinnervation and reduction of the end plates. In our study of functional reconstruction for unilateral recurrent laryngeal nerve paralysis, end-to-end anastomosis or free nerve grafting between the recurrent laryngeal nerve after extirpating the abductor muscle branch of this nerve was the most effective and practical method for improvement of the adductor function. Clinically reconstructive surgery was performed on five females suffering from thyroid cancer with unilateral recurrent laryngeal nerve paralysis. The abductor branch was cut selectively in four cases, followed by free nerve grafting of the ansa cervicalis and pedicle nerve muscle graft of the thyrohyoid muscle implanted in one case. Vocal cord atrophies were not observed and phonations were good in all cases six months after of operation. However, obvious adduction of the operated vocal fold at phonation was obtained only in two cases and other two cases showed slight adduction.
Recurrent laryngeal nerve paralysis is usually not a primary but a secondary disease. The most frequent causative disease is thyroid tumor (YANOHARA et al., 1978). The causes of this secondary symptom include operative manipulation as well as invasion of a thyroid tumor. Usually, extirpation of thyroid tumor after confirmation of the recurrent laryngeal nerve rarely causes nerve paralysis. Less frequently, neurapraxia (according to Seddon's classification in 1942) may occur after the operation, but is always cured within one month. The subjects in this report have already had unilateral recurrent laryngeal nerve paralysis and are cases whose paralysis can be diagnosed as being cuased by thyroid cancer. In the thyroid clinic of our department, such cases with a chief complaint of hoarseness are seen relatively often. For extirpation of thyroid cancer in these subjects, partial excision of the recurrent laryngeal nerve is always mandatory. However, no cases are satisfied by simple resection of the recurrent nerve. Special functional reconstructions of the larynx for unilateral recurrent laryngeal nerve paralysis were designed according to various basic studies (SATO and OGURA, 1978a, b; SATO et al., 1978; SATO, 1984) and favorable results were obtained. This is a report on the outlines and results of clinical cases which we have experienced so far.
F. SATO and H. SAITO
Table 1.
S211
Aim of dynamic reconstruction for unilateral laryngeal nerve paralysis.
_Im_pr_o_v_in_g_s_ym_m_e_tr_y_o_f_th_e_b_i_la_te_r_al_v_o_ca_l_c_o_rd_s_1
<-I
Reconstruction of vocal cord adduction
_an_d_an_a_to_m_I_.c_al_s_tr_a_ti_fie_d _ _ _ 1<-I Reconstruction of vocal muscle contraction _. _E_n_su_r_in_g_s_ti_ffn_e_s_s structure of the vocal cords _E_n_su_r_in_g_v_o_lu_m_e_o_f_t_h_e_v_oc_al_co_r_d_s_ _ _ _ _ 1..... 1 Prevention or improvement of muscle atrophy
1. Importance in Reconstruction of the NerveMuscle System from the Viewpoint of Basic Studies In cases with unilateral recurrent laryngeal nerve paralysis, dyspnea does not develop as it does in cases with bilateral paralysis, and the main symptom is hoarseness. More serious paralysis may cause aspiration. These symptoms are caused by asymmetry, decreased stiffness, and decreased quality and quantity of the vocal cords. In order to improve these symptoms, first of all symmetry of the vocal cords should be improved by reconstructing adduction of the vocal cords during phonation. The stiffness and layer structure of the vocal cords can be ensured by reconstructing contraction of the vocal muscle. Furthermore, protection of the vocalis atrophy from denervation can preserve the ql;ality and quantity of the vocal cords (Table I). For complete achievement of these points, there is no method other than reconstruction of the nerve-muscle system for the paralytic muscle. The reconstruction of the nerve-muscle system for this paralytic muscle is difficult in muscles with progressive atrophy, so that reconstruction should be pcrformed when the muscle has no progressive atrophy. Therefore, an experimental study on atrophy with a time course in the intrinsic laryngeal muscle after sectioning of thc rec~rrent laryngeal nerve was carried out. The result on prevention of the muscle atrophy by end-to-end anastomosis immediately after cutting of the recurrent laryngeal nerve was also investigated. Method. 1. Changes of the intrinsic laryngeal muscle weight with time course in the group with sectioned recurrent laryngeal nerve: In 23
adult dogs, the recurrent left side laryngeal nerve was sectioned and ligated. Then the larynx was extirpated according to the time schedule. The thyroarytenoid muscle, the lateral cricoarytenoid muscle, and the posterior cricoarytenoid muscle on the operated side were carefully separated to measure their wet weights. At the same time, the weight of the same contralateral muscle (control side) was measured to compare the degree of atrophy of each muscle with the operated side. After measurement of wet weight, each intrinsic laryngeal muscle was dried in a desiccator at 100°C for 2 hr and each dry weight was measured. 2. Changes of the intrinsic laryngeal muscle weight with time course after end-to-end anastomosis of the recurrent laryngeal nerve: In 30 adult dogs, after section of the recurrent laryngeal nerve in left side, 3-point epineural suture was performed microscopically with 9-0 nylon. Then, with the time course, the larynx was extirpated and each intrinsic laryngeal muscle on the operated and control sides was carefully separated to measure wet and dry weights. Results. Changes of the mean weight of each intrinsic laryngeal muscle in the cut and anastomosis experiments mentioned above are plotted in Fig. I. In the section experiment, as shown by a solid line in the figure, muscle atrophy after denervation progressed from 60 to 70% of the control muscle within I month, 50% in 6 months, and 30% in I year. On the other hand, in the anastomosis experiment, as shown by the broken line, muscle atrophy progressed from 50 to 60% up until I or 1.5 months. However, after that the muscle weight gradually increased and normalized within 6 months. This re-
F. SATO and H. SAITO
S 212
I,
100 , ..... .
