Nghiên cứu giải phẫu hệ thống ống bán khuyên ứng dụng trong phẫu thuật 9tt)

Though, in fact, each semicircular canal lies within separate bony mass those shape is similar to that such semicircular called bony cover; the bony mass covering semicircular canals lie

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF HEALTH

MILITARY MEDICAL UNIVERSITY

NGUYEN THANH VINH

RESEARCH IN ANATOMY OF SEMICIRCULAR CANALS APPLY TO SURGERY

Major: Biomedical Science Code : 9 72 01 01

ABSTRACT OF MEDICAL DOCTORAL DEGREE

HA NOI – YEAR 2019

Tutor of thesis:

1 Assoc.Prof.PhD PHAM NGOC CHAT

2 Prof.PhD LE GIA VINH

Reviewer 1: Prof.PhD LE VAN CUONG

Reviewer 2: PhD NGUYEN PHI LONG

Reviewer 3: Assoc.Prof.PhD PHAM TUAN CANH

The thesis was defended at assembly of the university

on: o’clock date months year

Can read for this thesis at:

1 National library

2 Military medical university’s library

3 ………

INTRODUCTION

Ear is divided into 3 parts: external ear, middle ear and inner ear; among those, the inner ear has a much more complicated anatomic structure, especially three-semicircular canal system: anterior, lateral and posterior There has been a lot of researches about anatomy of 3 semicircular canal system, which is described and illustrated quite thoroughly in anatomy textbooks Though, in fact, each semicircular canal lies within separate bony mass those shape is similar to that such semicircular called bony cover; the bony mass covering semicircular canals lies within a hard bony mass called inner ear covering bone, outside the inner ear covering, there are many layers

of developed mastoid air cell hidden, which hardly recognized Within semicircular canal bony cover, it contains bony semicircular canals; within bony semicircular canal, it contains membrane semicircular canal The latter one is more complex than the former cause membrane semicircular canals gain a much more smaller size comparing to bony semicircular canals; there are ampullae for each canals, the common limbs and separate limbs, those drain into utricle Semicircular canals system gains a little structure, locates deeply

in temporal bone, adjacent to important structures of body, for examples: utricle, saccule, facial nerve, meninges, ossicles … there are many layers of developed mastoid air cell surrounding and there

is no landmark aiming to identify each canals Because of such characteristics, studying, teaching, researching as well as clinical applying in treatment of 3 related specialties including anatomy, neurology and otorhinolaryngology face with many difficulty Therefore, identifying a bony semicircular canal without injury is already a challenge, identifying membranous semicircular canal

without injury to adjacent bony semicircular canal is much more difficult as well as not damaging important neighboring structures Furthermor, to operate common diseases of ear, the surgical approach

is usually near those semicircular canals; thus, it is easy to get injured In ear diseases, it is still difficult to identify affected semicircular canals and easy to pass by; or can identify but can not eliminate pathogenesis To solve such problem, we perform research about “The anatomy of semicircular canal system applying for ear surgery” with two following separate objectives:

1 Describing anatomic characteristics of semicircular canals system in Vietnamese aldults

2 Identifying the relation between semicircular canals and adjacent structures

Essential of the thesis:

In treatment, the diseases of the ear, that effect the semicircular system such as: BPPV, chronic otitis media, cholesteatoma, trauma amd temporal bone tumor …, need surgery Finding one bony semicircular canal without injuring itself is difficult, as well as identifying membrane semicircular canal and not injuring other semicircular canals or surrouding important structures such as middle cranial fossa, lateral venous sinus … is more difficult On the other hand, in surgical treatment of common diseases of the ear, the incision is usually close to the semicircular canal system so it is easy

to break through them

The new main scientific findings of the thesis:

The thesis provides specific measurements of bony as well as membranous semicircular canal Thereby, noting the changes in

morphology of bony sheath, bony and membranous semicircular canal Moreover, introducing new techniques: micro-surgical incision approaching semicircular canals and how to get inside the semicircular canals following techniques “Cleaving the section of the orange”

