Nerve welding using CO2 laser

Nerve welding using CO2 laser

International Congress Series 1240 (2003) 943 – 946 Nerve welding using CO2 laser Yousry M. Mostafa * National Institute of Laser Enhanced Sciences (...

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International Congress Series 1240 (2003) 943 – 946

Nerve welding using CO2 laser Yousry M. Mostafa * National Institute of Laser Enhanced Sciences (NILES), Cairo University, Cairo, Egypt

Abstract Although microsurgical techniques of nerve suture are now widely practiced, the prognosis is not always satisfactory. In many cases, conventional suture repair results in neuroma formation and a fibrotic reaction that is detrimental to nerve regeneration. Studies on the peripheral nerves in rats and other species have helped in the development of laser-assisted nerve anastomosis. In the field of otorhinolaryngology, facial nerve anastomosis, particularly in difficult-to-reach sites, may need such a non-contact sutureless laser technique to overcome the difficulties of other conventional methods. In this study, 40 rat sciatic nerves were sharply cut then immediately repaired using 100 mW CO2 laser with or without solder (two groups). The rats were followed up to record the functional studies, electrophysiological, and histopathological findings of the two groups (A and B). It was found that laser repair is faster and simpler with more stability and more function with the use of a solder (Group B). The long-term results of this laser nerve welding study are comparable to results of conventional methods in the literature. D 2003 International Federation of Otorhinolaryngological Societies (IFOS). All rights reserved. Keywords: Laser; Nerve; Welding

1. Materials and methods The aim of this work is to practice laser nerve welding evaluating the efficacy of CO2 laser in welding of peripheral nerves, and the effect of using a solder at the anastomotic site. This scientific experimental work was done in NILES (Cairo University). The sciatic nerve was exposed and cut (Fig. 1A). Laser nerve welding is done using 100 mw CO2 laser (Fig. 1B). The rats were classified into two groups (A and B), where in group (A), no solder was used, and in group B with a solder. At the end of the operation, immediate welding was seen and both nerve ends were

* Fax: +20-39-33-556. E-mail address: [email protected] (Y.M. Mostafa). 0531-5131/ D 2003 International Federation of Otorhinolaryngological Societies (IFOS). All rights reserved. doi:10.1016/S0531-5131(03)00698-8

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Fig. 1. (A) Exposure of sciatic nerve. (B) Welding of the two ends.

attached perfectly to each other. The movements of the foot and leg of the model were observed carefully during the postoperative follow-up period (recorded every 2 weeks). Electrophysiological measurements were recorded in samples twice (1 month postoperatively and before animal sacrifice) using electromyography. Finally, the animals were sacrificed at different times to submit the welded nerves for histopathological examinations.

2. Results Functional observation has revealed immediate loss of movement of the affected limb for about 1– 2 weeks after which most cases began to move their limb little by little. After 4 – 6 weeks, the movement became stronger in both groups (A and B), but there was no observable difference between them. After 8 –10 weeks, the majority of cases regain more or less normal movement. Electrophysiological observations, which were made after 1 month and before animal sacrifice (between 2 and 4 months), revealed, after 1 month, a slight difference between group (A) and group (B) samples (Table 1), and a considerable difference between them before sacrifice (Table 2). Histopathological picture of the welded nerve at ‘‘early stage’’ was the same in both groups (Fig. 2A) revealing severe nerve reaction with total degeneration in contrast to picture of ‘‘late stage’’ which shows slight distortion (Fig. 2B). Table 1 Electrophysiological records (one m. later) Group

No. of tested cases

Average amplitude (mV)

Average latency (ms)

(A) (B)

8 7

1.1 F 0.2 1.2 F 0.3

2.8 2.2

Table 2 Electrophysiological records (before sacrifice) Group

No. of tested cases

Average amplitude (mV)

Average latency (ms)

(A) (B)

12 13

2.3 F 0.4 2.6 F 0.5

1.8 1.6

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Fig. 2. (A) Early stage of welding. (B) Late stage of welding.

