Abstract
Objectives
The management of developmental anomalies of the ossicular chain and otic capsule in stapes surgery tests the otologist’s diagnostic skills and flexibility in technique and prosthesis choice. We review our experience in managing various incudostapedial developmental anomalies discovered during middle ear exploration for suspected otosclerosis in adult patients.
Design
A retrospective case-series review was used.
Setting
The study was set at a military tertiary referral center.
Patients and other Participants
A review of 185 stapes procedures yielded 8 cases of identified congenital anomalies of the stapes or incudostapedial complex including congenital absence of the oval window with malformed incus and stapes, columellar-type stapes with promontory fixation, stapes superstructure fixation to the fallopian canal, and malformed incus with stapes superstructure fixation to the promontory.
Interventions
The developmental anatomy and surgical technique in each case were reviewed. The surgical technique used in each case varied depending on the specific ossicular abnormality found and whether both the stapes and incus were affected.
Main outcome measures
Comparison of preoperative and postoperative audiometric testing results was performed.
Results
All 8 ears (7 patients) that underwent a stapes procedure for either an isolated congenital stapes anomaly or a combined incudostapedial anomaly had a favorable hearing outcome, with 7 ears improving to within 10-dB and 1 ear to within 13-dB air-bone gap on postoperative audiometry.
Conclusions
Despite unanticipated findings of congenital anomalies of the stapes and incus during middle ear exploration for conductive hearing loss, a flexible management approach can lead to successful hearing outcomes.
1
Introduction
Congenital abnormalities of the middle ear may be classified into major and minor categories . Major anomalies characteristically involve middle ear structures as well as the external auditory canal and pinna. Minor anomalies include abnormalities of a middle ear structure (stapes, incus, malleus, oval window, and round window) in isolation or as a combination of abnormalities involving more than one structure. The external auditory canal and tympanic membrane are normal in minor anomalies.
Although a variety of congenital middle ear anomalies responsible for conductive hearing loss have been described in the literature, several large series have identified the stapes and incudostapedial complex as the most commonly involved structures . These reports, however, included pediatric patients, patients with abnormalities of the external auditory canal and pinna, and/or patients with known syndromes. In a recent review of 1800 cases of bilateral otosclerosis in patients without external ear abnormalities, Daniels et al reported anomalies of the lenticular process as the most common middle ear abnormality accompanying a primary surgical diagnosis of otosclerosis.
The surgical techniques available to manage conductive hearing loss in patients with otosclerosis are well established. The surgical management of stapes fixation due to an isolated congenital ossicular anomaly, whether accompanied by otosclerosis, is less well described in the literature. This article will review the intraoperative findings, surgical techniques, and hearing results in 7 adult patients (8 ears) with isolated congenital anomalies of the incudostapedial complex. None of the patients in this series had an abnormality of either the external auditory canal or pinna, or demonstrated other physical characteristics suggestive of a congenital syndrome.
2
Materials and methods
A retrospective review of the operative and clinical records of 185 adult patients who underwent an exploratory tympanotomy, between 1996 and 2008, for a history of conductive hearing loss and a suspected diagnosis of otosclerosis yielded 7 patients (8 ears) with congenital anomalies of the stapes or incudostapedial complex. There were 5 women and 2 men. The mean age at the time of surgery was 44.4 years, ranging from 29 to 67 years old. There were 8 primary surgeries and 1 revision procedure. One patient had bilateral stapedectomy. There were 6 right ears and 7 left ears operated. All stapedectomies were performed by the primary author (J.J.K.) using a variety of techniques, as dictated by the intraoperative findings. All procedures were performed under general anesthesia through a transcanal approach. This study was approved by the Institutional Review Board at the Naval Medical Center, Portsmouth, VA.
