Complications of mastoid surgery

complications of mastoid surgery and their management

1. Complications of the Mastoid Surgery Dr. Rajendra Singh Lakhawat Department Of Otorhinolaryngology and Head & Neck Surgery SMS Medical College and Hospital, Jaipur, India

2. Recurrence, Residual, Recidivism The possibility of disease recurrence makes the surgical management of cholesteatoma challenging. Recurrent cholesteatoma is defined as cholesteatoma that re-forms after complete surgical excision. Residual cholesteatoma is disease left behind by the surgeon. Recidivism refers to the combination of recurrent and residual disease. The rate of recurrent disease after canal wall up surgery is high, ~20%, and may be even higher in children

3. Infection Postoperative infection may be a complication of surgery as in surgical procedures for other diseases, or because of the inherent nature of cholesteatoma, where infection is often present at the time of surgery, even in the absence of suppuration. Cholesteatoma harbors bacteria and often presents with purulent discharge. Despite the wish to operate on the ear while it is dry, it is sometimes necessary to remove the disease to bring the infection under control, and it is also possible to develop postoperative infection from dormant bacteria in the lesion.

4. Postoperative infection manifests itself as pain, swelling of the auricle or the postauricular wound, purulent discharge, and occasionally fever. Sometimes the infection is not obvious until the packing is removed 1 week postop when pus underneath the packing and a fetid odor are noted. Once discovered, culture and Gram stain should be taken, all nonresorbable packing removed, and the patient started on oral antibiotics and drops

5. Gram-negative organisms (Pseudomonas, Proteus, Escherichia coli) and Staphylococcus aureus (sometimes methicillin resistant) are most common. The chronic draining cavity can be a problem after canal wall down mastoidectomy. This may be caused by persistent granulation tissue, either along the lines of the meatal incisions, where new skin has failed to heal in, or at the base of the cavity, where persistent mastoid cells remain filled with mucosa rather than squamous epithelium.

6. Treatment of the draining ear is by suctioning or swabbing wet material in the office setting debriding any accumulated cerumen and squamous debris, and applying topical agents. A variety of medicaments have been devised for this purpose, but boric acid powder, applied through an atomizer, seems to work well as a bactericidal and drying agent. Other agents include wet or dry Gentian violet, a combination of antimicrobial agents in powder form or 3% acetic acid drops.

7. Acidification of the ear is initially attempted and then the antimicrobial agents are utilized if acidification does not reverse the process. Patches of granulation tissue can be lightly cauterized with silver nitrate (for larger areas) or 50% trichloroacetic acid (TCA). Care should be taken not to apply cauterizing agents to an exposed facial nerve. The draining ear may require frequent office visits at first, but the condition usually settles down over time in the majority of cases

8. Occasionally, the draining cavity can become refractory despite these measures, and revision surgery can be considered. The aim in these cases is to remove pockets of infected tissue, remove retained secreting air cells, lowering the posterior canal wall, removal of superior bony canal wall to the non- aircell tegmen, to provide drainage and aeration of the cavity and provide an adequate conchomeatoplasty to prevent retention of disease

9. A computed tomographic (CT) scan may be useful if focal osteitis is suspected. Sometimes a recurrent cholesteatoma may be discovered only during revision surgery because occasionally epithelial healing of the cavity will close over deep retraction areas, especially surrounding the superior to the superior semicircular canal or posterior semicircular canal.

10. Revision surgery should address each of these elements. The principles should be followed as in primary canal wall down surgery namely, creating a round, shallow cavity with beveled edges, lowering the facial ridge, eliminating the mastoid tip, and creating a wide meatus. The latter cannot be overemphasized— a generous meatoplasty including removal of much of the conchal and occasional antihelical cartilage is important to long-term success.

11. In addition, all cellular bone should be exenterated, and the depth of cavity polished with a coarse diamond burr. Sometimes a split -thickness skin graft is useful to resurface the floor of the cavity. Cholesterol granuloma cysts are blue-domed mucosal cysts that form in the floor of the antrum or in the sinodural angle. If they are asymptomatic, these can simply be followed. Occasionally, though, they cause discharge or pain and should be removed. Usually they can be incised, evacuated, and marsupialized in an office setting, but they do tend to re-collect

12. A blue-domed cyst of the mastoid cavity (cholesterol granuloma).

13. Meatal Stenosis Meatal stenosis is usually an error of technique. The meatoplasty is an important step in canal wall down surgery. The success of meatoplasty depends upon resecting (or at least breaking the spring of) the conchal cartilage, lengthening the canal incisions to create a conchomeatal fl ap , and using stay sutures to ensure meatal patency.

