Am J Otalaryngol 12:299-301.
1991
Temporal
Bone Histopathology: Residents’ Quiz
SANDRAPALASTI,MD, ANDJED KWARTLER,MD absent stapedial reflex. The remainder of the head and neck examination was unremarkable. A computed tomography scan of the temporal bones revealed opacification of the right middle ear cleft with excellent pneumatization and aeration of both mastoid cavities. At exploratory tympanotomy, a gray mass was found between the malleus and the incus: the mass was excised. A histologic section is shown in Fig I. What is your temporal bone diagnosis?
A 42-year-old man presented with a g-month history of right ear fullness and decreased hearing. He had been treated with antibiotics by medical clinic physicians, but had no response. He was then referred to an otolaryngologist for further evaluation. On physical examination, the patient’s right tympanic membrane appeared retracted, with a lucency behind the posterior superior quadrant. Audiologic examination revealed a 20- to 30-dB conductive hearing loss in the right ear with an
Figure1. Low-power photomicrograph of a facial nerve neuroma. Note the mucosal covering, clinically of middle ear.
299
300
DIAGNOSIS Facial nerve neuroma. DISCUSSION Neuromas of the facial nerve are uncommon tumors. First described by Schmidt1 in 1930, only 248 cases had been reported in the world literature as of 1986.’ The clinical manifestations of these tumors are often subtle; the diagnosis is frequently delayed or missed entirely. Neuromas (also referred to as schwannomas and neurilemmomas) are benign encapsulated neoplasms of nerve sheath origin. Neuromas may arise from any cranial nerve and are well documented in acoustic and trigeminal nerves.3 In a mixed nerve, such as the facial nerve, the neuroma is thought to arise from the sensory elementsa4 Grossly, these tumors present as gray, lobulated masses that arise eccentrically from the nerve. They often appear to be multicentric, but closer inspection usually reveals intraneural connections between these lobulations. Microscopically, the tumor is composed of long slender cells with elongated nuclei (Fig l),arranged in palisades and whorls. The tumor is composed of compact (Antoni A) and loose (Antoni B) areas with Verocay bodies occurring at the end of fibrillar bundles. Presenting symptoms of facial neuromas depend on the site of origin. Tumors may occur in any portion of the nerve from the cerebellopontine angle to the branches of facial expression, including the greater superficial petrosal nerve, the nerve to the stapedius, and the chorda tympanL5 The tumor in this case is believed to arise from the chorda tympani as it coursed between the malleus and the incus. Most investigators report facial nerve dysfunction as the most common presentThe paralysis is usually grading complaint.2~3+5S7 ual and progressive and becomes particularly suspect .when accompanied by facial spasm or persists for longer than 6 months. However, a sudden onset facial paralysis such as that found with Bell’s palsy was the presenting complaint in 20% of patients with a facial nerve neuroma in one series.8 It must also be noted that fully intact facial nerve function has also been reported,g-ll as was found in this case. Hearing loss, both conductive and sensorineural, is another common clinical manifestation. It is occasionally accompanied by tinnitus and vertigo. Facial nerve neuromas have also presented as external auditory canal “polyps” and as “chronic otitis media” when complicated by aural
QUIZ
discharge. Other less common findings include loss of taste to the anterior tongue and decreased flow from the submandibular gland. The patient in this case complained of a metallic taste immediately postoperatively. There is no classic mode of presentation of facial nerve neuromas. Indeed, a review of 600 temporal bones revealed four entirely asymptomatic tumors.4 Diagnosis begins with a full neurotologic examination with special attention paid to facial function. Audiologic and vestibular testing is also important and may aid in localizing the site of the tumor. The value of electromyography and electroneurography is a subject of great debate. Some investigators8*12 have found electrophysiologic tests useful in predicting degenerative changes in the presence of normal facial nerve function. Others, however, doubt the validity of these tests when varying degrees of motor unit loss and regeneration are present.zv7 Although magnetic resonance imaging with gadolinium enhancement delineates tumor, high-resolution computed tomography remains the most accurate tool available due to its ability to exhibit bony destruction.” The decision to operate must take into account the patient’s preoperative facial nerve function compared with predicted postoperative results. The best return of facial function following facial nerve grafting or reanastomosis is a grade III or moderate dysfunction (American Academy of Otolaryngology-Head and Neck Surgery facial nerve grading system] and is always accompanied by synkinesis.’ Few tumors are able to be peeled off the nerve due to extensive intraneural extensions. Most surgeons agree that the best return of facial function is accomplished with expediently planned surgery to avoid degenerative changes of the facial nerve nucleus,5*“~g*”although this decision is debatable in the very young and the very old. The surgical approach is tailored to the site of the tumor. The tympanic segment of the nerve is the most frequently involved (58%).’ If the lesion is proximal to the geniculate ganglion, either a translabyrinthine or a middle fossa approach may be used, depending on the patient’s audiologic function. Tumors distal to the geniculate ganglion may be reached via a transmastoid approach. Continuity of the nerve is re-established with an interposition graft or, if the defect is less than 1 cm, by performing an end-to-end anastomosis after rerouting the nerve. Facial nerve neuromas are uncommon entities that usually present a confusing clinical picture. Prompt diagnosis and treatment depend on a high index of suspicion on the part of the physician.
