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Diagnosis and management of extracranial head and neck schwannomas: a review of 27 cases.

1. Introduction

Schwannoma is a benign neural sheath tumor, and it occurs in overall body areas including the head and neck region. As a slowly growing benign tumor, it has been reported that 25 to 45% of schwannomas were located in the extracranial head and neck region [1]. It involves the cranial nerves such as V, VII, X, XI, and XII or sympathetic and peripheral nerves [2].

Preoperative diagnostic investigations included ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), and fine needle aspiration cytology (FNAC) [3-5]. However, the preoperative diagnosis of schwannoma is difficult and should be suggested by clinical features and supported by investigations.

As for the management of schwannomas, multiple treatment options exist including observation, complete tumor excision, and intracapsular enucleation [6, 7]. For tumors arising from the major cranial nerves, complete tumor resection renders lifelong morbidity to the patients. On the other hand, the nerve-preserving excision method, such as intracapsular enucleation, does not guarantee intact nerve function after surgery. Because of the substantial chance of nerve palsy after operation, obtaining an accurate preoperative diagnosis, and preferably, with the identification of the nerve of origin is crucial to the management of the disease.

In the present study, clinical records of 27 cases with extracranial head and neck schwannoma treated at our department were retrospectively reviewed.

2. Methods

Between 2003 and 2010, 27 patients with extracranial head and neck schwannoma were operated on in the Department of Otorhinolaryngology at Kyushu University Hospital. The data for the 27 patients, consisting of 14 males and 13 females, were analyzed. The subjects' ages ranged from 21 to 80 years, with a median age of 51 years. All cranial nerves were normal, and no Horner's syndrome was noted. Clinical history, surgical data, and postoperative morbidity were obtained. US were performed in all cases. Seven patients underwent CT with or without MRI. Twenty-five patients underwent MRI. Fine needle aspiration cytology (FNAC) was performed for 12 of the 27 patients after imaging. Tumor location, size, and demographic data are described in Table 1. The medical records of these patients were reviewed.

3. Results

3.1. Imaging Findings. The images of US typically showed a well-defined, ovoid or round, hypoechoic, and primarily homogeneous solid mass with or without a moderate posterior acoustic enhancement. None of them showed a direct connection to the nerve.

Seven of 27 patients underwent CT. Five patients (71%) had tumors that were hypoattenuated, with poor enhancement compared with adjoining skeletal muscles. Two tumors (29%) were isoattenuated to skeletal muscle. Only one of seven cases (14%) was able to suggest the diagnosis of schwannoma.

At MRI, all 25 schwannomas revealed relatively low signal intensity on T1-weighted imaging and signal hyperintensity on T2-weighted imaging, with 11 tumors (44%) showing homogeneously high intensity, and 14 tumors (56%) showing heterogeneously high intensity. There were no flow voids seen in any of the tumors. Twenty (80%) suggested the diagnosis of schwannoma. Figure 1 demonstrates the characteristic features of schwannomas on T1- and T2-weighting MRI. Depending on the site, a number of differential diagnoses were suggested including carotid body tumor, branchial cervical cyst, submandibular tumor, and metastases.

3.2. Fine Needle Aspiration Cytology (FNAC). From these 27 patients, 12 received fine needle aspiration cytology. Only three cases (25%) displayed a specific diagnosis of schwannoma rendered on preoperative FNAC.

3.3. Treatment and Neural Function Outcome. All of the tumors were resected through a transcervical approach. The nerve of origin was mainly determined by the postoperative neurological findings. The distribution of 27 nerve of origins was 10 (37%) vagus nerves, 6 (22%) sympathetic trunks, 5 (19%) cervical plexuses, 3 (11%) brachial plexuses, 2 (7%) hypoglossal nerves, and 1 (4%) accessory nerve (Figure 2).

Complete tumor resection was performed on 11 patients, and intracapsular enucleation of the tumor was performed on 16 patients (Figure 3). The preoperative and postoperative neurological functions were evaluated. The rate of nerve palsy at 6 months after complete tumor resection and intracapsular enucleation was 100 (11/11) and 31% (5/16), respectively. In the cases treated with intracapsular enucleation, only one case (20%) maintained normal postoperative neurological function of the five vagal schwannomas. Of the two sympathetic schwannomas, one case (50%) maintained normal postoperative neurological function. In the case of cervical plexus, brachial plexus, and accessory nerve schwannomas, there were no aggravated neurological deficits. In the cases with postoperative nerve palsy treated by intracapsular enucleation, 6 of 11 cases recovered from the palsy within 6 months after operation (Table 2).