14. When restenosis occurs, the meatoplasty might need to be revised. In these cases, a postauricular approach should be used, a strip of conchal cartilage is taken, and stay sutures should be placed between the subcutaneous tissue of the conchomeatal flap and the perichondrium of the concha. These sutures are important for keeping the meatus open. Nonresorbable packing should also be placed but should not be relied upon. Longterm stents can be used in stubborn cases.

15. In canal wall up surgery, a posterior and superior bony canalplasty is often performed to better visualize the disease process. In these patients it is helpful to perform a limited meatoplasty by making an extended superior soft tissue canal incision and removing soft tissue and sometimes a rim of superior conchal cartilage.

16. Hearing Loss (Conductive and Neurosensory) Conductive hearing loss is not uncommon after surgery, even in patients who have good hearing at the time of initial presentation It is often the case that the cholesteatoma–ossicular complex transmits sound as a solid mass even with incus and stapes erosion. Conductive hearing loss should not be regarded as a true complication because removal of the incus or separation of the ossicular chain cannot be avoided in many cases, and the success of ossicular reconstruction is never certain.

17. preservation of an intact ossicular chain should not take precedence over complete removal of disease. If the disease recurs, the eventual hearing outcome will almost surely decline. Postoperative scarring with fibrosis of the middle ear, reduction of the size of the middle ear cleft because of lowering the posterior bony canal wall to the fallopian canal, and reducing the middle ear space can potentially prevent future middle ear hearing reconstruction.

18. Staging surgery is accepted when there is intact canal wall surgery in extensive cholesteatoma. Staging is also performed in patients with signifi cant middle ear disease and eustachian tube dysfunction. A hearing aid can be offered to the patient once the ear is dry and stable. Bone-anchored hearing aid (BAHA, Cochlear Americas, Centennial, CO) is an option in chronically draining ears that cannot accept a hearing aid. A BAHA provides excellent hearing results when the middle ear cannot be reconstructed and when bone conduction is good, but it requires a second operation to implant a titanium post and the use of an external processor

19. Round window implantation with the Vibrant device ( MedEl , Durham, NC) is a newer option for hearing rehabilitation. This technique, in which a floating-mass transducer is placed against the round window membrane, introduced by Colletti et al as a means of restoring hearing by bypassing the middle ear conductive mechanism, produced very encouraging initial hearing outcomes, although other authors have reported mixed results.

20. Sensorineural hearing loss or deafness is fortunately not common after ear surgery. Preoperative sensorineural loss may be a feature of chronic middle ear infection, caused by the spread of inflammation to the inner ear. High-frequency postoperative sensorineural hearing loss occasionally occurs and may be undetected by the patient, but complete loss of hearing is a fairly serious complication. The incidence is increased when a fistula of the inner ear is present (labyrinthine or cochlear) from the disease, and especially in the presence of active infection.

21. If a fistula is present at the time of surgery, the matrix should be kept on the fistula and canal wall down surgery performed, or rarely a second- stage surgery is performed with the matrix intact. At the second stage bony regrowth will occur. Iatrogenic opening of the inner ear may occur if the semicircular canal is opened during drilling, or if the round window membrane is perforated during middle ear dissection, or if the annular ligament is broken while the surgeon is manipulating the stapes. When these events occur and are recognized during the surgery, immediate sealing of the inner ear with a fascial graft will usually prevent a significant cochlear loss

22. The pathogenesis of sensorineural hearing loss in these cases may be toxic or suppurative labyrinthitis, perilymph leak, or inner ear fibrosis. When labyrinthitis occurs postoperatively, steroids may forestall the progression of sensorineural hearing loss, but once this has occurred it is probably irreversible. High-frequency sensorineural hearing loss may result from vibrational trauma during drilling, particularly if the ossicular chain is intact.

