- Email: [email protected]
Endolymphatic sac surgery for Meniere’s Disease
Author’s Accepted Manuscript Endolymphatic sac surgery for meniere′s disease Michael D. Puricelli, Henrique Furlan Pauna, Michael M. Paparella
www.techgiendoscopy.com
PII: DOI: Reference:
S1043-1810(16)30051-3 http://dx.doi.org/10.1016/j.otot.2016.10.004 YOTOT732
To appear in: Operative Techniques in Otolaryngology - Head and Neck Surgery Cite this article as: Michael D. Puricelli, Henrique Furlan Pauna and Michael M. Paparella, Endolymphatic sac surgery for meniere′s disease, Operative Techniques in Otolaryngology - Head and Neck Surgery, http://dx.doi.org/10.1016/j.otot.2016.10.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Endolymphatic Sac Surgery for Meniere’s Disease Michael D. Puricelli, MD1 Henrique Furlan Pauna, MD2,5 Michael M. Paparella, MD2,3,4 1
University of Missouri Department of Otolaryngology Head and Neck Surgery Paparella Ear, Head and Neck Institute 3 Clinical Professor and Chairman Emeritus Department of Otolaryngology University of Minnesota 4 Director Otopathology Laboratory 5 Department of Otorhinolaryngology, Head and Neck Surgery University of CampinasUNICAMP 2
Grant Support: This study was supported by the National Institute on Deafness and Other Communication Disorders (NIDCD), grant number U24 DC011968-01; the International Hearing Foundation; the Starkey Hearing Foundation; the 5M Lions International; and the Scientific and Technological Research Council of Turkey (TUBITAK).
Michael M. Paparella Email: [email protected] Phone 612-339-2836 701 25th Ave S #200 Minneapolis, MN 55454
Abstract: Meniere’s disease and its pathologic correlate endolymphatic hydrops develop from endolymphatic malabsorption secondary to genetically determined and environmentally influenced factors. Medical therapy is effective in most cases. When insufficient, endolymphatic sac enhancement is a logical extension of conservative treatment, as it is organ sparing and hearing conserving therapy resulting in excellent symptomatic control with a low rate of complications. The senior author’s technique for endolymphatic sac enhancement is presented incorporating experience from over 5,000 such procedures.
Every year, worldwide, hundreds of thousands of patients suffer the chronic symptoms of Meniere’s disease: intermittent vertigo lasting from minutes to hours, fluctuating progressive sensorineural hearing loss, tinnitus, and aural pressure. For decades many and some currently have used the defeatist term “idiopathic endolymphatic hydrops” to describe Meniere’s disease. Meniere’s disease is neither idiopathic, nor is its pathologic correlate, endolymphatic hydrops.1 It is a clinical entity which renders the patient difficulty and distress and has multiple effective medical and interventional treatments.2 Central to understanding the role of endolymphatic sac enhancement is understanding of the pathogenesis. Meniere’s disease is believed to result from genetic aberration predisposing to endolymphatic malabsorption. The genetic root of Meniere’s disease was proposed in 1984 by the senior author; and, to date, there are over 90 articles published describing the genetics of Meniere’s disease.3,4 Heritability has been reported in 7-15% of patients.5 The proposed transmission mechanism is autosomal dominant with incomplete (approximately 60%)
penetrance and worsened symptoms with successive generations.4,6-8 To date, however, no causative gene or genes have been identified.4,6,9-11 Affected individuals frequently demonstrate anatomic anomalies that may not be seen in surgery performed for other indications. Characteristic findings of Meniere’s disease include hypopneumatization of the mastoid; a medially and anteriorly located sigmoid sinus; hypodevelopment of the aditus and suprapyramidal (facial) recess; hypoplastic vestibular aqueduct and endolymphatic sac; stiffening of the dura; and most importantly reduction in size and vertical orientation of the plate of bone separating the sigmoid sinus and posterior semicircular canal referred to as Trautmann’s triangle.12,13 The above described anomalies adversely impact the longitudinal flow of endolymph in the duct and contribute to malabsorption. 14 This mechanism is further supported by acquired Meniere’s disease reported in advanced otosclerosis obstructing the vestibular aqueduct 15,16. Other acquired causes include chronic inactive otitis media and mastoiditis, syphilis, and childhood measles or mumps. 17-19 Histopathologically, hydrops is identifiable in the pars superior and pars inferior including utricular enlargement. 1 Reissner’s membrane shows stretching in Meniere’s disease with increased intercellular distance.20 Membranous ruptures, precipitating ionic mixing and loss of the normal electrical gradient, are seen in some but not most cases at the time of pathologic examination.1 Repeated exposure of the basal aspect of hair cells to the toxic potassium rich endolymph may precipitate vertigo and reduce hearing.21 More than 90% of patients are helped with lifestyle modifications and medical management including low salt and caffeine diet, diuretic treatment, possibly betahistine and transtympanic steroid injections.2. In cases where medical therapy is insufficient, endolymphatic
