---------------------------------------------------------------------------- TITLE: TUMORS OF THE PARAPHARYNGEAL SPACE SOURCE: Dept. of Otolaryngology, UTMB, Grand Rounds DATE: February 9, 1994 RESIDENT PHYSICIAN: Chris P. Thompson, M.D. FACULTY: Chris H. Rassekh, M.D. DATABASE ADMINISTRATOR: Melinda McCracken, M.S. ------------------------------------------------------------------------------- "This material was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion." I. Introduction A. Tumors of the parapharyngeal space are rare comprising about 0.5% of head and neck tumors B. Clinical examination of this location is difficult 1. patients are often asymptomatic 2. the tumors often reach large size by time of diagnosis 3. CT, MRI, and FNA are important in the diagnosis C. Most of the tumors are benign so minimizing the morbidity of the treatment is a necessity II. Anatomy A. Synonyms 1. lateral parapharyngeal space 2. peripharyngeal space 3. pharyngomasticatory space 4. pterygopharyngeal space 5. pterygomandibular space B. Inverted pyramid 1. floor a. skull base b. greater wing of the sphenoid including the foramen ovale and spinosum 2. apex - greater cornu of the hyoid 3. medial wall a. superior constrictor b. tensor veli palatini c. levator veli palatini 4. lateral wall a. medial pterygoid b. vertical ramus of the mandible c. deep portion of the parotid d. posterior belly of the digastric 5. posterior wall a. vertebral column b. paravertebral musculature 6. anterior boundary a. pterygomandibular raphe b. pterygoid fascia C. Parapharyngeal Space Compartments 1. styloid process and associated soft tissues a. directed anteriorly, inferiorly and medially b. divides the space into prestyloid and retrostyloid 2. prestyloid space contents a. inferior alveolar nerve b. lingual nerve c. internal maxillary artery 3. poststyloid (carotid space) contents a. internal jugular vein b. internal carotid artery c. cranial nerves IX, X, XI, XII d. sympathetic chain 4. lateral retropharyngeal space a. the pharyngobasilar fascia separating the parapharyngeal space from the nasopharynx turns medially as it approaches the vertebral column b. the portion of the parapharyngeal space adjacent to that turn is the lateral retropharyngeal space c. some authors consider the parapharyngeal and the retropharyngeal spaces to be continuous at this junction d. this space contains the node of Rouviere which is just inferior to the carotid foramen and medial to the in- ternal carotid artery 5. adjacent spaces communicating with the parapharyngeal space a. infratemporal fossa laterally i. masticator space ii. parotid space - the deep portion of the parotid abuts the parapharyngeal space b. retropharyngeal space posterolaterally c. submandibular space anteroinferiorly II. Presentation A. Presenting symptoms 1. painless mass is the most common a. bony boundaries permit only medial and inferior growth b. masses present as a medial soft palate displacement or as a mass at the angle of the mandible c. Carrau and Myers study of parapharyngeal space tumors i. salivary tumors demonstrated an 88% frequency of protrusion into the pharyngeal area but only in 7% of cases were neck masses noted ii. paragangliomas presented with neck masses 91% of the time and with oropharyngeal bulging in 17% of cases 2. pain on presentation occurs in approximately 20% of cases 3. dysphagia 13% 4. hoarseness 7% 5. foreign body sensation 6% 6. parotid mass 4% 7. otalgia 4% 8. trismus 2% 9. fatigue 2% B. Physical exam 1. consistent with above symptoms 2. true vocal cord paralysis discovered in 11% 3. thrill 2% 4. bruit 2% 5. CN V3 deficit 2% 6. CN XI deficit 2% 7. CN XII deficit 2% III. Diagnosis A. Clinical differentiation of tumor types 1. physical exam very nonspecific 2. malignant tumors are more often associated with pain and cranial neuropathies 3. the findings in Carrau's study may assist in clinical differentiation of salivary tumors versus paragan- gliomas B. CT scan 1. this has been the initial diagnostic study of choice until recently, but it is now felt that MRI is superior 2. continues to be the most frequently used initial diagnostic study because of availability 3. the flowchart is from a study demonstrating an 88% diagnostic accuracy of parapharyngeal tumor types using CT scan alone 4. first branch in the decision tree is to identify the presence or absence of a lucent zone between the mass and the parotid gland a. lucent zone represents fibrofatty tissue separating the parotid from an extraparotid mass b. the absence of this line indicates a deep parotid origin i. 90% sensitive in the diagnosis of a deep parotid mass ii. 10% of