23. There is a potential for neurosensory hearing loss secondary to acoustic trauma of drilling (temporary or permanent threshold shift). Suction irrigation with drill sound may generate 100 dB levels for several minutes of drilling near the cochlea. Vibrations transmitted through the skull bones are probably not sufficient to cause a permanent threshold shift, but drilling directly on the ossicular chain might be

24. To prevent this, care should be taken to avoid touching the drill to the ossicles in the attic (the cholesteatoma may provide a protective cushion), reducing the bone to an eggshell thickness that can be manually removed with a curette. Incus erosion is common in the presence of cholesteatoma, but sometimes an intact ossicular chain can be found even when the cholesteatoma is large. The status of the incudostapedial joint can be determined at the start of the case by raising a tympanomeatal flap, and it may be safer to separate the incudostapedial joint before drilling

25. Tinnitus Tinnitus in the early postoperative period may be related to middle ear swelling and often recovers when the surgical packing is removed. Patients who have tinnitus preoperatively may experience louder tinnitus postoperatively. Fortunately this is usually transient. High-pitched tinnitus is usually a manifestation of cochlear loss and may result from vibrational trauma. Tinnitus can be a vexing problem for patients and does not have an outright cure. Ambient masking is helpful, and a masking device may be beneficial for some patients.

26. Benzodiazepines can alleviate anxiety and insomnia and often lessen the symptom. Tricyclic antidepressants (nortriptyline, amitriptyline) are also helpful and may act centrally to suppress tinnitus, rather than by an antidepressant effect.

27. Dizziness and Imbalance Dizziness and imbalance are not frequent. Like sensorineural loss, vestibular symptoms may arise from labyrinthitis or perilymph leakage. The chance of vertigo increases if an inner ear fistula is present. Vestibular symptoms may also result from surgical trauma to t he inner ear, such as excessive manipulation of the stapes. Postoperative vertigo is usually transient and can be managed with vestibular suppressant medications such as meclizine, promethazine, or diazepam.

28. Unilateral vestibular loss that is permanent generally recovers as central compensation takes hold. Imbalance will subside gradually and completely as activity is increased. Vestibular rehabilitation physical therapy may be helpful in cases that are slow to recover

29. Dysgeusia Dysgeusia arises from surgical trauma to the chorda tympani nerve. Patients may complain of a metallic or altered taste on that side of the tongue, or dryness of the mouth. Its occurrence cannot be predicted. The chorda tympani is often enveloped by the cholesteatoma and must be sacrificed, and yet dysgeusia is not inevitable. Stretch injury of the nerve may be more common than transection, and may result in greater symptoms.

30. Dysgeusia is usually temporary but may take 3 months or longer to resolve. In cases of bilateral chorda tympani sacrifice it may be permanent.

31. Vascular Injury The sigmoid sinus, internal jugular vein, and internal carotid artery are susceptible to surgical injury. The neurotologic skull base surgeon usually possesses firsthand experience in approaching and handling these structures, but the general otolaryngologist who operates on the ear may not. It is important therefore to know what to do if a vascular injury does arise.

32. The sigmoid sinus is usually identified anatomically during mastoidectomy. There is a thin plate of bone overlying the sinus, and in cholesteatoma surgery this should be maintained. A cutting burr can be used to skeletonize the sigmoid provided the surgeon keeps a very light hand, but a diamond burr is safer. The sinus is a dural structure, and removing the bony covering does not necessarily lead to venous injury, but this may happen if the sinus is thin or bulging.

33. Lacerating the sigmoid sinus causes profuse venous bleeding, and the surgeon should be equipped to deal with this. The first measure is to control the bleeding with external pressure, using oxidized cellulose ( Surgicel , Ethicon, Inc., Somerville NJ) gauze, a neurosurgical cottonoid , or even finger pressure. The bleeding can then be definitively controlled using an extraluminal plug of Gelfoam ( Pfi zer , Inc., New York, NY) soaked in thrombin.