sac enhancement may be considered as an extension of conservative (organ preserving) therapy and in many practices is offered prior to ablative interventions such as transtympanic gentamicin perfusion. Endolymphatic sac enhancement ameliorates the symptoms of hydrops by reversing the pathogenesis of the condition through removal of the bone near the posterior fossa dura where the endolymphatic sac resides and placing a silicone T-stent and spacers.14 Decompression of the endolymphatic sac and techniques on the associated dura alter the hydrostatic pressure and chemical osmotic gradients that can improve absorption of endolymph in the endolymphatic sac and relieve endolymphatic hydrops, rather than shunting the endolymph into the cerebrospinal fluid.14 Indications for endolymphatic sac enhancement include patients who have classic symptoms of Meniere’s disease including recurrent episodic dizziness, fluctuating hearing loss, aural fullness, and tinnitus who do not achieve adequate symptom control with prolonged medical management. Patients with prominent vestibular or cochlear symptoms alone may also be candidates . Surgical intervention is considered for severe disease, with individuals experiencing symptoms for a mean of six years prior to intervention.22,23 Prior to undertaking endolymphatic sac enhancement surgery, the presence and laterality of the affected ear must be determined. History and physical examination indicate the affected ear in most cases and audiometric findings including a low frequency, flat hearing loss, or peak configuration lend further support. Electrophysiologic studies such as videonystagmography (VNG) that might show peripheral vestibular caloric weakness, electrocochleography (Ecog) that might show elevated summation potential/action potential (SP/AP) ratios in cochlear sensory cells, or asymmetric vestibular evoked myogenic potential (VEMP) all may indicate the affected
ear. A computed tomography scan or magnetic resonance imaging study may help with surgical planning by delineating the nature of the compression and the location of the facial nerve as well as excluding confounding pathology such as a vestibular schwannoma.14 The following description and illustrations are of our recommended technique for endolymphatic sac enhancement. The technique described is successful for locating the endolymphatic sac in 98% of cases with need for progression to destructive interventions such as gentamicin infusion in less than 3-5% of cases treated in the senior author’s experience. A curvilinear postauricular incision is made in the skin one half inch posterior to the postauricular crease. Placing the incision here helps avoid depression of skin into the mastoid cavity and helps reduce scar tissue that is thought to grow from subcutaneous tissue into the area near the sac. Thick subcutaneous tissue and excessive fat are debulked to prevent the scar tissue that can be observed later during revision endolymphatic sac enhancement. The mastoid cortex is exposed and compete mastoidectomy is performed. Cutting drill bits with reverse mode are used for smoothing and hemostasis. To identify the antrum, the tegmen mastoideum is exposed and followed medially. The posterior bony wall of the external canal is thinned to help identify the region of the horizontal semicircular canal and the descending facial nerve. The aditus is widened, the incus is exposed, and the facial suprapyramidal recess is opened widely in most cases all of which help aerate the mastoid cavity and avoid aditus-block syndrome. When thinning the bone over the sigmoid and dura of the posterior fossa, depth of drilling is never extended below the dome of the horizontal semicircular canal or, to be safer, the level of the incus to avoid injury to the lateral semicircular canal. Measurements with a fenestrometer are made from the fossa incudes 10 mm along the axis of the linea temporalis and 12 mm inferioposteriorly in a line at 45 degrees from the linea temporalis. To avoid removing bone near
the solid angle that contains the canals, and to prevent labyrinthine injury, a zone around the solid angle is demarcated. Using a forward or reverse drill, bone over Trautmann’s triangle and the length of the sigmoid sinus are thinned. The thinned bone of Trautmann’s triangle is removed with mastoid curettes or a rongeur. If Trautmann’s triangle is large, then more bone over the sigmoid sinus can be left to avoid injury to the sinus. This is uncommon as the sigmoid sinus is characteristically prominent and in an anterior and medial (deep) location in patients with Meniere’s disease. If Trautmann’s triangle is small or absent, wide decompression of the sigmoid is often necessary in order to decompress the dura adequately. The retrolabyrinthine and retrofacial air cells are not removed, in order to keep intact a shelf of bone over the region of the sac that can contain the silicone sheeting spacers used for sustained decompression. Rather than removing those air cells, the dura of the posterior fossa is elevated off the bone of the labyrinth. With this gentle retraction, the thickened region of the dura that contains the sac can be identified. The patient’s bed often requires elevation with lowering of the surgical chair to the floor and perhaps slight rotation of the bed away from the surgeon. The sac is entered using a sickle knife with tip pointed upwards to cut beneath the solid angle of labyrinthine bone. Using a blunt right-angled instrument such as a whirlybird the epithelium of the sac can be visualized, especially towards the infralabyrinthine region. Entrance to the sac should not be opened to the mastoid cavity to prevent fibrous or granulation tissue from invading the sac. A T-strut made of silicone sheeting is placed into the lumen of the sac. It helps to have different sizes of T-struts (small, medium, and large) prepared in advance so that a T-strut appropriate for the size of the lumen can be chosen. The tail of the strut is placed outside the sac between dura and bone to help passive transfer of nanoliters of endolymph, which may help