Gross histological examination of samples from the two groups, after animal sacrifice, revealed evidence of adequate tissue bonding at the site of nerve anastomosis. It was observed during tissue manipulation that the bonding of tissues was much stronger in the laser solder group (B). At the repair site, most samples from group (A) showed a slightly depressed area (Fig. 3A) caused by the impact of the laser beam, which was not evident in the group (B) (Fig. 3B).

3. Discussion The efficacy of laser welding of peripheral and cranial nerves has been advocated by many authors [1 –8]. Our results proved the efficacy of laser nerve welding particularly with a solder (egg white). Both electrophysiological results and histopathological examinations confirmed the superior results of laser nerve solder welding (group B) than the laser nerve welding alone (group A). These results have been advocated by many reports in the literature [9,10]. Improvements of laser welding techniques have allowed for their application on cranial nerves as experimental studies [7,8,11]. Dort et al. [8], concluded that CO2 laser is useful for facial nerve welding. It is neither harmful nor beneficial to nerve regeneration, but has the advantage of allowing a faster anastomosis in a restricted surgical field. We hope to use such a technique in the future for human facial nerve anastomosis, particularly for inaccessible areas such as intracranial and labyrinthine parts of the nerve.

Fig. 3. (A) Section of group (A). (B) Section of group (B).

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4. Conclusion We conclude that laser nerve welding is a reliable rapid safe and effective technique and the use of a solder does improve its results. Further studies of this technique are warranted to use it safely for facial nerve and others.

References [1] D.W. Fischer, J.L. Beggs, D.L. Kenshalo, A.G. Shetter, Comparative study of microepineurial anastomoses with the use of CO2 laser and suture techniques in rat sciatic nerves: Part 1. Surgical technique, nerve action potentials, and morphological studies, Neurosurgery 17 (12) (1985 Aug.) 300 – 308. [2] M. Osedo, An experimental study on nerve repair using CO2 laser, Nippon Siekeigeka Gakkai Zassi 62 (6) (1988) 653 – 663. [3] T.A. Benke, J.W. Clark, P.J. Wisoff, et al., Comparative study of suture and laser-assisted anastomosis in rat sciatic nerves, Laser Surg. Med. 9 (6) (1989) 602 – 615. [4] M. Korff, S.W. Bent, M.T. Havig, et al., An investigation of the potential for laser nerve welding, Otolaryngol. Head Neck Surg. 106 (4) (1992 Apr.) 345 – 350. [5] T. Menovsky, J.F. Beef, S.L. Thomsen, Laser assisted nerve repair. A review, Neurosurg. Rev. 18 (4) (1995) 225 – 235. [6] W. Happak, C. Neumayer, G. Burggasser, et al., Nerve coaptation using CO2 milliwatt laser, Handchir. Microchir. Plast. Chir. 30 (2) (1998 Mar.) 116 – 121. [7] V. Seifert, D. Stolke, C. Goetz, Microsurgery, laser-assisted cranial nerve anastomosis. An experimental study, Handchir. Microchir. Plast. Chir. 22 (2) (1990 Mar.) 82 – 87. [8] J.C. Dort, M. Wolfensberger, H. Felix, CO2 laser repair of the facial nerve: an experimental study in the rat, J. Laryngol. Otol. 108 (6) (1994 Jun.) 466 – 469. [9] A. Lauto, J.M. Dawes, T. Cushway, J.A. Piper, E.R. Owen, Laser nerve repair by solid protein band technique. I and II, identification of optimal laser dose, power, and solder surface area, Microsurgery 18 (1) (1998) 55 – 59. [10] T. Menovsky, J.F. Beef, M.J. Van Gemert, CO2 laser nerve welding: optimal laser parameters and the use of solders in vitro, Microsurgery 15 (1994) 44 – 51. [11] B.L. Epply, E. Kalenderian, T. Winkelmann, J.J. Delfino, Facial nerve graft repair: suture versus laserassisted anastomosis, Int. J. Oral Maxillofac. Surg. 10 (1989) 50 – 54.