·r;'~i:~1.~'x 'o'~:c;~;;;,:~
,~:".~" "
ion of ST Graft into peA
li!?;i;'Y.1I~Jgiitl
,
RLN
Type A • TA J. LCA o PCA
2
3
4
5
6
7
8
9
10 11 12 month
Fig. 1. Atrophy of intrinsic laryngeal muscle. Changing of dry weight of the intrinsic laryngeal muscle in groups of denervation and reinnervation. Solid lines show changing of denervated muscle weight which decreased with time. The muscle weight became 30% of normal after 1 year. On the other hand, the broken lines indicate the reinnervated muscle weight. In this group, the weight decreased with time until 1 to 2 months later, Although from after 2 months the weight increased gradually, it recovered to the previous level 6 months after neurorrhaphy.
suit suggests that the quality and quantity of the vocal muscle and eventually the vocal cords decreased to less than 1/3 of the normal volume if no treatment was given after partial excision of the recurrent laryngeal nerve, which means that reconstruction of the nerve-muscle system such as free nerve grafting can prevent muscle atrophy of the vocal cords and can maintain the quality and quantity as a result. II. Surgical Techniques for Reconstruction of Vocal Cord Adduction during Phonation As mentioned above, the quantity and quality of the vocal cords can be maintained by free nerve grafting to the partially excised site of the recurrent laryngeal nerve. However, recovery of vocal cord movement cannot be expected, because the nerve fiber innervating the abductor of the vocal cord
RLN
TypeB
Fig. 2. Type A: After free nerve grafting into defect of RLN, severing abductor branch of RLN selectively and implanting PNMG of ST muscle into abductor. Type B: After free nerve grafting into defect of RLN, severing abductor branch ofRLN selectively. A branch of ansa cervicalis to the sternohyoid muscle was used as a free nerve graft. ST: sternothyroid, RLN: recurrent laryngeal nerve, PCA: posterior cricoarytenoid muscle.
and that innervating the adductor is mixed irregularly in one recurrent laryngeal nerve, and because the end-to-end anastomosis of the nerve and free nerve grafting always causes misdirected reinnervation. As a result, satisfactory physiological movement of the vocal cords that adducts during phonation and deglutition and that abducts during deep inspiration is not usually obtained by end-to-end anastomosis of the nerve and free nerve grafting (SATO and OGURA, 1978b). Therefore, among our functional reconstructions for recurrent laryngeal nerve paralysis, 3 operation techniques previously clinically applied to unilateral recurrent laryngeal nerve paralysis are introduced in this report. Type A. After implantation of a free nerve graft taken from the nerve branch to the sternohyoid muscle of the ansa cervicalis to partially resected site of the recurrent laryngeal nerve, the nerve branch to the posterior cricoaryntenoid muscle as abductor of the vocal cord is selectively cut in order to decrease abduction of the vocal cord during phonation caused by misdirected reinnervation. Furthermore, a small mass of the sternothyroid muscle with the ansa cer-
F. SATO and H. SAITO Ansa Cervi cal i s
Ansa Cervical is
I
ion of TH Muscle
TA Muscle
Fig. 3. Type C: Implanting PNMG of ST muscle into abductor and PNMG of TH muscle into adductors. PNMG: pedicle nerve muscle graft, ST: sternothyroid, TH : thyrhyoid, TA: thyroarytenoid, PCA: posterior cricoarytenoid muscle.
vicalis, namely, pedicle nerve muscle grafting (SATO et al., 1978), is used for the posterior cricoarytenoid muscle. Increase in tension of the vocal cords during head voice and abduction of the vocal cords during deep inspiration are expected to be obtained by this procedure (Fig. 2). Contraction of the sternothyroid muscle during inspiration has been previously noted electromyographically. Type B. In this type, the abductor muscle is not reconstructed as in type A but only the nerve branch to the posterior cricoarytenoid muscle is selectively sectioned after free nerve grafting. This type is applied to cases in which the sternothyroid muscle is not available. Type C. This type is performed on cases who cannot be treated with free nerve grafting. First, a small mass of the thyrohyoid muscle which contracts during phonation is implanted in the thyroarytenoid muscle. Secondly, a small mass of the stenothyroid muscle which contracts during inspiration is implanted in the posterior cricoarytenoid muscle. Both implanted muscles are pedicled with the ansa cervical is (Fig. 3).