relieve the endolymphatic hydrops. To decompress the dura and adjacent sigmoid sinus widely and keep them off the bone indefinitely, spacers (small, medium, or large strips of silicone sheeting) are folded and placed superior and inferior to the sac. To fully decompress the sac, as many strips of silicone as possible are placed, but not so many as to cause excessive tension on the sac and obviate the decompression. The spacers serve as soft, spring-like mechanisms to aid in longterm decompression of dura and sac. It is important that the silicone struts and spacers not be in communication with the mastoid. To keep the sac further separated from the mastoid and possible fibroblastic infiltration that would affect function of the sac, a large piece of Gelfoam is placed. This method has replaced previous techniques that used pedicle grafts, grafts of temporalis fascia and protective gold foil. All bone dust is removed before incision into the sac and prior to closure to ensure that no further bone dust is left in the mastoid or middle ear. If bone dust is not irrigated and suctioned out and enters the middle ear, it can lead to fixation of the stapes and a conductive hearing loss. All bleeding must be stopped. The wound is closed in three layers using subcutaneous absorbable sutures followed by sutures or stapes in the skin to ensure rapid healing and avoid infection of the wound. Finally, myringotomy is performed, the middle ear is suctioned and a ventilation tube is placed in the tympanic membrane to help drain the middle ear and mastoid as well as relieve pressure from any Valsalva maneuvers during recovery. Tympanostomy tubes can also help when barometric changes during or after the recovery period affect patients with Meniere’s disease. It is hoped that these measures also prevent formation of scarring in the middle ear and mastoid, aditus block syndrome, and formation of fibrous tissue invasion near the sac, which
help prevent exacerbations of Meniere’s disease and provide better long-term surgical results. The tube can be left to extrude naturally, which does not affect the patient’s symptoms. Most endolymphatic sac enhancement surgery is done as outpatient, but rarely patients may require observation overnight to manage pain and nausea using IV hydration with medication. A dressing on the mastoid is left for 24 hours, and sometimes longer if there is concern about drainage of cerebrospinal fluid. After one week, the ear is examined, the staples removed, and the tube suctioned if necessary. To help avoid post-operative infection, typically, the patient is given amoxicillin or another appropriate broad-spectrum antibiotic. Although pain medication is also prescribed, it is often not needed. Patients are told to avoid straining and lifting more than 20 pounds for two weeks and instructed to keep the ear dry until follow-up at one week to remove staples. Four weeks after surgery, an audiogram is obtained. Usually a patient is followed every six to twelve months after they have healed from the surgery and experienced adequate improvement of symptoms (Figures 1). Approximately 8% of individuals have a good result with endolymphatic sac enhancement surgery and then years (two to thirty or more) later experience recurrence of symptoms. These individuals are candidates for revision procedures. 13,14 When thick subcutaneous tissue is present, removal is helpful to prevent ingrowth of fibroblasts into the region of the sac. Reformation of bone may occur over the sigmoid sinus and dura requiring removal. Fibrous tissue is often significant in and around the endolymphatic sac and the dura is stiffened. All scar tissue and previous silicone implants must be removed so that decompression of the dura and sac can be accomplished. If there is good decompression and re-incision of the sac, a large piece of Gelfoam soaked in gentamicin may be applied to help chemically ablate the vestibular hair cells after the silicone spacers are placed. After this technique has been used, we
observe stable post-operative hearing. We find that revision endolymphatic sac enhancement surgery can be very successful in relieving patients’ symptoms of Meniere’s disease. The majority of patients who have had an endolymphatic sac enhancement revised go for a lifetime after without symptoms and with complete remission. Due to the typical anatomy of patients with Meniere’s disease, endolymphatic sac enhancement can be difficult, and it is often necessary to decompress the sigmoid and posterior fossa dura widely to permit identification of the endolymphatic sac. If bleeding occurs, apply pressure with Gelfoam followed by cotton soaked in adrenaline. While the subarachnoid space is avoided, the dura superior to the sac can be very thin (particularly in elderly patients). If a cerebrospinal fluid leak is encountered, this is manageable with pressure, Gelfoam packing and, sometimes, reverse Trendelenburg positioning. If there is cerebrospinal fluid drainage that persists at the end of the operation, Gelfoam is packed into the area and in the mastoid prior to closure. A tympanostomy tube is not placed. The patient is encouraged to stay recumbent with head elevated 30 degrees and avoid straining. Stool softeners, antiemetics and cough suppressants may be given. The sac does not have a well-demarked border so identifying it can be challenging. It is typically appreciated as a thickening of the dura inferior to the posterior semicircular canal. After the sac is incised with the tip of the knife pointed away from the subarachnoid space, blunt palpation can help identify the lumen which also looks shiny from the endothelial lining. In the rare event that the lumen is not visible, it is felt to be too hypoplastic to be seen and decompression of the dura is successful. Injury to important structures such as the posterior semicircular canal and facial nerve are rare but can happen. We advise honest assessment of the damage, open counseling and close
follow-up. Should injury be suspected, treatment with a perioperative steroid may be considered and a fresh perspective may be sought by phone or in person from a colleague in otologic surgery. Prognosis and counseling may be aided by electrodiagnostic studies of the facial nerve. In summary, many publications are available regarding the basic science and clinical experience supporting the utility of endolymphatic sac enhancement for progressive or intractable Meniere’s disease. It represents a logical extension of conservative therapy with lower risk of cochlear damage and hearing loss than destructive procedures. Further research is necessary to better understand the cellular and molecular function of the endolymphatic sac and duct and the pathophysiology of endolymphatic hydrops that correlates with Meniere’s disease. Such knowledge will help us to better understand the implications of medical and surgical interventions.
