Outcomes of Endoscopic Tympanoplasty for Large Perforations: A Multicenter Retrospective Study in South Korea

Objectives@#. Endoscopic tympanoplasty (ET) provides minimally invasive transcanal access to the middle ear and improves middle ear visibility for the treatment of tympanic membrane (TM) perforations. However, the literature on surgical outcomes for large TM perforations is lacking and limited to small series. This study aimed to evaluate the clinical benefits of ET for large TM perforations. @*Methods@#. This retrospective cohort study was conducted at nine tertiary referral hospitals in South Korea, where 252 patients who underwent ET as primary surgery from September 2019 to August 2021 were included. The outcome measures included the graft success rate and pre- and postoperative audiometric data. @*Results@#. In 239 patients, the graft success rate of ET for large or subtotal perforations was 86.2% (206 patients), while the graft failure rate was 13.8% (33 patients). The graft failure rate was directly correlated with surgical techniques, including overlay and medial or lateral underlay tympanoplasty (P=0.027). Lateral underlay tympanoplasty showed the most favorable results. Sex, laterality, etiology, site and size of perforation, operation time, and graft materials did not vary significantly between the graft success and failure groups (P>0.05). The mean air-bone gap (ABG) improved significantly in both groups (graft success group: 10.0±0.6 dB and graft failure group: 7.7±0.3 dB; P<0.001). However, the ABG improvement did not significantly differ between the groups. Analysis of covariance revealed that the postoperative 500-Hz bone conduction threshold improved after successful ET (adjusted coefficient, –11.351; 95% confidence interval, –21.491 to –1.212; P=0.028). @*Conclusion@#. This study involved the largest population to date of large TM perforations treated by ET. The study findings suggest that ET is feasible and effective in treating large TM perforations.

Effects of Particulate Matter Exposure on the Eustachian Tube and Middle Ear Mucosa of Rats

Objectives@#. Particulate matter (PM) is a risk factor for various diseases. Recent studies have established an association between otitis media (OM) and PM exposure. To confirm this relationship, we developed a novel exposure model designed to control the concentration of PM, and we observed the effects of PM exposure on the Eustachian tube (ET) and middle ear mucosa of rats. @*Methods@#. Forty healthy, 10-week-old, male Sprague-Dawley rats were divided into 3-day, 7-day, 14-day exposure, and control groups (each, n=10). The rats were exposed to incense smoke as the PM source for 3 hours per day. After exposure, bilateral ETs and mastoid bullae were harvested, and histopathological findings were compared using microscopy and transmission electron microscopy (TEM). The expression levels of interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and vascular endothelial growth factor (VEGF) in the middle ear mucosa of each group were compared using real-time reverse transcription polymerase chain reaction (RT-PCR). @*Results@#. In the ET mucosa of the exposure group, the goblet cell count significantly increased after PM exposure (P=0.032). In the middle ear mucosa, subepithelial space thickening, increased angio-capillary tissue, and inflammatory cell infiltration were observed. Moreover, the thickness of the middle ear mucosa in the exposure groups increased compared to the control group (P<0.01). The TEM findings showed PM particles on the surface of the ET and middle ear mucosa, and RT-PCR revealed that messenger RNA (mRNA) expression of IL-1β significantly increased in the 3-day and 7-day exposure groups compared to the control group (P=0.035). VEGF expression significantly increased in the 7-day exposure group compared to the control and 3-day exposure groups (P<0.01). @*Conclusion@#. The ET and middle ear mucosa of rats showed histopathologic changes after acute exposure to PM that directly reached the ET and middle ear mucosa. Therefore, acute exposure to PM may play a role in the development of OM.

Surgical Result of Resection of Benign Neoplasm on the External Auditory Canal Using Transcanal Endoscopic Ear Surgery / 대한이비인후과학회지

Various benign neoplasms such as osteoma, cholesteatoma, and cartilaginous choristoma can occur in the external auditory canal. The treatment method for these benign neoplasms is surgical excision. Previously, surgery had been performed using a microscope, but recently, a transcanal endoscopic ear surgery (TEES) method has been attempted. As a surgical method, it provides a better surgical view, enables rapid recovery and reduces pain through a minimally invasive approach. In this article, we introduce this endoscopic removal surgical method for benign neoplasms of the external auditory canal and the usefulness of the method.