III. Indications for This Reconstructive Surgery This operation should be applied to thyroid cancer with unilateral recurrent laryngeal nerve paralysis and should be combined with extirpation of the thyroid cancer. Cases suffering from recurrent laryngeal nerve pa-
S213
ra1ysis for less than 1 year are indicated for this operation. The shorter the suffering duration, the more successful the operation is.
IV. Clinical Cases and Their Results Case I . A 75-year-old female with thyroid cancer and recurrent laryngeal nerve paralysis on the left side. In audito-psychological examination, the severity of preoperative hoarseness was Grade 2, Rough 1, Breathy 2, Asthenic 1, and Strained 1 (abbreviated as G2RIB2AlSl) (OKAMOTO et al., 1979). Maximum phonation time was 4 sec. The vocal cord was fixed in the paramedian position on the left side, and was confirmed to be misdirected reinnervation from the vocalis by electromyography. Under general anesthesia, left hemithyroidectomy and paratracheal lymph node dissection were performed and a type-A operation was carried out at the same time. One year and 2 months after the operation, maximum phonation time was 20.9 sec and hoarseness was G1RIBoAoSl in auditopsychological examination. The vocal cords mildly adducted during phonation and very slightly abducted during deep inspiration. Case 2. A 71-year-old female with thyroid cancer and recurrent laryngeal nerve paralysis on the left side. Before the operation, the left vocal cord was fixed in the paramedian position, hoarseness was GaR2B3AlS2' and maximum phonation time was 2.8 sec. In addition, fibrillation potential from the vocalis was recorded electromyographically. Under general anesthesia, left hemithyroidectomy and dissection of pre- and paratracheal lymph nodes were performed and, additionally, type-A reconstruction of the larynx was done. As a pathohistological specimen from the esophageal muscle showed partial invasion of cancer cells, in this case 6OCo-irradiation of 6,000 rads was given. Abduction of the left vocal cord was noted during deep inspiration after 1 year, but adduction during phonation was not ob-
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F. SATO and H. SAITO
served. Hoarseness was Go and maximum phonation time was 16.5 sec. Case 3. A 49-year-old female with left thyroid cancer with left recurrent laryngeal nerve paralysis. Before operation, the left vocal cord was fixed in the paramedian position, maximum phonation time was 5.7 sec, and hoarseness was G3R2B3AlSo in audito-psychological examination. A type-A operation as well as thyroidectomy with neck dissection of the regional lymph nodes were performed under general anesthesia in this case. Eleven months after the operation, maximum phonation time was 11.5 sec and hoarseness was G 1 8 08 1 AoSo. Adduction and tension of the vocal cord on the left side were noted during phonation, but marked abduction was not be obtained. Case 4. A 41-year-old female suffering from left thyroid cancer and left recurrent laryngeal nerve paralysis. Though hoarseness was G1ROBIAoSl and the left vocal cord was fixed in the para-
median position before operation, compensatory adduction of the vocal cord on the normal side was observed and maximum phonation time was 23 sec. Electromyographically, normal muscular discharge from the vocalis was not seen but only partial fibrillation voltage was noted. In this case, dissection of the lymph nodes and type-B reconstruction were performed in addition to left hemithyroidectomy. Eight months after the operation, marked adduction of the vocal cord on the left side during phonation was seen. Moreover, hoarseness was Go and maximum phonation time was 22.2 sec. Case 5. A 53-year-old female with thyroid cancer and recurrent laryngeal nerve paralysis on the right side. The right vocal cord was fixed in the paramedian position but the normal left side showed compensatory adduction before operation. Hoarseness was G 1 Ro8 1 AoSo and maximum phonation time was 8 sec. Fibrillation potentials were electromyographically recorded from the right vocalis.
Fig. 4. Top left shows a glottic view without any reconstruction 5 months after thyroidectomy and partial resection of recurrent laryngeal nerve. The glottic chink was very wide with phonation. In other pictures, atrophic change of their vocal cords was not observed.
F. SATO and H. SAITO
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Table 2. Case I IK 2 KA 3 TE 40C 50T
Functional reconstruction for unilateral recurrent laryngeal nerve paralysis. Postoperation Period of Type of Causes Course PT V.C. paralysis surgery (sec) atrophy Adduction Abduction
75 (0 L-Thyroid Ca. 71 (f) L-Thyroid Ca. 49 (f) L-Thyroid Ca. 41 (f) L-Thyroid Ca. 53 (f) R-Thyroid Ca.
I y 6m I y 2m 6m
A A A B
C
I y2 m I y 11m 8m 1 y3 m
20.9 16.5 11.5 22.2 12.2
+
± ± ±
+ ± ±
±
PT: maximum phonation time, V.c.: vocal cord.