4. Discussion

Schwannomas are benign tumors that originate from the Schwann cells of the nerve sheath. Schwann cells are neural crest-derived glial cells that are responsible for providing myelin insulation to peripheral nervous system axons [8]. There are several important issues relating to the diagnosis and management of these tumors.

The first of these is difficulty with obtaining a preoperative diagnosis, since symptoms are usually nonspecific [9]. Symptoms, such as severe pain or cranial nerve palsy, would be unusual for these tumors. On examination, these benign masses are typically palpable. In treating schwannoma patients, it is critical to determine the origin of the tumor to preserve nerve function. Some authors suggest that preoperative evaluation with imaging modalities like CT and MRI in determining the nerve of origin may reduce the postoperative neural deficits [5,10].

In terms of preoperative investigations, FNAC, US, and radiographic imaging with CT or MRI are usually performed. However, schwannomas are frequently difficult to characterize on FNAC. Liu et al. reported that the accuracy of FNAC was only 20% [11]. Our results also showed that only three cases (25%) displayed a specific diagnosis of schwannoma. It was not found to be of help in diagnosis.

In the current study, US, was performed in all cases. King et al. showed that schwannomas are highly vascular tumors with an abundance of vessels and blood flow, and the direct connection to the nerve is specific to neurogenic tumors [12]. Although two of five cases showed a direct connection to the nerve in other literature [5], these findings were not detected on US in our cases and were not sensitive enough to use this method.

On noncontrast CT, it was reported that schwannomas were typically hypodense versus muscle; with contrast, these lesions tended to show some peripheral enhancement [10]. Only one case (14%) in our study was able to suggest the diagnosis of schwannoma by CT and clinical features. On the other hand, MRI consistently identifies these lesions on both T1- and T2-weighted imaging. T1-weighted images display low signal intensity, and T2-weighted images show high intensity [5,10,13]. Hirano et al., also reported that MRI was especially useful for the diagnosis and peripheral hyperin tense rim with central low intensity on enhanced T1 images of MRI [14]. The relationship between the schwannoma and its nerve of origin can be better appreciated with MRI than CT. In addition, MRI appears to be the investigation of choice for diagnosis and identification of nerve of origin. In our cases, twenty cases (80%) suggested the diagnosis of schwannoma. These results indicate that MRI is most sensitive and specific in the diagnosis of schwannoma [5]. The authors propose an algorithm for the management of extracranial head and neck schwannoma (Figure 4).

The decision of operation should be based on the balance between the risk and benefit of the surgery, that is, the severity of preoperative symptomatology and the anticipated postoperative neurological deficit. Surgical excision is the treatment of choice, but slow growth and the noninvasive nature of schwannomas of the neck also allow an observational approach. The preferred method of removing a schwannoma is intracapsular enucleation. Complications are usually transient and in most cases do not require treatment. According to the study by Valentino et al., intracapsular enucleation while preserving the nerve fibers preserved its function by more than 30% when compared to complete tumor resection [7]. In our cases, the rate of nerve palsy at 6 months after complete tumor resection and intracapsular enucleation was 100% and 31%, and none of them recurred more than two years from the operation. These results suggested that intracapsular enucleation was an effective and feasible method for preserving the neurological functions.

In conclusion, cervical schwannomas are rare neck tumors that are not widely discussed in the core surgical literature. Physicians who evaluate neck masses need to be aware of the diagnostic work-up, surgical treatment, and likely complications of this pathology. In addition, treatments assuring the preservation of neurological functions are needed, since surgical resection may cause fatal nerve damage unlike other tumors. An accurate preoperative diagnosis with identification of the nerve of origin, therefore, allows patients to make an informed decision on whether to undergo operation or observation. In addition, before the surgical procedure, we could explain the possible nerve damages to patients.

http://dx.doi.org/10.1155/2013/973045

References

[1] B. S. Ducatman, B. W. Scheithauer, D. G. Piepgras, H. M. Reiman, and D. M. Ilstrup, "Malignant peripheral nerve sheath tumors: a clinicopathologic study of 120 cases," Cancer, vol. 57, no. 10, pp. 2006-2021, 1986.

[2] M. P. Colreavy, P. D. Lacy, J. Hughes et al., "Head and neck schwannomas--a 10 year review," Journal of Laryngology and Otology, vol. 114, no. 2, pp. 119-124, 2000.