Pure-tone and speech audiometries were analyzed preoperatively and at the last follow-up visit. Of 7 patients, 5 had available audiometric data at 2 to 4 months postoperative, and 2 patients had postoperative audiograms obtained at 18 months or more. Hearing results were reported following the American Academy of Otolaryngology-Head and Neck Surgery guidelines . Pure-tone averages (PTAs) were computed for thresholds 0.5, 1, 2, and 3 kHz for air conduction and for thresholds 1, 2, and 4 kHz for bone conduction. Speech discrimination score was determined by using a standard sensation level of 40 dB.
Clinical information regarding the age of onset of hearing loss, bilaterality, medical history, family history of hearing loss, and the presence of other congenital anomalies that might suggest a syndromal diagnosis was reviewed. Any imaging studies that had been obtained preoperatively were also reviewed.
2
Materials and methods
A retrospective review of the operative and clinical records of 185 adult patients who underwent an exploratory tympanotomy, between 1996 and 2008, for a history of conductive hearing loss and a suspected diagnosis of otosclerosis yielded 7 patients (8 ears) with congenital anomalies of the stapes or incudostapedial complex. There were 5 women and 2 men. The mean age at the time of surgery was 44.4 years, ranging from 29 to 67 years old. There were 8 primary surgeries and 1 revision procedure. One patient had bilateral stapedectomy. There were 6 right ears and 7 left ears operated. All stapedectomies were performed by the primary author (J.J.K.) using a variety of techniques, as dictated by the intraoperative findings. All procedures were performed under general anesthesia through a transcanal approach. This study was approved by the Institutional Review Board at the Naval Medical Center, Portsmouth, VA.
Pure-tone and speech audiometries were analyzed preoperatively and at the last follow-up visit. Of 7 patients, 5 had available audiometric data at 2 to 4 months postoperative, and 2 patients had postoperative audiograms obtained at 18 months or more. Hearing results were reported following the American Academy of Otolaryngology-Head and Neck Surgery guidelines . Pure-tone averages (PTAs) were computed for thresholds 0.5, 1, 2, and 3 kHz for air conduction and for thresholds 1, 2, and 4 kHz for bone conduction. Speech discrimination score was determined by using a standard sensation level of 40 dB.
Clinical information regarding the age of onset of hearing loss, bilaterality, medical history, family history of hearing loss, and the presence of other congenital anomalies that might suggest a syndromal diagnosis was reviewed. Any imaging studies that had been obtained preoperatively were also reviewed.
3
Results
Review of the clinical records revealed that 6 patients complained of a slow progressive worsening of hearing since their teenage years and that only 1 patient described hearing loss since childhood. All patients denied a history of a significant underlying medical condition. There was no family history of hearing loss for any patient. None of the 7 patients demonstrated any abnormal physical characteristics that might suggest a syndromal diagnosis. The auricle, external auditory canal, and tympanic membrane were normal for each affected ear in all patients. Table 1 presents the patient demographics and type of hearing loss identified on audiometric testing. A high-resolution computed tomographic (HRCT) scan of the temporal bone was obtained preoperatively in the 1 patient with a history of unilateral hearing loss since childhood (patient 3; Table 1 ). This study demonstrated a well-defined bony plate in the expected region of the oval window in the left ear, an abnormal stapes, and a normally positioned facial nerve.
