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There is an extensive literature on PLFs. Substantial data and confirmed observations in the peer-reviewed literature have already addressed topics considered controversial by some members of the otologic community. The clinical presentation of PLFs is clear, the various treatment options available have been well described, and the recent prospective histopathologic confirmation of PLFs has established a gold standard for diagnosis.1,2,48

It is the responsibility of otologists to become familiar with the extensive PLF literature. Scholarly discourse should be encouraged so that we may better care for patients whose lives and livelihood have been devastated by PLFs.

REFERENCES

Black et al.—CHAPTER 55

1. Kohut RI, Hinojosa R, Budetti JA. Perilymphatic fistula: a histopathologic study. Ann Otol Rhinol Laryngol 1986;95: 466-471

2. Kohut RI, Hinojosa R, Ryu JH. Perilymphatic fistula: a single blind histopathological study. Adv Otol Rhinol Laryngol 1988;42:148-152

3. Dawes JD, Watson RT. Labyrinthine fistulae. J Laryngol Otol 1978;92(2):83-98

4. Sheehy JL, Brackmann DE. Cholesteatoma surgery: management of the labyrinthine fistula—a report of 97 cases. Laryngoscope 1979;89:78-87

5. Strohm M. Traumatic lesions of the round window membrane and perilymphatic fistulae. Adv Otolol Rhinol Laryngol 1986; 35:177-247

6. Parell GJ, Paige GD. Inner ear barotrauma in SCUBA divers. Arch Otolaryngol Head Neck Surg 1993;119:455-457

7. Edmonds C. Hearing loss with frequent diving (deaf divers). Undersea Biomed Res 1985;12:315-319

8. Molvaer OI, Natrud E. Ear damage due to diving. Acta Otolaryngol (Stockh) 1979;360(suppl):187-189

9. Caruso VG, Winkelmann PE, Correia MJ, et al. Otologic and otoneurologic injuries in divers: clinical studies on nine commercial and two sport divers. Laryngoscope 1977;4:508-521

10. Farmer JC. Diving injuries of the inner ear. Ann Otol Rhinol Laryngol 1977;86(suppl 36):1-20

11. Edmonds C, Freeman P, Tonkin J. Fistula of the round window in diving. Trans Am Acad Ophthalmol Otolaryngol 1974;78:444-447

12. Lundgren CEG. Alternobaric vertigo—a diving hazard. BMJ 1965;2:511-513

13. Head PW. Vertigo and barotrauma. In: Dix MR, Hood JD, eds. Vertigo. Bath, Avon, England: John Wiley & Sons Ltd; 1984:199-214

14. McNicoll WD. Traumatic perforation of the tympanic membrane with associated rupture of the round window membrane. J Laryngol 1978;92:895-903

15. Whinney DJD, Parikh AA, Brookes GB. Barotraumatic fracture of the stapes footplate. Am J Otol 1996;17:697-699

16. Miyazawa T, Ueda H, Yanagita N. Eustachian tube function and middle ear barotrauma associated with extremes in atmospheric pressure. Ann Otol Rhinol Laryngol 1996;105:887-892

17. Freeman P, Tonkin J, Edmonds C. Rupture of the round window membrane in inner ear barotrauma. Arch Otolaryngol 1974;99:437-442

18. Bruins WR. Blast injuries of the ear as a result of the Peterborough lorry explosion: 22 March 1989. J Laryngol Otol 1991;105:890-895

19. Konradsson KS, Carloborg BR, Farmer JC. Pressure gradients affecting the labyrinth during hypobaric pressure. Experimental study. Ann Otol Rhinol Laryngol 1997;106:495-502

20. Beuerlein M, Nelson RN, Welling B. Inner and midde ear hyperbaric oxygen-induced barotrauma. Laryngoscope 1997; 107:1350-1356

21. Guyot JP. Acoustic trauma caused by the telephone. OOtorhi-nolaryngology 1988;50:313-318

22. Schuknecht HF, Reisser C. The morphologic basis for perilymphatic gushers and oozers. Adv Otol Rhinol Laryngol 1988;39:1-12

23. Schepens YM, Schepens P. Complications which may be encountered in surgery for otospongiosis. Acta Otol Rhinol Laryngol Belg 1977;31:5-36