QUIZ
References 1. Schmidt C: Neurinom des nervus facialis. Zentralbl HalsNas Ohrenheilk 1939; 16:329 (abstr) 2. Lipkin AF, Coker NJ, Jenkins HA, et al: Intracranial and intratemporal facial neuroma. Otolaryngol Head Neck Surg 1967; 96:71-79 3. Isamat F, Bartumeus F, Miranda AM, et al: Neurinomas of the facial nerve. J Neurosurg 1975; 43:608-613 4. Saito H, Baxter A: Undiagnosed intratemporal facial nerve neurilemomas. Arch Otolaryngol 1972; 95:415-419 5. Pulec JL: Symposium on ear surgery II: Facial nerve neuroma. Laryngoscope 1972; 82:1160-1176 6. Pulec JL: Facial nerve tumors. Ann Otol Rhino1 Laryngol 1969; 78:962-982
301 7. Neely JG, Alford BR: Facial nerve neuromas. Arch Otolaryngol 1974; 100:298-301 8. Fisch U: Facial Nerve Surgery. Birmingham, AL, Aesculapius, 1977 9. O’Donoghue GM, Brackmann DE, House JW, et al: Neuromas of the facial nerve. Am J Otolaryngol 1989; 10:49-54 10. Sharp F, Kerr AIG, Carder P, et al: Facial schwannoma without facial paralysis. J Laryngol Otol 1969; 103:973-975 11. Bailey CM, Graham MD: Intratemporal facial nerve neuroma: A discussion of five cases. J Laryngol Otol 1983; 97:6572 12. Brackmann DE, House JW, Selters W: Auditory brainstem response in facial nerve neurinoma diagnosis, in “Graham MD, House WF (eds): Disorders of the Facial Nerve. New York, NY, Raven, 1982, pp 87-89
1991
Temporal
Bone Histopathology: Residents’ Quiz
SANDRAPALASTI,MD, ANDJED KWARTLER,MD absent stapedial reflex. The remainder of the head and neck examination was unremarkable. A computed tomography scan of the temporal bones revealed opacification of the right middle ear cleft with excellent pneumatization and aeration of both mastoid cavities. At exploratory tympanotomy, a gray mass was found between the malleus and the incus: the mass was excised. A histologic section is shown in Fig I. What is your temporal bone diagnosis?
A 42-year-old man presented with a g-month history of right ear fullness and decreased hearing. He had been treated with antibiotics by medical clinic physicians, but had no response. He was then referred to an otolaryngologist for further evaluation. On physical examination, the patient’s right tympanic membrane appeared retracted, with a lucency behind the posterior superior quadrant. Audiologic examination revealed a 20- to 30-dB conductive hearing loss in the right ear with an
Figure1. Low-power photomicrograph of a facial nerve neuroma. Note the mucosal covering, clinically of middle ear.