Transcanal Endoscopic Ear Surgery for The Management of Pediatric Perilymphatic Fistula Caused by Trauma / 대한이비인후과학회지

Perilymphatic fistula (PLF) is caused by leakage of perilymph through an abnormal communication between the inner and middle ear. Conservative treatment is considered in the initial stages; however, exploratory tympanotomy is performed if hearing does not improve or if dizziness persists. Transcanal endoscopic ear surgery (TEES) is considered an appropriate treatment option and is gaining popularity. We report a rare case of traumatic PLF in a 7-year-old male patient, in whom pneumolabyrinth without temporal bone fracture was diagnosed and treated by exploratory tympanotomy using TEES, and review the related research to discuss the usefulness of management using TEES for PLF.

Results of Active Middle Ear Implantation in Patients With Mixed Hearing Loss After Middle Ear Surgery: A Prospective Multicenter Study (the ROMEO Study)

Objectives@#. This study was conducted to evaluate the user satisfaction, efficacy, and safety of round window (RW) vibroplasty using the Vibrant Soundbridge (VSB) in patients with persistent mixed hearing loss after mastoidectomy. @*Methods@#. The study included 27 patients (mean age, 58.7 years; age range, 28–76 years; 11 men and 16 women) with mixed hearing loss after mastoidectomy from 15 tertiary referral centers in Korea. The VSB was implanted at the RW. The Korean translation of the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaire and the Korean version of the International Outcome Inventory for Hearing Aids (K-IOI-HA) questionnaire were used to evaluate user satisfaction as the primary outcome. The secondary outcome measures were audiological test results and complication rates. @*Results@#. The mean scores for ease of communication (61.3% to 29.7% to 30.2%), reverberation (62.1% to 43.1% to 37.4%), and background noise (63.3% to 37.7% to 34.3%) subscales of the APHAB questionnaire significantly decreased after VSB surgery. The mean K-IOI-HA scores at 3 and 6 months after surgery were significantly higher than the mean preoperative score (18.6 to 27.2 to 28.1). The postoperative VSB-aided thresholds were significantly lower than the preoperative unaided and hearing aid (HA)-aided thresholds. There was no significant difference between preoperative unaided, preoperative HA-aided, and postoperative VSB-aided maximum phonetically balanced word-recognition scores. None of the 27 patients experienced a change in postoperative bone conduction pure tone average. One patient developed temporary facial palsy and two developed surgical wound infections. @*Conclusion@#. RW vibroplasty resulted in improved satisfaction and audiological test results in patients with mixed hearing loss after mastoidectomy, and the complication rate was tolerable.

Extratympanic Observation of Middle and Inner Ear Structures in Rodents Using Optical Coherence Tomography

Objectives@#. This study aimed to investigate whether optical coherence tomography (OCT) provides useful information about the microstructures of the middle and inner ear via extratympanic approach and thereby could be utilized as an alternative diagnostic technology in ear imaging. @*Methods@#. Five rats and mice were included, and the swept-source OCT system was applied to confirm the extent of visibility of the middle and inner ear and measure the length or thickness of the microstructures in the ear. The cochlea was subsequently dissected following OCT and histologically evaluated to compare with the OCT images. @*Results@#. The middle ear microstructures such as ossicles, stapedial artery and oval window through the tympanic membrane with the OCT could be confirmed in both rats and mice. It was also possible to obtain the inner ear images such as each compartment of the cochlea in the mice, but the bone covering bulla needed to be removed to visualize the inner ear structures in the rats which had thicker bulla. The bony thickness covering the cochlea could be measured, which showed no significant differences between OCT and histologic image at all turns of cochlea. @*Conclusion@#. OCT has been shown a promising technology to assess real-time middle and inner ear microstructures noninvasively with a high-resolution in the animal model. Therefore, OCT could be utilized to provide additional diagnostic information about the diseases of the middle and inner ear.