24. Glasscock ME. The stapes gusher. Arch Otolaryngol 1973; 98:82-91

25. Hemenway WG, Hildyard VH, Black FO. Post stapedectomy perilymph fistulas in the Rocky Mountain area: the importance of nystagmography and audiometry in diagnosis and early tympanotomy in prognosis. Laryngoscope 1968;78:1687-1715

26. House HP. The fistula problem in otosclerosis surgery. Laryngoscope 1967:1410-1426

27. Goodhill V. Sudden deafness and round window rupture. Laryngoscope 1971;81:1462-1474

28. Fee GA. Traumatic perilymphatic fistulas. Arch OOtolaryngol 1969;88:43-46

29. Glasscock ME, McKennan KX, Levine SC. Persistent traumatic perilymph fistulas. Laryngoscope 1987;97:860-863

30. Goodhill V. Traumatic fistulae. J Laryngol Otol 1980;94: 123-128

31. Sidi J, Tovi F. Traumatic labyrinthine fistulas. Isr J Med Sci 1979;15:156-158

32. Lehrer JF, Rubin RC, Poole DC, et al. Perilymphatic fistula— a definitive and curable cause of vertigo following head trauma. West J Med 1984;141:57-61

33. Hemenway WG, Black FO, Grimm RJ, Pesznecker SC. Traumatic perilymph fistula. In: Claussen CF, Kirtane MV, eds. Vertigo, Nausea, Tinnitus, and Hypoacusis Due to Head and Neck Trauma. Proceedings of the Seventh Scientific Meeting of the Neurotological and Equilibriometric Society. Amsterdam: Elsevier; 1991:167-170

34. Healy GB. Hearing loss and vertigo secondary to head injury. N Engl J Med 1982;306:1029-1031

35. Healy GB, Friedman JM, Strong MS. Vestibular and auditory findings of perilymphatic fistula: a review of 40 cases. Trans Am Acad Ophthalmol Otolaryngol 1976;82:44-49

36. Chester JB. Whiplash, postural control, and the inner ear. Spine 1991;16:716-720

37. Ferber-Viart C, Postec F, Duclaux R, Dubreuil C. Perilym-phatic fistula following airbag trauma. (Letter to the Editor.) Laryngoscope 1998;108:1255-1257

38. Huelke DF, Moore JL, Compton TW, Samuels J, Levine RS. Upper extremity injuries related to airbags deployments. J Trauma 1995;4:482-488

39. Thomas P, Bradford MO. The nature and source of the head injuries sustained by restrained front-seat car occupants in frontal collisions. Accident Anal Prev 1995;4:561-570

40. Duma SM, Kress TA, Porta DJ, et al. Airbag-induced eye injuries: a report of 25 cases. JTrauma 1996;41:114-119

41. Facer GW, Farrell KH, Cody DT. Spontaneous perilymph fistula. Mayo Clin Proc 1973;48:203-206

42. Althaus SR. Spontaneous and traumatic perilymph fistulas. Laryngoscope 1977;87:364-371

43. Shea JJ III. The myth of spontaneous perilymph fistula. Otolaryngol Head Neck Surg 1992;107:613-616

44. Cole GG. Validity of spontaneous perilymphatic fistula. Am J Otol 1995;16:815-819

45. Meyerhoff WL. Spontaneous perilymphatic fistula: myth or fact. Am J Otol 1993;14:478-481

46. Sando I, Takahara T, Ogawa A. Congenital anomalies of the inner ear. Ann Otol Rhinol Laryngol 1984;93:110-117

47. Reilly JS. Congenital perilymphatic fistula: a prospective study in infants and children. Laryngoscope 1989;99:393-397

48. Kohut RI, Hinojosa R, Ryu JH. The histologic characteristics of the core of the fissula ante fenestram. Acta Otolaryngol (Stockh) 1991;481(suppl):158-162

49. Dawes JD, Pearman K, Kochilas X. Patent fissula ante fenestram. J Laryngol Otol 1983;97:357-360

50. Jackler RK, Hwang PH. Enlargement of the cochlear aqueduct: fact or fiction? Otolaryngol Head Neck Surg 1993; 109:14-25

