|Year : 2017 | Volume
| Issue : 1 | Page : 43-45
Congenital absence of stapedius muscle and tendon: Rare finding in two cases
Deepak Dalmia, Sanjaya Kumar Behera
Department of ENT, Dr. BAM Central Railway Hospital, Rani Bagh, Mumbai, Maharashtra, India
|Date of Web Publication||6-Feb-2017|
Dr. Sanjaya Kumar Behera
Department of ENT, Dr. BAM Central Railway Hospital, Rani Bagh, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
During surgery for otosclerosis, the surgeon cut the stapedius tendon before removing stapes suprastructure. The absence of the stapedius tendon is uncommon. In this case report, we present two cases of the absence of the unilateral stapedius tendon with muscle. During exploratory tympanotomy of the right ear in the first patient and left ear in the second patient with moderately severe mixed hearing loss, the absence of the stapedius tendon was found. The tympanic cavity was explored with the help of a Zeiss microscope by endomeatal route. The pyramidal process and stapedius muscle with its tendon were absent. Awareness of the variations or anomalies of the stapedius muscle and tendon is important for surgeons who operate upon the tympanic cavity, especially during surgery for ossicular fixation or ossicular discontinuity. As most of the time, these anomalies may be associated with the other middle ear anomalies.
Keywords: Exploratory tympanotomy, impedance audiometry, stapedius muscle
|How to cite this article:|
Dalmia D, Behera SK. Congenital absence of stapedius muscle and tendon: Rare finding in two cases. Indian J Otol 2017;23:43-5
| Introduction|| |
Congenital malformations of the middle ear have been described in association with various head and neck anomalies., The isolated middle ear anomalies may present with only conductive hearing loss and are rarely encountered during middle ear surgery or during surgical explorations., Stapedius muscle extends from the wall of the pyramidal eminence; its tendon passes forward through the apex of the pyramid to the neck of the stapes., The stapedius and the tensor tympani muscle contract together in a reflex response for sounds of high intensity, and the stapedius pulls the footplate of the stapes for decreasing the amplitude of vibrations at the oval window. It also prevents the excessive movement of the stapes.,, The stapedius muscle may be doubled or ectopic,,, and its tendon may ossificate  or muscular unit may be absent.,, The incidence of the absence of the tendon of stapedius is 0.5%. There are limited literature reports on the absence of the stapedius muscular unit., The absence of this muscular unit can be associated with other anomalies or pathological conditions. During surgery for otosclerosis, cutting of the stapedius tendon is common. We present these two rare cases with the aim of different anatomic variations of the stapedius muscle with tendon in relation to clinical diagnosis and for surgical procedures.
| Case Reports|| |
A 47-year-old female patient reported to the ENT outpatient department with decreased hearing to both ears. Pure tone audiometry (PTA) showed moderate to severe conductive hearing loss with mixed hearing loss at 2 kHz on left ear and moderately severe to severe mixed hearing loss in right ear. Impedance audiometry showed As type of tympanogram. Exploratory tympanotomy of the right ear was planned under local anesthesia. Rosen's endomeatal incision was given. The tympanomeatal flap was elevated from 7 to 12 o'clock position. Posterosuperior bony overhang curetted till visualisation of posterior half of the footplate. Stapedius tendon along with muscle with pyramid was found absent. Malleus, incus, and stapes suprastructure were intact [Figure 1]. The mobility of ossicular chain was checked from anterior to posterior. Incudomalleolar and incudostapedial joint were mobile, but stapes footplate was found fixed. Careful drilling of posterior crus of the stapes was done for exposure of the footplate. Stapedotomy was performed using serial increase in size of perforators. Teflon piston of size 4.25 mm × 0.6 mm was put in fenestra and crimped to the long process of incus. Outfracturing of the stapes suprastructure was done and removed. The flap was reposited. Postoperative PTA showed improvement of 15–30 dB in all frequencies.
|Figure 1: Case 1 - Absence of stapedius tendon with muscle With absent pyramid.|
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A 45-year old female patient presented with moderately-severe to severe mixed hearing loss of the left ear. Exploratory tympanotomy planned after tympanogram showing As type of curve. After giving the incision and curetting the posterosuperior bony overhang, the stapedius tendon with stapedius muscle with pyramid was found absent [Figure 2]a. Malleus, incus, and stapes suprastructure were intact. The mobility of ossicular chain was checked from anterior to posterior. Incudomalleolar and incudostapedial joint were mobile, but stapes footplate was found fixed. While doing fenestra, we came across floating footplate [Figure 2]b. We used vein graft to close the oval window and put a piston of 4.25 mm × 0.6 mm with crimping done with long process of incus. Postoperative PTA showed improvement of 25–30 dB in all frequencies.
|Figure 2: (a) Absence of stapedius tendon with muscle with absent pyramid. (b) Absence of stapedius tendon with muscle and fracture footplate with absent pyramid.|
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| Discussion|| |
The ossicular chain and their attachment develop from the mesenchyme of the first (mandibular) and second (hyoid) branchial arches.,, The origin of the stapedius muscle is the fasciculi of the posterior belly of the digastric muscle. The digastric muscle reaches the eminence of the mastoid process, gives fibers of muscle into the tympanic cavity, passing through the stylomastoid opening and approaching the neck of stapes to form the stapedius muscle. Hence both muscles are being innervated by the facial nerve. The stapedial reflex is important for protection against hazardous levels of noise, and for improving better speech in the presence of background noise.,,, A number of variations or anomalies of the stapes bone have been described., The absence of the stapedius tendon appears to be a rare congenital malformation of the middle ear. Hough reported five cases of total absence of the stapedius muscle in his series. Magnuson and Har-El found the absence of the stapedius muscle; in their case, few tendinous fibers connected the stapes head to a well-developed pyramidal process. Other reports showed that the isolated absence of the total stapedius can be considered as a relatively rare variant. In the present cases, the middle ear stapedius tendon with stapedius muscle were absent. The pyramid was absent in both the cases. In our experience of more than 500 stapedotomy surgeries, we came across two cases of absence of stapedius tendon with stapedius muscle with absent pyramid. We have observed that in middle ear anomalies such as absence of stapedius tendon, deformed incus and there is a chance of floating footplate during surgery.
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There are no conflicts of interest.
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[Figure 1], [Figure 2]
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