CLINICAL PAPER
Management of Extremity Neurilemmomas Clinical Series and Literature Review Chih-Sheng Lai, MD,* I-Chen Chen, MD,* Haw-Chang Lan, MD,Þ Chen-Te Lu, MD,* Jung-Hsing Yen, MD,* Ding-Yu Song, MD,* and Yu-Wen Tang, MD* Background: Delicate enucleation of neurilemmoma preserves most of nerve fascicles and causes minimal nerve function impairment. Accurate preoperative diagnosis of neurilemmoma is based on clinical findings and image studies. Materials and Methods: Between November 2003 and February 2013, operations for the treatment of neurilemmoma were performed on 14 patients (12 men and 2 women) at our institution. The image studies in this series were collected. The tumor mass was approached by splitting the epineurium. In a few cases, enucleation of the neurilemmoma caused some fascicles loss, but reconstruction with sural nerve grafts preserved nerve function. Results: Before surgery, 7 patients received computed tomographic scan, 4 patients underwent magnetic resonance imaging, and 3 patients received sonography. Six patients presented with motor or sensory deficits immediately after tumor enucleation. Three patients recovered completely from the neurological defects with or without nerve reconstruction. Conclusions: Our results indicate that neurilemmoma can be removed by delicate enucleation with an acceptable risk of injury to the nerve trunk. Key Words: neurilemmoma, enucleation (Ann Plast Surg 2013;71: S37YS42)
N
erve sheath tumor, generally known as neurilemmoma or schwannoma, is the most common benign neoplasm of peripheral nerve sheaths.1 In most patients, the lesion is detected as a painless mass.1 Neurilemmomas originate from the cells of the Schwann sheath. This tumor lies in the course of the nerve. The nerve bundles are not involved in the process, but fan out over the tumor, which can be excised from the nerve through a longitudinal incision in the epineurium.2 En bloc excision of neurilemmoma from the nerve trunk may result in significant function impairment. In contrast, delicate enucleation of the tumor mass inside the nerve trunk preserves most of the nerve fascicles and causes minimal nerve function impairment. Strict adherence to the principle of enucleation for preservation of nerve function relies on accurate preoperation diagnosis of neurilemmoma, which is based on clinical findings and image studies. The aim of this study was to correlate the preoperative diagnosis of neurilemmoma from image studies in a series of 14 histopathologically confirmed cases and to evaluate the results of tumor excision by enucleation with or without reconstruction of the involved nerve trunk.
Received October 2, 2013, and accepted for publication, after revision, October 6, 2013. From the *Plastic and Reconstructive Surgery, Department of Surgery, and †Department of Radiology, Taichung Veterans General Hospital, Taiwan, Republic of China. Conflicts of interest and sources of funding: none declared. Reprints: I-Chen Chen, MD, Plastic and Reconstructive Surgery, Department of Surgery, Taichung Veterans General Hospital, No. 1650, Sec. 4, Taiwan Blvd, Taichung 40705, Taiwan, Republic of China. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0148-7043/13/7101-S037 DOI: 10.1097/SAP.0000000000000042
Annals of Plastic Surgery
PATIENTS AND METHODS Patients Between November 2003 and February 2013, operations for the treatment of neurilemmoma were performed on 14 patients (12 men and 2 women) at our institution. Basic demographic data including age, sex, size of nerve tumor, and image study, including computed tomography (CT), magnetic resonance imaging (MRI), and sonography, are summarized in Table 1. The image studies in this series were collected and reviewed. A radiologist (L.H.C.) was consulted for review and interpretation of the image studies.
Surgical Technique For excision of neurilemmoma in the upper or lower extremity, the patient received general anesthesia and a pneumatic tourniquet was applied to the extremity. A zigzag skin incision was made to expose the main tumor. The nerve trunk was then dissected and looped proximally and distally to the tumor lesion (Fig. 1). The epineurium was opened longitudinally. Care was taken to avoid injury to visible nerve fascicles. The tumor was approached by splitting the perineurium over the mass under loupes or microscope magnification. In a small tumor, the mass can be peeled off the nerve trunk (intraneural enucleation) without severing the nerve fascicles (Fig. 2). During enucleation of a large mass, nerve fascicles may be damaged. For reconstruction of nerve fascicles after tumor enucleation, the sural nerve was harvested from the lower limb. The nerve graft was prepared under loupes and placed within the gap of nerve fascicle. A limited number of sutures using 9-0 or 10-0 nylon were applied to secure the interposition nerve graft (Fig. 3). The epineurium was repaired using 8-0 or 9-0 nylon (Figs. 4 and 5). The tourniquet was then deflated and bleeding was controlled using a bipolar coagulator. Oozing from the nerve trunk was stanched with 1:100,000 epinephrinesoaked gauzes and skin closure was achieved. The limb was splinted in a natural position for 2 to 3 weeks if the nerve was reconstructed with a sural graft.
Evaluation of Results Complications that occurred after operation specific to excision of neurilemmoma (sensory and motor deficits, tumor recurrence) were recorded in the follow-up period (Table 2).