| Patient | Age (y) | Sex | Ear | Hearing loss type |
|---|---|---|---|---|
| 1 | 55 | F | L | Moderate-severe mixed |
| R | Moderate-severe mixed | |||
| 2 | 29 | F | R | Moderate CHL |
| 3 | 43 | M | L | Moderate-severe CHL |
| 4 | 33 | F | R | Moderate-profound mixed |
| 5 | 41 | F | R | Mild-moderate CHL |
| 6 | 43 | M | R | Mild-moderate CHL |
| 7 | 67 | F | R | Moderate-severe mixed |
Tables 2 and 3 present the intraoperative findings and reconstruction methods, respectively, for the primary cases. These tables also reference the figures that correspond to the intraoperative findings and/or the reconstruction method for selected patients. The congenital ossicular anomalies found at the time of surgery included (1) elongated long process of incus and columellar stapes fixation to the promontory (bilateral in 1 patient; Fig. 1 A , B), (2) foreshortened long process of incus and stapes superstructure fixation to the fallopian canal ( Fig. 2 A , B), (3) absence of the oval window associated with a rudimentary stapes and abnormal lenticular process of incus ( Fig. 3 ), (4) bony bridge between the lenticular process of incus and the malleus handle with accompanying otosclerosis ( Fig. 4 ), and (5) elongated long process of incus and stapes superstructure fixation to the promontory (3 ears; Fig. 5 A , B). In the group of patients with stapes-promontory fixation, 1 patient had concomitant otosclerosis and 1 patient demonstrated absence of the stapedial tendon.
| Patient | Ear | Ossicular abnormality | Facial nerve anatomy (tympanic segment) |
|---|---|---|---|
| 1 | L | Elongated long process of incus | Dehiscence with 25% overhang of oval window niche |
| Columellar stapes-promontory fixation (broad attachment to promontory) | |||
| R | Elongated long process of incus | Dehiscence with 25% overhang of oval window niche | |
| Columellar stapes-promontory fixation (broad attachment to promontory) | |||
| 2 | R | Foreshortened long process of incus | Dehiscence medial to point of crural fixation |
| Stapes crura-fallopian canal fixation ( Fig. 2 A) | |||
| Thick footplate/circular obturator foramen ( Fig. 2 B) | |||
| 3 | L | Malformed lenticular process of incus | Normal position |
| Stapedial tendon attached to lenticular process | |||
| Rudimentary monocrural stapes | |||
| Absent oval window | |||
| 4 | R | Incus-malleus bony bridge ( Fig. 4 ) | Normal position |
| Otosclerosis (anterior focus) | |||
| 5 | R | Elongated long process of incus | Normal position |
| Stapes crura-promontory fixation ( Fig. 5 A) | |||
| Absent stapedial tendon | |||
| 6 | R | Elongated long process of incus | Normal position |
| Stapes crura-promontory fixation (broad fixation to level of footplate) | |||
| 7 | R | Elongated long process of incus | Normal position |
| Stapes crura-promontory fixation | |||
| Otosclerosis (anterior focus) |
| Patient | Ear | Surgical procedure |
|---|---|---|
| 1 | L | Mechanical division of bony ankylosis ( Fig. 1 A) |
| Resulted in footplate subluxation ( Fig. 1 B) | ||
| Total stapedectomy | ||
| Modified cupped piston prosthesis | ||
| R | Mechanical division of bony ankylosis | |
| Resulted in footplate subluxation | ||
| Total stapedectomy | ||
| Modified cupped piston prosthesis | ||
| 2 | R | Mechanical division of crural ankylosis |
| Resulted in footplate subluxation | ||
| Total stapedectomy | ||
| Modified cupped piston prosthesis | ||
| 3 | L | CO 2 laser vestibulotomy ( Fig. 3 ) |
| Teflon-wire piston prosthesis | ||
| 4 | R | CO 2 laser vaporization of bony bridge |
| Total stapedectomy | ||
| Modified cupped piston prosthesis | ||
| 5 | R | Mechanical division crural ankylosis |
| Resulted in footplate fracture | ||
| Total stapedectomy | ||
| Modified HA Universal prosthesis ( Fig. 5 B) | ||
| 6 | R | CO 2 laser vaporization of posterior crus |
| Mechanical separation of anterior crus | ||
| CO 2 laser stapedotomy | ||
| Teflon-wire piston prosthesis | ||
| 7 | R | CO 2 laser vaporization of posterior crus |
| Mechanical separation of anterior crus | ||
| CO 2 laser stapedotomy | ||
| Modified cupped piston prosthesis |
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