Vestibular Schwannoma Presenting With Sudden Facial Paralysis David B.
Wexler, MD; Theodore W. Fetter, MD; Bruce J. Gantz, MD
\s=b\ Facial paralysis is an unusual manifestation of vestibular schwannoma, and generally signifies an advanced stage of tumor growth. We describe a case of eighth-nerve schwannoma that presented initially with rapid-onset complete unilateral facial paralysis. At the time of operation the nerve was found to be electrically intact despite marked compression by tumor. The facial nerve was preserved and facial motion has partially recovered post\x=req-\ operatively. All unexplained persistent facial paralysis should be evaluated by magnetic resonance imaging with paramagnetic contrast enhancement. (Arch Otolaryngol Head Neck Surg.
1990;116:483-485)
Sir
Terence Cawthorne1 once stated "All that palsies is not Bell." While Bell's (idiopathic) facial palsy is the most common clinical entity of fa¬ cial weakness, tumor is always in the differential diagnosis of a persistent facial paralysis. An estimated 5% of facial palsies are secondary to tumors.2 These relatively uncommon cases of facial paralysis due to tumor are usu¬ ally associated with either facial nerve Accepted
for publication September 19, 1989. From the Department of Otolaryngology\p=n-\Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City. Reprint requests to the Department of Otolaryngology\p=n-\Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242
(Dr Gantz).
tumor contiguous with the facial nerve, or metastatic dis¬ ease.34 Facial paralysis can also occur in eighth-nerve schwannomas, where it is regarded as a late finding.5 The following unusual case demonstrates rapid-onset facial paralysis as the ini¬ tial manifestation of a relatively small vestibular nerve schwannoma.
neurilemoma,
REPORT OF A CASE
Hearing was normal on the left side. Acous¬ tic reflexes were consistent with right-sided anakusis. An electronystagmogram showed mild spontaneous left-beating eyes-closed nystagmus. Severe vestibular hypofunction on the right side was evident on 20°C and ice-water caloric testing. Facial nerve electrodiagnostic tests were performed. Pontogram results were compatible with a rightsided peripheral facial nerve lesion. An electromyogram demonstrated fibrillation
A 23-year-old white woman presented to her physician for treatment of right-sided facial paralysis. This had developed over the course of several hours, less than half a day. The initial diagnosis was Bell's palsy and she was treated with a trial of oral ste¬ roid therapy. The treatment had no benefi¬ cial effect on her facial paralysis. Two weeks later she developed right-sided hear¬ ing loss. There was no vertigo or dysequilibrium. The patient also denied tinnitus and any prior otologie problems. There were no facial paresthesias, but a flattening of taste sensation was noted. Three months after her symptoms developed she was re¬ ferred to us for further evaluation and treatment. Results of a physical examination re¬ vealed tympanic membranes of normal ap¬ pearance and mobility. Tuning fork local¬ ized to the left side on the Weber test. No spontaneous nystagmus was observed. There was a complete right-sided facial pa¬ ralysis, but no other focal neurologic find¬ ings. Audiogram showed profound senso¬ rineural hearing loss on the right side.
Fig 1.—Towne projection roentgenogram showing widened internal auditory canal on the right side (arrows).
Downloaded From: http://archotol.jamanetwork.com/ by a University of Iowa User on 06/16/2015
Fig 2.— ,-weighted magnetic resonance imaging scan in the coronal plane showing gadolinium-enhanced lesion in the right internal auditory canal region.