RESULTS Fourteen patients underwent operation for removal of 15 neurilemmomas. There were 12 male patients and 2 female patients with an average age at presentation of 46.4 years (range, 14Y71 years). The mean duration of symptoms (a mass) at presentation was 4.8 years (range, 4 month-12 years), and tumor size ranged from 1 1 1 to 18 3.5 3 cm (mean, 4.4 2.4 2 cm). Preoperative CT scan performed in 7 patients showed a well-defined ovoid mass, homogeneous low soft tissue density, and heterogeneous contrast enhancement in all cases. The MRIs performed in 4 patients revealed that all of them had predominantly high-signal intensity lesions and tumors eccentric to the nerve trunk of origin. Sonography done in 3 patients disclosed that all of them had a well-defined ovoid hypoechoic mass. No image study was performed in 1 patient
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TABLE 1. Basic Data of Patients Case No.
Sex
Age, y
Duration of Symptoms (a Mass)
Tumor Size, cm
Image Study
1 2 3 4 5 6 7 8 9 10 11 12 13 14
M M M M M M M F M M F M M M
38 71 39 41 43 56 39 14 59 61 40 69 40 40
8 mo 3y 40 mo 10 y 12 y 10 y 2y 8 mo 11 y 10 y 2.5 y 1 mo 2.5 mo 2y
2.5 2 1.5 855 432 2 2 1.6 111 2 2 1.3 2 1.5 1.5 18 3.5 3 111 6.5 4 2.5 3 3 2.7 3 2.5 1.7 3 2 2 and 8 2.5 2.2 2 1.5 1.5
Sonography, CT MRI MRI CT No Sonography CT MRI Sonography CT MRI CT CT CT
because the lesion was small and superficial. One patient had an additional CT scan due to a nonconclusive sonography report (Table 1). All tumors were completely excised. In 12 patients, the tumors were located in the upper limbs. In the other 2 patients, the tumors were located in the lower limbs. The mean duration of postoperative follow-up was 21.9 months (range, 4Y92 months). In 1 patient (patient 13), a tumor was located in the median nerve and another tumor was found in the ulnar nerve of the same extremity. Eight of the 14 patients had minimal neurological defects after intraneural enucleation of neurilemmoma in this series. However, 6 patients presented with motor or sensory deficits immediately after tumor enucleation (patients 1, 2, 3, 8, 10, and 11). In 3 patients (patients 1, 2, and 3), the neurological defects were resolved completely with or without nerve reconstruction. Three patients received nerve reconstruction with sural nerve grafts to bridge the fascicle. Patient 1 was a 38-year-old man. The neurilemmoma was located in the sciatic nerve of his right thigh area and measured 2.5 2 1.5 cm. After enucleation of the tumor, a sural nerve graft was used (2 cables, 3 cm in length) for reconstruction of the nerve trunk. Hypoaesthesia of the knee was noted in the early postoperative period, but it gradually reduced in size and disappeared after 1 year.
Patient 8 was a 14-year-old girl who presented with a long sausage-like tumor lesion in the ulnar nerve of her left arm. The tumor mass (18 cm in length, 3.5 cm in width, and 2.5 cm in height) was extremely difficult to dissect from the nerve trunk without severing the nerve fascicles inside the nerve trunk. Despite nerve reconstruction with cable sural nerve grafts, the patient still experienced persistent left claw hand deformity after 28 months of follow-up. Patient 11 was a 40-year-old woman, who presented with a 3 3 2.7-cm tumor mass in the sciatic nerve of right thigh. The MRI disclosed a neurogenic tumor in favor of neurilemmoma. The patient received enucleation of the tumor inside the sciatic nerve and reconstruction of nerve fascicles using ipsilateral sural nerve grafts. Postoperatively, the patient experienced numbness on the lateral side of the foot and weakness in plantar f lexion of the foot and toes. The
FIGURE 1. Operative photograph showing a neurilemoma of the nerve.
FIGURE 2. After partial dissection of fascicles surrounding the tumor, the tumor proper became evident.
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Management of Extremity Neurilemmomas
FIGURE 3. The nerve graft was placed between the gap of nerve fascicle and 9-0 or 10-0 nylon was used to secure interposition nerve graft.
FIGURE 5. The epineurium of ulnar nerve after nerve graft was repaired by using 8-0 or 9-0 nylon with a continuous suture method.
symptoms gradually resolved after 10 months. The patient was able to walk without support within a year, but the numbness persisted. The results are summarized in Table 2. At final follow-up, all patients were free from recurrence.
