Facial Nikolas H.

Paralysis due to Benign Parotid Tumors Blevins, MD; Robert K. Jackler, MD; Michael J. Kaplan, MD; Roger Boles,

occasions, facial paralysis associated with a parotid tumor need not denote malignancy. We present two cases in which, contrary to appropriate conventional wisdom, facial paralysis resulted from benign mixed tumors. Each patient presented over 8 years following primary surgical excision. In neither patient was a mass palpable, and facial paralysis was the sole sign of recurrent disease. Each patient had been followed up for several months with a presumptive diagnosis of Bell's palsy prior to discovery of recurrent tumor by radiologic imaging. In each case, at operation the tumor was found to infiltrate the temporal bone via the stylomastoid foramen. Facial paralysis presumably resulted from extrinsic compression of the facial nerve. These two cases add to the few previous reports of facial paralysis due to benign parotid gland tumors. (Arch Otolaryngol Head Neck Surg. 1992;118:427-430) \s=b\ On rare

paralysis associated parotid gland Facial clinical classically denotes malignancy. have established the of the with




ominous significance dysfunction and have perpetuated its appropriate use as one of the most reliable clinical cri¬ teria for parotid malignancy.1"4 We recently encountered two patients in whom, contrary to conventional wisdom, facial palsy resulted from benign neoplasms. series

seventh cranial


REPORT OF CASES CASE 1.—A 59-year-old white woman was referred with the diagnosis of unresolving Bell's palsy. She had a 4-year history of gradually progressive left facial spasm. The spasms were of short duration, and occurred almost hourly. Over the last 6 months, she developed a gradually increasing left facial paresis. Relevant medical history included a left superficial parotidectomy for a pleomorphic adenoma 8 years before presentation. She made an uneventful recovery and was neurologically intact. Examination revealed a grade 3/6 left facial paresis with rela¬ tive sparing of the forehead and eye. The remainder of the cra¬ nial nerves were normal. No masses were palpable in the parotid bed or neck. Results of otologie and audiologic examinations were normal. A magnetic resonance imaging scan demonstrated an enhancing 3 x 2-cm mass in the left infratemporal fossa that extended into the temporal bone (Fig 1). High-resolution com-


publication October 14, 1991. Department of Otolaryngology\p=m-\Headand Neck Surgery, University of California, San Francisco. Presented at the Western Sectional Triological Society Meeting, Santa Barbara, Calif, January 20, 1991. Reprint requests to 350 Parnassus Ave, Room 210, San Francisco, for

From the

CA 94117 (Dr Jackler).


puted tomography revealed irregular temporal bone destruction involving the lower mastoid air cell system, with partial destruc¬ tion of the descending fallopian canal. The middle ear and otic capsule were normal. At operation a large tumor was found in the infratemporal fossa that invaded the temporal bone via the stylomastoid foramen region and circumferentially involved the descending facial nerve. The intratemporal portion of the tumor was removed via an intact canal wall mastoidectomy that spared auditory function. The involved portion of the facial nerve was resected with the tumor specimen. Normal nerve was encountered proximally at the level of the posterior semicir¬ cular canal and distally at the terminal branches well beyond the pes anserinus. A split sural nerve graft was used for immediate reconstruction. Histologie examination confirmed the presence of a recurrent pleomorphic adenoma. There was no evidence of malignant transformation or infiltration of facial nerve by tumor. There was dense scar tissue surround¬ ing both tumor and nerve, and intrafascicular fibrosis. The patient was offered, but declined, postoperative radiation therapy. At 16 months follow-up the patient showed no evi¬ dence of disease and had partial recovery of facial function in

the lower division. Case 2. —A 62-year-old Chinese man was referred with persistent dense left facial paralysis and the diagnosis of unre¬ solved Bell's palsy. Eight years previously, he had undergone a left parotidectomy for a pleomorphic adenoma. The tumor sur¬ rounded the facial nerve in the region of the stylomastoid fora¬ men. Postoperatively, the patient had normal facial nerve func¬ tion and remained asymptomatic for 8 years. Prior to referral, he experienced a 4-month period of gradually progressive left facial weakness accompanied by involuntary twitching of the eyelid and cheek. Over the next 3 months, this progressed to complete paralysis. Physical examination revealed a grade 6/6 left facial palsy, a well-healed Blair incision, and no palpable masses in the parotid bed or neck. A computed tomographic scan showed subtle erosion of the temporal bone in the area of the stylomas¬ toid foramen. A magnetic resonance imaging scan demonstrated extensive tumor involving the stylomastoid foramen, the parotid gland, and the infra temporal fossa (Fig 2). Surgical exploration revealed a 2x0.7x0.5-cm tumor in the infratemporal fossa that penetrated the mastoid process of the temporal bone in the region of the stylomastoid foramen. The facial nerve was exposed via an intact canal wall mastoidectomy and was found to be markedly swollen in its lower descending portion. A total left parotidectomy was performed, along with infratemporal fossa dissection. The involved portion of facial nerve was excised and a greater auricular nerve graft was used for immediate reconstruction. Pathologic evaluation confirmed the diagnosis of recurrent pleomorphic adenoma with no evi¬ dence of malignant transformation. There was scarring around both tumor and nerve, as well as intrafascicular fibrosis. The pa¬ tient received 55 Gy of postoperative radiation therapy. At latest