The excised length of the recurrent laryngeal nerve was 3 cm after right hemithyroidectomy and dissection of the regional lymph nodes. Therefore, type-C reconstruction was applied. One year and 3 months after the operation, the right vocal cord adducted slightly during phonation and abducted mildly during inspiration. Maximum phonation time was 12.2 sec and hoarseness was G1RIBoAoSo. The summaries and postoperative glottic views during phonation of the 5 cases mentioned above are shown in Fig. 4 and Table 2. After operation, there were no atrophic changes of the vocal cords. Although no cases markedly recovered normal adduction and abdunction, removal of the vocal cord during phonation was found in 4 cases consisting of 2 cases with mild adduction and of 2 cases which recovered very slight adduction. Additionally, improvement of postoperative maximum phonation time and hoarseness suggests that this operation maintains efficient mucous membrane fluctuation of the vocal cord efficiently during phonation.
Discussion As described in the previous paragraphs, when thyroid cancer complicated with unilateral recurrent laryngeal nerve paralysis is extirpated, free nerve grafting should actively be performed to lead to intrinsic laryngeal muscle reinnervation without leaving a partial defect of the recurrent laryngeal nerve. Furthermore, the nerve branch innervating the posterior cricoarytenoid muscle should be cut and the pedicle nerve muscle graft V.
with the sternothyroid muscle should be implanted in the same muscle in hopes of removal of the vocal cord. In cases who cannot receive free nerve grafting, a pedicle nerve muscle graft with the thyrohyoid muscle should be implanted in the vocalis to prevent vocal cord atrophy. It has already been emphasized that this operation should be done at the same time as thyroidectomy. A few reasons for this are as follows: First of all, discovery of the sectioned end of the recurrent laryngeal nerve is difficult when this operation is delayed. Even though the nerve end can be discovered, the ansa cervicalis and the strap muscle are damaged in most cases. Secondly, the existence of the cicatrix interferes with the approach to the back of the larynx. Therefore, in many cases successful results cannot be obtained. Table 3. Surgical procedure laryngeal nerve paralysis.
for
recurrent
Static reconstruction Unilateral paralysis Mediofixation of the arytenoid cartilage Mediofixation of the vocal cord Intracordal silicone injection Bilateral paralysis Lateral fixation of the arytenoid cartilage Arytenoidectomy Dynamic reconstruction Unilateral paralysis Decompression Neurorrhaphy of the recurrent laryngeal nerve *Free nerve grafting *Pedicle nerve muscle grafting Bilateral paralysis Neurorrhaphy using phrenic nerve Pedicle nerve muscle grafting
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F. SATO and H. SAITO
For unilateral recurrent laryngeal nerve paralysis due to other causes, silicon injection in the vocal cord, thyroplasty by Isshiki, and mediofixation of the arytenoid cartilage with bioglue recently designed by us, which are classified as static reconstructions as shown in Table 3, have been performed and the results are favorable. VI. Conclusion Basic experiments and clinical results were described concerning reconstruction of the nerve-muscle system which we have been adopting for unilateral recurrent nerve paralysis due to invasion of thyroid cancer. References OKAMOTO, K., TAKAHASHI, H., SUZUKI, S., HIKI, S., and IMAIZUMI, T.: Auditory psychological ex-
amination for hoarseness. In Voice Examination (The Japan Society of Logopedics and Phoniatrics, ed.), pp. 131-209, Ishiyaku Shuppan, Tokyo, 1979. SATO, F.: Phonosurgery for recurrent laryngeal nerve paralysis. In The Latest Advancement in Phonosurgery (Hirano, M., ed.), pp. 159-185, Igaku Kyoiku-Shuppansya, Tokyo, 1984. SATO, F., and OGURA, J.H.: Functional restoration for recurrent laryngeal nerve paralysis: An experimental study. Laryngoscope 88: 855-871, 1978a. SATO, F., and OGURA, J.H.: Neurorrhaphy of the recurrent laryngeal nerve. Laryngoscope 88: 1034-1041, 1978b. SATO, F., TAKENOUCHI, S., and OGURA, J.H.: Pedicle nerve muscle grafting. Transplant. Jpn. 13(3): 105-109, 1978. YANOHARA, K., SATO, F., HISA, Y., SUZUKI, Y., MIZUTA, Y., MATSUI, T., and MIZUKOSHI, 0.: Clinical view of the recurrent laryngeal nerve paralysis. Pract. Otol. Kyoto 71: 1201-1207, 1978.