function and try to preserve the continuity of nerve should be the ultimate goal in surgical resection of neurilemmomas. Donner et al5 reported that 13% of 85 patients with nerve sheath tumors developed muscle weakness after resection surgery. Theoretically, it is possible to remove the lesion without causing significant nerve deficit6 (Fig. 2). Russell,7 using a fascicle-sparing approach, reported that neurilemmoma can often be removed without causing neurological deficit or neuropathic pain. He also suggested using higher magnification and sharp dissection with microscissors. Ozdemir et al recommended incising the capsule and removing the mass (enucleating the tumor) intracapsularly for excision of neurilemmomas of the hand and wrist area. The authors believe that the risk of neural damage is lower with intracapsular enucleation.8 Prognosis after surgery for neurilemmoma of the brachial plexus showed 88% of patients maintained normal strength, and 90% either showed no changed or improved muscle power.9 An accurate preoperative diagnosis of neurilemmoma is critical in terms of the pathologic nature of the lesion so that nerve preserving tumor resection can be performed. Enucleation of a solid tumor with potential of malignancy is an illogical approach. In our series, all 7 patients who received preoperative CT scan had a welldefined ovoid mass, homogeneous low soft tissue density, and heterogeneous contrast enhancement. Sonography done in 3 patients showed that all of them had a well-defined ovoid hypoechoic mass. The MRIs performed in 4 patients revealed that all of them had predominantly high-signal intensity lesions and tumors that were eccentric to the nerve trunk of origin. Magnetic resonance imaging is a powerful instrument for diagnosis of a mass lesion, especially in determining whether the mass is intrinsic or extrinsic to the nerve, and showing relationships with surrounding tissues.7,10 On MRI with T1-weighted imaging, neurilemmomas have an intermediate signal intensity similar to that of muscle (Figs. 6 and 7). They show a very bright signal on T2-weighted imaging (Figs. 8 and 9).10 Besides, when the nerve trunk is identified, an eccentrically positioned lesion (in relation to the nerve) suggests a neurilemmoma (Fig. 9).10 Nilsson et al11 showed that MRI can localize and diagnose a nerve tumor in the upper extremity in 75% of cases, but found it was difficult to specify the type of tumor. Hung et al12 believe MRI provides more information than ultrasonography. In their series of patients, 22 ultrasonography scan and 20 MRIs were performed. The diagnostic accuracies of ultrasonography and MRI were 77% and 100%, respectively. Besides, Hung et al showed that MRI can delineate involvement of adjacent structures as a guide to surgical approach.8,12 On
DISCUSSION Neurilemmomas are benign neoplasms arising from the peripheral nerve sheath. In most patients, neurilemmomas are asymptomatic when the tumor is small. However, dysesthesia, neuropathic pain, sensory loss, and weakness can occur when the tumor grows larger and exerts local pressure on the nerve of origin.3 Encapsulated neurilemmoma is considered completely benign and does not undergo malignant transformation.4 Preservation of the nerve
FIGURE 4. The epineurium of median nerve after tumor enucleation was repaired by using 8-0 or 9-0 nylon with a continuous suture method. * 2013 Lippincott Williams & Wilkins
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TABLE 2. Summary of Results in Each Patient Case No.
Site of Lesion
Nerve Involved
Motor Deficit
Functional Outcome
Follow-up, mo Nerve Reconstruction
+ (right knee numbness)
j
Restored
35
j
Restored
92
j j j j j +
Restored
63 6 4 5 5 28
1
Right thigh
2 3 4 5 6 7 8
Right axilla fossa Cutaneous sensory + (incisional wound nerve branch numbness) Right forearm Median nerve + (RMF numbness) Left wrist Median nerve j Right palm Median nerve j Right wrist Median nerve j Right palm Median nerve j Left arm Ulnar nerve +
9 10 11
Left palm Left palm Right thigh
Ulnar nerve Median nerve Sciatic nerve
j j +
j + +
12 13
Left arm Left forearm and left hand Right wrist
Median nerve Median nerve and ulnar nerve Median nerve
j j
j j
8 4
j j j j j Fascicle reconstruction with interposition nerve graft j j Fascicle reconstruction with interposition nerve graft j j
j
j
4
j
14
Sciatic nerve
Sensory Deficit
CT scan, a neurilemmoma seems like a well-demarcated round or oval mass that frequently demonstrates prominent cystic degeneration.10,13 On contrast-enhanced CT, a neurilemmoma demonstrates homogeneous hypodensity with thin-smooth contrast enhancement at the margin and irregular enhancement at the centrum (Fig. 10). In this series, the preoperative diagnosis based on the image studies combined with clinical history and physical examination were compatible with the
Left claw hand deformity
Thenar muscle atrophy Right calf slightly atrophy
4 39 10
Fascicle reconstruction with interposition nerve graft j
histopathological diagnosis in all patients. However, we recommend MRI as the most important modality in establishing the accurate preoperative diagnosis due to its resolution in soft tissue tumors. We adopted the procedure recommended by Russell.7 By splitting the epineurium and avoiding the visible nerve fascicles under magnification, the tumor mass was enucleated from the nerve trunk. A small tumor can be peeled off the nerve without damaging
FIGURE 6. Patient 11 was a 40-year-old woman with a neurilemoma involving the sciatic nerve in a lower extremity. Coronal T1-weighted MR image of the right thigh shows a round lesion (arrowhead) eccentrically located in the distribution of the sciatic nerve. The intermediate signal intensity was similar to that of muscle. S40
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Management of Extremity Neurilemmomas
FIGURE 7. Patient 8 was a 14-year-old girl with a neurilemoma involving the ulnar nerve in an upper extremity. Sagittal T1-weighted MR image of the left upper extremity shows a large ovoid lesion (arrowheads) eccentrically located in the distribution of the ulnar nerve. The intermediate signal intensity was similar to that of muscle.