299
300
DIAGNOSIS Facial nerve neuroma. DISCUSSION Neuromas of the facial nerve are uncommon tumors. First described by Schmidt1 in 1930, only 248 cases had been reported in the world literature as of 1986.’ The clinical manifestations of these tumors are often subtle; the diagnosis is frequently delayed or missed entirely. Neuromas (also referred to as schwannomas and neurilemmomas) are benign encapsulated neoplasms of nerve sheath origin. Neuromas may arise from any cranial nerve and are well documented in acoustic and trigeminal nerves.3 In a mixed nerve, such as the facial nerve, the neuroma is thought to arise from the sensory elementsa4 Grossly, these tumors present as gray, lobulated masses that arise eccentrically from the nerve. They often appear to be multicentric, but closer inspection usually reveals intraneural connections between these lobulations. Microscopically, the tumor is composed of long slender cells with elongated nuclei (Fig l),arranged in palisades and whorls. The tumor is composed of compact (Antoni A) and loose (Antoni B) areas with Verocay bodies occurring at the end of fibrillar bundles. Presenting symptoms of facial neuromas depend on the site of origin. Tumors may occur in any portion of the nerve from the cerebellopontine angle to the branches of facial expression, including the greater superficial petrosal nerve, the nerve to the stapedius, and the chorda tympanL5 The tumor in this case is believed to arise from the chorda tympani as it coursed between the malleus and the incus. Most investigators report facial nerve dysfunction as the most common presentThe paralysis is usually grading complaint.2~3+5S7 ual and progressive and becomes particularly suspect .when accompanied by facial spasm or persists for longer than 6 months. However, a sudden onset facial paralysis such as that found with Bell’s palsy was the presenting complaint in 20% of patients with a facial nerve neuroma in one series.8 It must also be noted that fully intact facial nerve function has also been reported,g-ll as was found in this case. Hearing loss, both conductive and sensorineural, is another common clinical manifestation. It is occasionally accompanied by tinnitus and vertigo. Facial nerve neuromas have also presented as external auditory canal “polyps” and as “chronic otitis media” when complicated by aural
QUIZ
discharge. Other less common findings include loss of taste to the anterior tongue and decreased flow from the submandibular gland. The patient in this case complained of a metallic taste immediately postoperatively. There is no classic mode of presentation of facial nerve neuromas. Indeed, a review of 600 temporal bones revealed four entirely asymptomatic tumors.4 Diagnosis begins with a full neurotologic examination with special attention paid to facial function. Audiologic and vestibular testing is also important and may aid in localizing the site of the tumor. The value of electromyography and electroneurography is a subject of great debate. Some investigators8*12 have found electrophysiologic tests useful in predicting degenerative changes in the presence of normal facial nerve function. Others, however, doubt the validity of these tests when varying degrees of motor unit loss and regeneration are present.zv7 Although magnetic resonance imaging with gadolinium enhancement delineates tumor, high-resolution computed tomography remains the most accurate tool available due to its ability to exhibit bony destruction.” The decision to operate must take into account the patient’s preoperative facial nerve function compared with predicted postoperative results. The best return of facial function following facial nerve grafting or reanastomosis is a grade III or moderate dysfunction (American Academy of Otolaryngology-Head and Neck Surgery facial nerve grading system] and is always accompanied by synkinesis.’ Few tumors are able to be peeled off the nerve due to extensive intraneural extensions. Most surgeons agree that the best return of facial function is accomplished with expediently planned surgery to avoid degenerative changes of the facial nerve nucleus,5*“~g*”although this decision is debatable in the very young and the very old. The surgical approach is tailored to the site of the tumor. The tympanic segment of the nerve is the most frequently involved (58%).’ If the lesion is proximal to the geniculate ganglion, either a translabyrinthine or a middle fossa approach may be used, depending on the patient’s audiologic function. Tumors distal to the geniculate ganglion may be reached via a transmastoid approach. Continuity of the nerve is re-established with an interposition graft or, if the defect is less than 1 cm, by performing an end-to-end anastomosis after rerouting the nerve. Facial nerve neuromas are uncommon entities that usually present a confusing clinical picture. Prompt diagnosis and treatment depend on a high index of suspicion on the part of the physician.
QUIZ
References 1. Schmidt C: Neurinom des nervus facialis. Zentralbl HalsNas Ohrenheilk 1939; 16:329 (abstr) 2. Lipkin AF, Coker NJ, Jenkins HA, et al: Intracranial and intratemporal facial neuroma. Otolaryngol Head Neck Surg 1967; 96:71-79 3. Isamat F, Bartumeus F, Miranda AM, et al: Neurinomas of the facial nerve. J Neurosurg 1975; 43:608-613 4. Saito H, Baxter A: Undiagnosed intratemporal facial nerve neurilemomas. Arch Otolaryngol 1972; 95:415-419 5. Pulec JL: Symposium on ear surgery II: Facial nerve neuroma. Laryngoscope 1972; 82:1160-1176 6. Pulec JL: Facial nerve tumors. Ann Otol Rhino1 Laryngol 1969; 78:962-982
301 7. Neely JG, Alford BR: Facial nerve neuromas. Arch Otolaryngol 1974; 100:298-301 8. Fisch U: Facial Nerve Surgery. Birmingham, AL, Aesculapius, 1977 9. O’Donoghue GM, Brackmann DE, House JW, et al: Neuromas of the facial nerve. Am J Otolaryngol 1989; 10:49-54 10. Sharp F, Kerr AIG, Carder P, et al: Facial schwannoma without facial paralysis. J Laryngol Otol 1969; 103:973-975 11. Bailey CM, Graham MD: Intratemporal facial nerve neuroma: A discussion of five cases. J Laryngol Otol 1983; 97:6572 12. Brackmann DE, House JW, Selters W: Auditory brainstem response in facial nerve neurinoma diagnosis, in “Graham MD, House WF (eds): Disorders of the Facial Nerve. New York, NY, Raven, 1982, pp 87-89