The thesis determines the relationship between the semicircular canals and surrouding structures There are structures that directly affecting micro-surgical opening of the semicircular canals such as temporal air bone cells projecting to the semicircular canals, there are structures that affecting micro-surgical incision approaching the semicircular canals such as: lateral venous sinus, middle cranial fossa… And there are structures that help identify or avoid injuring another ones: the ossicles, section 3 of facial nerve … These results help surgery diseases related to the semicircular canals safe, effective and less sequalea

Thesis layout:

The thesis has 122 pages, including: Introduction, Overview (29 pages), Subjects and methods (24 pages), Results (32 pages), Discussion (33 pages), Conclusion and Recommendation

There are 47 tables, 73 images and 134 references (16 Vietnamese and 118 English references)

Chapter 1: SUMMARY OF DOCUMENTS

The inner ear is located within the petrous part of the temporal bones, covered in bone mass called the bony labyrinth The semicircular canal system is in the inner ear and consists of hollow, circular, semicircular tubes, aligned in three perpendicular planes

There are three semicircular canals: anterior, posterior, lateral semicircular canal Each has two end points The end points are bigger than their diameters, which are called ampullar limb and bony limb The plane containing lateral semicircular canal creates with the transverse plane of the head an angle of 30 degree The other two semicircular canals: one is upright and one is horizontal, they are perpendicular to each-other In human beings, the plane of anterior semicircular canal of one ear is parallel to the plane of posterior semicircular canal of the other ear and vice versa The semicircular canals which have the same name of two ears (anterior and posterior) have the planes that perpendicular to each-other The semicircular canals are oriented in different planes, and two prominent points, one projects into transverse plane (utricle), the other projects into vertical plane (saccule) There are two vertical semicircular canals: posterior and anterior; one horizontal semicircular canal: lateral The vertical semicircular canals creates with the sagital plane of the head an angle

of 45 degree The horizontal semicircular canal is slightly up in the front, and creates an 30 degree angle with the transverse plane of the head Each semicircular canal is arranged in 3 different perpendicular plane Each semicircular canal is almost perpendicular to the others and is sensitive to the rotational movement in its plane The result of this 3 different planes arrangement corresponds to any movement of the head The canals function as unified accelerometer, each stimulation to each canal acts as an angular acceleration, the information is subsequently encrypted and stimulates centripetal nerves relevant to angular momentum These canals are organized in pairs and in the same plane Any rotational motion will stimulate one canal and inhitbit the other canal in pair The pair of two horizontal

semicircular canals has more complex location and function than the vertical semicircular canals In human beings, anterior semicircular canal on one side is parallel to the posterior semicircular canal on the other side For example, the right anterior one and the left posterior one create a functional pair The others two semicircular canals are located almost perpendicularly to the lateral semicircular canal The posterior semicircular canal is located just behind the lateral semicircular canal The back border of lateral semicircular canal is the midpoint of posterior semicircular canal The posterior semicircular canal is almost parallel to the posterior cranial fossa The ampulla of posterior semicircular canal, the end point of lower branch, right inside the mastoid part of the facial nerve, the upper end point of the posterior semicircular canal joints with the superior semicircular canal to form a common limb

The anterior SCC creates the prominence of the middle cranial fossa, called arcuate eminence; this is an important landmark to identify the anterior SCC and the internal auditory canal through the middle cranial fossa Moreover, the lateral SCC protrudes into the medial wall of the antrum, it is also an important landmark in mastoid surgery.On morphology, the average diameter of SCCs is about 1 mm; the average length between two crus of SCC is approximately 6.5 mm Lateral SCC connected with the utricle at both ends; crus of posterior SCC and superior SCC join to form the crus commune, while the remaining crus of these SCCs is connected with the utricle separately Thus, the SCCs open into the vestibule actually by five orifices The membranous labyrinth is suspended in the bony labyrinth by the perilymphatic space and connective tissue; membranous SCCs is a very thin walled tube (diameter 0.4 mm) in