FIGURE 9. Sagittal T2-weighted MR image of the left upper extremity shows a large ovoid lesion eccentrically located in the distribution of the ulnar nerve. The lesion had predominantly high-signal intensity and the tumor was eccentric to the nerve trunk of origin, which was displaced inside (arrowhead).
the nerve fascicles. Enucleation of a large tumor may cause some fascicle loss, but reconstruction with sural nerve grafts can preserve the nerve function. Eight of the 14 patients recorded minimal nerve deficits after surgery. Three of the 6 patients with postoperative
motor or sensory deficits completely recovered. Two of the 3 patients with nerve reconstruction had persistent nerve deficits at the final follow-up. Patient 8 had a very large (18 cm long) sausage-like mass in proximal ulnar nerve. In patient 11, the lesion was located in the
FIGURE 8. Coronal T2-weighted MR image of the right thigh shows a round lesion (arrowhead) eccentrically located in the distribution of the sciatic nerve. The lesion had predominantly high-signal intensity. * 2013 Lippincott Williams & Wilkins
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located proximally to the extremity will be less predictable than distally located lesions. Nevertheless, early detection and treatment of neurilemmomas can prevent complications. In conclusion, most neurilemmomas can be safely and adequately removed and nerve function usually can be preserved or restored by appropriate surgery. Our results indicate that neurilemmomas can be removed by enucleation with an acceptable risk of injury to the nerve. If nerve fascicles are damaged during enucleation, the nerve gaps can be reconstructed with sural nerve grafts to preserve the nerve function. REFERENCES 1. Holdsworth BJ. Nerve tumours in the upper limb. A clinical review. J Hand Surg Br. 1985;10:236Y238. 2. Stack HG. Tumours of the hand. Postgrad Med J. 1964;40:290Y298. 3. El-Sherif Y, Sarva H, Valsamis H. Clinical reasoning: an unusual lung mass causing focal weakness. Neurology. 2012;78:e4Ye7. 4. Das Gupta, Brasfield RD, Strong EW, et al. Benign solitary schwannomas (neurilemomas). Cancer. 1969;24:355Y366. 5. Donner TR, Voorhies RM, Kline DG, et al. Neural sheath tumors of major nerves. J Neurosurg. 1994;81:362Y373. 6. Louis DS, Hankin FM. Benign nerve tumors of the upper extremity. Bull N Y Acad Med. 1985;61:611Y620. 7. Russell SM. Preserve the nerve: microsurgical resection of peripheral nerve sheath tumors. Neurosurgery. 2007;61:ONS-113YONS-118.
FIGURE 10. Patient 13 was a 40-year-old man with 2 neurilemomas, one involving the median nerve of the left forearm and the other involving the ulnar nerve of the left hand (arrowheads). On contrast-enhanced CT, neurilemmomas demonstrated homogeneous hypodensity with thin-smooth contrast enhancement at the margin and irregular enhancement at the centrum.
sciatic nerve trunk at proximal thigh, which inf luenced nerve recovery even with meticulous reconstruction. Holdsworth1 reported good results after repair of the excised gap with sural nerve grafts. It is clear that a graft repaired nerve can never function perfectly. The functional result of tumor enucleation from nerve trunk with totally intact fascicle is better compared to a notable fascicle gap with graft reconstruction or without. The result of neurilemmoma lesions
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8. Ozdemir O, Ozsoy MH, Kurt C, et al. Schwannomas of the hand and wrist: long-term results and review of the literature. J Orthop Surg (Hong Kong). 2005;13:267Y272. 9. Kim DH, Murovic JA, Tiel RL, et al. Operative outcomes of 546 Louisiana State University Health Sciences Center peripheral nerve tumors. Neurosurg Clin N Am. 2004;15:177. 10. Pilavaki M, Chourmouzi D, Kiziridou A, et al. Imaging of peripheral nerve sheath tumors with pathologic correlation: pictorial review. Eur J Radiol. 2004;52:229. 11. Nilsson J, Sandberg K, Nielsen N, et al. Magnetic resonance imaging of peripheral nerve tumours in the upper extremity. Scand J Plast Reconstr Surg Hand Surg. 2009;43:153Y159. 12. Hung YW, Tse WL, Cheng HS, et al. Surgical excision for challenging upper limb nerve sheath tumours: a single centre retrospective review of treatment results. Hong Kong Med J. 2010;16:287Y291. 13. Agrawal A, Singh GK, Rauniyar RK, et al. CT characteristics of dumbbell schwannomma arising from the fifth cervical nerve root. Eur J Gen Med. 2009;6:123Y126.