potentials. Electroneurography showed
no
(to maximal stimulation) on the right. A Towne projection roentgenogram
response
demonstrated a widened internal auditory canal on the right side (Fig 1). Magnetic resonance imaging (MRI) with intravenous gadolinium contrast was obtained, and an enhancing intracanalicular lesion was clearly visualized on the right side (Figs 2 and 3). A translabyrinthine surgical approach was undertaken for removal of the lesion. The main tumor mass originated in the su¬ perior vestibular nerve; in addition, non¬ contiguous tumor was present within the posterior semicircular canal. A portion of the intracanalicular segment of nerve VII was substantially thinned and had de¬ creased perineural vascularity due to com¬ pression by the tumor. However, after exci¬ sion of the lesion, stimulation of the facial nerve with 0.25-volt DC pulses distal to the geniculate ganglion and 0.5-volt pulses proximal to the compressed region pro¬ duced facial movement. In the immediate postoperative period, facial movement was not present. However, 3 months postopera¬ tively right-sided midfacial motion was
Fig 3. Magnetic resonance imaging scan in the transverse plane showing gadolinium-enhancing right internal auditory canal mass. —
though the true incidence of this lesion is not reliably known, any unexplained unilateral otologie symptoms must be regarded with suspicion for presence of an eighth-nerve tumor. Typically the tumors involve the vestibular nerve in the medial internal auditory canal, and they may extend out into the cerebellopontine angle or, less fre¬ quently, remain primarily intracan¬ alicular.6 Histologically, schwannoma is found 80% to 90% of the time. Meningioma and cholesteatoma are the next most common masses found in the
eye closure and moderate orbicularis oris
cerebellopontine angle.7 Auditory symptoms, either unilat¬ eral sensorineural hearing loss or tin¬ nitus, are by far the most common clinical presentations of a vestibular schwannoma. Vestibular dysfunction may be evident from complaints of vertigo or unsteadiness. As the tumor enlarges, other cranial nerve findings may appear, most notably sensory changes reflecting impingement on the trigeminal nerve.8 Curiously, facial paralysis is an un¬
function. The
common
partly recovered, including diagnosis
was
near
complete
schwannoma.
COMMENT
Vestibular nerve schwannoma is the most common mass lesion to occur in the cerebellopontine angle region. Al-
manifestation of vestibular schwannoma. Neely and Neblett9 re¬ ported preoperative facial paralysis in 6.1% of their review of 49 eighth-nerve schwannomas, and a rate of only 3.2% was noted in a series of 500 patients by
Downloaded From: http://archotol.jamanetwork.com/ by a University of Iowa User on 06/16/2015
Brow.10 When facial paralysis occurs as a late finding, a large tumor is found, generally with other cranial nerve nerves
deficits, particularly involving IX and X." In contrast, the rare
primary facial nerve neoplasms (neurilemomas) may present relatively early with facial weakness. Progres¬
sive facial weakness or, less commonly, sudden facial paralysis or recurrent paralysis, may occur in such cases.11·12 The integrity of facial nerve motor function in the setting of compression by adj acent eighth-nerve tumors is not easily explained. Jung et al3 suggest that the nerve sheath provides a crit¬ ical protective barrier. Their study of facial nerve tumors showed a correla¬ tion between tumor invasion through the nerve sheath and development of facial paralysis. In the absence of nerve sheath invasion, the facial nerve generally appears to tolerate gradual pressure stresses exceedingly well. Thus, it is doubtful that mass effect alone caused the original paralysis in our patient, since there were no other symptoms initially. Perhaps a local vascular compromise produced her fa¬ cial paralysis. The finding of greatly diminished perineural vascularity in the region of the nerve compression, as was observed under the operating mi-
supports this view. The finding of electrical excitability of the facial nerve after decompression at the time of surgery was unexpected. It again illustrates the resiliency of the nerve to local compression. Also, a limitation of electroneurogram testing is pointed out. A preoperative electro¬ neurogram showing no response does not necessarily imply that the nerve is nonviable. Loss of the compound mus¬ cle action potential may be due to either actual neural degeneration or may reflect desynchrony within the facial nerve.1314 Desynchrony occurs during regeneration and may be present when the nerve is compressed or invaded by tumor. For this reason electroneurography is of prognostic value only during the acute phase of facial paralysis.13 A translabyrinthine approach was elected in anticipation of possible facroscope,
grafting. This approach un¬ expectedly revealed schwannoma in the posterior aspect of the semicircu¬ cial
nerve
lar canal. Little attention has been given to distally situated schwannomas. Babin and Harker15 described two cases of intralabyrinthine acoustic neuroma. They emphasized that an awareness of possible tumor in such usual sites is important in managing patients with retrocochlear lesions. Although the incidence of these intra¬ labyrinthine tumors is unknown, longterm
follow-up
seems
warranted after
particularly
hearing conservation procedures. Magnetic resonance imaging is now the key imaging modality for evalua¬ tion of temporal bone soft-tissue masses.16 The introduction of gadolin¬ ium diethylenetriamine pentaacetic acid, an intravenous paramagnetic contrast agent, has greatly improved
the sensitivity of MRI in detecting small soft-tissue lesions of the internal auditory canal. While not specific for schwannoma, the gadolinium dieth-
ylenetriamine pentaacetic acid-en¬ hanced MRI nevertheless provides a
highly sensitive examination for masses of the cerebellopontine angle and internal auditory canal. We be¬ lieve it has replaced air computed tomographic cisternography as the pro¬ cedure of choice for suspected intra¬
canalicular soft-tissue lesions. In summary, vestibular schwan¬ noma can present atypically with rap¬ id-onset facial paralysis. Although this case is at the far end of the clini¬ cal spectrum for eighth-nerve schwan¬ noma, it upholds Cawthorne's dictum regarding facial palsies. Any unex¬ plained persistent facial paralysis should be evaluated by MRI with gad¬ olinium contrast.