51. Griffith AJ, Arts HA, Downs C, et al. Familial large vestibular aqueduct syndrome. Laryngoscope 1996;106:960-965

52. Illum P. The Mondini type of cochlear malformation. Arch Otolaryngol 1972;96:305-311

53. Schuknecht HF. Mondini dysplasia: a clinical and pathological study. Ann Otol Rhinol Laryngol 1980;89(suppl 65):3-23

54. Kamerer DB, Sando I, Hirsch BE, Takagi A. Perilymph fistula resulting from microfissures. Am J Otol 1987;8:489-494

55. Harada T, Sando I, Myers EN. Microfissure in the oval window area. Ann Otol Rhinol Laryngol 1981;90:174-180

56. Weider DJ, Musiek FE. Bilateral congenital oval window microfistulae in a mother and son. Laryngoscope 1984;94: 1455-1458

57. Bluestone CD. Otitis media and congenital perilymphatic fistula as a cause of sensorineural hearing loss in children. Pedi-atr Infect Dis J 1988;7:141-145

58. Crook JP. Congenital fistula in the stapedial footplate. South Med J 1967;60:1168-1170

59. Guindi GM. Congenital labyrintho-tympanic fistula—a recently recognized entity in children. J Laryngol Otol 1981; 10:1:67-71

60. Healy GB, Friedman JM, DiTroia J. Ataxia and hearing loss secondary to perilymphatic fistula. Pediatrics 1978;61:238-241

61. Healy GB, Strong MS, Sampogna D. Ataxia, vertigo, and hearing loss. Arch OOtolaryngol 1991;100:130-135

62. Black FO, Pesznecker SC, Norton TL, et al. Surgical management of perilymph fistulas: a new technique. Arch Otolaryngol Head Neck Surg 1991;117:641-648

63. Black FO, Pesznecker SC. Surgical management of motion sickness in perilymph fistula patients. In: Twentieth Meeting of the International Barany Society. Würzburg, Germany; 1998

64. Grimm RJ, Hemenway WG, LeBray PR, Black FO. The perilymph fistula syndrome defined in mild head trauma. Acta Otolaryngol 1989;464(suppl):5-40

65. Erickson KR, DeWeese M, Simons A. A specific syndrome of memory impairment in patients with vestibular disorder: selective acquisition and retrieval deficits. International Conference: Perilymph fistula—a common cause of dizziness and dysequi-librium? September 6, 1990;Portland, Oregon. Am J Otol 1990:887-891

66. Kohut RI, Waldorf RA, Haenel JL, Thompson JN. Minute perilymph fistulas: vertigo and Hennebert's sign without hearing loss. Ann Otol Rhinol Laryngol 1979;88:153-159

67. Simmons FB. Fluid dynamics in sudden sensorineural hearing loss. Otolaryngol Clin North Am 1978;11:55-61

68. Simmons FB. Perilymph fistula: some diagnostic problems. Adv Otol Rhinol Laryngol 1982;28:68-72

69. Daspit CP, Churchill D, Linthicum FH. Diagnosis of perilymph fistula using ENG and impedance. Laryngoscope 1980; 90:217-223

70. Causse JR, Causse JB, Bel J. Tympanometry and fistula test. Audiology 1983;22:451-462

71. Black FO, Lilly DJ, Nashner LM, Peterka RJ, Pesznecker SC. Quantitative diagnostic test for perilymph fistula. Otolaryngol Head Neck Surg 1987;96:125-134

72. Black FO, Lilly DJ, Peterka RJ, et al. The dynamic posturo-graphic pressure test for the presumptive diagnosis of perilymph fistulas. Neurol Clin 1990;8:361-374

73. Nadol JB Jr. Positive Hennebert's sign in Meniere's disease. Arch Otolaryngol 1977;103:524-530

74. Arenberg IK, Ackley RS, Ferraro JA, Muchnik C. ECoG results in perilymphatic fistula: clinical and experimental studies. Otolaryngol Head Neck Surg 1988;99:435-443

75. Campbell KCM, Savage MM, Harker LA. Electrocochleogra-phy in the presence and absence of perilymphatic fistula. Ann Otol Rhinol Laryngol 1992;101:403-407

76. Black FO, Pesznecker SC. Perilymphatic fistula. The method of F. Owen Black. In: Gates GA, ed. Current Therapy in Otolaryngology Head and Neck Surgery. 6th Ed. St. Louis, MO: CV Mosby; 1998:71-78

77. Nomura Y. Otologic Significance of the Round Window. Munich: Karger-Basel; 1984

78. Seltzer S, McCabe BF. Perilymph fistula: the Iowa experience. Laryngoscope 1986;94:37-49

79. Coats AC. The summating potential and Meniere's disease. Summating potential amplitude in Meniere's and non-Meniere's ears. Arch Otolaryngol Head Neck Surg 1979;107: 199-208