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Management of Extremity Neurilemmomas Clinical Series and Literature Review Chih-Sheng Lai, MD,* I-Chen Chen, MD,* Haw-Chang Lan, MD,Þ Chen-Te Lu, MD,* Jung-Hsing Yen, MD,* Ding-Yu Song, MD,* and Yu-Wen Tang, MD* Background: Delicate enucleation of neurilemmoma preserves most of nerve fascicles and causes minimal nerve function impairment. Accurate preoperative diagnosis of neurilemmoma is based on clinical findings and image studies. Materials and Methods: Between November 2003 and February 2013, operations for the treatment of neurilemmoma were performed on 14 patients (12 men and 2 women) at our institution. The image studies in this series were collected. The tumor mass was approached by splitting the epineurium. In a few cases, enucleation of the neurilemmoma caused some fascicles loss, but reconstruction with sural nerve grafts preserved nerve function. Results: Before surgery, 7 patients received computed tomographic scan, 4 patients underwent magnetic resonance imaging, and 3 patients received sonography. Six patients presented with motor or sensory deficits immediately after tumor enucleation. Three patients recovered completely from the neurological defects with or without nerve reconstruction. Conclusions: Our results indicate that neurilemmoma can be removed by delicate enucleation with an acceptable risk of injury to the nerve trunk. Key Words: neurilemmoma, enucleation (Ann Plast Surg 2013;71: S37YS42)
N
erve sheath tumor, generally known as neurilemmoma or schwannoma, is the most common benign neoplasm of peripheral nerve sheaths.1 In most patients, the lesion is detected as a painless mass.1 Neurilemmomas originate from the cells of the Schwann sheath. This tumor lies in the course of the nerve. The nerve bundles are not involved in the process, but fan out over the tumor, which can be excised from the nerve through a longitudinal incision in the epineurium.2 En bloc excision of neurilemmoma from the nerve trunk may result in significant function impairment. In contrast, delicate enucleation of the tumor mass inside the nerve trunk preserves most of the nerve fascicles and causes minimal nerve function impairment. Strict adherence to the principle of enucleation for preservation of nerve function relies on accurate preoperation diagnosis of neurilemmoma, which is based on clinical findings and image studies. The aim of this study was to correlate the preoperative diagnosis of neurilemmoma from image studies in a series of 14 histopathologically confirmed cases and to evaluate the results of tumor excision by enucleation with or without reconstruction of the involved nerve trunk.
Received October 2, 2013, and accepted for publication, after revision, October 6, 2013. From the *Plastic and Reconstructive Surgery, Department of Surgery, and †Department of Radiology, Taichung Veterans General Hospital, Taiwan, Republic of China. Conflicts of interest and sources of funding: none declared. Reprints: I-Chen Chen, MD, Plastic and Reconstructive Surgery, Department of Surgery, Taichung Veterans General Hospital, No. 1650, Sec. 4, Taiwan Blvd, Taichung 40705, Taiwan, Republic of China. E-mail: [email protected]. Copyright * 2013 by Lippincott Williams & Wilkins ISSN: 0148-7043/13/7101-S037 DOI: 10.1097/SAP.0000000000000042
Annals of Plastic Surgery
PATIENTS AND METHODS Patients Between November 2003 and February 2013, operations for the treatment of neurilemmoma were performed on 14 patients (12 men and 2 women) at our institution. Basic demographic data including age, sex, size of nerve tumor, and image study, including computed tomography (CT), magnetic resonance imaging (MRI), and sonography, are summarized in Table 1. The image studies in this series were collected and reviewed. A radiologist (L.H.C.) was consulted for review and interpretation of the image studies.
Surgical Technique For excision of neurilemmoma in the upper or lower extremity, the patient received general anesthesia and a pneumatic tourniquet was applied to the extremity. A zigzag skin incision was made to expose the main tumor. The nerve trunk was then dissected and looped proximally and distally to the tumor lesion (Fig. 1). The epineurium was opened longitudinally. Care was taken to avoid injury to visible nerve fascicles. The tumor was approached by splitting the perineurium over the mass under loupes or microscope magnification. In a small tumor, the mass can be peeled off the nerve trunk (intraneural enucleation) without severing the nerve fascicles (Fig. 2). During enucleation of a large mass, nerve fascicles may be damaged. For reconstruction of nerve fascicles after tumor enucleation, the sural nerve was harvested from the lower limb. The nerve graft was prepared under loupes and placed within the gap of nerve fascicle. A limited number of sutures using 9-0 or 10-0 nylon were applied to secure the interposition nerve graft (Fig. 3). The epineurium was repaired using 8-0 or 9-0 nylon (Figs. 4 and 5). The tourniquet was then deflated and bleeding was controlled using a bipolar coagulator. Oozing from the nerve trunk was stanched with 1:100,000 epinephrinesoaked gauzes and skin closure was achieved. The limb was splinted in a natural position for 2 to 3 weeks if the nerve was reconstructed with a sural graft.
Evaluation of Results Complications that occurred after operation specific to excision of neurilemmoma (sensory and motor deficits, tumor recurrence) were recorded in the follow-up period (Table 2).