Figures Figure 1: Surgical approach. The images depict the typical post-auricular incision located one half inch posterior to the post-auricular crease (A), dissection of subcutaneous tissue with removal as necessary and subperiosteal flap elevation (B and C). Mastoidectomy. The images depict the complete mastoidectomy procedure (D and E) and method of using the solid angle to prevent labyrinthine injury (F). The distance between the short process of the incus and the bottom of the otic capsule of the posterior canal is 10.4 mm (range, 9.5 to 11.5 mm). The distance from the tip of the short process of the incus to the inferiormost point on the endolymphatic sac is 16.9 mm (range, 13.0 to 19.0 mm). The distance from the otic capsule of the posterior canal to the bottom of the sac is 4.3 mm (range, 1.9 to 6.6 mm). Endolymphatic sac enhancement. The sigmoid is skeletonized (G) permitting access to the endolymphatic sac (H1). It is identified and incised.
The dimensions of the endolymphatic sac are 8.9 X 9.0 mm (H2). T-struts and spacers inserted (I). Gelfoam is placed over the enhancement site (J).
References: 1. Paparella MM. Meniere’s Disease (Cause, Pathogenesis and symptoms of Meniere’s Disease). 7th International Symposium on Meniere’s Disease and Inner Ear Disorders. October 17-20, 2015. 2. Sharon JD, Trevino C, Schubert MC, Carey JP. Treatment of Menière's Disease. Curr Treat Options Neurol. 2015 Apr;17(4):341. doi: 10.1007/s11940-015-0341-x. PubMed PMID: 25749846. 3. Paparella MM. The cause (multifactorial inheritance) and pathogenesis (endolymphatic malabsorption) of Meniere’s disease and its symptoms (mechanical and chemical). Acta Otolaryngol 99 (3-4):445-51, 1985. 4. Klockars T, Kentala E. Inheritance of Meniere's disease in the Finnish population. Arch Otolaryngol Head Neck Surg. 2007 Jan;133(1):73-7. PubMed PMID: 17224529. 5. Chiarella G, Petrolo C, Cassandro E. The genetics of Ménière's disease. Appl Clin Genet. 2015 Jan 8;8:9-17. doi: 10.2147/TACG.S59024. eCollection 2015. Review. PubMed PMID: 25609993; PubMed Central PMCID: PMC4293923. 6. Frykholm C, Larsen HC, Dahl N, Klar J, Rask-Andersen H, Friberg U. Familial Ménière's disease in five generations. Otol Neurotol. 2006 Aug;27(5):681-6. PubMed PMID: 16868516. 7. Oliveira CA, Braga AM. Meniere's syndrome inherited as an autosomal dominant trait. Ann Otol Rhinol Laryngol. 1992 Jul;101(7):590-4. PubMed PMID: 1626905. 8. Morrison AW. Anticipation in Menière's disease. J Laryngol Otol. 1995 Jun;109(6):499-502. PubMed PMID: 7642988. 9. Fung K, Xie Y, Hall SF, Lillicrap DP, Taylor SA. Genetic basis of familial Meniere's disease. J Otolaryngol. 2002 Feb;31(1):1-4. PubMed PMID: 11883436. 10. Hietikko E, Kotimäki J, Okuloff A, Sorri M, Männikkö M. A replication study on proposed candidate genes in Ménière's disease, and a review of the current status of genetic studies. Int J Audiol. 2012 Nov;51(11):841-5. doi: 10.3109/14992027.2012.705900. Epub 2012 Aug 30. Review. PubMed PMID: 22934933. 11. Martini A. Hereditary Menière's disease: report of two families. Am J Otolaryngol. 1982 May-Jun;3(3):163-7. PubMed PMID: 7102953. 12. Paparella MM, Sajjadi H, da Costa SS, Yoon TH, Chap TL. Significance of the lateral sinus and Trautmann’s triangle in Meniere’s disease. Second International Symposium on Meniere’s Disease. Cambridge, MA June 20-22, 1988. 13. Paparella MM. Endolymphatic sac revision for recurrent intractable Meniere's disease. Otolaryngol Clin North Am. 2006 Aug;39(4):713-21, vi. Review. PubMed PMID: 16895780. 14. Sajjadi H, Paparella MM. Meniere's disease. Lancet. 2008 Aug 2;372(9636):406-14. doi: 10.1016/S0140-6736(08)61161-7. Review. PubMed PMID: 18675691.