80. Coats AC. Electronystagmography. In: Bradford LJ, ed. Physiological Measures of the Audio-vestibular System. San Diego, CA: Academic Press, 1975:37-83

81. Coats A. On electrocochleographic electrode design. JAcoust Soc Am 1974;56:708-711

82. Arenberg IK, May M, Stroud MH. Perilymphatic fistula: an unusual cause of Meniere's syndrome in a prepubertal child. Laryngoscope 1974;84:243-246

83. Black FO. Vertigo: the method of F. Owen Black, M.D., F.A.C.S. In: Decker BC, ed. Current Therapy in Otolaryngology-Head and Neck Surgery. 1990:59-65

84. Epley JM. The canalith repositioning procedure: for management of benign paroxysmal positional vertigo. Otolaryngology Head Neck Surg 1992;107:399-404

85. Semont A. Curing the BPPV with a liberatory maneuver. In: Annual Meeting of the Barany Society, Marseille, France; 1987

86. Serafini G, Palmieri AMR, Simoncelli C. Benign paroxysmal positional vertigo of posterior semicircular canal: results in 160 cases treated with Semont's maneuver. Ann Otol Rhinol Laryngol 1996;105:770-775

87. Fisch U, Murata K, Hossli G. Measurement of oxygen tension in human perilymph. Acta Otolaryngol 1981;81:278-282

88. Nagahara K, Fisch U, Yagi N. Perilymph oxygenation in sudden and progressive sensorineural hearing loss. Acta Otolaryngol (Stockh) 1983;96:57-68

89. Fisch U. Management of sudden deafness. Otolaryngol Head Neck Surg 1983;91:3-8

90. Bhansali SA. Perilymph fistula. Ear Nose Throat J 1989; 68:11-27

91. Bennett RJ. On subarachnoid-tympanic fistulae: a report of two cases of the rare indirect type. J Laryngol Otol 1966;80: 1242-1252

92. Lingam S, Singh A. Recurrent meningitis due to labyrinthine fistula. J Neurol Neurosurg Psychiatry 1982;45:1168-1176

93. Grewal DS, Hiranandani NL, Pusalkar AG. Traumatic perilymph fistulae of the round and oval windows. J Laryngol Otol 1983;97:1149-1155

94. Schuknecht HF. Pathology of the Ear. 2nd Ed. Philadelphia: Lea & Febiger; 1993

Perilymph Fistulae

CHAPTER 56

Richard R. Gacek

Since the description by Fee1 of perilymphatic fistula (PLF) to the middle ear space, there has been an explosion in the number of reports describing PLF. It is likely that PLF has been used to explain clinical cases of unexplained sensorineural hearing or vertigo, or both. The diagnostic criteria of PLF are not clearly defined and surgical exploration has been used as the principal approach to diagnosis as well as management. A major impediment to recognition of perilymph in the oval or round window niches (RWN) is the presence of tissue fluid produced by middle ear mucosa that reaccumulates when aspirated. An additional misconception responsible for reported round window membrane fistulae is the assumption that a fenestrated membrane, which often covers the entrance to the RWN, represents the RWM. Removal of the bony overhang of the RWN is necessary for exposure of the RWM. It is not surprising that PLF is overdiagnosed and overtreated. This has formed the basis for controversy regarding the issue of diagnosis, recognition, and treatment of PLF.

A perilymphatic fistula (PLF) may be defined as a communication of the perilymphatic space to the middle ear space. The volume of perilymph in the labyrinth is normally small, as it is derived as a transudate of the vasculature in the spiral ligament and, to a limited degree, the cerebrospinal fluid (CSF) space through the cochlear aqueduct. Therefore, perilymph loss in a PLF is small and reaccumulates slowly. A large volume of fluid from a fistula in the oval or round windows (surgical or traumatic) represents the flow of CSF through a congenital defect in the labyrinth that allows the subarachnoid space to communicate with the perilymphatic space. This form of CSF otorrhea will not be considered in this discussion of PLF, as its presence is easily recognized by its copious flow, and treatment is non-controversial. The PLF, which has attracted considerable controversy, is represented by a defect either in the ligamentous or bony structures of the oval or round windows in a normal labyrinth. It should also be pointed out that fistulization of the bony labyrinth (cochlea and semicircular canals) from chronic middle ear inflammation, particularly cholesteatoma, does not include communication into the perilymphatic compartment. The inflammatory response to bone erosion from cholesteatoma creates fibrosis of the endosteal membrane and variable degrees of labyrinthitis rather than a defect permitting perilymph loss. Issues of diagnosis and recognition of PLF at surgery form the main areas of disagreement.