Hearing Outcome According to the Intratympanic Steroid Injection Starting Timing in Combined Intratympanic and Oral Steroid Treatment for Idiopathic Sudden Sensorineural Hearing Loss / 대한이비인후과학회지

Background and Objectives@#The combined intratympanic and oral steroid treatment has been accepted as effective treatment strategy for idiopathic sudden sensorineural hearing loss (ISSNHL). However, the treatment protocol of combined treatment for ISSNHL has not been established. In this study, we investigated whether hearing outcome differed according to different starting timing of intratympanic steroid injection (ITSI) in combined treatment for ISSNHL.Subjects and Method Tertiary academic referral center-based retrospective medical records of idiopathic 144 ISSNHL patients who received combined treatment from January 2015 to April 2018 were reviewed. All patients underwent a 2-week oral systemic steroid treatment and multiple ITSI. The hearing results of 3 months after treatment were compared according to the timing of ITSI. @*Results@#The mean pure tone audiogram gain was 24.3±23.6 dB. When Siegel’s criteria was applied, the overall rate of hearing improvement was 63.9% (92/144). The rate of hearing improvement was significantly higher in women (p=0.043) statistically, and there was a statistically significant lower rate of recovery in the former history of hearing loss (p＜0.01) or otitis media (p＜0.01). Moreover, the shorter the delay between symptom onset and initial ITSI, greater the statistical significance of hearing recovery rate became (p＜0.01). @*Conclusion@#The result of this study suggests that early ITSI during combined intratympanic and oral steroid treatment increases the chance of hearing recovery.

The Role of digital subtraction angiography in the ventricular spot sign on the computed tomography angiography

OBJECTIVE: The spot sign on computed tomography angiography is little known about the relationship between the spot sign and the results of cerebral angiography We retrospectively analyzed the spot sign, digital subtraction angiography results, and other factors.MATERIAL AND METHODS: From December 2009 to May 2014, DSA was performed in 52 ICH patients with non-specific location or abnormalities on CTA findings. 26 of those patients, whose initial CTA showed the spot sign, were analyzed. Two groups, one with the spot sign in the ventricle (Group A) and others with the spot sign in another location (Group B) were statistically compared.RESULTS: The mean age of the study subjects was 46.9 years (range, 15 to 80 years) and the percentage of males was 53.8%. Thirteen of 26 patients had ICH without intraventricular hemorrhage, and 6 patients had co-existing IVH. In 17 cases, the DSA results were negative. Seven patients were diagnosed with pseudoaneurysms, and two cases showed developmental venous anomalies. Group A consisted of the 8 patients (30.8%) who showed the spot sign in a ventricle. The number of pseudoaneurysms was statistically significantly higher in Group A than in Group B (71.4% versus 28.6%; OR, 13.3; 95% CI, 1.7-103.8 P = 0.014). All three patients who underwent endovascular treatment were members of Group A (P = 0.022), whereas most (92.3%) of those in Group B underwent surgical evacuation. (P = 0.030).CONCLUSION: When CTA shows the spot sign in a ventricle, it is a clue that an existing underlying vascular lesion requires endovascular treatment.

Successful Mechanical Thrombectomy Using Solumbra Technique In a 35-year-old Man With Achondroplasia: a case report

BACKGROUND: Achondroplasia is one of the most common types of dwarfism and is inherited as an autosomal dominant disease. The patients with achondroplasia suffer from various complications such as craniofacial, central nervous system, spinal, respiratory and cardiac anomalies.CASE DESCRIPTION: We report a case of a 35-year-old man with achondroplasia who visited the emergency room with right hemiplegia and aphasia within 6 hours after onset. An Initial CT angiography showed the total occlusion of a left internal cerebral artery due to the thrombus. We treated the patient with endovascular thrombectomy using “Solumbra technique” with balloon guiding catheter. The procedure was successful and result was completely recanalized with Thrombolysis in Cerebral Infarction (TICI) scale 3 and the weakness also improved from grade II to grade IV.CONCLUSION: Acute ischemic stroke patients with achondroplasia could be treated with mechanical thrombectomy.

Development of a Korean-Type Qualitative Case History Tinnitus Questionnaire / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Qualitative and quantitative data of tinnitus are both important to obtain necessary information for assessing tinnitus evaluation. But contrary to quantitative questionnaire, qualitative data is not standardized in Korea. This study aimed to standardize the qualitative data of tinnitus by developing a Korean-type integrated qualitative tinnitus questionnaires. SUBJECTS AND METHOD: A cross-sectional survey of Korean otolaryngologists was performed. The questionnaires were administered to otologists who were registered as participants in the tinnitus study group of otology research interest group (ORIG). RESULTS: Most of the otologists (100% of responders) have used the quantitative tinnitus questionnaire measurement (90.5%), but only 76% have used qualitative tinnitus questionnaire. From the responses of otologists who regularly use qualitative questionnaire, 25 items were adopted from the 35 item list. Questionnaire items were selected according to the frequency of listed items in the individual lists. CONCLUSION: We made a qualitative questionnaire consisting of 25 items that were essential and widely accepted. We expect this work will integrate and standardize qualitative tinnitus questionnaires in Korea.