References 1. Cawthorne T. Bell's palsies. Ann Otol Rhinol Laryngol. 1963;72:774-779. 2. Shambaugh GE, May M. Facial nerve paralysis. In: Paparella MM, Schumrick DS, eds. Otolaryngology. Philadelphia, Pa: WB Saunders Co; 1980:1697. 3. Jung TT, Byung-hoon J, Shea D, Paparella MM. Primary and secondary tumors of the facial nerve. Arch Otolaryngol Head Neck Surg. 1986; 112:1269-1273. 4. Wiet RJ, Lotan AN, Monsell EM, Shambaugh GE. Tumor involvement of the facial nerve.
Laryngoscope. 1983;93:1301-1309. 5. Sheehy JL. Neuro-otologic evaluation. In: House WF, Luetje CM, eds. Acoustic Tumors: Diagnosis. Baltimore, Md: University Park Press; 1979;1:199-208. 6. Nager GT. Acoustic neurinomas. Acta Otolaryngol. 1985;99:245-261.
7. Brackmann DE, Bartels LJ. Rare tumors of the cerebellopontine angle. Otolaryngol Head Neck Surg. 1980;88:555-559. 8. Bebin J. Pathophysiology of acoustic tumors. In: House WF, Luetje CM, eds. Acoustic Tumors: Diagnosis. Baltimore, Md: University Park Press;
1979;1:71.
Neely JG, Neblett CR. Differential facial function in tumors of the internal auditory meatus. Ann Otol Rhinol Laryngol. 1983;92:39-41. 10. Brow RE. Pre- and postoperative management of the acoustic tumor patient. In: House WF, Luetje CM, eds. Acoustic Tumors: Management. Baltimore, Md: University Park Press; 1979;2:155. 11. Clemis JD. Neurogenic tumors of the skull base. Otolaryngol Head Neck Surg. 1980;88:511\x=req-\ 9.
nerve
518. 12. mas.
Neely JG, Alford BR. Facial nerve neuroArch Otolaryngol Head Neck Surg. 1974;
In Other AMA Journals
ARCHIVES OF OPHTHALMOLOGY Four Years of Ophthalmology Training: Has Its Time Come? John L. Keltner, MD (Arch Ophthalmol. 1990;108:35-36) Should Postresidency Fellowships Be Mandatory? David W. Parke II, MD (Arch Ophthalmol. 1990;108:37-39)
Downloaded From: http://archotol.jamanetwork.com/ by a University of Iowa User on 06/16/2015
100:298-301. 13. Gantz BJ, Gmuer AA,
Holliday M, Fisch U. Electroneurographic evaluation of the facial nerve: method and technical problems. Ann Otol Rhinol Laryngol. 1984;93:394-398. 14. Hughes GB, Josey AF, Glasscock ME III, Jackson CG, Ray WA, Sismanis A. Clinical electroneurography: statistical analysis of controlled measurements in twenty-two normal subjects. Laryngoscope. 1981;91:1834-1846. 15. Babin RW, Harker LA. Intralabyrinthine acoustic neurinomas. Otolaryngol Head Neck Surg. 1980;88:455-461. 16. Council on Scientific Affairs. Magnetic resonance imaging of the head and neck region: present status and future-potential. JAMA. 1988; 260:3313-3326.