15. Yoon TH, Paparella MM, Schachern PA. Otosclerosis involving the vestibular aqueduct and Meniere’s disease. Otolaryngol Head Neck Surg 103:107-12, 1990. 16. Paparella MM, Cureoglu S, Shao W, Schachern PA. Otosclerosis and associated pathologies. Advanced in Oto-Rhino-Laryngology. In Otosclerosis and Stapes Surgery State-of-the-art. Arnold W, Hausler R, Eds. 65:31-44, 2007 17. Paparella MM, de Souza LC, Mancini F. Meniere’s syndrome and otitis media. Laryngoscope 93:1408-15, 1983. 18. Paparella MM. Pathogenesis of Meniere’s disease and Meniere’s syndrome. Acta Otolaryngol Suppl. 406:10-25, 1984. 19. Schuknecht HF, Suzuka Y, Zimmerman C. Delayed endolymphatic hydrops and its relationship to Meniere’s disease. Ann Otol Rhinol Laryngol 99(11):843-53, 1990. 20. Cureoglu S, Schachern PA, Paul S, Paparella MM, Singh RK. Cellular changes of Reissner's membrane in Meniere's disease: human temporal bone study. Otolaryngol Head Neck Surg. 2004 Jan;130(1):113-9. PubMed PMID: 14726919. 21. Agrawal Y, Minor LB. Physiologic effects on the vestibular system in Meniere's disease. Otolaryngol Clin North Am. 2010 Oct;43(5):985-93. doi: 10.1016/j.otc.2010.05.002. Review. PubMed PMID: 20713238. 22. Liston S, Paparella MM, da Costa SS. Surgical Treatment of Vertigo. In Otolaryngology Ed Vol 3, Paparella MM ed, 1990. WB Saunders: Philadelphia pp 1715-1732. 23. Paparella MM, Hanson DG. Endolymphatic sac drainage for intractable vertigo (method and experiences). Laryngoscope. 1976 May;86(5):697-703. PubMed PMID: 933659.
Further Reading Lim MY, Zhang M, Yuen HW, Leong JL. Current evidence for endolymphatic sac surgery in the treatment of Meniere's disease: a systematic review. Singapore Med J. 2015 Nov;56(11):593-8. doi: 10.11622/smedj.2015166. Review. PubMed PMID: 26668402; PubMed Central PMCID: PMC4656865. Paparella MM, Kimberley BP. Pathogenesis of Menière's disease. J Vestib Res. 19901991;1(1):3-7. Review. PubMed PMID: 1670134. Kusunoki T, Cureoglu S, Schachern PA, Baba K, Kariya S, Sampaio A, Paparella MM. Effects of gentamicin on sensorineural elements of the cochlea in human temporal bones. Am J Otolaryngol. 2004 Sep-Oct;25(5):313-7. PubMed PMID: 15334394.
www.techgiendoscopy.com
PII: DOI: Reference:
S1043-1810(16)30051-3 http://dx.doi.org/10.1016/j.otot.2016.10.004 YOTOT732
To appear in: Operative Techniques in Otolaryngology - Head and Neck Surgery Cite this article as: Michael D. Puricelli, Henrique Furlan Pauna and Michael M. Paparella, Endolymphatic sac surgery for meniere′s disease, Operative Techniques in Otolaryngology - Head and Neck Surgery, http://dx.doi.org/10.1016/j.otot.2016.10.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Endolymphatic Sac Surgery for Meniere’s Disease Michael D. Puricelli, MD1 Henrique Furlan Pauna, MD2,5 Michael M. Paparella, MD2,3,4 1
University of Missouri Department of Otolaryngology Head and Neck Surgery Paparella Ear, Head and Neck Institute 3 Clinical Professor and Chairman Emeritus Department of Otolaryngology University of Minnesota 4 Director Otopathology Laboratory 5 Department of Otorhinolaryngology, Head and Neck Surgery University of CampinasUNICAMP 2
Grant Support: This study was supported by the National Institute on Deafness and Other Communication Disorders (NIDCD), grant number U24 DC011968-01; the International Hearing Foundation; the Starkey Hearing Foundation; the 5M Lions International; and the Scientific and Technological Research Council of Turkey (TUBITAK).
Michael M. Paparella Email: [email protected] Phone 612-339-2836 701 25th Ave S #200 Minneapolis, MN 55454
Abstract: Meniere’s disease and its pathologic correlate endolymphatic hydrops develop from endolymphatic malabsorption secondary to genetically determined and environmentally influenced factors. Medical therapy is effective in most cases. When insufficient, endolymphatic sac enhancement is a logical extension of conservative treatment, as it is organ sparing and hearing conserving therapy resulting in excellent symptomatic control with a low rate of complications. The senior author’s technique for endolymphatic sac enhancement is presented incorporating experience from over 5,000 such procedures.