Cerebrospinal Fluid Lumbar Tapping Utilization for Suspected Ventriculoperitoneal Shunt Under-Drainage Malfunctions

OBJECTIVE: The diagnosis of shunt malfunction can be challenging since neuroimaging results are not always correlated with clinical outcomes. The purpose of this study was to evaluate the efficacy of a simple, minimally invasive cerebrospinal fluid (CSF) lumbar tapping test that predicts shunt under-drainage in hydrocephalus patients. METHODS: We retrospectively reviewed the clinical and radiological features of 48 patients who underwent routine CSF lumbar tapping after ventriculoperitoneal shunt (VPS) operation using a programmable shunting device. We compared shunt valve opening pressure and CSF lumbar tapping pressure to check under-drainage. RESULTS: The mean pressure difference between valve opening pressure and CSF lumbar tapping pressure of all patients were 2.21±24.57 mmH₂O. The frequency of CSF lumbar tapping was 2.06±1.26 times. Eighty five times lumbar tapping of 41 patients showed that their VPS function was normal which was consistent with clinical improvement and decreased ventricle size on computed tomography scan. The mean pressure difference in these patients was −3.69±19.20 mmH₂O. The mean frequency of CSF lumbar tapping was 2.07±1.25 times. Fourteen cases of 10 patients revealed suspected VPS malfunction which were consistent with radiological results and clinical symptoms, defined as changes in ventricle size and no clinical improvement. The mean pressure difference was 38.07±23.58 mmH₂O. The mean frequency of CSF lumbar tapping was 1.44±1.01 times. Pressure difference greater than 35 mmH₂O was shown in 2.35% of the normal VPS function group (2 of 85) whereas it was shown in 64.29% of the suspected VPS malfunction group (9 of 14). The difference was statistically significant (p=0.000001). Among 10 patients with under-drainage, 5 patients underwent shunt revision. The causes of the shunt malfunction included 3 cases of proximal occlusion and 2 cases of distal obstruction and valve malfunction. CONCLUSION: Under-drainage of CSF should be suspected if CSF lumbar tapping pressure is 35 mmH₂O higher than the valve opening pressure and shunt malfunction evaluation or adjustment of the valve opening pressure should be made.

Craniosynostosis : Updates in Radiologic Diagnosis

The purpose of this article is to review imaging findings and to discuss the optimal imaging methods for craniosynostosis. The discussion of imaging findings are focused on ultrasonography, plain radiography, magnetic resonance imaging and computed tomography with 3-dimensional reconstruction. We suggest a strategy for imaging work-up for the diagnosis, treatment planning and follow-up to minimize or avoid ionized radiation exposure to children by reviewing the current literature.

Anatomical Relationships between Eustachian Tube and Internal Carotid Artery Using Computed Tomography / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: It is important to figure out the location between the internal carotid artery (ICA) and the Eustachian tube (ET) for conducting safe ET surgery. Using computed tomography (CT), this study was aimed to evaluate the anatomical relationship between ET and ICA according to age and gender. SUBJECTS AND METHOD: Contrast enhanced CT scans of the paranasal sinus taken between January 2005 and December 2010 were reviewed retrospectively. A total of 216 patients (432 ears) were enrolled. In each patient, we measuresed the distance from the anterior cushion of torus tubarius to ICA (AC-ICA), the distance from the posterior cushion of torus tubarius to ICA (PC-ICA), the distance from the Rosenmuller fossa to ICA, the shortest distance from ET lumen to ICA (ET-ICA), and the angle between the imaginary lines from the orifice of ET to the posterior end point of nasal septum to point ICA (ET-NS-ICA). Patients were divided into 10 groups based on age difference of 15-years. RESULTS: For the female patients aged 65 to 80 years old, AC-ICA, PC-ICA were closest from the nasopharynx. For this group, at p<0.05, the distances of AC-ICA, PC-ICA and ET-ICA showed a negative correlation with increasing age, whereasET-NS-ICA (p<0.05) showed a positive correlation, indicating a tendency of medicalization with increased age. CONCLUSION: The distance between ET and ICA represents a variety of distribution according to gender and age. When performing a surgery for the nasopharyngeal portion of ET, the surgeon should be aware of the location of ICA in the preoperative CT findings.