RESULTS Fourteen patients underwent operation for removal of 15 neurilemmomas. There were 12 male patients and 2 female patients with an average age at presentation of 46.4 years (range, 14Y71 years). The mean duration of symptoms (a mass) at presentation was 4.8 years (range, 4 month-12 years), and tumor size ranged from 1 1 1 to 18 3.5 3 cm (mean, 4.4 2.4 2 cm). Preoperative CT scan performed in 7 patients showed a well-defined ovoid mass, homogeneous low soft tissue density, and heterogeneous contrast enhancement in all cases. The MRIs performed in 4 patients revealed that all of them had predominantly high-signal intensity lesions and tumors eccentric to the nerve trunk of origin. Sonography done in 3 patients disclosed that all of them had a well-defined ovoid hypoechoic mass. No image study was performed in 1 patient
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TABLE 1. Basic Data of Patients Case No.
Sex
Age, y
Duration of Symptoms (a Mass)
Tumor Size, cm
Image Study
1 2 3 4 5 6 7 8 9 10 11 12 13 14
M M M M M M M F M M F M M M
38 71 39 41 43 56 39 14 59 61 40 69 40 40
8 mo 3y 40 mo 10 y 12 y 10 y 2y 8 mo 11 y 10 y 2.5 y 1 mo 2.5 mo 2y
2.5 2 1.5 855 432 2 2 1.6 111 2 2 1.3 2 1.5 1.5 18 3.5 3 111 6.5 4 2.5 3 3 2.7 3 2.5 1.7 3 2 2 and 8 2.5 2.2 2 1.5 1.5
Sonography, CT MRI MRI CT No Sonography CT MRI Sonography CT MRI CT CT CT
because the lesion was small and superficial. One patient had an additional CT scan due to a nonconclusive sonography report (Table 1). All tumors were completely excised. In 12 patients, the tumors were located in the upper limbs. In the other 2 patients, the tumors were located in the lower limbs. The mean duration of postoperative follow-up was 21.9 months (range, 4Y92 months). In 1 patient (patient 13), a tumor was located in the median nerve and another tumor was found in the ulnar nerve of the same extremity. Eight of the 14 patients had minimal neurological defects after intraneural enucleation of neurilemmoma in this series. However, 6 patients presented with motor or sensory deficits immediately after tumor enucleation (patients 1, 2, 3, 8, 10, and 11). In 3 patients (patients 1, 2, and 3), the neurological defects were resolved completely with or without nerve reconstruction. Three patients received nerve reconstruction with sural nerve grafts to bridge the fascicle. Patient 1 was a 38-year-old man. The neurilemmoma was located in the sciatic nerve of his right thigh area and measured 2.5 2 1.5 cm. After enucleation of the tumor, a sural nerve graft was used (2 cables, 3 cm in length) for reconstruction of the nerve trunk. Hypoaesthesia of the knee was noted in the early postoperative period, but it gradually reduced in size and disappeared after 1 year.
Patient 8 was a 14-year-old girl who presented with a long sausage-like tumor lesion in the ulnar nerve of her left arm. The tumor mass (18 cm in length, 3.5 cm in width, and 2.5 cm in height) was extremely difficult to dissect from the nerve trunk without severing the nerve fascicles inside the nerve trunk. Despite nerve reconstruction with cable sural nerve grafts, the patient still experienced persistent left claw hand deformity after 28 months of follow-up. Patient 11 was a 40-year-old woman, who presented with a 3 3 2.7-cm tumor mass in the sciatic nerve of right thigh. The MRI disclosed a neurogenic tumor in favor of neurilemmoma. The patient received enucleation of the tumor inside the sciatic nerve and reconstruction of nerve fascicles using ipsilateral sural nerve grafts. Postoperatively, the patient experienced numbness on the lateral side of the foot and weakness in plantar f lexion of the foot and toes. The
FIGURE 1. Operative photograph showing a neurilemoma of the nerve.
FIGURE 2. After partial dissection of fascicles surrounding the tumor, the tumor proper became evident.
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Management of Extremity Neurilemmomas
FIGURE 3. The nerve graft was placed between the gap of nerve fascicle and 9-0 or 10-0 nylon was used to secure interposition nerve graft.