34. If the bleeding site is very small it can be controlled with bipolar cautery. If it is 1 or 2 mm in size, a Gelfoam -thrombin plug can be gently inserted into the opening. If it is larger than 2 mm, a square of Gelfoam -thrombin can be placed extraluminally and held in place by sandwiching it between the edges of the bony opening and the sinus Wall. Intraluminal packing should be avoided because it can embolize toward the heart; if this is ever necessary, the internal jugular vein should be ligated in the neck

35. The jugular bulb can also bleed if treated roughly, and bleeding from the jugular is handled in the same way. The jugular is encountered in two places—in the hypotympanum through the middle ear, and in the retrofacial cell tract through the mastoid. The jugular bulb is highly variable in position. A high jugular bulb can be injured during seemingly innocuous maneuvers, such as elevating a tympanomeatal flap, if it lies in a vulnerable location.

36. The internal carotid artery is not often encountered during surgery for chronic ear disease, and injury to the carotid is rare. The carotid can be reliably found medial to the eustachian tube in the protympanum . The bony wall there is thin or can be absent, placing the carotid at risk in that location. The carotid has a thick muscular wall. Surgical injury when it occurs results from penetrating trauma; sharp instrumentation should therefore be avoided in that area.

37. A laceration of the carotid artery will cause dramatic pulsatile bleeding. Temporary control can be gained with extraluminal pressure; definitive control will require an endovascular procedure performed by an interventional neuroradiologist . In a dire emergency, ligation of the internal carotid artery in the neck might be required.

38. Cerebrospinal Fluid Leak/Encephalocele CSF leakage is an infrequent occurrence in cholesteatoma surgery. It can occur iatrogenically if the dura is accidentally lacerated, or spontaneously, from a brain herniation (meningoencephalocele) that erodes through its dural covering. Iatrogenic CSF leaks can occur when drilling near the tegmen, usually when using a cutting burr. The tegmen has an undulating contour, and it is possible to perforate it when skeletonizing its bony surface. The underlying dura is vascular and has a pink appearance when seen through a thin layer of bone.

39. Once exposed, the dural surface will often bleed; the small epidural vessels are easily controlled with bipolar cautery. This epidural bleeding is an important warning to the surgeon because dura will usually withstand one brush with the burr, but not a second one. Cholesteatoma matrix can adhere to bare dura and can be difficult to remove safely . Good technique requires that the margins of the bony tegmen defect first be defined visually.

40. Then the disease can be elevated away from the dura with a blunt dissector using a peeling motion. Small, sessile meningoencephaloceles can be left alone if they are not involved with disease. Larger, broad-based meningoencephaloceles can be reduced and the tegmen defect repaired with cartilage, banked bone, split calvarial bone, hydroxyapatite discs, or synthetic commercially sold dura substitutes.

41. CSF leaks should always be repaired. The presence of CSF leakage and the site of the leak may be difficult to verify preoperatively. When a leak is suspected, a fluid sample should be collected if possible. Testing for glucose (two thirds of the serum value) or chloride (higher than serum) content is suggestive but not definitive. Beta-2- transferrin assay is the most specific confirmatory test for CSF. Pre operative CT will demonstrate bony erosion of the tegmen or, less commonly, the posterior fossa dural plate.

42. Magnetic resonance imaging (MRI) scanning in the coronal or sagittal plane will demonstrate an encephalocele but possibly not a meningocele. Radionuclide cisternography can definitively establish the presence of an active leak by showing pooling of intrathecally injected material in the mastoid. CT cisternography with intrathecal contrast is the most precise method of localizing a leak, but it depends on a high rate of flow; slow or intermittent leaks will likely yield a negative study

43. Ultimately, once the diagnosis of CSF leakage is made, surgical repair will be needed. At surgery, the site and size of the leak can be accurately determined, and a meningoencephalocele if present will usually be readily apparent. CSF leaks can be repaired from “above” (intracranially, using a middle cranial fossa approach), or from “below” ( transmastoid ). The transmastoid approach is preferable for leaks that coexist with chronic middle ear disease when the defect is within the mastoid tegmen.

44. The transcranial approach may also be more effective for controlling leaks that involve a larger area of dura, that involve multiple defects, or that recur after an unsuccessful transmastoid repair. The transmastoid approach is performed by creating a canal wall up mastoidectomy and transmastoid atticotomy , exposing and skeletonizing the entire length of the tegmen . Once the leak is visualized, the surrounding bone is thinned with a diamond burr to maximize exposure.