The Risk Factors for Hydrocephalus and Subdural Hygroma after Decompressive Craniectomy in Head Injured Patients

OBJECTIVE: The present study aims to investigate 1) the risk factors for hydrocephalus and subdural hygroma (SDG) occurring after decompressive craniectomy (DC), and 2) the association between the type of SDG and hydrocephalus. METHODS: We retrospectively reviewed the clinical and radiological features of 92 patients who underwent DC procedures after severe head injuries. The risk factors for developing post-traumatic hydrocephalus (PTH) and SDG were analyzed. Types of SDGs were classified according to location and their relationship with hydrocephalus was investigated. RESULTS: Ultimately, 26.09% (24/92) of these patients developed PTH. In the univariate analyses, hydrocephalus was statically associated with large bone flap diameter, large craniectomy area, bilateral craniectomy, intraventricular hemorrhage, contralateral or interhemisheric SDGs, and delayed cranioplasty. However, in the multivariate analysis, only large craniectomy area (adjusted OR=4.66; p=0.0239) and contralateral SDG (adjusted OR=6.62; p=0.0105) were significant independent risk factors for developing hydrocephalus after DC. The incidence of overall SDGs after DC was 55.43% (51/92). Subgroup analysis results were separated by SDG types. Statistically significant associations between hydrocephalus were found in multivariate analysis in the contralateral (adjusted OR=5.58; p=0.0074) and interhemispheric (adjusted OR=17.63; p=0.0113) types. CONCLUSION: For patients who are subjected to DC following severe head trauma, hydrocephalus is associated with a large craniectomy area and contralateral SDG. For SDGs after DC that occur on the interhemispherical or controlateral side of the craniectomy, careful follow-up monitoring for the potential progression into hydrocephalus is needed.

A Case of Chronic Invasive Fungal Sinusitis after Endoscopic Sinus Surgery for Chronic Rhinosinusitis / 대한이비인후과학회지

Chronic invasive fungal sinusitis is a relatively rare disease that can span from months to years in its clinical course and is described to be more common in immunocompetent patients. Most cases of chronic invasive fungal sinusitis are due to the Aspergillus species and have been treated with a combination of surgery and antifungal agents. However, the incidence is increasing with frequent use of antibiotics, cytotoxic drugs, and systemic corticosteroids. We report a case of chronic invasive fungal sinusitis with orbital complication in the patient who underwent endoscopic sinus surgery for chronic rhinosinusitis. Although chronic invasive fungal sinusitis is relatively rare, it is important for otolaryngologists to be aware of its diagnosis and treatment.

A Case of Temporal Lobe Abscess Following Mastoidectomy / 대한이비인후과학회지

We report a case of complicated temporal lobe abscess following mastoidectomy. The patient complained of a headache after surgery, however, he was discharged as his symptom was considered to be a common postoperative headache. He revisited our due to a generalized tonic-clonic seizure, and the CT and MRI findings suggested the diagnosis of temporal lobe abscess. The patient was successfully treated with antibiotics instead of surgical treatment. Although the cerebral abscess following mastoidectomy is extremely rare, it is necessary to pay attention to it. Particularly when the patient complains of a headache, it is important to consider the aspects of headache carefully. Bone defect in tegmen tympani and exposure of dura will increase the risk of cerebral abscess, therefore careful caution is required in the presence of lower dura mater.