the time the large size of the mass was such that this fibrofatty tissue was obliterated 5. the next branches are determined by the presence or absence of tumor enhancement a. the enhancing lesions represent those with highly vascular characteristics or neural elements i. glomus tumors ii. meningiomas iii. neuromas/neurofibroma b. the nonenhancing lesions are further subdivided on the basis of their density i. isodense with muscle density usually indicates a minor salivary gland tumor, but may indicate a node, branchial cleft cyst, or a neurofibroma ii. low density masses were most commonly branchial cleft cysts, but abscesses, necrotic nodes, neuro- fibromas with fatty infiltration, jugular vein throm- bosis, and lipomas all presented in this fashion C. Angiography 1. in the past all enhancing masses were subsequently evaluated with angiography 2. the study described above determined that in virtually every case, the radiologic diagnosis could be made without the use of angiography 3. currently, angiography is indicated for the highly vascular tumors like the paragangliomas in which emboliza- tion therapy is being contemplated D. MRI 1. this is the modality of choice in parapharyngeal neoplasms 2. superior contrast resolution establishes precise tumor margins and normal anatomic structures 3. gives a better three dimensional assessment 4. there is no ionizing radiation, and contrast agent can usually be avoided 5. disadvantages i. suboptimal detection of calcification and subtle bony landmarks ii. additional cost iii. limited availablity IV. PATHOLOGY A. Salivary neoplasms 1. epidemiology i. most common tumor comprising anywhere from 30 - 50% of parapharyngeal neoplasms ii. less than 5% of parotid tumors extend into the parapharyngeal space 2. origin i. deep portion of the parotid a. most common origin of the parapharyngeal space tumors b. 20% of parotid tumors originate in the deep portion but only one quarter of these deep tumors will invade the pps c. pleomorphic adenoma most common tumor type d. mucoepidermoid carcinoma most frequent malignant type ii. minor salivary glands a. ectopic rests intrinsic to the pps b. pleomorphic adenoma most common histology unlike those of the pharyngeal mucosa 3. tumor characteristics i. dumbbell tumors a. derive their shape as they are squeezed anterior to the styolmandibular ligament b. narrowest portion in the stylomandibular tunnel ii. round tumors a. pass posterior to the stylomandibular ligament b. originate from the retromandibular portion of the parotid B. Neurogenic tumors 1. epidemiology i. most common post-styloid tumor ii. second most common prestyloid tumor 2. tumor types i. schwannoma a. synonyms 1. neuroma 2. neurinoma 3. neurilemoma b. origin 1. vagus - most common 2. sympathetic chain 3. cranial nerves IX, XI, XII c. imaging 1. homogeneous appearance in smaller tumors 2. foci of necrosis, hemorrhage, or calcification in larger tumors 3. arise posterior to the internal carotid artery and displace it anteromedially 4. enhancement with contrast due to extravascular uptake in the tumor 5. angiography demonstrates avascular mass with a faint tumor stain d. tumor characteristics 1. benign 2. well developed capsule 3. nerve of origin usually easily identifiable ii. neurofibroma a. origin 1. schwann cells and perineural fibroblasts 2. nerve of origin usually vagus or sympathetic chain b. imaging characteristics similar to schwannomas c. tumor characteristics 1. benign 2. often multiple 3. intimate nerve involvement make nerve sacrifice common 4. may or may not be associated with neurofibromatosis iii. paragangliomas a. synonyms 1. chemodectoma 2. ganglioneuroma 3. glomus tumor b. epidemiology 1. rare 2. female preponderance 2.7:1 c. tumor types 1. glomus tympanicum i. not a pps tumor ii. occurs in the middle ear 2. glomus vagale i. arises from the nodose ganglion of the vagus ii. second most common paraganglioma 3. glomus jugulare i. occur in the jugular bulb ii. may extend inferiorly into the post- styloid space iii. demonstrates characteristic bony erosion at the jugular foramen 4. carotid body tumors i. arise from chemoreceptors at the carotid bifurcation ii. may invade superiorly to involve the pps iii. most common of the paragangliomas d. imaging 1. CT enhancement with contrast due to hypervascularity of the tumor 2. MRI i. demonstrates serpiginous areas of low signal intensity caused by high velocity blood flow ii. allows these tumors to be differentiated from the less vascular schwannomas iii. characteristic salt and pepper appearance 3. angiography i. done routinely in the past ii. currently indicated in tumors in which embolization