[3] Y. S. Leu and K. C. Chang, "Extracranial head and neck schwannomas: a review of 8 years experience," Acta Oto-Laryngologica, vol. 122, no. 4, pp. 435-437, 2002.

[4] R. N. Satarkar, S. S. Kolte, and S. K. Vujhini, "Cystic schwannoma in neck: fallacious diagnosis arrived on fine needle aspiration cytology," Diagnostic Cytopathology, vol. 39, pp. 866-867, 2011.

[5] Y. N. Kami, T Chikui, K. Okamura et al., "Imaging findings of neurogenic tumours in the head and neck region," Dentomax-illofacial Radiology, vol. 41, pp. 18-23, 2012.

[6] M. J. Gibber, J. P. Zevallos, and M. L. Urken, "Enucleation of vagal nerve schwannoma using intraoperative nerve monitoring," Laryngoscope, vol. 122, pp. 790-792, 2012.

[7] J. Valentino, M. A. Boggess, J. L. Ellis, T O. Hester, and R. O. Jones, "Expected neurologic outcomes for surgical treatment of cervical neurilemomas," Laryngoscope, vol. 108, no. 7, pp. 1009-1013, 1998.

[8] M. A. Shugar, W. W. Montgomery, and E. J. Reardon, "Management of paranasal sinus schwannomas," Annals of Otology, Rhinology and Laryngology, vol. 91, no. 1, pp. 65-69, 1982.

[9] J. D. Suh, V R. Ramakrishnan, P. J. Zhang et al., "Diagnosis and endoscopic management of sinonasal schwannomas," ORL--Journal for Otorhinolaryngology and Its Related Specialties, vol. 73, pp. 308-312, 2011.

[10] G. Anil and T. Y. Tan, "Imaging characteristics of schwannoma of the cervical sympathetic chain: a review of 12 cases," American Journal of Neuroradiology, vol. 31, no. 8, pp. 1408-1412, 2010.

[11] H. L. Liu, S. Y. Yu, G. K. Li, and W. I. Wei, "Extracranial head and neck schwannomas: A Study of the Nerve of Origin," European Archives of Oto-Rhino-Laryngology, vol. 268, pp. 1343-1347, 2011.

[12] A. D. King, A. T Ahuja, W. King, and C. Metreweli, "Sonography of peripheral nerve tumors of the neck," American Journal of Roentgenology, vol. 169, no. 6, pp. 1695-1698, 1997

[13] T Tomita, H. Ozawa, K. Sakamoto, K. Ogawa, K. Kameyama, and M. Fujii, "Diagnosis and management of cervical sympathetic chain schwannoma: a review of 9 cases," Acta Oto-Laryngologica, vol. 129, no. 3, pp. 324-329, 2009.

[14] S. Hirano, H. Kitamura, K. Miyata et al., "Extracranial neurinomas of head and neck," Jibiinkouka Rinsyo, vol. 87, pp. 253-257, 1994 (Japanese).

Ryuji Yasumatsu, Torahiko Nakashima, Rina Miyazaki, Yuichi Segawa, Shizuo Komune

Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan

Correspondence should be addressed to Ryuji Yasumatsu; yasuryuj@qent.med.kyushu- u.ac.jp

Received 16 March 2013; Revised 9 April 2013; Accepted 13 April 2013

Academic Editor: Peter S. Roland

TABLE 1: Demographic data, radiological findings,
and fine needle aspiration cytology.

Case   Gender   Age   Nerve origin        Tumor size

1      M        54    Vagus nerve         50 x 42 x 40 mm
2      M        40    Vagus nerve         100 x 45 x 40 mm
3      M        58    Vagus nerve         45 x 35 x 33 mm
4      F        37    Vagus nerve         50 x 40 x 42 mm
5      F        68    Vagus nerve         80 x 35 x 35 mm
6      F        32    Vagus nerve         20 x 18 x 15 mm
7      F        80    Vagus nerve         30 x 25 x 25 mm
8      F        61    Vagus nerve         30 x 28 x 20 mm
9      M        54    Vagus nerve         27 x 25 x 25 mm
10     F        49    Vagus nerve         30 x 25 x 25 mm

11     M        52    Sympathetic trunk   70 x 35 x 35 mm
12     M        47    Sympathetic trunk   30 x 28 x 22 mm
13     M        79    Sympathetic trunk   45 x 25 x 20 mm
14     F        35    Sympathetic trunk   40 x 30 x 25 mm