the bony SCCs; is located at the eccentricity in the bony SCCs, which

is held by the connective tissue The membranous labyrinth is surrounded by perilymphatic space which is filled with perilymph, the membrane SCCs is filled with endolymph and communicated with the utricle The region of the canal is enlarged which opens into the utricle and has a dilated sac at one end called the ampullae The frontal-upper boundary of the semicircular canals is the epitympanum, the frontal-lower boundary is utricle, saccule, cochlea; the inner boundary is temporal bone, and behind is the third part of facial nerve, mastoid cells system of mastoid bone, upper is middle skull base, behind-lower is posterior skull base, lower-frontal is the internal auditory canal The middle cranial fossa relating: The superior SCC protrudes into the middle cranial fossa in most cases, this protrusion is called arcuate eminence; In a few cases, due to the development of the perilabyrinthine cells, especially on the anterior cells, the arcuate eminence will be inserted between the superior SCC and the middle cranial fossa, separating these two components, so that the arcuate eminence will be lower or not protrude into the middle cranial fossa The posterior cranial fossa relating: The bone of the posterior cranial fossa can be continued or separated to the posterior SCC, depend on the infralabyrinthine cell; if there are numerous infralabyrinthine cells, it will be separated the posterior cranial fossa from the posterior SCC If there are few infralabyrinthine cells, the posterior SCC will contact directly with the posterior cranial fossa The posterior boundary of the mastoid bone is the sigmoid sinus (also known as external sinus); the sigmoid sinus is located below the posterior cranial fossa, usually protrude into the mastoid bone and divide the posterior cranial fossa into the

presinus and postsinus areas The sigmoid sinus is less related to the SCCs system, but the protrusion of the sigmoid sinus directly affects the approach to the SCCs, especially the posterior SCC The facial nerve relating: The second segment runs from the geniculate ganglion posteriorly, has a length of 10-12, directs horizontally; is called the tympanic segment Also called the atrium Then, the tympanic segment turns laterally at a 70º angle and inferiorly at a 10º angle, next to the ampulla of the lateral SCC and superior to the oval window, then curves inferiorly to become the second genu of the facial nerve At the second genu, the facial nerve turns at a 125º angle and close to the lateral SCC, in some cases, the Fallopian canal is overlying deeply the lateral SCC Then, it runs vertically to become the third segment (the mastoid segment of the facial nerve); directs to the stylomastoid foramen The third segment runs from the second genu, closes to the lateral SCC and superior to posterior SCC, become the medial wall of the facial recess; there is no another structures inferior to the posterior SCC The perilabyrinthine cells relating: The superior prelabyrinthine cell tracts: superior to the ampulla of the superior and lateral SCCs, inferior to the geniculate ganglion and Fallopian canal Then, they extend medially through the superior SCC to the superlabyrinthine cells located on the internal auditory canal, they are the superior prelabyrinthine cells The translabyrinthine or intralabyrinthine cells: These air cells derived from the antrum, located in a "triangle" formed from three SCCs It traverses the subarcuate cell tract and the subarcuate artery, through the vestibule to the medial surface of the superior SCC before reaching the supralabyrinthine cells and the suprameatal cells They can pass through the entire temporal bone in about 2-3% of cases, but

on the surface of the antrum, the intralabyrinthine cells are often seen between the SCCs The supralabyrinthine cells: these air cells are the prolongation of the periantral air cells, extending along the middle cranial fossa, superior to the superior SCC and the crus commune between the superior and posterior SCCs, and terminating superior to the internal auditory canal as the suprameatal cells

