European Archives of Oto-Rhino-Laryngology

, Volume 267, Issue 5, pp 765–772

Transoral and combined transoral–transcervical approach in the surgery of parapharyngeal tumors

Authors

  • Jan Betka
    • Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Faculty Hospital MotolCharles University
    • Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Faculty Hospital MotolCharles University
    • Institute of Anatomy, 1st Faculty of MedicineCharles University
    • Center for Cell Therapy and Tissue Repair, 2nd Faculty of MedicineCharles University
  • Jan Klozar
    • Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Faculty Hospital MotolCharles University
  • Miloš Taudy
    • Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Faculty Hospital MotolCharles University
  • Jan Plzák
    • Department of Otorhinolaryngology and Head and Neck Surgery, 1st Faculty of Medicine, Faculty Hospital MotolCharles University
    • Institute of Anatomy, 1st Faculty of MedicineCharles University
    • Center for Cell Therapy and Tissue Repair, 2nd Faculty of MedicineCharles University
  • Dana Kodetová
    • Institute of Pathology and Molecular Medicine, 2nd Faculty of MedicineCharles University
  • Jiří Lisý
    • Department of Radiodiagnostics, 2nd Faculty of MedicineCharles University
Head & Neck

DOI: 10.1007/s00405-009-1071-z

Cite this article as:
Betka, J., Chovanec, M., Klozar, J. et al. Eur Arch Otorhinolaryngol (2010) 267: 765. doi:10.1007/s00405-009-1071-z

Abstract

The goal of parapharyngeal space (PPS) tumor surgery is to obtain adequate visualization to ensure complete removal with preservation of the surrounding nerves and vessels. Different surgical approaches have been described. Transoral approach is the most controversial one due to cited limited exposure, risk of tumor spillage, and possibility of neurovascular injury. We performed retrospective analysis of 26 consecutive patients who had undergone transoral or combined transoral–transcervical resection of PPS tumors from January 1997 to December 2007. Both approaches were safely employed to remove selected PPS tumors. Majority of treated tumors were pleomorphic adenomas (14 minor salivary gland and 7 deep lobe parotid gland tumors). Two cases of malignant salivary gland tumors, 4 nerve sheath tumors and 1 lymphangioma were also excised. Mean tumor size was 6.1 cm (range 2–11 cm). Visualization was felt to be adequate and dissection safe. Radical resection was achieved in 24 cases. Near-total resection was achieved in two cases where otherwise other approach would be suitable but cannot be undertaken because of patient refusal and comorbidities. Patients with malignant tumors had postoperative radiotherapy. Radically treated cases are disease free. One of the near-totally resected tumors needed revision surgery. Neither major complications nor disordered healing were observed. Transoral approach provides access to selected cases of PPS tumors based on preoperative imaging methods and fine-needle aspiration cytology. Risk of non-radical resection is acceptable. It can be combined with external approach to achieve safe resection of some benign tumors which would need transmandibular approach.

Keywords

Parapharyngeal spaceTransoral approachExternal approachSurgerySalivary glandTumorNerve sheath tumor

Introduction

Parapharyngeal space (PPS) is deep potential neck space shaped like an inverted pyramid extending from the base of the skull to the hyoid bone. It may be divided into two compartments (pre- and post-styloid) on the basis of its relationship to the tensor-vascular-styloid fascia. Tumors arising in the PPS comprise less than 1% of head and neck neoplasms [1]. Wide variety of histological types have been described in this location but neoplasms in this area most often represent salivary gland or neurogenic tumors.

Clinically, its difficult to access the parapharyngeal space, therefore imaging methods are vital part of the evaluation of these patients. The main objectives are to determine extent of the lesion, to assess its resectability, to delineate its relationship to the carotid artery and skull base and eventual intracranial spread. Both MRI and CT provide excellent imaging of the PPS [2]. These help to differentiate pre- from a post-styloid tumors, deep lobe of parotid gland origin and vascular lesions (e.g., paragangliomas) which are critical for differential diagnosis, further workup as well as choice of surgical approach. Fine-needle aspiration biopsy represents safe method significantly contributing to the preoperative evaluation [3].

The majority of tumors in this region are benign, and surgical excision is the primary treatment. Many surgical procedures have been described [4]. The goal of parapharyngeal surgery is to obtain adequate tumor visualization to ensure complete tumor removal with preservation of the surrounding nerves and vessels and to control any hemorrhage. Surgical approaches to tumors of the parapharyngeal space can be classified as: transoral, transcervical–submandibular, transcervical, transparotid, modified transcervical (transcervical–transparotid, transcervical–transmastoid, transcervical with mandibular osteotomy), transmandibular and lateral skull base approaches [5].