15     F        54    Sympathetic trunk   30 x 28 x 25 mm
16     M        62    Sympathetic trunk   35 x 25 x 20 mm
17     F        42    Cervical plexus     60 x 35 x 33 mm
18     M        50    Cervical plexus     35 x 30 x 30 mm
19     M        21    Cervical plexus     40 x 35 x 33 mm
20     F        55    Cervical plexus     68 x 45 x 40 mm
21     F        54    Cervical plexus     20 x 18 x 15 mm
22     F        31    Brachial plexus     20 x 15 x 15 mm
23     M        34    Brachial plexus     30 x 30 x 25 mm
24     M        60    Brachial plexus     45 x 40 x 25 mm
25     M        32    Hypoglossal nerve   50 x 35 x 35 mm
26     F        57    Hypoglossal nerve   30 x 30 x 25 mm
27     F        69    Accessory nerve     40 x 30 x 30 mm

Case   CT               MRI               FNAC

1      ND               Schwannoma        Schwannoma
2      ND               Glomus tumor      ND
                         or schwannoma
3      ND               Glomus tumor      ND
                          or schwannoma
4      ND               Schwannoma        Nondiagnostic
5      Schwannoma       Schwannoma        ND
6      Cervical tumor   Schwannoma        Nondiagnostic
7      Cervical tumor   Schwannoma        ND
8      Cervical tumor   Schwannoma        Nondiagnostic
9      Cervical tumor   ND                ND
10     ND               Glomus tumor      Nondiagnostic
                          or schwannoma
11     ND               Schwannoma        ND
12     ND               Schwannoma        ND
13     ND               Schwannoma        ND
14     ND               Glomus tumor      ND
                        or schwannoma
15     ND               Schwannoma        ND
16     ND               Glomus tumor      ND
17     ND               Schwannoma        Schwannoma
18     Cervical tumor   Schwannoma        ND
19     ND               Schwannoma        Nondiagnostic
20     ND               Schwannoma        Schwannoma
21     ND               Schwannoma        Nondiagnostic
22     ND               Schwannoma        Nondiagnostic
23     ND               Schwannoma        ND
24     ND               Schwannoma        Schwannoma
25     ND               Schwannoma        ND
26     Submandibullar   ND                Nondiagnostic
       gland tumor
27     ND               Schwannoma        ND

ND: not done.

TABLE 2: Neural function outcome after tumor intracapsular
enucleation.

Case   Nerve origin      Preoperative   Post-         6 months after
                         status         operrative      operation
                                        status

6      Vagus nerve       Normal         Vocal cord    Vocal cord
                                          paralysis     paralysis
7      Vagus nerve       Normal         Vocal cord    Vocal cord
                                          paralysis     paralysis
8      Vagus nerve       Normal         Vocal cord    Vocal cord
                                          paralysis     paralysis
9      Vagus nerve       Normal         Vocal cord    Vocal cord
                                          paralysis     paralysis
10     Vagus nerve       Normal         Normal        Normal
14     Sympathetic       Normal         Ptosis        Ptosis
         trunk
15     Sympathetic       Normal         Ptosis        Normal
         trunk                                          (improved)
17     Cervical plexus   Normal         Paralysis     Normal
                                                        (improved)
18     Cervical plexus   Normal         Paralysis     Normal
                                                        (improved)
19     Cervical plexus   Normal         Normal        Normal
20     Cervical plexus   Normal         Normal        Normal
21     Cervical plexus   Normal         Normal        Normal
22     Brachial plexus   Normal         Paralysis     Normal
                                                        (improved)
23     Brachial plexus   Normal         Paralysis     Normal
                                                        (improved)
24     Brachial plexus   Normal         Paralysis     Normal
                                                        (improved)
27     Accessory nerve   Normal         Normal        Normal

FIGURE 2: The nerve of origin of 27
extracranial head and neck schwannomas

Accessory nerve     4%
Hypoglossal nerve   7%
Brachial plexus     11%
Cervical            19%
Sympathetic truck   22%
Vagus nerve         37%

Note: Table made from pie graph.

FIGURE 3: Operation method.

Intracapsular   59%
enucleation

Resection       41%

Note: Table made from bar graph.
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Article Details
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Title Annotation:Clinical Study
Author:Yasumatsu, Ryuji; Nakashima, Torahiko; Miyazaki, Rina; Segawa, Yuichi; Komune, Shizuo
Publication:International Journal of Otolaryngology
Article Type:Report
Date:Jan 1, 2013
Words:2596
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