FIGURE 5. The epineurium of ulnar nerve after nerve graft was repaired by using 8-0 or 9-0 nylon with a continuous suture method.
symptoms gradually resolved after 10 months. The patient was able to walk without support within a year, but the numbness persisted. The results are summarized in Table 2. At final follow-up, all patients were free from recurrence.
function and try to preserve the continuity of nerve should be the ultimate goal in surgical resection of neurilemmomas. Donner et al5 reported that 13% of 85 patients with nerve sheath tumors developed muscle weakness after resection surgery. Theoretically, it is possible to remove the lesion without causing significant nerve deficit6 (Fig. 2). Russell,7 using a fascicle-sparing approach, reported that neurilemmoma can often be removed without causing neurological deficit or neuropathic pain. He also suggested using higher magnification and sharp dissection with microscissors. Ozdemir et al recommended incising the capsule and removing the mass (enucleating the tumor) intracapsularly for excision of neurilemmomas of the hand and wrist area. The authors believe that the risk of neural damage is lower with intracapsular enucleation.8 Prognosis after surgery for neurilemmoma of the brachial plexus showed 88% of patients maintained normal strength, and 90% either showed no changed or improved muscle power.9 An accurate preoperative diagnosis of neurilemmoma is critical in terms of the pathologic nature of the lesion so that nerve preserving tumor resection can be performed. Enucleation of a solid tumor with potential of malignancy is an illogical approach. In our series, all 7 patients who received preoperative CT scan had a welldefined ovoid mass, homogeneous low soft tissue density, and heterogeneous contrast enhancement. Sonography done in 3 patients showed that all of them had a well-defined ovoid hypoechoic mass. The MRIs performed in 4 patients revealed that all of them had predominantly high-signal intensity lesions and tumors that were eccentric to the nerve trunk of origin. Magnetic resonance imaging is a powerful instrument for diagnosis of a mass lesion, especially in determining whether the mass is intrinsic or extrinsic to the nerve, and showing relationships with surrounding tissues.7,10 On MRI with T1-weighted imaging, neurilemmomas have an intermediate signal intensity similar to that of muscle (Figs. 6 and 7). They show a very bright signal on T2-weighted imaging (Figs. 8 and 9).10 Besides, when the nerve trunk is identified, an eccentrically positioned lesion (in relation to the nerve) suggests a neurilemmoma (Fig. 9).10 Nilsson et al11 showed that MRI can localize and diagnose a nerve tumor in the upper extremity in 75% of cases, but found it was difficult to specify the type of tumor. Hung et al12 believe MRI provides more information than ultrasonography. In their series of patients, 22 ultrasonography scan and 20 MRIs were performed. The diagnostic accuracies of ultrasonography and MRI were 77% and 100%, respectively. Besides, Hung et al showed that MRI can delineate involvement of adjacent structures as a guide to surgical approach.8,12 On
DISCUSSION Neurilemmomas are benign neoplasms arising from the peripheral nerve sheath. In most patients, neurilemmomas are asymptomatic when the tumor is small. However, dysesthesia, neuropathic pain, sensory loss, and weakness can occur when the tumor grows larger and exerts local pressure on the nerve of origin.3 Encapsulated neurilemmoma is considered completely benign and does not undergo malignant transformation.4 Preservation of the nerve
FIGURE 4. The epineurium of median nerve after tumor enucleation was repaired by using 8-0 or 9-0 nylon with a continuous suture method. * 2013 Lippincott Williams & Wilkins
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TABLE 2. Summary of Results in Each Patient Case No.
Site of Lesion
Nerve Involved
Motor Deficit
Functional Outcome
Follow-up, mo Nerve Reconstruction
+ (right knee numbness)
j
Restored
35
j
Restored
92
j j j j j +
Restored
63 6 4 5 5 28
1
Right thigh
2 3 4 5 6 7 8
Right axilla fossa Cutaneous sensory + (incisional wound nerve branch numbness) Right forearm Median nerve + (RMF numbness) Left wrist Median nerve j Right palm Median nerve j Right wrist Median nerve j Right palm Median nerve j Left arm Ulnar nerve +
9 10 11
Left palm Left palm Right thigh
Ulnar nerve Median nerve Sciatic nerve
j j +
j + +
12 13
Left arm Left forearm and left hand Right wrist
Median nerve Median nerve and ulnar nerve Median nerve
j j
j j
8 4
j j j j j Fascicle reconstruction with interposition nerve graft j j Fascicle reconstruction with interposition nerve graft j j
j
j
4
j
14
Sciatic nerve
Sensory Deficit
CT scan, a neurilemmoma seems like a well-demarcated round or oval mass that frequently demonstrates prominent cystic degeneration.10,13 On contrast-enhanced CT, a neurilemmoma demonstrates homogeneous hypodensity with thin-smooth contrast enhancement at the margin and irregular enhancement at the centrum (Fig. 10). In this series, the preoperative diagnosis based on the image studies combined with clinical history and physical examination were compatible with the
Left claw hand deformity
Thenar muscle atrophy Right calf slightly atrophy
4 39 10
Fascicle reconstruction with interposition nerve graft j
histopathological diagnosis in all patients. However, we recommend MRI as the most important modality in establishing the accurate preoperative diagnosis due to its resolution in soft tissue tumors. We adopted the procedure recommended by Russell.7 By splitting the epineurium and avoiding the visible nerve fascicles under magnification, the tumor mass was enucleated from the nerve trunk. A small tumor can be peeled off the nerve without damaging
FIGURE 6. Patient 11 was a 40-year-old woman with a neurilemoma involving the sciatic nerve in a lower extremity. Coronal T1-weighted MR image of the right thigh shows a round lesion (arrowhead) eccentrically located in the distribution of the sciatic nerve. The intermediate signal intensity was similar to that of muscle. S40
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Management of Extremity Neurilemmomas
FIGURE 7. Patient 8 was a 14-year-old girl with a neurilemoma involving the ulnar nerve in an upper extremity. Sagittal T1-weighted MR image of the left upper extremity shows a large ovoid lesion (arrowheads) eccentrically located in the distribution of the ulnar nerve. The intermediate signal intensity was similar to that of muscle.