FUNCTIONAL RECONSTRUCTION FOR UNILATERAL RECURRENT LARYNGEAL NERVE PARALYSIS CAUSED BY THYROID CANCER Fumihiko SATO, M.D. and Hitoshi SAITO, M.D. Department 0/ Otolaryngology, Fukui Medical School, Fukui, 910-11 Japan
Surgery for unilateral recurrent laryngeal nerve paralysis, which is caused by thyroid cancer, appearing within the past six months, should be aimed at improvement of the asymmetrical vocal cord and preservation of the stiffness and the mass of the vocal fold. To accomplish these aims, reconstructive surgery of the neuromuscular systems is available and it should be performed at the same time as thyroidectomy. Our surgical procedures for unilateral recurrent laryngeal nerve paralysis caused by thyroid cancer are reported along with some experimental investigations in dogs. Experimentally, muscle atrophy was prevented by neurorrhaphy or by free nerve grafting of the recurrent laryngeal nerve, although movement of the vocals cord was not recovered due to misdirected reinnervation and reduction of the end plates. In our study of functional reconstruction for unilateral recurrent laryngeal nerve paralysis, end-to-end anastomosis or free nerve grafting between the recurrent laryngeal nerve after extirpating the abductor muscle branch of this nerve was the most effective and practical method for improvement of the adductor function. Clinically reconstructive surgery was performed on five females suffering from thyroid cancer with unilateral recurrent laryngeal nerve paralysis. The abductor branch was cut selectively in four cases, followed by free nerve grafting of the ansa cervicalis and pedicle nerve muscle graft of the thyrohyoid muscle implanted in one case. Vocal cord atrophies were not observed and phonations were good in all cases six months after of operation. However, obvious adduction of the operated vocal fold at phonation was obtained only in two cases and other two cases showed slight adduction.
Recurrent laryngeal nerve paralysis is usually not a primary but a secondary disease. The most frequent causative disease is thyroid tumor (YANOHARA et al., 1978). The causes of this secondary symptom include operative manipulation as well as invasion of a thyroid tumor. Usually, extirpation of thyroid tumor after confirmation of the recurrent laryngeal nerve rarely causes nerve paralysis. Less frequently, neurapraxia (according to Seddon's classification in 1942) may occur after the operation, but is always cured within one month. The subjects in this report have already had unilateral recurrent laryngeal nerve paralysis and are cases whose paralysis can be diagnosed as being cuased by thyroid cancer. In the thyroid clinic of our department, such cases with a chief complaint of hoarseness are seen relatively often. For extirpation of thyroid cancer in these subjects, partial excision of the recurrent laryngeal nerve is always mandatory. However, no cases are satisfied by simple resection of the recurrent nerve. Special functional reconstructions of the larynx for unilateral recurrent laryngeal nerve paralysis were designed according to various basic studies (SATO and OGURA, 1978a, b; SATO et al., 1978; SATO, 1984) and favorable results were obtained. This is a report on the outlines and results of clinical cases which we have experienced so far.
F. SATO and H. SAITO
Table 1.
S211
Aim of dynamic reconstruction for unilateral laryngeal nerve paralysis.
_Im_pr_o_v_in_g_s_ym_m_e_tr_y_o_f_th_e_b_i_la_te_r_al_v_o_ca_l_c_o_rd_s_1
<-I
Reconstruction of vocal cord adduction
_an_d_an_a_to_m_I_.c_al_s_tr_a_ti_fie_d _ _ _ 1<-I Reconstruction of vocal muscle contraction _. _E_n_su_r_in_g_s_ti_ffn_e_s_s structure of the vocal cords _E_n_su_r_in_g_v_o_lu_m_e_o_f_t_h_e_v_oc_al_co_r_d_s_ _ _ _ _ 1..... 1 Prevention or improvement of muscle atrophy
1. Importance in Reconstruction of the NerveMuscle System from the Viewpoint of Basic Studies In cases with unilateral recurrent laryngeal nerve paralysis, dyspnea does not develop as it does in cases with bilateral paralysis, and the main symptom is hoarseness. More serious paralysis may cause aspiration. These symptoms are caused by asymmetry, decreased stiffness, and decreased quality and quantity of the vocal cords. In order to improve these symptoms, first of all symmetry of the vocal cords should be improved by reconstructing adduction of the vocal cords during phonation. The stiffness and layer structure of the vocal cords can be ensured by reconstructing contraction of the vocal muscle. Furthermore, protection of the vocalis atrophy from denervation can preserve the ql;ality and quantity of the vocal cords (Table I). For complete achievement of these points, there is no method other than reconstruction of the nerve-muscle system for the paralytic muscle. The reconstruction of the nerve-muscle system for this paralytic muscle is difficult in muscles with progressive atrophy, so that reconstruction should be pcrformed when the muscle has no progressive atrophy. Therefore, an experimental study on atrophy with a time course in the intrinsic laryngeal muscle after sectioning of thc rec~rrent laryngeal nerve was carried out. The result on prevention of the muscle atrophy by end-to-end anastomosis immediately after cutting of the recurrent laryngeal nerve was also investigated. Method. 1. Changes of the intrinsic laryngeal muscle weight with time course in the group with sectioned recurrent laryngeal nerve: In 23
adult dogs, the recurrent left side laryngeal nerve was sectioned and ligated. Then the larynx was extirpated according to the time schedule. The thyroarytenoid muscle, the lateral cricoarytenoid muscle, and the posterior cricoarytenoid muscle on the operated side were carefully separated to measure their wet weights. At the same time, the weight of the same contralateral muscle (control side) was measured to compare the degree of atrophy of each muscle with the operated side. After measurement of wet weight, each intrinsic laryngeal muscle was dried in a desiccator at 100°C for 2 hr and each dry weight was measured. 2. Changes of the intrinsic laryngeal muscle weight with time course after end-to-end anastomosis of the recurrent laryngeal nerve: In 30 adult dogs, after section of the recurrent laryngeal nerve in left side, 3-point epineural suture was performed microscopically with 9-0 nylon. Then, with the time course, the larynx was extirpated and each intrinsic laryngeal muscle on the operated and control sides was carefully separated to measure wet and dry weights. Results. Changes of the mean weight of each intrinsic laryngeal muscle in the cut and anastomosis experiments mentioned above are plotted in Fig. I. In the section experiment, as shown by a solid line in the figure, muscle atrophy after denervation progressed from 60 to 70% of the control muscle within I month, 50% in 6 months, and 30% in I year. On the other hand, in the anastomosis experiment, as shown by the broken line, muscle atrophy progressed from 50 to 60% up until I or 1.5 months. However, after that the muscle weight gradually increased and normalized within 6 months. This re-
F. SATO and H. SAITO
S 212
I,
100 , ..... .