Every year, worldwide, hundreds of thousands of patients suffer the chronic symptoms of Meniere’s disease: intermittent vertigo lasting from minutes to hours, fluctuating progressive sensorineural hearing loss, tinnitus, and aural pressure. For decades many and some currently have used the defeatist term “idiopathic endolymphatic hydrops” to describe Meniere’s disease. Meniere’s disease is neither idiopathic, nor is its pathologic correlate, endolymphatic hydrops.1 It is a clinical entity which renders the patient difficulty and distress and has multiple effective medical and interventional treatments.2 Central to understanding the role of endolymphatic sac enhancement is understanding of the pathogenesis. Meniere’s disease is believed to result from genetic aberration predisposing to endolymphatic malabsorption. The genetic root of Meniere’s disease was proposed in 1984 by the senior author; and, to date, there are over 90 articles published describing the genetics of Meniere’s disease.3,4 Heritability has been reported in 7-15% of patients.5 The proposed transmission mechanism is autosomal dominant with incomplete (approximately 60%)
penetrance and worsened symptoms with successive generations.4,6-8 To date, however, no causative gene or genes have been identified.4,6,9-11 Affected individuals frequently demonstrate anatomic anomalies that may not be seen in surgery performed for other indications. Characteristic findings of Meniere’s disease include hypopneumatization of the mastoid; a medially and anteriorly located sigmoid sinus; hypodevelopment of the aditus and suprapyramidal (facial) recess; hypoplastic vestibular aqueduct and endolymphatic sac; stiffening of the dura; and most importantly reduction in size and vertical orientation of the plate of bone separating the sigmoid sinus and posterior semicircular canal referred to as Trautmann’s triangle.12,13 The above described anomalies adversely impact the longitudinal flow of endolymph in the duct and contribute to malabsorption. 14 This mechanism is further supported by acquired Meniere’s disease reported in advanced otosclerosis obstructing the vestibular aqueduct 15,16. Other acquired causes include chronic inactive otitis media and mastoiditis, syphilis, and childhood measles or mumps. 17-19 Histopathologically, hydrops is identifiable in the pars superior and pars inferior including utricular enlargement. 1 Reissner’s membrane shows stretching in Meniere’s disease with increased intercellular distance.20 Membranous ruptures, precipitating ionic mixing and loss of the normal electrical gradient, are seen in some but not most cases at the time of pathologic examination.1 Repeated exposure of the basal aspect of hair cells to the toxic potassium rich endolymph may precipitate vertigo and reduce hearing.21 More than 90% of patients are helped with lifestyle modifications and medical management including low salt and caffeine diet, diuretic treatment, possibly betahistine and transtympanic steroid injections.2. In cases where medical therapy is insufficient, endolymphatic
sac enhancement may be considered as an extension of conservative (organ preserving) therapy and in many practices is offered prior to ablative interventions such as transtympanic gentamicin perfusion. Endolymphatic sac enhancement ameliorates the symptoms of hydrops by reversing the pathogenesis of the condition through removal of the bone near the posterior fossa dura where the endolymphatic sac resides and placing a silicone T-stent and spacers.14 Decompression of the endolymphatic sac and techniques on the associated dura alter the hydrostatic pressure and chemical osmotic gradients that can improve absorption of endolymph in the endolymphatic sac and relieve endolymphatic hydrops, rather than shunting the endolymph into the cerebrospinal fluid.14 Indications for endolymphatic sac enhancement include patients who have classic symptoms of Meniere’s disease including recurrent episodic dizziness, fluctuating hearing loss, aural fullness, and tinnitus who do not achieve adequate symptom control with prolonged medical management. Patients with prominent vestibular or cochlear symptoms alone may also be candidates . Surgical intervention is considered for severe disease, with individuals experiencing symptoms for a mean of six years prior to intervention.22,23 Prior to undertaking endolymphatic sac enhancement surgery, the presence and laterality of the affected ear must be determined. History and physical examination indicate the affected ear in most cases and audiometric findings including a low frequency, flat hearing loss, or peak configuration lend further support. Electrophysiologic studies such as videonystagmography (VNG) that might show peripheral vestibular caloric weakness, electrocochleography (Ecog) that might show elevated summation potential/action potential (SP/AP) ratios in cochlear sensory cells, or asymmetric vestibular evoked myogenic potential (VEMP) all may indicate the affected
ear. A computed tomography scan or magnetic resonance imaging study may help with surgical planning by delineating the nature of the compression and the location of the facial nerve as well as excluding confounding pathology such as a vestibular schwannoma.14 The following description and illustrations are of our recommended technique for endolymphatic sac enhancement. The technique described is successful for locating the endolymphatic sac in 98% of cases with need for progression to destructive interventions such as gentamicin infusion in less than 3-5% of cases treated in the senior author’s experience. A curvilinear postauricular incision is made in the skin one half inch posterior to the postauricular crease. Placing the incision here helps avoid depression of skin into the mastoid cavity and helps reduce scar tissue that is thought to grow from subcutaneous tissue into the area near the sac. Thick subcutaneous tissue and excessive fat are debulked to prevent