Wexler, MD; Theodore W. Fetter, MD; Bruce J. Gantz, MD
\s=b\ Facial paralysis is an unusual manifestation of vestibular schwannoma, and generally signifies an advanced stage of tumor growth. We describe a case of eighth-nerve schwannoma that presented initially with rapid-onset complete unilateral facial paralysis. At the time of operation the nerve was found to be electrically intact despite marked compression by tumor. The facial nerve was preserved and facial motion has partially recovered post\x=req-\ operatively. All unexplained persistent facial paralysis should be evaluated by magnetic resonance imaging with paramagnetic contrast enhancement. (Arch Otolaryngol Head Neck Surg.
1990;116:483-485)
Sir
Terence Cawthorne1 once stated "All that palsies is not Bell." While Bell's (idiopathic) facial palsy is the most common clinical entity of fa¬ cial weakness, tumor is always in the differential diagnosis of a persistent facial paralysis. An estimated 5% of facial palsies are secondary to tumors.2 These relatively uncommon cases of facial paralysis due to tumor are usu¬ ally associated with either facial nerve Accepted
for publication September 19, 1989. From the Department of Otolaryngology\p=n-\Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City. Reprint requests to the Department of Otolaryngology\p=n-\Head and Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242
(Dr Gantz).
tumor contiguous with the facial nerve, or metastatic dis¬ ease.34 Facial paralysis can also occur in eighth-nerve schwannomas, where it is regarded as a late finding.5 The following unusual case demonstrates rapid-onset facial paralysis as the ini¬ tial manifestation of a relatively small vestibular nerve schwannoma.
neurilemoma,
REPORT OF A CASE
Hearing was normal on the left side. Acous¬ tic reflexes were consistent with right-sided anakusis. An electronystagmogram showed mild spontaneous left-beating eyes-closed nystagmus. Severe vestibular hypofunction on the right side was evident on 20°C and ice-water caloric testing. Facial nerve electrodiagnostic tests were performed. Pontogram results were compatible with a rightsided peripheral facial nerve lesion. An electromyogram demonstrated fibrillation
A 23-year-old white woman presented to her physician for treatment of right-sided facial paralysis. This had developed over the course of several hours, less than half a day. The initial diagnosis was Bell's palsy and she was treated with a trial of oral ste¬ roid therapy. The treatment had no benefi¬ cial effect on her facial paralysis. Two weeks later she developed right-sided hear¬ ing loss. There was no vertigo or dysequilibrium. The patient also denied tinnitus and any prior otologie problems. There were no facial paresthesias, but a flattening of taste sensation was noted. Three months after her symptoms developed she was re¬ ferred to us for further evaluation and treatment. Results of a physical examination re¬ vealed tympanic membranes of normal ap¬ pearance and mobility. Tuning fork local¬ ized to the left side on the Weber test. No spontaneous nystagmus was observed. There was a complete right-sided facial pa¬ ralysis, but no other focal neurologic find¬ ings. Audiogram showed profound senso¬ rineural hearing loss on the right side.
Fig 1.—Towne projection roentgenogram showing widened internal auditory canal on the right side (arrows).
Downloaded From: http://archotol.jamanetwork.com/ by a University of Iowa User on 06/16/2015
Fig 2.— ,-weighted magnetic resonance imaging scan in the coronal plane showing gadolinium-enhanced lesion in the right internal auditory canal region.