·r;'~i:~1.~'x 'o'~:c;~;;;,:~
,~:".~" "
ion of ST Graft into peA
li!?;i;'Y.1I~Jgiitl
,
RLN
Type A • TA J. LCA o PCA
2
3
4
5
6
7
8
9
10 11 12 month
Fig. 1. Atrophy of intrinsic laryngeal muscle. Changing of dry weight of the intrinsic laryngeal muscle in groups of denervation and reinnervation. Solid lines show changing of denervated muscle weight which decreased with time. The muscle weight became 30% of normal after 1 year. On the other hand, the broken lines indicate the reinnervated muscle weight. In this group, the weight decreased with time until 1 to 2 months later, Although from after 2 months the weight increased gradually, it recovered to the previous level 6 months after neurorrhaphy.
suit suggests that the quality and quantity of the vocal muscle and eventually the vocal cords decreased to less than 1/3 of the normal volume if no treatment was given after partial excision of the recurrent laryngeal nerve, which means that reconstruction of the nerve-muscle system such as free nerve grafting can prevent muscle atrophy of the vocal cords and can maintain the quality and quantity as a result. II. Surgical Techniques for Reconstruction of Vocal Cord Adduction during Phonation As mentioned above, the quantity and quality of the vocal cords can be maintained by free nerve grafting to the partially excised site of the recurrent laryngeal nerve. However, recovery of vocal cord movement cannot be expected, because the nerve fiber innervating the abductor of the vocal cord
RLN
TypeB
Fig. 2. Type A: After free nerve grafting into defect of RLN, severing abductor branch of RLN selectively and implanting PNMG of ST muscle into abductor. Type B: After free nerve grafting into defect of RLN, severing abductor branch ofRLN selectively. A branch of ansa cervicalis to the sternohyoid muscle was used as a free nerve graft. ST: sternothyroid, RLN: recurrent laryngeal nerve, PCA: posterior cricoarytenoid muscle.
and that innervating the adductor is mixed irregularly in one recurrent laryngeal nerve, and because the end-to-end anastomosis of the nerve and free nerve grafting always causes misdirected reinnervation. As a result, satisfactory physiological movement of the vocal cords that adducts during phonation and deglutition and that abducts during deep inspiration is not usually obtained by end-to-end anastomosis of the nerve and free nerve grafting (SATO and OGURA, 1978b). Therefore, among our functional reconstructions for recurrent laryngeal nerve paralysis, 3 operation techniques previously clinically applied to unilateral recurrent laryngeal nerve paralysis are introduced in this report. Type A. After implantation of a free nerve graft taken from the nerve branch to the sternohyoid muscle of the ansa cervicalis to partially resected site of the recurrent laryngeal nerve, the nerve branch to the posterior cricoaryntenoid muscle as abductor of the vocal cord is selectively cut in order to decrease abduction of the vocal cord during phonation caused by misdirected reinnervation. Furthermore, a small mass of the sternothyroid muscle with the ansa cer-
F. SATO and H. SAITO Ansa Cervi cal i s
Ansa Cervical is
I
ion of TH Muscle
TA Muscle
Fig. 3. Type C: Implanting PNMG of ST muscle into abductor and PNMG of TH muscle into adductors. PNMG: pedicle nerve muscle graft, ST: sternothyroid, TH : thyrhyoid, TA: thyroarytenoid, PCA: posterior cricoarytenoid muscle.