The transoral approach is the most controversial one. Problems with this approach cited are limited exposure, increased risk of tumor spillage, and possibility of neurovascular injury. In large studies it is usually mentioned as the approach rarely used in selected cases of small circumscribed tumors [6].

This retrospective review focuses on the feasibility of transoral and combined transoral–transcervical approaches to parapharyngeal space tumors.

Methods

We retrospectively reviewed the medical records of 137 patients surgically treated for parapharyngeal space tumors in the Department of Otorhinolaryngology and Head and Neck Surgery, Faculty Hospital Motol, 1st Faculty of Medicine, Charles University, Prague, Czech Republic, between January 1997 and December 2007 (Table 1). Transoral approach was used in 23 patients and combined transoral–transcervical approach in three patients. Only patients who have undergone transoral or combined transoral–transcervical approach were subjected to further analysis. 22 patients (85%) had primary surgery. In 4 patients (15%) revision surgery was performed (primary surgery were undertaken elsewhere: 2 transoral; 1 transoral and transparotid; 1 transoral, transparotid-transcervical and transmandibular). In all 26 patients surgery was attempted with intention of radical resection.
Table 1

Summary data on treatment of parapharyngeal space tumors in our center

Variable

Value

Total no. of surgically treated patients

137

Male/female

52/85

Benign/malignant

115/22

Primary surgery/revision surgery

124/13

TC

54

TC–SM

13

TP

26

TM

6

IT

12

TO

23

TO–TC

3

The treatment period was January 1997 and December 2007

TC transcervical approach, TC–SM transcervical–submandibular approach, TP transparotid approach, TM transmandibular approach, IT infratemporal approach, TO transoral approach, TO–TC combined transoral–transcervical approach

There were 16 women (61%) and 10 men (39%) (Table 2). All patients were White Caucasians. Their ages varied from minimum of 17 to maximum of 76 years (mean 50.2 years). The most frequent clinical symptom was bulging oropharyngeal mass (25 cases). In two cases there was also upper neck mass; one patient had CN X dysfunction. Two patients suffered form conductive hearing loss due to Eustachian tube compression. One patient was asymptomatic, diagnosed with parapharyngeal tumor on MRI for unrelated condition.
Table 2

Patient and tumor characteristics of treated tumors

Case

Gender

Age

Diagnosis

Size (cm)

Approach

Radicality

Other treatment

Minor salivary gland tumors

1

M

70

PLA r

10 × 6 × 5

TO

R

 

2

M

76

PLA r

6 × 4 × 3

TO

R

 

3

M

21

PLA l

6 × 4 × 4

TO

R

 

4

F

34

PLA l

10 × 8 × 4

TO

R

 

5

F

73

PLA l

7 × 4.5 × 4

TO

R

 

6

F

55

PLA r

6 × 5.5 × 3.5

TO

R

 

7

F

51

PLA r

4.5 × 3 × 3

TO

R

 

8

F

67

Well differentiated adenocarcinoma r

4 × 3 × 2

TO

R

RT

9

M

27

PLA r

9 × 7 × 6

TO–TC

R

 

10

F

76

PLA r (revision)

5 × 4.5 × 4.5

TO

NT

 

11

M

17

PLA l

10 × 7 × 7

TO–TC

R

 

12

M

52

PLA l

4 × 3 × 2

TO

R

 

13

F

68

PLA r

3 × 3 × 2

TO

R

 

14

M

55

PLA l

11 × 8 × 6

TO

R

 

Deep lobe parotid gland tumors

1

F

68

PLA l (revision)

5 × 3 × 2

TO

R

 

2

M

37

PLA l (revision)

7 × 5 × 4

TO

NT

Revision SG

3

F

54

PLA l

5 × 4.5 × 3

TO

R

 

4

F

72

PLA l (revision)

6 × 5 × 4

TO

R

 

5

F

36

PLA r

5 × 4 × 4

TO

R

 

6

F

52

Adenocarcinoma in PLA l

5.5 × 5 × 3.5

TO

R

RT

7

F

53

PLA r

5.5 × 3 × 3

TO

R

 

Schwannoma/neurofibroma

1

M

42

CN X schwannoma l

6 × 5 × 4

TO–TC

R

 

2

M

39

Sympathetic trunk schwannoma r

5.5 × 4 × 3

TO

R

 

3

F

26

Neurofibroma r (Recklinghausen′s disease)

4 × 2 × 2

TO

R

 

4

F

59

Schwannoma r

6 × 3 × 2

TO

R

 

Miscellaneous

1

F

26

Lymphangioma r

2 × 2 × 1

TO

R

 

PLA pleomorphic adenoma, r right, l left, TO transoral approach, TO–TC combined transoral–transcervical approach, R radical resection, NT near-total resection, RT adjuvant external beam radiation, SG surgery

Preoperative evaluation and selection of patients

Before treatment all patients had cross-sectional imaging (CT and/or MRI): 75% had MRI and 70% had CT; 18 patients had undergone ultrasonography and 1 patient angiography. Of the newly diagnosed 22 cases fine-needle aspiration biopsy and cytopathologic examination were undertaken in 18 patients. It was diagnostic in 15 cases (85%).