is being considered e. additional diagnostics 1. used to rule out secretory lesions which occur in 2 - 5% of glomus tumors 2. Green et.al. suggest that suspected paragangliomas be screened with urinary vanillyl- mandelic acid 3. other centers perform MBIG (meta-iodinated benzyl guanidine scan) f. tumor characteristics 1. highly vascular 2. often multicentric 3. rarely malignant - 0.9% in the largest series 4. arise from paraganglia along the course of the vagus nerve i. paraganglia are neural crest cells ii. similar to cells of the adrenal medulla which have secretory ability iv. malignant tumors a. pathology 1. squamous cell carcinomas i. nasopharynx and oropharynx ii. oral cavity iii. paranasal sinuses 2. salivary carcinomas i. mucoepideroid ii. adenoid cystic 3. sarcomas are rare but documented cases include i. liposarcoma ii. fibrosarcoma iii. neurofibrosarcoma iv. osteo and chondrosarcoma v. malignant schwannoma vi. rhabdomyosarcoma vii. synnovial sarcoma 4. malignant lymphomas 5. malignant meningioma 6. metastatic malignancies b. imaging 1. infiltrative or destructive characteristics 2. regional lymphadenopathy 3. found in the pre or post styloid space v. other non-inflammatory tumors a. teratomas b. hemangiomas c. branchial cleft cysts d. lipomas e. aberrant or tortuous carotid arteries f. jugular vein thrombosis vi. inflammatory lesions (abscesses and inflammatory nodes) a. origin 1. nasopharyngeal 2. tonsillar 3. pps lymph nodes b. presentation 1. rarely affects nerves 2. may involve internal carotid artery 3. may involve internal jugular thrombophlebitis c. imaging 1. minimally enhancing lesions 2. identifiable as separate masses or as a conglomer- ation of nodes 3. necrosis represented by well circumscribed, low density mass V. Treatment A. Surgical theories 1. most tumors are benign, so surgery must have minimal morbidity 2. approach dictated by: i. size ii. location iii. relationship with vessels iv. suspicion of malignancy B. Surgical approaches 1. transoral i. direct route to tumors presenting in the pharynx ii. no control of great vessels iii. Goodwin and Chandler used transoral approach on six pleomorphic adenomas a. one recurrence as a malignant mixed tumor b. no complications b. only four were followed for five years c. yields a recurrence rate of 25% iv. may have indications in small tumors which do not extend as far as the styloid process vi. may be used in combination with external approach 2. transcervical i. useful for non-parotid tumors or abscesses of the pps ii. procedure a. incision begins near midline above the hyoid and is carried up to the mastoid tip b. subplatysmal flaps elevated c. carotid sheath entered and neurovascular structures identified d. digastric and stylohyoid muscles are identified and divided e. additional exposure with division of stylomandibular ligament and styloglossal muscle f. mandible retracted anteriorly exposing posteroinferior portion of tumor iii. criticized for limited working space, but according to Carrau, transection of the stylomandibular ligament with anterior mandibular retraction widens exposure by 50%, allowing for removal of even the largest of tumors 3. transcervicosubmaxillary i. differs from transcervical only in that the submandibular triangle is entered ii. provides access to tumors with anteroinferior extension 4. transmandibular i. indication a. approximately 10% of pps tumors will require this exposure b. used in composite resections in pharyngeal malignancies c. provides vessel control and exposure for vascular tumors extending to the skull base d. tracheotomy required ii. procedure a. transcervical approach with the addition of a mandibulotomy b. mandibulotomy performed in a stair step fashion 1. at the angle of the mandible 2. at the paramedian position medial to the mental nerve c. stylomandibular ligament essential for anterior displacement of mandibular fragment d. wiring or compression plating used to reapproximate mandible 5. transparotid i. indicated for deep lobe tumors of the parotid ii. superficial parotidectomy performed and the facial nerve is freed up iii. dissection is carried medially and the deep lobe is removed iv. access is improved by manipulating the mandible as mentioned previously C. Radiation therapy 1. recommended for malignant tumors in combination with surgery because of the difficulty in getting wide margins 2. unresectable paragangliomas i. considered radiosensative but only neuroblastomas have been cured ii. response varies widely among individuals 3. primary therapy for stage I malignant lymphomas -------------------------------END-----------------------------------------