vicalis, namely, pedicle nerve muscle grafting (SATO et al., 1978), is used for the posterior cricoarytenoid muscle. Increase in tension of the vocal cords during head voice and abduction of the vocal cords during deep inspiration are expected to be obtained by this procedure (Fig. 2). Contraction of the sternothyroid muscle during inspiration has been previously noted electromyographically. Type B. In this type, the abductor muscle is not reconstructed as in type A but only the nerve branch to the posterior cricoarytenoid muscle is selectively sectioned after free nerve grafting. This type is applied to cases in which the sternothyroid muscle is not available. Type C. This type is performed on cases who cannot be treated with free nerve grafting. First, a small mass of the thyrohyoid muscle which contracts during phonation is implanted in the thyroarytenoid muscle. Secondly, a small mass of the stenothyroid muscle which contracts during inspiration is implanted in the posterior cricoarytenoid muscle. Both implanted muscles are pedicled with the ansa cervical is (Fig. 3).
III. Indications for This Reconstructive Surgery This operation should be applied to thyroid cancer with unilateral recurrent laryngeal nerve paralysis and should be combined with extirpation of the thyroid cancer. Cases suffering from recurrent laryngeal nerve pa-
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ra1ysis for less than 1 year are indicated for this operation. The shorter the suffering duration, the more successful the operation is.
IV. Clinical Cases and Their Results Case I . A 75-year-old female with thyroid cancer and recurrent laryngeal nerve paralysis on the left side. In audito-psychological examination, the severity of preoperative hoarseness was Grade 2, Rough 1, Breathy 2, Asthenic 1, and Strained 1 (abbreviated as G2RIB2AlSl) (OKAMOTO et al., 1979). Maximum phonation time was 4 sec. The vocal cord was fixed in the paramedian position on the left side, and was confirmed to be misdirected reinnervation from the vocalis by electromyography. Under general anesthesia, left hemithyroidectomy and paratracheal lymph node dissection were performed and a type-A operation was carried out at the same time. One year and 2 months after the operation, maximum phonation time was 20.9 sec and hoarseness was G1RIBoAoSl in auditopsychological examination. The vocal cords mildly adducted during phonation and very slightly abducted during deep inspiration. Case 2. A 71-year-old female with thyroid cancer and recurrent laryngeal nerve paralysis on the left side. Before the operation, the left vocal cord was fixed in the paramedian position, hoarseness was GaR2B3AlS2' and maximum phonation time was 2.8 sec. In addition, fibrillation potential from the vocalis was recorded electromyographically. Under general anesthesia, left hemithyroidectomy and dissection of pre- and paratracheal lymph nodes were performed and, additionally, type-A reconstruction of the larynx was done. As a pathohistological specimen from the esophageal muscle showed partial invasion of cancer cells, in this case 6OCo-irradiation of 6,000 rads was given. Abduction of the left vocal cord was noted during deep inspiration after 1 year, but adduction during phonation was not ob-
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served. Hoarseness was Go and maximum phonation time was 16.5 sec. Case 3. A 49-year-old female with left thyroid cancer with left recurrent laryngeal nerve paralysis. Before operation, the left vocal cord was fixed in the paramedian position, maximum phonation time was 5.7 sec, and hoarseness was G3R2B3AlSo in audito-psychological examination. A type-A operation as well as thyroidectomy with neck dissection of the regional lymph nodes were performed under general anesthesia in this case. Eleven months after the operation, maximum phonation time was 11.5 sec and hoarseness was G 1 8 08 1 AoSo. Adduction and tension of the vocal cord on the left side were noted during phonation, but marked abduction was not be obtained. Case 4. A 41-year-old female suffering from left thyroid cancer and left recurrent laryngeal nerve paralysis. Though hoarseness was G1ROBIAoSl and the left vocal cord was fixed in the para-
median position before operation, compensatory adduction of the vocal cord on the normal side was observed and maximum phonation time was 23 sec. Electromyographically, normal muscular discharge from the vocalis was not seen but only partial fibrillation voltage was noted. In this case, dissection of the lymph nodes and type-B reconstruction were performed in addition to left hemithyroidectomy. Eight months after the operation, marked adduction of the vocal cord on the left side during phonation was seen. Moreover, hoarseness was Go and maximum phonation time was 22.2 sec. Case 5. A 53-year-old female with thyroid cancer and recurrent laryngeal nerve paralysis on the right side. The right vocal cord was fixed in the paramedian position but the normal left side showed compensatory adduction before operation. Hoarseness was G 1 Ro8 1 AoSo and maximum phonation time was 8 sec. Fibrillation potentials were electromyographically recorded from the right vocalis.
Fig. 4. Top left shows a glottic view without any reconstruction 5 months after thyroidectomy and partial resection of recurrent laryngeal nerve. The glottic chink was very wide with phonation. In other pictures, atrophic change of their vocal cords was not observed.