45. The healthy dura is carefully separated from the surrounding bone using a blunt elevator. If an encephalocele is present, it is either reduced or excised, depending on its size. A multilayer repair is undertaken by placing tissue against the dural defect (fascia, perichondrium, or AlloDerm can be used), then using stiffer material (cartilage, cortical bone, or banked bone) to repair the tegmen Defect.

46. As the intracranial contents expand they prevent the repair from migrating. Additional security can be gained by using fibrin glue over the repair and using an abdominal fat graft to fill the mastoid cavity. When a CSF leak occurs in a canal wall down cavity, the mastoid cavity cannot be isolated from the ear canal as it can when the canal wall up is maintained. In this situation, the ear canal will usually have to be oversewn and the mastoid cavity obliterated with fat. The eustachian tube should also be sealed by packing muscle into the protympanum .

47. Facial paralysis No matter what type of ear surgery is performed, one of the most dreaded complications is facial paralysis. Therefore, before discussing what to do after the nerve has been injured, it is prudent to discuss how to avoid this particular injury in the first place. The best way to avoid an injury to the facial nerve is to understand its anatomy thoroughly. A preoperative CT scan of the temporal bones is recommended because the facial nerve can have an anomalous course in a small percentage of patients or be dehiscent within the horizontal or vertical segments; either naturally or by erosion from disease.

48. A CT scan can demonstrate the course of the facial nerve and its relationship to known landmarks, alerting the surgeon to potential areas of danger. If the surgeon knows in advance that the nerve is located more anteriorly than usual, that disease goes deeply posteriorly and inferiorly, or that disease directly involves the facial nerve, the surgeon may be able to avoid any injury. Even in patients who may not be expected to be at risk for a facial nerve injury, such as those undergoing an operation for exostosis or keratitis obturans , a CT scan can help avert a facial nerve complication.

49. Demonstrates the course of the facial nerve from the view of a mastoidectomy with a facial recess approach.

50. A mastoidectomy should always be performed in a systematic fashion. One should identify known landmarks from lateral to medial. Although not routinely done, the actual identification of the facial nerve during surgery can be beneficial. If the surgeon intentionally identifies the nerve, unexpected injury to the nerve is less likely, especially if a thin bone layer is left over the nerve. Initially, the recommended procedure is to drill a wide mastoidectomy and to stay superiorly and anteriorly into the zygomatic root, that is, hugging the tegmen as one proceeds medially

51. This technique can significantly help in avoiding the facial nerve and lateral semicircular canal, especially in most chronically diseased mastoid bones, which resemble cue balls with no air cells until the antrum is reached. If the surgeon creates too low or too inferior a mastoidectomy in chronically diseased mastoids, there is a risk of injuring the lateral/horizontal semicircular canal or the facial nerve. Once the antrum, incus, and the lateral semicircular canal have been identified, a facial recess approach is the easiest method by which to identify the facial nerve

52. Another way to identify the facial nerve is to follow the digastric ridge to the stylomastoid foramen, which in turn leads to the facial nerve. Although the actual incidence of facial nerve injury is quite low for first time ear surgery (less than 1%), it can be as high as 4% to 10% in revision Cases. Intraoperative monitoring of the facial nerve helps the surgeon protect the nerve, but it is not mandatory for ear surgery and cannot replace anatomic knowledge.

53. When severe disease has eroded the bony covering of the facial nerve, the facial nerve monitor can help the surgeon determine what is disease and what is normal nerve. up to 50% of normal temporal bones can have a small dehiscence (less than 0.4-mm in diameter) in the tympanic segment. Other natural areas of dehiscence include the geniculate ganglion, facial recess, and the mastoid area (most commonly when the mucosa of an air cell covers the facial nerve)

54. what to do for an injured nerve Ideally, the Injury is recognized in the operating theater. If the injury is identified in the operating room, the surgeon must first determine the degree of injury. Exposing the nerve ( ie , inadvertently removing bone from over the nerve) does not necessarily require any further action on the part of the surgeon. The same is true for a minor contusion of the facial nerve. The facial nerve is actually quite hardy and can be manipulated without significant effect.

55. Opening the sheath of the nerve to allow expansion and to decrease any untoward effect of edema or hematoma is controversial, and the surgeon must make that decision when assessing damage to the nerve. Occasionally, the injury is more extensive either a partial or total transection of the nerve. This type of injury can be devastating for both the surgeon and the patient. Even otologists who are fellowship trained may be too distressed to assess the true extent of the damage adequately. Consultation or referral is not a sign of defeat and in some cases might be in the best interest of the patient.