FIGURE 9. Sagittal T2-weighted MR image of the left upper extremity shows a large ovoid lesion eccentrically located in the distribution of the ulnar nerve. The lesion had predominantly high-signal intensity and the tumor was eccentric to the nerve trunk of origin, which was displaced inside (arrowhead).
the nerve fascicles. Enucleation of a large tumor may cause some fascicle loss, but reconstruction with sural nerve grafts can preserve the nerve function. Eight of the 14 patients recorded minimal nerve deficits after surgery. Three of the 6 patients with postoperative
motor or sensory deficits completely recovered. Two of the 3 patients with nerve reconstruction had persistent nerve deficits at the final follow-up. Patient 8 had a very large (18 cm long) sausage-like mass in proximal ulnar nerve. In patient 11, the lesion was located in the
FIGURE 8. Coronal T2-weighted MR image of the right thigh shows a round lesion (arrowhead) eccentrically located in the distribution of the sciatic nerve. The lesion had predominantly high-signal intensity. * 2013 Lippincott Williams & Wilkins
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located proximally to the extremity will be less predictable than distally located lesions. Nevertheless, early detection and treatment of neurilemmomas can prevent complications. In conclusion, most neurilemmomas can be safely and adequately removed and nerve function usually can be preserved or restored by appropriate surgery. Our results indicate that neurilemmomas can be removed by enucleation with an acceptable risk of injury to the nerve. If nerve fascicles are damaged during enucleation, the nerve gaps can be reconstructed with sural nerve grafts to preserve the nerve function. REFERENCES 1. Holdsworth BJ. Nerve tumours in the upper limb. A clinical review. J Hand Surg Br. 1985;10:236Y238. 2. Stack HG. Tumours of the hand. Postgrad Med J. 1964;40:290Y298. 3. El-Sherif Y, Sarva H, Valsamis H. Clinical reasoning: an unusual lung mass causing focal weakness. Neurology. 2012;78:e4Ye7. 4. Das Gupta, Brasfield RD, Strong EW, et al. Benign solitary schwannomas (neurilemomas). Cancer. 1969;24:355Y366. 5. Donner TR, Voorhies RM, Kline DG, et al. Neural sheath tumors of major nerves. J Neurosurg. 1994;81:362Y373. 6. Louis DS, Hankin FM. Benign nerve tumors of the upper extremity. Bull N Y Acad Med. 1985;61:611Y620. 7. Russell SM. Preserve the nerve: microsurgical resection of peripheral nerve sheath tumors. Neurosurgery. 2007;61:ONS-113YONS-118.
FIGURE 10. Patient 13 was a 40-year-old man with 2 neurilemomas, one involving the median nerve of the left forearm and the other involving the ulnar nerve of the left hand (arrowheads). On contrast-enhanced CT, neurilemmomas demonstrated homogeneous hypodensity with thin-smooth contrast enhancement at the margin and irregular enhancement at the centrum.
sciatic nerve trunk at proximal thigh, which inf luenced nerve recovery even with meticulous reconstruction. Holdsworth1 reported good results after repair of the excised gap with sural nerve grafts. It is clear that a graft repaired nerve can never function perfectly. The functional result of tumor enucleation from nerve trunk with totally intact fascicle is better compared to a notable fascicle gap with graft reconstruction or without. The result of neurilemmoma lesions
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8. Ozdemir O, Ozsoy MH, Kurt C, et al. Schwannomas of the hand and wrist: long-term results and review of the literature. J Orthop Surg (Hong Kong). 2005;13:267Y272. 9. Kim DH, Murovic JA, Tiel RL, et al. Operative outcomes of 546 Louisiana State University Health Sciences Center peripheral nerve tumors. Neurosurg Clin N Am. 2004;15:177. 10. Pilavaki M, Chourmouzi D, Kiziridou A, et al. Imaging of peripheral nerve sheath tumors with pathologic correlation: pictorial review. Eur J Radiol. 2004;52:229. 11. Nilsson J, Sandberg K, Nielsen N, et al. Magnetic resonance imaging of peripheral nerve tumours in the upper extremity. Scand J Plast Reconstr Surg Hand Surg. 2009;43:153Y159. 12. Hung YW, Tse WL, Cheng HS, et al. Surgical excision for challenging upper limb nerve sheath tumours: a single centre retrospective review of treatment results. Hong Kong Med J. 2010;16:287Y291. 13. Agrawal A, Singh GK, Rauniyar RK, et al. CT characteristics of dumbbell schwannomma arising from the fifth cervical nerve root. Eur J Gen Med. 2009;6:123Y126.
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