Only tumors with imaging characteristics excluding the possibility of hypervascular tumors (e.g., paragangliomas), sharply demarcated from surrounding tissues, medially from major neck vessels, non-dumbbell shaped (except one case) without the expectancy of malignancy were attempted to radically resect transorally.

Transoral approach was undertaken for 19 cases of salivary gland tumors. In two cases of salivary gland tumors, approach was combined transoral–transcervical. In two cases with known previous histology of pleomorphic adenoma, where otherwise the transmandibular approach would be suitable but not undergone because of poor medical condition (revision surgery for minor salivary gland pleomorphic adenoma in 72-year-old woman) and refusal of mandibulotomy (third revision surgery in 37-year-old man with multilocular deep lobe parotid gland pleomorphic adenoma located solely in prestyloid compartment), we also attempted radical transoral resection. Thirteen of the new diagnosed cases were well demarcated tumors in the pre-styloid compartment with imaging characteristics suggestive of minor salivary gland pleomorphic adenomas confirmed cytopathologically in eight cases. In six cases the tumors were deep lobe parotid gland tumors according the imaging methods. Four tumors were non-dumbbell shaped connected with the gland by the thin bridge of normally appearing tissue. However, one tumor was dumbbell shaped with major part protruding to the pre-styloid compartment and minor part in the deep lobe of parotid gland in front of the constriction of widened stylomandibular tunnel (Fig. 1). Again all the tumors had imaging characteristics of possible pleomorphic adenoma and were well demarcated from the surrounding tissues. Cytopathologic diagnosis was known in five cases.
https://static-content.springer.com/image/art%3A10.1007%2Fs00405-009-1071-z/MediaObjects/405_2009_1071_Fig1_HTML.jpg
Fig. 1

Transoral resection of right dumbbell shaped deep lobe parotid gland pleomorphic adenoma. a Preoperative bulging of lateral oropharyngeal wall; b preoperative CT of tumor, only small extension to the stylomandibular canal is noted, but the tumor was dumbbell shaped and resection necessitated transoral stylomandibular ligament sectioning; c postoperative facial nerve function; d postoperative CT

Transoral approach was used in two schwannomas and one neurofibroma. Combined transoral–transcervical approach was employed in one schwannoma. One lymphangioma was resected transorally. In cases of schwannomas the diagnosis was based on imaging characteristics and confirmed in two cases by cytopathology. Patient with neurofibroma had known diagnosis of von Recklinghausen’s disease. All of the nerve sheath tumors were well demarcated masses in the post-styloid compartment neither extending to nor through the foramina of the skull base. Only one patient had preoperative neurologic deficit of vagus nerve (CN X). Diagnosis of small lymphangioma was based on MRI imaging characteristics.

Surgical technique

Under general anesthesia with orotracheal intubation with armed tracheal canula, the mouth gag has been inserted. If the tonsil was present tonsillectomy was performed first. In other cases mucosa was incised over the bulging tumor. In large tumors, the incision was prolonged to the soft palate. Muscle fibers of superior pharyngeal constrictor were incised. After identification of the tumor careful tissue-conserving dissection was performed between the tumor capsule and surrounding tissues. Dissection proceeded from medial surface to the superior and inferior pole, than anteriorly and posteriorly. The lateral surface was dissected last (Fig. 2). In one case of dumbbell shaped deep lobe parotid gland tumor, the stylomandibular ligament was transected and then the dissection of the remaining part of the tumor from the parotid gland proceeded easily (Fig. 1). In one case of schwannoma of sympathetic trunk, we performed first internal debulking of the tumor and then separated the tumor capsule from the internal carotid artery.
https://static-content.springer.com/image/art%3A10.1007%2Fs00405-009-1071-z/MediaObjects/405_2009_1071_Fig2_HTML.jpg
Fig. 2

Transoral resection of right poststyloid schwannoma. a Preoperative T2W MRI showing tumor located medially from the internal carotid artery; b postoperative MRI; c lateral surface of the tumor is dissected last; d arrow showing the deliberated internal carotid artery after tumor removal