Vast clinical experience is based on the signs and symptoms that result from a humanmade fistula in the oval window. This derives from the stapedectomy or stapedotomy procedure where either a large or small fenestra is fashioned in a fixed footplate and sealed with a tissue prosthesis to recon struct a sound transmission mechanism. Although the fenestra with PLF in this procedure is of short duration, as it is sealed with tissue and the healing response of the labyrinth and the middle ear, poststapedectomy symptoms reflect a controlled PLF. Both vestibular and auditory symptoms follow stapedectomy with the vestibular symptoms consisting of dizziness and dysequilibrium, occasionally accompanied by spontaneous nystagmus being the most troublesome. Auditory system effects appear as elevated bone conduction thresholds with some decrease in speech discrimination, which may require one or several weeks to return to normal levels. It is for this reason that the usual post stapedectomy auditory examination is obtained at 4 to 5 weeks. Animal research2 has demonstrated rapid healing of a defect in the oval window by regeneration of the endosteal membrane within 24 to 48 h, followed by regeneration of middle ear mucous membrane. This reparative response is more rapid with a small fenestra than with a large (total stapedectomy) fistula.

Clinical experience with the end result of an unhealed PLF comes from our experience with direct trauma to the tympanic membrane and ossicular chain as a result of the introduction of an instrument (toothpick, hairpin) into the external ear canal. When such an injury is accompanied by vestibular symptoms, it is axiomatic that immediate surgical exploration and removal of a subluxed or fractured stapes footplate with soft tissue seal of the PLF be performed.3'4 If such repair is not performed the PLF leads to irreversible sensorineural hearing loss with eventual resolution of vestibular symptoms as a result of central vestibular compensation. Early surgical repair of the oval window fistula insures recovery of auditory and vestibular deficits. Thus, surgical repair of PLF is capable of reversing the labyrinthine deficits caused by PLF.

Round window membrane ruptures can be produced in the laboratory animal (cat) by increasing subarachnoid pressure.5 However, the cochlear aqueduct is short and wide in the cat but is long, narrow, and filled with periotic duct tissue in humans. Therefore, this pathway usually will not permit transmitted CSF pressure in humans as in the laboratory animal, at least in the majority of temporal bones. Furthermore, the RWM is very thin with a reduced lamina propria in the laboratory animal (cat, guinea pig, chinchilla),6 whereas the human RWM has a thick lamina propria that will resist disruption by increased

pressure.

Animal research has demonstrated that cochlear potentials do not change8,9 after RWM ruptures. Furthermore, RWM breaks, no matter how large, undergo spontaneous healing in 7 to 10 days.8 However, when such RWM ruptures are accompanied by intracochlear membrane breaks (Reissner's membrane, basilar membrane) there is a significant sensorineural hearing loss or change in cochlear potentials.10'11

These clinical and experimental observations indicate that a serous labyrinthitis occurs in PLF. The definition of serous labyrinthitis rests on the reversibility of auditory and vestibular dysfunction, implying that if function does not recover, a more advanced stage of labyrinthitis has been reached. Therefore, if the PLF does not heal either spontaneously or by repair, the serous labyrinthitis may progress to a serofibrinous labyrinthitis with irreversible loss of auditory and vestibular function. If the PLF is repaired while the stage of inflammation is serous, recovery of the function and reversibility of auditory and vestibular symptoms will occur.12 The time period beyond which repair will not prevent irreversible loss of function is unknown but probably has a duration of 1 to 2 weeks. This suggested time period is based on clinical experience with treatment of post-stapedectomy granuloma. Most ears with the granuloma removed within 2 weeks recover function completely, whereas those removed later than 2 weeks, or not at all, are associated with severe sensorineural hearing loss.