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Fig Ì. —Sagittal (left) and axial (right) magnetic resonance images from patient , illustrating a recurrent mixed tumor of the parotid gland (X) invading the temporal bone near the stylomastoid foramen. Tumor has circumferentially involved the distal facial nerve (arrow).

Fig 2. Left, Sagittal magnetic resonance image demonstrating a recurrent mixed tumor of the parotid gland (X) in patient 2. Horizontal (up¬ per arrow) and vertical (lower arrow) facial nerves are uninvolved. However, intratemporal tumor impinges on the distal descending nerve. Right, Coronal computed tomographic scan of patient 2, illustrating osseous erosion in the region of the stylomastoid foramen (arrow). —

follow-up 7 months postoperatively, he showed no evidence of disease but his seventh




to recover


COMMENT In the evaluation of a parotid gland mass the clinical signs that classically denote malignancy are local invasion

of adjacent structures, the presence of metastatic lesions, and ipsilateral facial nerve dysfunction.3 Although con¬ siderable evidence exists to confirm the strong association

paresis, paralysis, and/or spasm with malignant parotid gland tumors, facial nerve dysfunction accompa¬ nying a parotid mass does not invariably indicate the presence of malignancy. Cases of parotid gland tumors reviewed by Frazell1 (877 of facial

cases), Beahrs et al2 (760 cases), and Bardwill3 ( 153 cases)

all demonstrated palsy occurring only in conjunction with malignancy. In 1972, Eneroth4 reviewed 2158 cases of pa¬ rotid neoplasms and found no instances of facial


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Ten Cases of Facial

Palsy due to Benign

Parotid Gland Tumors

Patient Data

Source, y

Age, y/Sex

Mamakos et al,12, 1977 La Ventura and Moore,15 1969

al,161972 and Alkalai,17


Pleomorphic adenoma Pleomorphic adenoma







Cimorra et



Ward and Lesser and

Whillis et




Delozier et Present


Histologie Findings Pleomorphic adenoma






Presumed Mechanism






















Inflammation/stretch Inflammation/stretch Inflammation/stretch

59/F 62/M

Pleomorphic Pleomorphic

3 2

Temporal Temporal


adenoma adenoma

in the 1780 patients with benign patients with malignant parotid gland (12%) demonstrated some degree of palsy.


tumors. Of the 378

tumors, 46 Notably, the presence of facial paralysis was an indicator of distant metastatic disease. Among those patients with paralysis, 77% had clinically detectable metastatic dis¬ ease, compared with 27% in those patients with normal facial function. A similarly significant difference in 10year survival was apparent: no survival in those with palsy and 33% in those without palsy. Other reviews have confirmed the grim prognosis of facial nerve involvement. A multi-institutional study by Eneroth6 in 1977 found 14% of the 1029 patients reviewed who had parotid gland ma¬ lignancies also had facial weakness, and only 9% of them survived 5 years. In 1975, Spiro et al7 found a 14% 5-year survival rate in 43 patients with malignancy and seventh nerve involvement. A comprehensive review of the literature revealed only eight additional cases of benign neoplasms accounting for facial palsy (Table). In no case was the facial nerve actu¬ ally invaded by tumor; palsy resulted instead from extrinsic mechanical forces on the nerve, producing either compression or stretch. An expanding lesion encroaching on the facial nerve will produce compression if the nerve is confined by surrounding structures, as by the fallopian canal. An expanding lesion will cause stretch if the facial nerve is allowed to elongate, as it may in its extratempo¬ ral portion. Microscopically, mechanical and ischemie disruption occur in both compression and stretch, since they originate from a similar extrinsic deforming force. Malignant tumors may produce facial paralysis via the same extrinsic mechanisms or by directly infiltrating the nerve.8·9 Sunderland10 described three stages of facial nerve compression. Stage 1 occurs when epineural veins be¬ come occluded, leading to venous congestion in intrafas¬ cicular capillaries and subsequent rise in intrafascicular hydrostatic pressure. The disruption of normal pressure gradients and resulting ischemia produce a reversible nerve dysfunction. With prolonged compression injury progresses to stage 2, in which endothelial damage allows extravascular leakage of protein, causing intrafascicular edema. Fluid may be trapped within the impermeable perineurium, establishing a "miniature closed compart-