56. Demonstrates a complete transection of the facial nerve in the vertical segment

57. But The surgeon involved is usually best equipped to treat the complication because he/she has intimate knowledge of the patient’s surgery. Complete transection is easy to identify, but it is harder to tell if a partial injury or transection is slight ( ie , less than one third of the nerve) or is greater than one third of the nerve. When less than one third of the nerve is cut, decompress on either side of the injury. If more than one third of the nerve is cut, a nerve graft has a better chance of preserving facial nerve function at the level of grade 3 on the House- Brackman scale

58. Fortunately, grafting the nerve back together does not require extensive equipment. If the nerve can easily be put back together primarily without tension, then this method is preferred because no graft is needed, and only one anastomosis is required. Sometime it is easier to make one clean cut of the damaged nerve, especially if half of the nerve is transected. If the damage seems to be more extensive, then it is better to cut the nerve obliquely on either side of the damage so that there are two good, clean ends to reapproximate.

59. If the two ends do not meet without tension, a graft is needed. An extra centimeter of length can be obtained from the facial nerve by drilling out the stylomastoid foramen. This technique may cause some disruption of the blood supply and can cause problems with healing. It has not been shown that one anastomosis, as opposed to two, causes any less synkinesis or better facial nerve function

60. To repair the transected nerve, the nerve or the nerve graft can be sutured together using a 9-0 or 10-0 monofilament suture. In ear surgery, it is very difficult to place a suture. But the fallopian canal offers a suitable bed in which to place the nerve graft where it should not move. In this case, the ends can be reapproximated and then held in place using a sealant such as fibrin glue and Gelfoam

61. Demonstrates the suturing in of a nerve graft. Note the beveled ends. Often sutures can not be placed, but laying the nerve graft next to each cut end may suffice or it can be sealed with fibrin glue.

62. Demonstrates the nerve graft in place

63. In placing the graft, it is important to cut the nerve graft and facial nerve obliquely to increase the surface area for axon regeneration. Great care must be taken to assure that all bone spicules are removed from the nerve as well. Historically, two nerves have been used for facial nerve grafting: the great auricular nerve or the sural nerve Because the length of nerve that is needed certainly should be less than 10 cm, which is about the length that can be obtained from the great auricular nerve, there is no reason to perform a sural nerve graft

64. The great auricular nerve is readily available, and the incision needed has usually already been prepped and is in the field for any type of ear surgery. To access the auricular nerve, a line is drawn from the mastoid tip to the angle of the jaw and about two thirds away an incision is made down onto the sternocleidomastoid muscle where the great auricular nerve is usually found. To maximize healing and to maximize the area that can be used for the reapproximation , the ends are cut at a beveled angle.

65. Demonstrates the course of the great auricular nerve.

66. The patient and the family must be appropriately counseled regarding the type of injury. If the nerve was grafted, they should understand that the final degree of facial function will not be known for at least 1 year and there will probably not be any type of activity in the fact for 6 to 9 months. The final outcome in grafting is about 75% of normal function, at best . Synkinesis may be a problem and should be explained. The use of high-dose steroids is certainly recommended; the dose usually given is about 60 to 80 mg/d for (prednisone) 7 to 10 days. For nerves that are only contused, recovery is usually quicker.

67. When the facial paralysis is discovered in the recovery room, rather than in the operating theater, a decision must be made as to the course of action. If the paralysis is not complete ( ie , the patient has a good nasal sniff or has good reaction with grimacing), the nerve in all likelihood is not totally transected and has a less severe injury. In these cases, high-dose steroids are used, and the patient is monitored. If the injury does become a complete facial paralysis, electrical testing is performed, and a decision must be made whether any further surgical management ( ie , facial nerve decompression) is warranted

68. Electroneurography (ENOG) is the preferred test. When degeneration is less than 95%, the possibility of decompression can be considered. One must be careful about relying on eye closure alone to assess facial function, because some eye closure is possible even with complete paralysis. If a complete paralysis is noted in the recovery room, the surgeon must consider a few other possibilities besides surgical trauma. If the surgeon has placed a lot of packing in the mastoid cavity or even the middle ear, the packing may be too tight, especially in a dehiscent nerve, and may need to be loosened slightly