In three cases (2 pleomorphic adenomas and 1 schwannoma of CN X) tumors were deliberated in more than 80% of its surface from the surrounding tissues and structures; however, it was not possible to separate tumor from the main neck vessels under the clear visual control. Thus, the last part of dissection continued from the external transcervical approach after identification of parapharyngeal cranial nerves, carotid bifurcation, its branches and internal jugular vein (Fig. 3).
https://static-content.springer.com/image/art%3A10.1007%2Fs00405-009-1071-z/MediaObjects/405_2009_1071_Fig3_HTML.jpg
Fig. 3

Combined transoral–transcervical resection of left giant pleomorphic adenoma of the minor salivary gland origin. a Preoperative T2W MRI; b transoral part of dissection from pharyngeal wall and skull base; c last part of dissection from the external transcervical approach after identification of parapharyngeal cranial nerves, carotid bifurcation, its branches and internal jugular vein; d tumor is removed

In all but the two cases (both revision surgeries where transmandibular approach would be preferred, see above) dissection proceeded smoothly. We found superior visual control of dissection over the upper parts of the tumor close to the skull base. After irrigation, the wound was closed in layers with absorbable suture material, making certain that the various muscle layers were accurately reaproximated to prevent velopharyngeal dysfunction. In combined transoral–transcervical approach, external wound was closed in layers. Nasogastric tube was inserted at the end of the procedure. Mean operating time was 80 min (minimum 40 min, maximum 180 min). All procedures and healing were performed under antibiotic coverage (cefuroxim). Nasogastric tube was removed after 2–10 days (average 3.7 days) and patients were started on liquid diet.

Results

Between January 1997 and December 2007, we used transoral approach in 23 patients (17%) and combined transoral–transcervical approach in 3 patients (2%) of 137 patients with parapharyngeal space tumors (Table 1). In all 26 patients surgery was attempted with intention of radical resection.

In 24 cases (92%) we were able to perform radical resection of the tumor. Of the radically operated cases there were 18 pleomorphic adenomas, 2 adenocarcinomas, 4 schwannomas, 1 neurofibroma and 1 lymphangioma. Mean tumor size was 6.1 cm (range 2–11 cm) (Table 2).

Transoral approach was used in 19 of cases of salivary gland tumors. In remaining two giant tumors we used combined transoral–transcervical approach (Fig. 3). In all seven cases of deep lobe of parotid gland tumors there was not any dysfunction of the facial nerve. In 17 of the tumor diagnosis of pleomorphic adenomas based on preoperative cytopathology was confirmed on definitive histopathology. Diagnosis of malignant salivary gland tumor on definitive histopathology was surprise in both of the remaining cases. In one of these tumors (well differentiated adenocarcinoma from the oxyphillic cells), the preoperative cytopathology was non-diagnostic and the working diagnosis of pleomorphic adenoma was based on preoperative MRI features. In the other case (low grade adenocarcinoma in pleomorphic adenoma), preoperative cytology was consistent with the diagnosis of pleomorphic adenoma. Both of these patients underwent adjuvant external radiotherapy and are disease free (5 and 6 years, respectively).

Of the surgically treated neurogenic tumors (Fig. 2), there was preoperative dysfunction of CN X in one case that was operated via combined transoral–transcervical approach. However, the cranial nerve was spared the function did not improve and patient underwent medialisation thyroplasty. In one case of schwannoma of sympathetic trunk there was postoperative Horner’s syndrome. In the remaining two cases of schwannoma and neurofibroma, there was not any pre- and post-operative cranial nerve dysfunction. Case of lymphangioma was resected radically.

Resection was near total in two cases where other approach would seem preferable (e.g., transmandibular) but not done due to poor medical condition and patient refusal. Both of the near-totally operated tumors were benign pleomorphic adenomas. In the first case suspicious residual tumor is stationary on repeated MRIs and clinically and patient feels free of the symptoms (pressure, hearing loss). In the second case we performed revision surgery 14 months later due to progression of residual tumor from the transcervical–submandibular approach modified with the angular osteotomy of the mandible. Patient is currently free of the disease.

All patients with radically removed tumors are without evidence of disease on repeated clinical visits and control MRI exams (mean follow-up 77 months, range 25–144 months). Healing was uneventful in all the cases. Excluding the above mentioned cranial nerve and sympathetic chain dysfunction in two of four cases of neurogenic tumors, we did not observe any functional problems including velopharyngeal incompetence or trismus. None of the most threatened complications (cranial nerve, carotid artery or internal jugular vein injury) or mortality was observed. Average length of hospital stay was 7 days (range 2–10 days). All patients after transoral surgery appreciated the absence of externally visible scar. In cases of combined approach, patients appreciated the absence of lip and mandible splitting and only small externally visible scar (4–5 cm, easily camouflaged to skin crease).