bone bone

invasion/compression invasion/compression

syndrome."11 The pressure on surrounding nerve fibers is sufficient at this stage to halt normal axonal transport. Progressive ischemia results in segmental demyelination and scattered axonal disruption and degen¬ eration. At stage 3, increasing pressure obstructs arterial flow leading to permanent dysfunction. Fibroblasts mi¬ grate and proliferate in the proteinacious edema fluid, eventually transforming the normal nerve into a fibrous cord. In our cases, we propose that facial nerve injury resulted from direct extension of tumor into the fallopian canal via the stylomastoid foramen. It is likely that each patient's tumor was initially incompletely resected at the stylomastoid foramen, leading to recurrence that as¬ cended into the temporal bone and subsequently com¬ pressed the facial nerve. A similar mechanism was proposed by Mamakos et al12 in the presentation of a 9-year-old boy with facial weakness from a primary pleo¬ morphic adenoma. The facial nerve is particularly vul¬ nerable in its mastoid segment because (1) of the tight confines of the canal (fascicles occupy 30% to 50% of ca¬ nal space10); (2) of the well-developed perineurium, which can both transmit external compression to the intrafascic¬ ular structures and also prevent the egress of edema fluid; and (3) the arterial supply is largely dependent on a branch off the stylomastoid artery13 that is at risk for com¬ pression by tumor in the area of the stylomastoid fora¬ ment


A segment of nerve that is rigidly fixed is particularly vulnerable to injury when an adjacent segment is sub¬ jected to stretch. This is true even if the stretch occurs without the acuity needed to produce mechanical discon¬ tinuity. As seen in acoustic neuroma patients, the por¬ tions of the vestibulocochlear and facial nerves most at risk are those tethered at the porus acousticus, while the more proximal nerve gradually deforms in the cerebellopontine angle.14 In our cases, an analogous injury may have contributed to facial nerve dysfunction. Distal branches were stretched by the infratemporal tumor, while the nerve trunk was held fixed by bone and tumor in the region of the stylomastoid foramen. Several stud¬ ies have presented cases of facial paralysis in which the extratemporal branches of the facial nerve were progres¬ sively deformed by slow-growing benign neoplasms.15"17

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reported facial weakness from a progres¬ sively enlarging parotid cyst. It is possible that in these cases the neurologic lesion occurred at an adjacent area of nerve that was tethered by surrounding structures such as the stylomastoid foramen. In 1950, Ward and Hendrick19 presented a woman who had had a "grapefruit-sized" pleomorphic adenoma for 17 years without consequence, until local trauma produced rapid tumor expansion and facial paralysis. When the tumor was excised, recent hemorrhage was evidenced, not the ma¬ lignant transformation that had been suspected. A similar case was presented by Wilkie and White,20 in which hemor¬ rhage into a benign parotid cyst in the absence of neoplasia produced rapid seventh nerve deformation and palsy. The probable mechanism in these cases was a conduction block followed by axonal and connective tissue disruption. This has been shown to occur in the rapid elongation of peripheral nerves.11 When the facial nerve is allowed to gradually elon¬ gate and adapt to an extrinsic mass, however, it generally does so without impaired function. This tolerance explains the normal facial nerve findings usually seen in massive be¬ nign parotid tumors. In three other patients with facial palsy caused by be¬ nign neoplasms, local inflammation from infection or tu¬ mor necrosis appears to be a cofactor in precipitating weakness.21"23 Each of these patients had a histologie di¬ agnosis of Warthin's tumor, a tumor type predisposed to cystic and inflammatory degeneration. Parotid abscesses Gaisford et al18

have also been reported to inhibit facial nerve function.23 Inflammation may act synergistically with the effects of extrinsic compression by adhering nerves to adjacent structures and preventing adaptive elongation or defor¬ mation. Inflammatory mediators may also directly pre¬ cipitate ischemia via microvascular thrombosis, edema formation, and possibly neurotoxic effects. Both of our patients were referred with the diagnosis of unresolving idiopathic facial palsy (Bell's). Although the physicians were aware of the history of parotid gland tu¬ discounted as mor, in each case this was the tumor had been of a benign type, many years had passed since it had been removed, and there was no pal¬ pable evidence of recurrence. This experience emphasizes the need to rigorously exclude other possible causes of facial palsy before making the diagnosis of Bell's palsy. As noted by Jackson et al,24 the onset of slowly progressive palsy beyond 3 weeks, the lack of resolution after 6 months, and the presence of facial hyperkinesia are all suggestive of a potential neoplastic cause. Although facial weakness associated with a parotid gland tumor remains a reliable indicator of malignancy, it is important for the clinician to be aware that, on rare oc-


casions, facial nerve disease.