69. Another possibility is the effect of lidocaine, which can cause temporary paralysis in a dehiscent nerve for 3 to 12 hours. If the surgeon is reasonably sure that the nerve is actually injured and feels comfortable with re-exploration, then re-exploration should be done, usually as expeditiously as possible ( i.e , within 24–72 hours). The needed repair should be completed on this exploration as previously described. Some favor waiting 3 to 4 weeks to allow possible neurologic regrowth before undertaking any reanastamosis . Most surgeons do not favor waiting 3 to 4 weeks. If the surgeon is certain that the nerve has not injured in any way and had identified it during surgery, it may be prudent to follow the patient with electrical testing.

70. The other issue to consider is whether a thermal injury has occurred, especially during facial recess surgery. The shaft of the bur spinning at a high rate of speed can produce enough heat to cause a thermal injury to the nerve if the nerve is slightly exposed or is covered with only a thin layer of bone. Thermal injuries usually get better with time, but 5 to 9 months may be needed to see a significant improvement in function. Steroids may help, but the role of decompression is unknown.

71. Always, the best method for dealing with facial paralysis is to try to avoid it in the first place; should it occur, one must be calm and approach the injury in a systematic fashion to achieve the best result for the patient .

72. Canal dehiscences During mastoid surgery, there are three chances of injuring a semicircular canal, because three canals—the horizontal (lateral), the posterior, and the superior—exist. Injury to the oval window, promontory, or round window can be equally as devastating, if not more so. It is more common to injure the semicircular canals when dissecting cholesteatoma off a dehiscent canal than to drill into a semicircular canal inadvertently. Indeed, a drilling accident probably occurs less than 0.1% of the time. Drilling the canal open to expose the membranous portion of the semicircular canal or disrupting the membranous portion does not necessarily lead to permanent hearing loss.

73. What creates a problem is not even significant violation of the membranous portion, but rather significant suction into the vestibular system. The suction in an open canal invariably results in sensorineural hearing loss and vertigo, with possible long-lasting disequilibrium resulting from a partial loss of vestibular function. Patients with a partial loss of vestibular function have more difficulty compensating than those who have a complete loss. Early identification of an iatrogenic injury is the key to minimizing symptoms. If the injury is noted immediately, the surgeon should not suction but rather should seal the fistula with bone wax, fascia, or muscle

74. It is more common to encounter disease (cholesteatoma) that has eroded bone over the semicircular canal, causing a fistula. Preoperative CT scanning can usually identify this pathology. When it is identified, there are three options. One is removing the matrix while preserving the membranous canal and then sealing the dehiscence with muscle, fascia, or bone wax. The other is to leave a thin matrix covering the exposed fistula of the semicircular canal and then returning after 4 to 6 months to see if the matrix can be peeled off easily. Waiting may increase the chance of preserving the membranous portion, because the matrix is much easier to remove once the inflammation dissipates. The third option is to complete a canal wall–down mastoidectomy and leave the matrix over the fistula providing an epithelial layer. Profound sensorineural hearing loss can occur in 3% to 22% of patients with a disease-induced canal fistula

75. Fistulization of the oval window is a more common iatrogenic injury than injury of the semi-circular canals. The fistulization occurs not from drilling but usually from the dissection of disease, such as cholesteatoma, off the footplate or stapes. The other avenue for fistulization is an inadvertent stapes dislocation incurred when raising a tympanomeatal flap or with ossicular manipulations. If the footplate can be put back into position, it should be sealed with connective tissue, but one must make sure that it will not sink into the vestibule.

76. If the footplate cannot be returned to its position, sealing the open window with fascia is recommended. If there is fistulization of the footplate, but the footplate is still in place and intact, sealing with a fascial muscle plug is recommended, as one would do for a perilymphatic fistula. Hearing loss and dizziness may occur in the short term, but these techniques are much less likely to cause indeterminate longterm problems. The possibility of a fistula or loss of stapes/stapes footplate is not to be taken lightly. It is better in cholesteatoma surgery to leave a little cholesteatoma and disease on the stapes and return in 6 to 9 months, when it should be easier to remove (it should form a small pearl), than to attempt total removal all at once.

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