potentials. Electroneurography showed
no
(to maximal stimulation) on the right. A Towne projection roentgenogram
response
demonstrated a widened internal auditory canal on the right side (Fig 1). Magnetic resonance imaging (MRI) with intravenous gadolinium contrast was obtained, and an enhancing intracanalicular lesion was clearly visualized on the right side (Figs 2 and 3). A translabyrinthine surgical approach was undertaken for removal of the lesion. The main tumor mass originated in the su¬ perior vestibular nerve; in addition, non¬ contiguous tumor was present within the posterior semicircular canal. A portion of the intracanalicular segment of nerve VII was substantially thinned and had de¬ creased perineural vascularity due to com¬ pression by the tumor. However, after exci¬ sion of the lesion, stimulation of the facial nerve with 0.25-volt DC pulses distal to the geniculate ganglion and 0.5-volt pulses proximal to the compressed region pro¬ duced facial movement. In the immediate postoperative period, facial movement was not present. However, 3 months postopera¬ tively right-sided midfacial motion was
Fig 3. Magnetic resonance imaging scan in the transverse plane showing gadolinium-enhancing right internal auditory canal mass. —
though the true incidence of this lesion is not reliably known, any unexplained unilateral otologie symptoms must be regarded with suspicion for presence of an eighth-nerve tumor. Typically the tumors involve the vestibular nerve in the medial internal auditory canal, and they may extend out into the cerebellopontine angle or, less fre¬ quently, remain primarily intracan¬ alicular.6 Histologically, schwannoma is found 80% to 90% of the time. Meningioma and cholesteatoma are the next most common masses found in the
eye closure and moderate orbicularis oris
cerebellopontine angle.7 Auditory symptoms, either unilat¬ eral sensorineural hearing loss or tin¬ nitus, are by far the most common clinical presentations of a vestibular schwannoma. Vestibular dysfunction may be evident from complaints of vertigo or unsteadiness. As the tumor enlarges, other cranial nerve findings may appear, most notably sensory changes reflecting impingement on the trigeminal nerve.8 Curiously, facial paralysis is an un¬
function. The
common
partly recovered, including diagnosis
was
near
complete
schwannoma.
COMMENT
Vestibular nerve schwannoma is the most common mass lesion to occur in the cerebellopontine angle region. Al-
manifestation of vestibular schwannoma. Neely and Neblett9 re¬ ported preoperative facial paralysis in 6.1% of their review of 49 eighth-nerve schwannomas, and a rate of only 3.2% was noted in a series of 500 patients by
Downloaded From: http://archotol.jamanetwork.com/ by a University of Iowa User on 06/16/2015
Brow.10 When facial paralysis occurs as a late finding, a large tumor is found, generally with other cranial nerve nerves
deficits, particularly involving IX and X." In contrast, the rare
primary facial nerve neoplasms (neurilemomas) may present relatively early with facial weakness. Progres¬
sive facial weakness or, less commonly, sudden facial paralysis or recurrent paralysis, may occur in such cases.11·12 The integrity of facial nerve motor function in the setting of compression by adj acent eighth-nerve tumors is not easily explained. Jung et al3 suggest that the nerve sheath provides a crit¬ ical protective barrier. Their study of facial nerve tumors showed a correla¬ tion between tumor invasion through the nerve sheath and development of facial paralysis. In the absence of nerve sheath invasion, the facial nerve generally appears to tolerate gradual pressure stresses exceedingly well. Thus, it is doubtful that mass effect alone caused the original paralysis in our patient, since there were no other symptoms initially. Perhaps a local vascular compromise produced her fa¬ cial paralysis. The finding of greatly diminished perineural vascularity in the region of the nerve compression, as was observed under the operating mi-
supports this view. The finding of electrical excitability of the facial nerve after decompression at the time of surgery was unexpected. It again illustrates the resiliency of the nerve to local compression. Also, a limitation of electroneurogram testing is pointed out. A preoperative electro¬ neurogram showing no response does not necessarily imply that the nerve is nonviable. Loss of the compound mus¬ cle action potential may be due to either actual neural degeneration or may reflect desynchrony within the facial nerve.1314 Desynchrony occurs during regeneration and may be present when the nerve is compressed or invaded by tumor. For this reason electroneurography is of prognostic value only during the acute phase of facial paralysis.13 A translabyrinthine approach was elected in anticipation of possible facroscope,
grafting. This approach un¬ expectedly revealed schwannoma in the posterior aspect of the semicircu¬ cial
nerve
lar canal. Little attention has been given to distally situated schwannomas. Babin and Harker15 described two cases of intralabyrinthine acoustic neuroma. They emphasized that an awareness of possible tumor in such usual sites is important in managing patients with retrocochlear lesions. Although the incidence of these intra¬ labyrinthine tumors is unknown, longterm
follow-up
seems
warranted after
particularly
hearing conservation procedures. Magnetic resonance imaging is now the key imaging modality for evalua¬ tion of temporal bone soft-tissue masses.16 The introduction of gadolin¬ ium diethylenetriamine pentaacetic acid, an intravenous paramagnetic contrast agent, has greatly improved
the sensitivity of MRI in detecting small soft-tissue lesions of the internal auditory canal. While not specific for schwannoma, the gadolinium dieth-
ylenetriamine pentaacetic acid-en¬ hanced MRI nevertheless provides a
highly sensitive examination for masses of the cerebellopontine angle and internal auditory canal. We be¬ lieve it has replaced air computed tomographic cisternography as the pro¬ cedure of choice for suspected intra¬
canalicular soft-tissue lesions. In summary, vestibular schwan¬ noma can present atypically with rap¬ id-onset facial paralysis. Although this case is at the far end of the clini¬ cal spectrum for eighth-nerve schwan¬ noma, it upholds Cawthorne's dictum regarding facial palsies. Any unex¬ plained persistent facial paralysis should be evaluated by MRI with gad¬ olinium contrast.