Assessment of the Optimal Site of Femoral Artery Puncture and Angiographic Anatomical Study of the Common Femoral Artery

OBJECTIVE: The purpose of this study was to evaluate demographic and clinical factors affecting the common femoral artery diameter and length, and anatomical relationship between the femoral head and the common femoral artery during angiography. METHODS: We retrospectively reviewed 109 femoral angiograms. We collected the clinical data of the patients and estimated the common femoral artery diameter and length. We divided the areas in the angiogram from cephalic to caudal direction (zone 0 to 5). The lowest levels of the inferior epigastric artery loop and points of the common femoral artery bifurcation were checked. RESULTS: The luminal diameter of the common femoral artery was 6.19+/-1.20 mm. Height, weight, body surface area, as well as common femoral artery diameter were significantly greater in men than in women (p<0.005). The length of the common femoral artery was 27.59+/-8.87 mm. Height, weight and body surface area showed strong positive relationships with common femoral artery diameter. All of the inferior epigastric artery loops were located above the center of the femoral head. The point of common femoral artery bifurcation was above the center of the femoral head in 4.59% of femoral angiograms. CONCLUSIONS: Males and patients with a high body surface area have a larger common femoral artery diameter. The cumulative probability of optimal targeting between the lowest margin of the inferior epigastric artery loop and the common femoral artery bifurcation is the highest in zone 3 puncture.

Recurrent Benign Myoepithelioma of the Auricle

Myoepithelioma, a generally benign tumor comprised of myoepithlial cells, is an uncommon salivary gland tumor. Myoepithelioma originates primarily in the parotid gland, but several isolated cases have been described. Although myoepithelioma has a benign nature, but there is a potential risk of malignant change and recurrence in case of incomplete resection. We acknowledge that benign myoepithelioma originating from the auricle has not been reported in the English literature. We present a rare case of 27-year-old female who had recurrent benign myoepithelioma originating from the auricle and already had been given twice operations at the other clinic.

Development of Simplified Version of Korean-Type Tinnitus Handicap Inventory / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The Tinnitus Handicap Inventory (THI) is a useful measure to evaluate the tinnitus and to quantify the functional and psychosocial consequences of tinnitus. However, it can be difficult for patients to understand the items of questionnaire and may take 10 to 15 minutes for them to complete the questionnaire, which can be problematic. The objective of this study is to develop a simplified version of the Korean type Tinnitus Handicap Inventory (THIS). SUBJECTS AND METHOD: A retrospective clinical study was conducted to analyze the THI-S cutoff score used for referral purpose and the level of predictability between the THI and the THIS. 100 patients participated. The subject samples were drawn from outpatients who reported tinnitus as their primary complaints at the time of the initial audiology and otolaryngology evaluations. The 10-item THI-S, selected by using Cronbach's alpha coefficient, showed a high correlation with the scores of the THI. Based on their clinical experiences, the four otologists developed their own screening versions of THI, which were designated as THI-A, B, C and D. The Pearson product-moment correlation was used to assess the comparability of the scores between the THI and the THI-S, A, B, C and D. RESULTS: The results showed that there is a higher correlation between the THIS and the THI-S. A high comparability was shown in the comparison between the THI and the THI-S. CONCLUSION: Further studies will be needed if the THI-S can be applied for clinical use.

Rat Peripheral Nerve Regeneration Using Nerve Guidance Channel by Porcine Small Intestinal Submucosa

OBJECTIVE: In order to develop a novel nerve guidance channel using porcine small intestinal submucosa (SIS) for nerve regeneration, we investigated the possibility of SIS, a tissue consisting of acellular collagen material without cellular immunogenicity, and containing many kinds of growth factors, as a natural material with a new bioactive functionality. METHODS: Left sciatic nerves were cut 5 mm in length, in 14 Sprague-Dawley rats. Grafts between the cut nerve ends were performed with a silicone tube (Silicon group, n=7) and rolled porcine SIS (SIS group, n=7). All rats underwent a motor function test and an electromyography (EMG) study on 4 and 10 weeks after grafting. After last EMG studies, the grafts, including proximal and distal nerve segments, were retrieved for histological analysis. RESULTS: Foot ulcers, due to hypesthesia, were fewer in SIS group than in Silicon group. The run time tests for motor function study were 2.67 seconds in Silicon group and 5.92 seconds in SIS group. Rats in SIS group showed a better EMG response for distal motor latency and amplitude than in Silicon group. Histologically, all grafts contained some axons and myelination. However, the number of axons and the degree of myelination were significantly higher in SIS group than Silicon group. CONCLUSION: These results show that the porcine SIS was an excellent option as a natural biomaterial for peripheral nerve regeneration since this material contains many kinds of nerve growth factors. Furthermore, it could be used as a biocompatible barrier covering neural tissue.