The main controversy centers around the diagnosis and management of PLF. In my opinion, history is an extremely important diagnostic criterion for spontaneous PLF. A traumatic event, either direct or indirect, to the tympanic membrane and ossicular chain must precede the onset of symptoms. This may occur after severe barotrauma, in which the patient feels sudden pressure change as a result of rapid ascent or descent. A similar force can be created in head injury without TB fracture, where a concussive force is delivered to the labyrinth and ossicular chain. The presence of auditory and vestibular symptoms after such an event may represent the diagnostic manifestations of PLF. These should be demonstrated with auditory and vestibular tests that include pneumatic otoscopy to exhibit a possible fistula.13-15

Marked displacement of the ossicular chain is more likely to produce a tear in the ligamentous structures of the oval window than the RWM because of the shearing force between the footplate and the margin of the oval window. This may produce disruption of the stapediovestibular ligament and the creation of PLF. This author has identified four PLFs in the oval window out of 20 surgically explored cases over a 25-year period. No PLFs were identified in the RWM. A higher incidence of PLF in the oval window than in the round window has also been reported by Singleton et al.13 It is possible that the thicker RWM in close proximity to a channel (cochlear aqueduct), which may decompress the pressure within the perilym-phatic compartment, is at least partially responsible for the infrequency of disruption at this area. Adequate exposure is necessary to precisely identify a tear in the RWM. Because the RWM is usually obscured by the bony overhang of the round window niche, exposure requires drilling off the overhang after the removal of the mucosal fold that is frequently draped over the aperture of the round window niche. This mucosal fold often has a small fenestra which may be mistaken for an RWM defect. This mucosal curtain may assume various positions in the RW niche that simulate the RWM.

When the criteria for diagnosis of PLF are fulfilled, a conservative management is recommended initially. The following criteria are sufficient to support a diagnosis of PLF: (1) a history of trauma (barotrauma or head trauma), (2) sensorineural hearing loss and dysequilibrium, and (3) dissimilarity to other known labyrinth disorders. The presence of a positive fistula test is additional supporting evidence. Conservative management consists of a period of bed rest with head elevation for a period of 7 to 10 days to provide an opportunity for spontaneous healing of the defect by the endosteal membrane of the vestibular wall as well as the middle ear mucosa. Procedures that reduce subarachnoid pressure and possibly perilymphatic pressure are encouraged to assist healing. Should there be no improvement or should auditory or vestibular symptoms worsen, surgical exploration for PLF is indicated.

Exploration of the middle ear for PLF should be performed under local anesthesia with light sedation. Local rather than general anesthesia reduces the incidence of bleeding and fluid accumulation from manipulation of the middle ear mucosa. It also allows the patient to respond with a Valsalva maneuver when requested to enhance perilymph leakage. Complete control of bleeding is necessary before examination of the middle ear space is performed. Adequate exposure of the oval and round windows may require curettage of the posterior and superior ear canal wall. Both labyrinthine windows should be examined without manipulation of a mucosal surface since this maneuver may induce a serous transudate that can simulate per-ilymph. A sensitive and specific marker of perilymph would greatly facilitate identification of PLF. Attempts to find a marker using colorimetric markers such as fluorescein have not been successful. Chemical markers specific for CSF (b-2-trans-ferrin) have also not proven reliable as an indicator of perilymph in clinical studies.16 A recent report17 described detection of human apolipo-protein D using chemo- luminescent Western blot assay in human perilymph taken at surgery. A 75% positive identification rate for perilymph and no false-positive results among 15 controls (middle ear fluid) were recorded. Further confirmation of the use of such protein fractions specific for perilymph will aid the diagnosis of PLF.

A No. 24 aspirator tip is carefully used to examine the margins of the oval window with and without displacement of the ossicular chain. If no fluid accumulation is seen, the patient is asked to perform Valsalva maneuvers at least twice to determine whether an enhancement of subarachnoid pressure will produce perilymph flow. If the oval window examination is negative, the round window niche is examined initially without instrumentation following a Valsalva maneuver and ossicular manipulation. If no fluid has accumulated, the bony overhang of the round window niche is carefully removed with a microdrill to expose and examine the RWM while depressing the ossicular chain. If this examination is also negative, tissue augmentation of the membrane is not performed. I believe that repair in the absence of any visible evidence of PLF confuses the evaluation of the effectiveness of the procedure. A fistula small enough to escape detection by the preceding method of examination should have healed spontaneously.

If fluid has been detected in either of the labyrinthine windows, the precise location of the defect is revealed by use of a No. 24 aspirator and is prepared to receive a tissue graft by removal of mucosal membrane from adjacent bony surfaces. Small (1-mm) adipose tissue grafts are secured in place with gelfoam pledgets. The patient's activity postoperatively should be restricted for at least 1 week to 10 days to aid adequate fibrous healing of the PLF. Auditory function should be evaluated in 6 to 8 weeks postoperatively and at later periods if incomplete recovery is seen initially.