the scar tissue that can be observed later during revision endolymphatic sac enhancement. The mastoid cortex is exposed and compete mastoidectomy is performed. Cutting drill bits with reverse mode are used for smoothing and hemostasis. To identify the antrum, the tegmen mastoideum is exposed and followed medially. The posterior bony wall of the external canal is thinned to help identify the region of the horizontal semicircular canal and the descending facial nerve. The aditus is widened, the incus is exposed, and the facial suprapyramidal recess is opened widely in most cases all of which help aerate the mastoid cavity and avoid aditus-block syndrome. When thinning the bone over the sigmoid and dura of the posterior fossa, depth of drilling is never extended below the dome of the horizontal semicircular canal or, to be safer, the level of the incus to avoid injury to the lateral semicircular canal. Measurements with a fenestrometer are made from the fossa incudes 10 mm along the axis of the linea temporalis and 12 mm inferioposteriorly in a line at 45 degrees from the linea temporalis. To avoid removing bone near
the solid angle that contains the canals, and to prevent labyrinthine injury, a zone around the solid angle is demarcated. Using a forward or reverse drill, bone over Trautmann’s triangle and the length of the sigmoid sinus are thinned. The thinned bone of Trautmann’s triangle is removed with mastoid curettes or a rongeur. If Trautmann’s triangle is large, then more bone over the sigmoid sinus can be left to avoid injury to the sinus. This is uncommon as the sigmoid sinus is characteristically prominent and in an anterior and medial (deep) location in patients with Meniere’s disease. If Trautmann’s triangle is small or absent, wide decompression of the sigmoid is often necessary in order to decompress the dura adequately. The retrolabyrinthine and retrofacial air cells are not removed, in order to keep intact a shelf of bone over the region of the sac that can contain the silicone sheeting spacers used for sustained decompression. Rather than removing those air cells, the dura of the posterior fossa is elevated off the bone of the labyrinth. With this gentle retraction, the thickened region of the dura that contains the sac can be identified. The patient’s bed often requires elevation with lowering of the surgical chair to the floor and perhaps slight rotation of the bed away from the surgeon. The sac is entered using a sickle knife with tip pointed upwards to cut beneath the solid angle of labyrinthine bone. Using a blunt right-angled instrument such as a whirlybird the epithelium of the sac can be visualized, especially towards the infralabyrinthine region. Entrance to the sac should not be opened to the mastoid cavity to prevent fibrous or granulation tissue from invading the sac. A T-strut made of silicone sheeting is placed into the lumen of the sac. It helps to have different sizes of T-struts (small, medium, and large) prepared in advance so that a T-strut appropriate for the size of the lumen can be chosen. The tail of the strut is placed outside the sac between dura and bone to help passive transfer of nanoliters of endolymph, which may help
relieve the endolymphatic hydrops. To decompress the dura and adjacent sigmoid sinus widely and keep them off the bone indefinitely, spacers (small, medium, or large strips of silicone sheeting) are folded and placed superior and inferior to the sac. To fully decompress the sac, as many strips of silicone as possible are placed, but not so many as to cause excessive tension on the sac and obviate the decompression. The spacers serve as soft, spring-like mechanisms to aid in longterm decompression of dura and sac. It is important that the silicone struts and spacers not be in communication with the mastoid. To keep the sac further separated from the mastoid and possible fibroblastic infiltration that would affect function of the sac, a large piece of Gelfoam is placed. This method has replaced previous techniques that used pedicle grafts, grafts of temporalis fascia and protective gold foil. All bone dust is removed before incision into the sac and prior to closure to ensure that no further bone dust is left in the mastoid or middle ear. If bone dust is not irrigated and suctioned out and enters the middle ear, it can lead to fixation of the stapes and a conductive hearing loss. All bleeding must be stopped. The wound is closed in three layers using subcutaneous absorbable sutures followed by sutures or stapes in the skin to ensure rapid healing and avoid infection of the wound. Finally, myringotomy is performed, the middle ear is suctioned and a ventilation tube is placed in the tympanic membrane to help drain the middle ear and mastoid as well as relieve pressure from any Valsalva maneuvers during recovery. Tympanostomy tubes can also help when barometric changes during or after the recovery period affect patients with Meniere’s disease. It is hoped that these measures also prevent formation of scarring in the middle ear and mastoid, aditus block syndrome, and formation of fibrous tissue invasion near the sac, which