dysfunction may result from benign

We are grateful to William Dillon, MD, for his review of the radiographic images, Richard Davis, MD, and Alfred Yamamoto, MD, for their review of the pathology slides, and to Denise Hodges for her editorial assistance in the preparation of the manuscript. References 1. Frazell EL. Clinical aspects of tumors of the

major salivary glands.

Cancer. 1954;7:637-659. 2. Beahrs OH, Woolner LB, Carveth SW, Devine KD. Surgical management of parotid lesions. Arch Surg. 1960;80:890-904. 3. Bardwill JM. Tumors of the parotid gland. Am J Surg. 1967;114:498\x=req-\ 502. 4. Eneroth CM. Facial nerve paralysis: a criterion of malignancy in parotid tumors. Arch Otolaryngol. 1972;95:300-304. 5. McDowell F. Do benign parotid tumors produce facial paralysis? Plast Reconstr Surg. 1969;43:512-514. 6. Eneroth CM, Andreasson L, Beran M, et al. Preoperative facial paralysis in malignant parotid tumors. ORL J Otorhinolaryngol Relat Spec.

1977;39:272. 7. Spiro RH, Huvos AG, Strong EW. Cancer of the J Surg. 1975;130:452.

parotid gland. Am

8. Saito H. Tumor invasion of the facial nerve: a study of eight tembones. In: Graham MD, House WF, eds. Disorders of the Facial Nerve: Anatomy, Diagnosis, and Management. New York, NY: Raven Press; 1982:225-236. 9. Adams GL, Paparella MM, El-Fiky FM. Primary and metastatic tumors of the temporal bone. Laryngoscope. 1971;81:1273-1285. 10. Sunderland S. Some anatomical and pathophysiological data relevant to facial nerve injury and repair. In: Fisch U, ed. Facial Nerve Surgery. Birmingham, Ala: Aesculapius Publishing Co; 1977:47-61. 11. Lundborg G. Nerve Injury and Repair. New York, NY: Churchill Livingstone Inc; 1988:70. 12. Mamakos MS, Wright R, Earl SA. Facial palsy in a child with a parotid tumor. Int Surg. 1977;62:468-469. 13. Guerrier Y. Surgical anatomy, particularly vascular supply of the facial nerve. In: Fisch U, ed. Facial Nerve Surgery. Birmingham, Ala: Aesculapius Publishing Co; 1977:13-23. 14. Jackler RK, Pitts LH. Acoustic neuroma. Neurosurg Clin North Am.



15. La Ventura F, Moore JA. Facial nerve paralysis secondary to benign parotid tumor. Arch Otolaryngol. 1969;90:603-604. 16. Cimorra GA, Ferreira V, Martinez-Tello FJ. Spontaneous facial nerve paralysis associated with an ipsilateral benign parotid tumor. Plast Reconstr Surg. 1972;50:523-525. 17. Papangelou LP, Alkalai K. Facial nerve paralysis in the presence of a benign parotid tumor. Arch Otolaryngol. 1982;108:458-459. 18. Gaisford JC, Hanna DC, Richardson GS, Bindra RN. Parotid Plast Reconst Surg. 1969;43:504-510. 19. Ward GE, Hendrick JW. Tumors of the Head and Neck. Baltimore, Md: Williams & Wilkins; 1950:388-389. 20. Wilkie TF, White RA. Benign parotid tumor with facial nerve paralysis. Plast Reconstr Surg. 1969;43:528-530. 21. Lesser RW, Spector JG. Facial nerve palsy associated with War-


thin's tumor. Arch Otolaryngol. 1985;111:548-549. 22. Whillis D, Goepel JR, Shorthouse AJ. Facial paralysis due to a be-

nign parotid

tumour. Br J

Surg. 1989;76:95. HL, Spinella MJ, Johnson GD. Facial

nerve paralysis with Laryngol. 1989;98:644-647. 24. Jackson CG, Glasscock ME, Hughes G, Simanis A. Facial paralysis of neoplastic origin: diagnosis and management. Laryngoscope. 1980;

23. Delozier

benign parotid


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Ann Otol Rhinol

Facial paralysis due to benign parotid tumors.

On rare occasions, facial paralysis associated with a parotid tumor need not denote malignancy. We present two cases in which, contrary to appropriate...
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