A reasonable statement of PLF incidence is that they do occur but are infrequent. The survey conducted by Hughes et al.18 of 167 surgeons of the American Otologic Society indicated that most (60%) performed three or fewer explorations for PLF per year. The average number of explorations for the group was less than five per year. The number of confirmed PLF was even smaller. If the diagnosis of PLF is based on strict criteria and surgical exploration carried out only after a conservative therapeutic trial has been offered, the number of confirmed PLFs will be very small.

REFERENCES

Gacek—CHAPTER 56

1. Fee GA. Traumatic perilymphatic fistulas. Arch (Otolaryngol 1968;88:477-480

2. Hohmann A. Inner ear reactions to stapes surgery (animal experiments). In: Schunecht HF, ed. Otosclerosis. Boston: Little, Brown; 1962:305-317

3. Silverstein H. Penetrating wounds of the tympanic membrane and ossicular chain. Trans Am Acad Ophthalmol Otolaryngol 1973;77:125-135

4. Emmett JR, Shea JJ. Traumatic perilymph fistula. Laryngoscope 1980;90:1513-1520

5. Harker L, Norante JD, Ryu JH. Experimental rupture of the round window membrane. Trans Am Acad Ophthalmol Otolaryngol 1974;78:448-452

6. Richardson T, Ishiyama E, Keels E. Submicroscopic studies of the round window membrane. Acta Otolaryngol 1971;71:9-21

7. Kawabata I, Paparella M. Fine structures of the round window membrane. Ann Otol Rhinol Laryngol 1971;80:13-26

8. Simmons FB, Burton RD, Beatty D. Round window injury: auditory, behavioral and electrophysiological consequences in the cat. Trans Am Acad Ophthalmol Otolaryngol 1962;66:715

9. Weisskopf A, Murphy JT, Merzenich MM. Genesis of the round window rupture syndrome: some experimental observations. Laryngoscope 1978;88:389-397

10. Oshiro EM, Shelton C, Lusted HS. Role of perilymphatic fistula in sudden hearing loss: an animal model. Ann Otol Rhinol Laryngol 1989;98:491-495

11. Simmons FB. The double-membrane break syndrome in sudden hearing loss. Laryngoscope 1979;89:59-66

12. Arragg F, Paparella M. Traumatic fracture of the stapes. Laryngoscope 1964;74:1329

13. Singleton GT, Post KN, Karlan MS, Bock DG. Perilymph fistulas: diagnostic criteria and therapy. Ann Otol Rhinol Laryngol 1978;87:797-803

14. Simmons FB. Perilymph fistula: some diagnostic problems. Adv Otorhinolaryngol 1982;18:68-72

15. Love JT, Waguespack RD. Perilymphatic fistulas. Laryngoscope 1981;91:1118-1128

16. Buckman CA, Luxford WM, Hirsch BE, et al. Beta-2-trans-ferrin assay in the identification of perilymph. In: Abstracts of the One hundred thirty-first Meeting of the American Otologic Society; May 9-10, 1998

17. Telian SA, Disher MJ, Sun Q, Andrews PC. Biochemical markers for identification of human perilymph. In: Abstracts of the One hundred thirty-first Meeting, of the American Otologic Society; May 9-10, 1998

18. Hughes GB, Sismanis A, House J. Is there consensus in perilymph fistula management? Otolaryngol Head Neck Surg 1990; 102:111-117

Perilymph Fistulae

CHAPTER 57

John F. Kveton

The diagnosis of perilymph fistula continues to be elusive, spawning both extremes of overdiagnosis and underdiagno-sis. In this situation, the otolaryngologist is confronted with the possibility of becoming either a charlatan for overdiag-nosing, and therefore overoperating on patients, or a therapeutic nihilist, and so failing to eliminate inner ear symptoms in one of the rare instances in which surgical intervention can remedy sensorineural impairment. The question of whether such a condition even exists has been raised by some investigators.1,2 By contrast, Goodhill's3 original descriptions of the pathophysiology of perilymphatic fistula and my personal experience with elimination of symptoms after surgical repair of obvious perilymph leaks would indicate that this condition does in fact exist. This chapter reviews my understanding of this entity and outlines my approach to arriving at the diagnosis and management of patients who present with the appropriate symptoms.

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