PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 32 no. 1 January – June 2017
PhiliPPine Journal of otolaryngology-head and neck Surgery 51
SURGICAL INNOVATIONS AND INSTRUMENTATION
Philipp J Otolaryngol Head Neck Surg 2017; 32 (1): 51-54 c Philippine Society of Otolaryngology – Head and Neck Surgery, Inc.
Optical Myringotomy KnifeRozelle O. De Leon, MDJay Pee M. Amable, MD
Department of Otorhinolaryngology
Head and Neck Surgery
UERM-Memorial Medical Center, Inc.
Correspondence: Dr. Jay Pee M. Amable
Department of Otorhinolaryngology
Head & Neck Surgery
Rm. 463, Hospital Service Bldg., UERMMMC, Inc.
64 Aurora Blvd., Quezon City 1113
Philippines
Phone: (632) 715 0861 local 257
Fax: (632) 7161789
E-mail: orlhns_uerm@yahoo.com
The authors declared that this represents original material
that is not being considered for publication or has not been
published or accepted for publication elsewhere, in full or in
part, in print or electronic media; that the manuscript has been
read and approved by the authors, that the requirements for
authorship have been met by the authors, and that the authors
believe that the manuscript represent honest work.
Disclosures: The authors signed a disclosure that there are no
financial or other (including personal) relationships, intellectual
passion, political views or beliefs, and institutional affiliations
that might lead to conflict of interest.
ABSTRACT
Objective: To describe an improvised optical myringotomy knife essential in creation of an
incision in a myringotomy simulator.
Methods:
Design: Instrumental Innovation
Setting: Tertiary Private Hospital
Subject: None
Results: The optical myringotomy knife was able to create incisions on mock membranes
made up of polyethylene film (Cling Wrap) in a myringotomy simulator. The incisions measured
approximately 2mm with sharp edges indicating that the myringotomy knife was able to
penetrate the mock membrane with ease. It provided good control in performing myringotomy
incisions under endoscopic visualization of the tympanic membrane.
Conclusion: Our initial experience with this optical myringotomy knife for tympanostomy tube
insertion suggests that it may greatly improve the performance of myringotomy especially
among less experienced surgeons. Further studies may establish its accuracy and replicability in
vitro, after which formal in vivo trials can be attempted.
Keywords: tympanostomy, middle ear ventilation, endoscopy, instrumentation
Otitis Media with Effusion (OME) is the presence of fluid in the middle ear with no signs of
infection or tympanic membrane perforation.1 OME is a very common disease affecting people
of all ages worldwide though more commonly encountered in children. Myringotomy with or
without tympanostomy tube insertion has become the standard of care for patients with OME
lasting more than three months with associated significant hearing loss and unresponsive to
conservative management.2
Through the years, approaches to myringotomy have evolved, recently involving microscopic,
endoscopic and even laser-assisted procedures.3 With the advent of endoscopes, endoscopic
myringotomy under topical anesthesia has been proven to be safe and practical.4 Endoscopic
myringotomy provides better visualization of the tympanic membrane and some of the middle
ear structures. We describe a simple optical myringotomy knife with accuracy and precision in
placement of myringotomy incisions.
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PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 32 no. 1 January – June 2017
SURGICAL INNOVATIONS AND INSTRUMENTATION
52 PhiliPPine Journal of otolaryngology-head and neck Surgery
METHODS
A. Endosheath Fabrication
A 3/10cc insulin syringe was used to create the endosheath for a
0 degree 2.7mm x 110mm rigid endoscope. (Figure 1) The attached
needle and flange were removed using a cutter creating a 55mm
hollow tube with inner diameter of 3mm and outer diameter of 6mm
with smooth edges. (Figure 2) Two insulin syringes were utilized in the
construction to form a 110mm endosheath. (Figure 3)
puncturing of the tympanic membrane. The needle was then attached
to the distal end of the insulin syringe using 100% Ethyl Cyanoacrylate
exposing 5mm of the tip. This ensured that only 5mm of the needle
would penetrate the tympanic membrane and the middle ear cavity.
(Figure 5)
Figure 1. 3/10cc Insulin syringe
Figure 2. Trimmed insulin syringe
Figure 3. Two insulin syringes connected with attached needle at one end
Figure 4. Gauge 19 needle
B. Improvised Myringotomy Knife
A gauge 19 needle was flattened to create a 2mm improvised knife
using pliers without violating the sharp edge of the needle. (Figure 4)
The pinpoint sharpness of the needle was maintained to facilitate
Figure 5. Attachment of needle to insulin syringe
Figure 6. Optical myringotomy knife with endoscope
C. Technique
The optical myringotomy knife was fitted into the endoscope with
just enough length to visualize the tip of the needle from the scope. The
needle tip was designed to create a stab incision of 2mm in length with
sharp edges. (Figure 6)
In a myringotomy simulator measuring 2.5 cm long x 0.7 cm wide to
more or less replicate the average length and diameter of the Filipino
adult ear canal, polyethylene film (Cling Wrap) was used to create the
mock membrane. (Figure 7) The optical myringotomy knife with the
Figure 7. Myringotomy simulator (anterior, lateral and posterior view)
PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 32 no. 1 January – June 2017
PhiliPPine Journal of otolaryngology-head and neck Surgery 53
SURGICAL INNOVATIONS AND INSTRUMENTATION
endoscope was advanced into the model ear canal using a one-hand
technique. (Figure 8) The endoscope had an advantage of allowing
visualization of the entire tympanic membrane, allowing the surgeon
to determine where to perform the stab incision and to direct the
needle tip to that particular quadrant. Once the quadrant of choice was
identified and visualized, the device could be advanced using the index
and middle fingers without moving the endoscope. As the needle tip
punctured the mock membrane, an incision was created. (Figure 9) The
endoscope also allowed immediate evaluation of incision placement.