F. SATO and H. SAITO
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Table 2. Case I IK 2 KA 3 TE 40C 50T
Functional reconstruction for unilateral recurrent laryngeal nerve paralysis. Postoperation Period of Type of Causes Course PT V.C. paralysis surgery (sec) atrophy Adduction Abduction
75 (0 L-Thyroid Ca. 71 (f) L-Thyroid Ca. 49 (f) L-Thyroid Ca. 41 (f) L-Thyroid Ca. 53 (f) R-Thyroid Ca.
I y 6m I y 2m 6m
A A A B
C
I y2 m I y 11m 8m 1 y3 m
20.9 16.5 11.5 22.2 12.2
+
± ± ±
+ ± ±
±
PT: maximum phonation time, V.c.: vocal cord.
The excised length of the recurrent laryngeal nerve was 3 cm after right hemithyroidectomy and dissection of the regional lymph nodes. Therefore, type-C reconstruction was applied. One year and 3 months after the operation, the right vocal cord adducted slightly during phonation and abducted mildly during inspiration. Maximum phonation time was 12.2 sec and hoarseness was G1RIBoAoSo. The summaries and postoperative glottic views during phonation of the 5 cases mentioned above are shown in Fig. 4 and Table 2. After operation, there were no atrophic changes of the vocal cords. Although no cases markedly recovered normal adduction and abdunction, removal of the vocal cord during phonation was found in 4 cases consisting of 2 cases with mild adduction and of 2 cases which recovered very slight adduction. Additionally, improvement of postoperative maximum phonation time and hoarseness suggests that this operation maintains efficient mucous membrane fluctuation of the vocal cord efficiently during phonation.
Discussion As described in the previous paragraphs, when thyroid cancer complicated with unilateral recurrent laryngeal nerve paralysis is extirpated, free nerve grafting should actively be performed to lead to intrinsic laryngeal muscle reinnervation without leaving a partial defect of the recurrent laryngeal nerve. Furthermore, the nerve branch innervating the posterior cricoarytenoid muscle should be cut and the pedicle nerve muscle graft V.
with the sternothyroid muscle should be implanted in the same muscle in hopes of removal of the vocal cord. In cases who cannot receive free nerve grafting, a pedicle nerve muscle graft with the thyrohyoid muscle should be implanted in the vocalis to prevent vocal cord atrophy. It has already been emphasized that this operation should be done at the same time as thyroidectomy. A few reasons for this are as follows: First of all, discovery of the sectioned end of the recurrent laryngeal nerve is difficult when this operation is delayed. Even though the nerve end can be discovered, the ansa cervicalis and the strap muscle are damaged in most cases. Secondly, the existence of the cicatrix interferes with the approach to the back of the larynx. Therefore, in many cases successful results cannot be obtained. Table 3. Surgical procedure laryngeal nerve paralysis.
for
recurrent
Static reconstruction Unilateral paralysis Mediofixation of the arytenoid cartilage Mediofixation of the vocal cord Intracordal silicone injection Bilateral paralysis Lateral fixation of the arytenoid cartilage Arytenoidectomy Dynamic reconstruction Unilateral paralysis Decompression Neurorrhaphy of the recurrent laryngeal nerve *Free nerve grafting *Pedicle nerve muscle grafting Bilateral paralysis Neurorrhaphy using phrenic nerve Pedicle nerve muscle grafting
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For unilateral recurrent laryngeal nerve paralysis due to other causes, silicon injection in the vocal cord, thyroplasty by Isshiki, and mediofixation of the arytenoid cartilage with bioglue recently designed by us, which are classified as static reconstructions as shown in Table 3, have been performed and the results are favorable. VI. Conclusion Basic experiments and clinical results were described concerning reconstruction of the nerve-muscle system which we have been adopting for unilateral recurrent nerve paralysis due to invasion of thyroid cancer. References OKAMOTO, K., TAKAHASHI, H., SUZUKI, S., HIKI, S., and IMAIZUMI, T.: Auditory psychological ex-
amination for hoarseness. In Voice Examination (The Japan Society of Logopedics and Phoniatrics, ed.), pp. 131-209, Ishiyaku Shuppan, Tokyo, 1979. SATO, F.: Phonosurgery for recurrent laryngeal nerve paralysis. In The Latest Advancement in Phonosurgery (Hirano, M., ed.), pp. 159-185, Igaku Kyoiku-Shuppansya, Tokyo, 1984. SATO, F., and OGURA, J.H.: Functional restoration for recurrent laryngeal nerve paralysis: An experimental study. Laryngoscope 88: 855-871, 1978a. SATO, F., and OGURA, J.H.: Neurorrhaphy of the recurrent laryngeal nerve. Laryngoscope 88: 1034-1041, 1978b. SATO, F., TAKENOUCHI, S., and OGURA, J.H.: Pedicle nerve muscle grafting. Transplant. Jpn. 13(3): 105-109, 1978. YANOHARA, K., SATO, F., HISA, Y., SUZUKI, Y., MIZUTA, Y., MATSUI, T., and MIZUKOSHI, 0.: Clinical view of the recurrent laryngeal nerve paralysis. Pract. Otol. Kyoto 71: 1201-1207, 1978.