Clinical importance of endoscopic middle ear dissection on cadaver



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CLINICAL IMPORTANCE OF ENDOSCOPIC MIDDLE EAR DISSECTION ON CADAVER
Umesh Prasad Sinha1, Dhirendra Kumar Singh2



1Assistant Professor, Department of Anatomy, Government Medical College, Bettiah.

2Professor and HOD, Department of Anatomy, Government Medical College, Bettiah.



ABSTRACT

BACKGROUND

In recent years use of endoscope for diagnostic and surgical procedures is increasing in ENT practice due to clear and wide vision of anatomical structures. However, there are some difficulties with use of endoscope because one hand remains engaged in holding endoscope and dissection should be carried out with one hand only on viewing the monitor.

The aims and objectives of this study is to assess the difficulties during dissection and visualise the different structures of middle ear cavity.
MATERIALS AND METHODS

During 2014 to 2016, 34 temporal bone were dissected with endoscopic vision. We used 0 degrees to 45 degrees and 4mm endoscope.


RESULTS

After initial difficulties of holding of endoscope with left hand and doing dissection with right hand on viewing the monitor, there was no major technical difficulty later on. We were able to see middle ear structures with minimal dissection.


CONCLUSION

The hand control of holding endoscope and doing dissection on viewing monitor was adopted very soon and there was wide and clear view of middle ear structures.


KEYWORDS

Clinical Importance, Endoscopic, Middle Ear Dissection, Cadaver.



HOW TO CITE THIS ARTICLE: Sinha UP, Singh DK. Clinical importance of endoscopic middle ear dissection on cadaver. J. Evolution Med. Dent. Sci. 2017;6(19):1534-1537, DOI: 10.14260/Jemds/2017/337




BACKGROUND

Today the surgical procedures of the middle ear are traditionally carried out with the help of operating microscope. In spite of some benefits, because of its restricted and linear view field, the microscope does not allow a proper viewing of some spaces of middle ear. Exposure for viewing these areas often requires wide drilling of mastoid either by retroauricular or endaural incision. It disturbs the normal anatomy of middle ear, which gives discomfort after surgery and even after such wide exploration some retrotympanic spaces is out of vision by operating microscope. Such type of challenges requires alternative instruments for ear surgery. Endoscopic ear surgery is nowadays has become popular, because it has ability to fulfil such type of requirements. Although, the endoscopes are already used in our speciality for at least 15 years, in otology use of such instruments is still very uncommon. One of the main reasons may be the role of prominent otologists who indicate the use of endoscope only for secondary procedures and diagnosis.1,2,3,4


Financial or Other, Competing Interest: None.

Submission 27-01-2017, Peer Review 21-02-2017,

Acceptance 27-02-2017, Published 06-03-2017.

Corresponding Author:

Dr. Umesh Prasad Sinha,

#77, LIC Colony,

Po-Lohianagar,

Kankar Bagh,

Patna-20.

E-mail: umesh18163@yahoo.co.in

DOI: 10.14260/jemds/2017/337



Aims and Objectives

The aims and objectives of this study was to become familiar with use of endoscope for the exploration of middle ear cavity. With the use of endoscope, the structure of middle ear was viewed on monitor. So, some practice was required for coordination of hands for dissection. After regular dissection, left hand was adjusted for holding endoscope as well as dissecting the tissue with right hand.

The endoscopic anatomy of middle ear was so clear and vision was so wide and extensive that anatomical structures was clearly visualised with minimal dissection. So, it helps to understand proper anatomy of middle ear cavity and gives extra confidence to otologists during ear surgery.
MATERIALS AND METHODS


  1. Wet temporal bone.

  2. Endoscope (0 degree and 45 degrees, 4 mm wide and 18 cm long).

  3. Endoscopic camera.

  4. Monitor.

  5. Cold light source.

  6. Middle ear surgery instruments.

  7. Power suction machine.

This study was done in the Department of Anatomy, Govt. Medical College, Bettiah during the period of July 2014 - June 2016 on 34 temporal bones. External auditory canal of cadaver was cleaned by fresh water and power suction machine. The dissection was done through transcanal access. Tympanomeatal flap was elevated at posterior meatal wall from 12’o clock to 7’o clock position. Precaution was taken not to injure skin of posterior meatal wall and tympanic membrane. Tympanic membrane was carefully dissected from handle of malleus. Now tympanomeatal flap was positioned anteriorly on the anterior meatal wall. Structures of middle ear like chorda tympani nerve, handle of malleus, opening of Eustachian tube, Promontory, Pyramids with tendon of stapedius muscle, facial recess, sinus tympani, ponticulus subiculum and round window were examined. Now epitympanic area was dissected with the help of curettage for proper visualisation of head of malleus, body and short process of incus. Finally, all structures of middle ear cavity were examined under 0 degree and 45 degrees endoscope. Middle ear ossicles was removed and then medial wall was inspected carefully with 0 degree and 45 degrees endoscope. In different cadavers, different types of sinus tympani was observed.


RESULTS

The hand control of endoscope was difficult, because it should be held by left hand. The coordination to do dissection by observing on monitor needs some practice, because the visualised area is two dimensional so the depth of area should be guessed by repeated practice. The visualisation of middle ear structures was excellent, even those areas which was hidden behind a structure can be visualised by 45 degree endoscope. So, it needs minimum dissection to visualise a particular structure. Out of 34 temporal bones, 2 bones had deep sinus tympani which was hidden posteriorly behind pyramid. Such type of sinus tympani could not be visualised by operating microscope.


Tabular Column


Number of temporal bones dissected

34

Tympanic membrane found intact

30

Number of temporal bones in which all the ossicles found intact

28

Number of temporal bones in which all structures of middle ear cavity visualised

31

Number of temporal bones in which Type A sinus tympani found

24

Number of temporal bones in which Type B sinus tympani found

8

Number of temporal bones in which Type C sinus tympani found

2

Causes of non-visualisation of structures

Damaged during dissection

Figures showing the clear view of middle ear structures as well as those hidden areas, which was impossible to visualise by operating microscope due to its linear field of vision.



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