References 1. Cawthorne T. Bell's palsies. Ann Otol Rhinol Laryngol. 1963;72:774-779. 2. Shambaugh GE, May M. Facial nerve paralysis. In: Paparella MM, Schumrick DS, eds. Otolaryngology. Philadelphia, Pa: WB Saunders Co; 1980:1697. 3. Jung TT, Byung-hoon J, Shea D, Paparella MM. Primary and secondary tumors of the facial nerve. Arch Otolaryngol Head Neck Surg. 1986; 112:1269-1273. 4. Wiet RJ, Lotan AN, Monsell EM, Shambaugh GE. Tumor involvement of the facial nerve.
Laryngoscope. 1983;93:1301-1309. 5. Sheehy JL. Neuro-otologic evaluation. In: House WF, Luetje CM, eds. Acoustic Tumors: Diagnosis. Baltimore, Md: University Park Press; 1979;1:199-208. 6. Nager GT. Acoustic neurinomas. Acta Otolaryngol. 1985;99:245-261.
7. Brackmann DE, Bartels LJ. Rare tumors of the cerebellopontine angle. Otolaryngol Head Neck Surg. 1980;88:555-559. 8. Bebin J. Pathophysiology of acoustic tumors. In: House WF, Luetje CM, eds. Acoustic Tumors: Diagnosis. Baltimore, Md: University Park Press;
1979;1:71.
Neely JG, Neblett CR. Differential facial function in tumors of the internal auditory meatus. Ann Otol Rhinol Laryngol. 1983;92:39-41. 10. Brow RE. Pre- and postoperative management of the acoustic tumor patient. In: House WF, Luetje CM, eds. Acoustic Tumors: Management. Baltimore, Md: University Park Press; 1979;2:155. 11. Clemis JD. Neurogenic tumors of the skull base. Otolaryngol Head Neck Surg. 1980;88:511\x=req-\ 9.
nerve
518. 12. mas.
Neely JG, Alford BR. Facial nerve neuroArch Otolaryngol Head Neck Surg. 1974;
In Other AMA Journals
ARCHIVES OF OPHTHALMOLOGY Four Years of Ophthalmology Training: Has Its Time Come? John L. Keltner, MD (Arch Ophthalmol. 1990;108:35-36) Should Postresidency Fellowships Be Mandatory? David W. Parke II, MD (Arch Ophthalmol. 1990;108:37-39)
Downloaded From: http://archotol.jamanetwork.com/ by a University of Iowa User on 06/16/2015
100:298-301. 13. Gantz BJ, Gmuer AA,
Holliday M, Fisch U. Electroneurographic evaluation of the facial nerve: method and technical problems. Ann Otol Rhinol Laryngol. 1984;93:394-398. 14. Hughes GB, Josey AF, Glasscock ME III, Jackson CG, Ray WA, Sismanis A. Clinical electroneurography: statistical analysis of controlled measurements in twenty-two normal subjects. Laryngoscope. 1981;91:1834-1846. 15. Babin RW, Harker LA. Intralabyrinthine acoustic neurinomas. Otolaryngol Head Neck Surg. 1980;88:455-461. 16. Council on Scientific Affairs. Magnetic resonance imaging of the head and neck region: present status and future-potential. JAMA. 1988; 260:3313-3326.