Several myringotomy trials using the optical myringotomy knife were
conducted to verify the technique.
DISCUSSION
Myringotomy with or without tympanostomy tube insertion
is one of the most common procedures in Otolaryngology. It is a
relatively rapid procedure which can be performed under local or
general anesthesia. Generally, myringotomy entails at least two
maneuvers to achieve the end result. First, myringotomy is performed
using a myringotome to create a stab incision which is usually at the
antero-inferior (sometimes postero-inferior) quadrant. Afterwards,
insertion of tympanostomy tubes can be done using applicators
or alligator forceps. Commercial devices like the Hummingbird™
TTS (Tympanostomy Tube System) claim to lessen maneuvers and
facilitate myringotomy and tympanostomy tube insertion in one
pass.5 In our setting, a novel low-cost tympanostomy tube with
applicator was conceptualized which also perforated the tympanic
membrane and inserted the tympanostomy tube at the same time.8
With the aid of endoscopy, one is able to perform myringotomy with
better visualization and a closer view of the tympanic membrane.4
The EndoSheath® Technology is a sterile, disposable protective
barrier between the scope and the patient which works like a condom.
This technology also incorporates a channel for suction, irrigation
and tool passage.6 This was the inspiration for the development of
this device. The insulin syringe served as the “EndoSheath” which
snugly fits the endoscope. Optical forceps have been also part of
ENT instrumentation ideal for foreign body removal and biopsy
procedures.9 The telescope joined with the forceps provides a close-
up view and allow control and visualization in biopsy or foreign
body removal. This resulted in the idea for the improvised optical
myringotomy knife wherein a Gauge 19 needle was attached to the
distal end of the syringe. The endoscope and optical myringotomy
knife provided a close-up view of the tympanic membrane and
allowed precise control and accurate placement of the myringotomy
incision. The endoscope provides better resolution and depth
perception in performing myringotomy. It has been reported that
the most frequent human errors during myringotomy are failure to
perform a unidirectional myringotomy incision and multiple attempts
to complete the myringotomy.10 This can be eliminated with the use
of an optical myringotomy knife that provides excellent visualization
of the tympanic membrane and allows creation of a 2mm single stab
incision sufficient for inserting tympanostomy tubes.
The dimensions of the adult external auditory canal and tympanic
membrane were taken into account in conceptualizing the design of
this optical myringotomy knife. During the procedure, instruments
would have to be maneuvered in the external auditory canal and
visualize the tympanic membrane. The average length of an adult
ear canal is approximately 25mm with an average diameter of 7
Figure 8. Endoscopic view of tympanic membrane with optical myringotomy
knife at the 5 o’clock position (arrowhead)
Figure 9. Endoscopic view of tympanic membrane with incision at the antero-
inferior quadrant (arrowhead)
PhiliPPine Journal of otolaryngology-head and neck Surgery Vol. 32 no. 1 January – June 2017
SURGICAL INNOVATIONS AND INSTRUMENTATION
54 PhiliPPine Journal of otolaryngology-head and neck Surgery
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to 10mm.4,7 With this in mind, we utilized a rigid endoscope with
a diameter of 2.7mm to fit inside an insulin syringe with an inner
diameter of 3mm and outer diameter of 6mm. This would have
enough room for manipulation inside the ear canal although its
shape and cross sectional dimensions change along its length.4,7 The
tympanic membrane dimensions along its two major perpendicular
axes are 9 to 10 mm and 8 to 9 mm with an average thickness of
approximately 70 μm but can vary from approximately 30 to 120 μm7
The exposed needle tip used to puncture the tympanic membrane is
approximately 5mm which would safely penetrate the usual middle
ear cavity without injuring middle ear structures.
This exploratory study has several limitations. Due to the lack
of appropriate equipment for fabrication, the ideal size and shape
of the myringotomy knife was not achieved since we utilized a
flattened gauge 19 needle as the knife. A customized medical grade
stainless steel myringotomy knife can be fabricated to ensure sharp
instrumentation, but it would definitely cost more than our fabricated
instrument. Difficulties in the one-hand technique were also
identified such as a good hand-eye coordination, ease of advancing
the endoshealth and handling the endoscope at the same time and
the finesse in puncturing the tympanic membrane. The lack of formal
trials by multiple operators is another limitation of our study.
Our initial experience with this optical myringotomy knife for
tympanostomy tube insertion suggests that it may greatly improve
the performance of myringotomy especially among less experienced
surgeons. Further studies may establish its accuracy and replicability
in vitro, after which formal in vivo trials can be attempted.