help prevent exacerbations of Meniere’s disease and provide better long-term surgical results. The tube can be left to extrude naturally, which does not affect the patient’s symptoms. Most endolymphatic sac enhancement surgery is done as outpatient, but rarely patients may require observation overnight to manage pain and nausea using IV hydration with medication. A dressing on the mastoid is left for 24 hours, and sometimes longer if there is concern about drainage of cerebrospinal fluid. After one week, the ear is examined, the staples removed, and the tube suctioned if necessary. To help avoid post-operative infection, typically, the patient is given amoxicillin or another appropriate broad-spectrum antibiotic. Although pain medication is also prescribed, it is often not needed. Patients are told to avoid straining and lifting more than 20 pounds for two weeks and instructed to keep the ear dry until follow-up at one week to remove staples. Four weeks after surgery, an audiogram is obtained. Usually a patient is followed every six to twelve months after they have healed from the surgery and experienced adequate improvement of symptoms (Figures 1). Approximately 8% of individuals have a good result with endolymphatic sac enhancement surgery and then years (two to thirty or more) later experience recurrence of symptoms. These individuals are candidates for revision procedures. 13,14 When thick subcutaneous tissue is present, removal is helpful to prevent ingrowth of fibroblasts into the region of the sac. Reformation of bone may occur over the sigmoid sinus and dura requiring removal. Fibrous tissue is often significant in and around the endolymphatic sac and the dura is stiffened. All scar tissue and previous silicone implants must be removed so that decompression of the dura and sac can be accomplished. If there is good decompression and re-incision of the sac, a large piece of Gelfoam soaked in gentamicin may be applied to help chemically ablate the vestibular hair cells after the silicone spacers are placed. After this technique has been used, we
observe stable post-operative hearing. We find that revision endolymphatic sac enhancement surgery can be very successful in relieving patients’ symptoms of Meniere’s disease. The majority of patients who have had an endolymphatic sac enhancement revised go for a lifetime after without symptoms and with complete remission. Due to the typical anatomy of patients with Meniere’s disease, endolymphatic sac enhancement can be difficult, and it is often necessary to decompress the sigmoid and posterior fossa dura widely to permit identification of the endolymphatic sac. If bleeding occurs, apply pressure with Gelfoam followed by cotton soaked in adrenaline. While the subarachnoid space is avoided, the dura superior to the sac can be very thin (particularly in elderly patients). If a cerebrospinal fluid leak is encountered, this is manageable with pressure, Gelfoam packing and, sometimes, reverse Trendelenburg positioning. If there is cerebrospinal fluid drainage that persists at the end of the operation, Gelfoam is packed into the area and in the mastoid prior to closure. A tympanostomy tube is not placed. The patient is encouraged to stay recumbent with head elevated 30 degrees and avoid straining. Stool softeners, antiemetics and cough suppressants may be given. The sac does not have a well-demarked border so identifying it can be challenging. It is typically appreciated as a thickening of the dura inferior to the posterior semicircular canal. After the sac is incised with the tip of the knife pointed away from the subarachnoid space, blunt palpation can help identify the lumen which also looks shiny from the endothelial lining. In the rare event that the lumen is not visible, it is felt to be too hypoplastic to be seen and decompression of the dura is successful. Injury to important structures such as the posterior semicircular canal and facial nerve are rare but can happen. We advise honest assessment of the damage, open counseling and close
follow-up. Should injury be suspected, treatment with a perioperative steroid may be considered and a fresh perspective may be sought by phone or in person from a colleague in otologic surgery. Prognosis and counseling may be aided by electrodiagnostic studies of the facial nerve. In summary, many publications are available regarding the basic science and clinical experience supporting the utility of endolymphatic sac enhancement for progressive or intractable Meniere’s disease. It represents a logical extension of conservative therapy with lower risk of cochlear damage and hearing loss than destructive procedures. Further research is necessary to better understand the cellular and molecular function of the endolymphatic sac and duct and the pathophysiology of endolymphatic hydrops that correlates with Meniere’s disease. Such knowledge will help us to better understand the implications of medical and surgical interventions.
Figures Figure 1: Surgical approach. The images depict the typical post-auricular incision located one half inch posterior to the post-auricular crease (A), dissection of subcutaneous tissue with removal as necessary and subperiosteal flap elevation (B and C). Mastoidectomy. The images depict the complete mastoidectomy procedure (D and E) and method of using the solid angle to prevent labyrinthine injury (F). The distance between the short process of the incus and the bottom of the otic capsule of the posterior canal is 10.4 mm (range, 9.5 to 11.5 mm). The distance from the tip of the short process of the incus to the inferiormost point on the endolymphatic sac is 16.9 mm (range, 13.0 to 19.0 mm). The distance from the otic capsule of the posterior canal to the bottom of the sac is 4.3 mm (range, 1.9 to 6.6 mm). Endolymphatic sac enhancement. The sigmoid is skeletonized (G) permitting access to the endolymphatic sac (H1). It is identified and incised.
The dimensions of the endolymphatic sac are 8.9 X 9.0 mm (H2). T-struts and spacers inserted (I). Gelfoam is placed over the enhancement site (J).
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Further Reading Lim MY, Zhang M, Yuen HW, Leong JL. Current evidence for endolymphatic sac surgery in the treatment of Meniere's disease: a systematic review. Singapore Med J. 2015 Nov;56(11):593-8. doi: 10.11622/smedj.2015166. Review. PubMed PMID: 26668402; PubMed Central PMCID: PMC4656865. Paparella MM, Kimberley BP. Pathogenesis of Menière's disease. J Vestib Res. 19901991;1(1):3-7. Review. PubMed PMID: 1670134. Kusunoki T, Cureoglu S, Schachern PA, Baba K, Kariya S, Sampaio A, Paparella MM. Effects of gentamicin on sensorineural elements of the cochlea in human temporal bones. Am J Otolaryngol. 2004 Sep-Oct;25(5):313-7. PubMed PMID: 15334394.