Concerning the surgical procedure, we found transoral approach advantageous to achieve visual control of dissection over the medial side and upper parts of the tumor close to the skull base. In cases where visual control of dissection over the lateral aspect of tumor was felt inadequate, the procedure was converted to combined transoral–transcervical approach. In neither of operated cases we had to convert for transmandibular approach.

During surgery, we encountered rupture of tumor pseudocapsule due to manipulation in two cases of pleomorphic adenomas. In both of these cases this neither influenced achievement of radical resection nor led to tumor spillage. Technique of internal debulking of schwannoma with the aim of cranial nerve origin preservation was successfully applied in one case. Because of potential risk for major vascular injury during each procedure vascular clips were prepared, neck draped for the purposes of eventual urgent neck exploration and interventional neuroradiologist prepared was on call. Transoral and combined transoral–transcervical approaches however gave the opportunity to dissect major neck vessels from tumors uneventfully.

Discussion

Parapharyngeal space is complex anatomic region located between the mandibular ramus laterally and pharyngeal wall medially and extending as an inverted pyramid from the skull base superiorly to the hyoid bone inferiorly. Within this potential space are cranial nerves IX, X, XI and XII, sympathetic chain, internal carotid artery, internal jugular vein, paraganglia, ectopic salivary glands and lymph nodes. Due to the complex anatomy, location and surrounding vital structures, resection of parapharyngeal space tumors is often challenging to the head and neck surgeon. Surgical approach to allow adequate tumor removal should meet two criteria: intraoperative visibility for safe radical dissection and minimal functional and cosmetic side effects of treatment. Presence of mandibular ramus prevents direct access to this region. Many surgical approaches have been described to parapharyngeal tumors. The choice of surgical approach is dependent on the location, extent, vascularity, and malignant potential. Transcervical approach provides direct access to the poststyloid compartment with adequate exposure of the neurovascular structures [5]. Transcervical–submandibular and transcervical–transparotid approaches are often used for resection of primary tumors in the prestyloid compartment [7]. Transparotid approach is preferred approach to the deep lobe parotid tumors [8]. Transmandibular approach is preferred approach for giant and vascular tumors, tumors extending to the upper portion of parapharyngeal space or whenever improved exposure of neurovascular structures is needed [9, 10]. Various forms of mandibular osteotomies have been described [11]. Transcervical–transmastoid and infratemporal approaches are chosen for tumors originating in the jugular foramen and extending to the parapharyngeal space [12]. All of the above described approaches are external approaches with some advantages and disadvantages (e.g., length of dissection, manipulation with neurovascular structures, mandibulotomy).

Transoral approach to the parapharyngeal space is applicable in selected cases of parapharyngeal abscesses [13]. Its use in surgery of parapharyngeal tumors is often discredited by many authorities [4, 14]. Among the stated disadvantages are limited exposure, increased risk of tumor spillage, and possibility of neurovascular injury. Goodwin and Chandler [6] have been the first authors presenting series of parapharyngeal tumors resected transorally in 1988. Since then only isolated cases were reported in the published literature [15, 16].

We present series of 26 patients who were operated for parapharyngeal tumors via transoral and combined transoral–transcervical approach, respectively. Both pre- and post-styloid tumors were treated. Patient selection was based on imaging methods and preoperative cytology. Minor salivary gland tumors, selected cases of deep lobe parotid gland tumors, nerve sheath tumors and lymphangioma were among the treated tumors. We were able to perform radical resection in all primary surgeries including the two unexpected malignant tumors. Radically treated patients are disease free. In two cases of reoperations for pleomorphic adenomas we achieved only near-total resection. In both cases other approach would seem preferable, but not undergone because of poor medical condition and patient refusal. One of these patients needed reoperation. In three of the cases transoral approach was combined with external approach to achieve safe resection in giant tumors. Superior visual control of dissection over the medial side and upper parts of the tumor close to the skull base, short surgical and hospitalization time and good cosmetic and functional outcome were observed. Complications were not encountered.

According to our experience, transoral approach can be viewed as safe in surgery of parapharyngeal tumors. In well selected cases the risk of non-radical resection is little and acceptable. It can be combined with external approach to achieve radical and safe resection. If transoral approach is considered, there is imminent need for preoperative information about the tumor characteristics to rule out hypervascular, dumbbell shaped and malignant tumors.

Copyright information

© Springer-Verlag 2009