The microsurgery pathways to approach the SCCs include: The microsurgery through temporal bone: drill the temporal bone to expose lateral sinus and the dural of the middle cranial fossa;open the antrum to expose the lateral SCC Identify the short process ocf the incus lateral to the lateral SCC Identify the length of the third segment of VII CN, reserve the buttress Open the aditus and attic, exopose the preattic

The microsurgery through the cranial fossa: Open the skull by 4x5 cm, two third anterior to the outer ear canal and one third posterior to the outer ear canal After lifting the dural, open the anterior SCC anterior to the arcuate eminence

The microsurgery through the perilabyrinthine: drill all the air cells, expose the inferior border of the posterior SCC, open the labyrinthine from the lateral SCC, then open the posterior SCC and the anterior SCC, exopose totally the bony cover of the SCCs, the bony SCCs and the membranous SCCs

Application in treatment of BPPV by opening the bony SCCs and the membranous SCCs Application in cover the dehiscence of the bony SCC in patients with COM with cholesteatoma which cause erosion of the SCCS and cause dizziness, or in dehiscence of the SCCs after trauma or congenital

Chapter 2: MATERIALS - METHODS

2.1 Materials: 32 ears from 16 cadavers in Vietnam, handled

at the Anatomy Department, University of Medicine and Pharmacy, Ho Chi Minh City

2.2 Methods:

This was a cross-sectional study performed at the Anatomy Department, University of Medicine and Pharmacy, Ho Chi Minh City Inclusion criterias include 16 cadavers > 18 years old, handled at the Anatomy Department, University of Medicine and Pharmacy, Ho Chi Minh City and normal temporal bone in anapathology Exclusion criteria include cadavers without standard handling, ear surgery intervention; congenital malformations in the head and neck, head or temporal bone trauma

2.2.1 Instrument:

Include instruments for temporal bone and semicircular canal dissection, electric drill and drill bits; microscope; camera; measuring instruments, measurement units is

millimeter (tested); computer

2.2.2 Conducting research:

Combining 2 dissection approachs: through skull base to identify the arcuate eminence, open anterior to arcuate eminence to identify anterior SCC; through temporal bone to identify SCCs and adjacent structures such as antrum, aditus ad antrum, lateral sinus, mastoid segment of the facial nerve, ossicles,… microsurgery of SCCs to open SCCs and measure dimensions

2.2.3 Research variables:

Qualitative variables like gender; ear research:

+ Membranous SCC: general morphology of 3 SCCs;

position of membranous SCC inside bony SCC; the ampullae

of membranous SCC inside ampullae of bony SCC; membranous lateral SCC in the crura; position of the ampullae

of membranous anterior SCC – membranous lateral SCC; position of subarcuate artery Quantitative variables include age

of cadaver; common crus length; the distance between

subarcuate artery and common crus

+ Bony SCC: width, length, thickness, diameter of bony SCC; diameter of the ampullae of SCC, the diatance between subarcuate artery and SCC

+ The relevant variables include: antrum – aditus ad antrum; lateral sinus; bone of midlle cranial fossa; distance from the buttress to the midpoint of SCCs; distance from the mastoid segment of the facial nerve to the midpoint of SCCs:

perilabyrinthine air cells

2.2.4 Data processing:

Collected data is processed by SPSS 16.0 statistical software; use independent t-tests and Mann-Whitney U to test statistics

2.2.5 Medical ethics:

Study carried out on cadavers in the Anatomy Department, University of Medicine and Pharmacy, Ho Chi Minh City; under the guidance of the Anatomy Departmen, Vietnam Military Medical University, do not violate the medical ethics

Chapter 3: RESULT OF STUDY

In our research there is 32 ears of 16, involved 8 males and 8 females, mean age is 67,69 ± 13,04; 16 right ears và 16 left ear

+ Morphology of semicircular canals

Table 3.4: Morphology of semicircular canals (n = 32)

Morphology Cases Percentage %

+ Position of subarcuate artery

Table 3.6: Position of subarcuate artery (n = 32)

Position Cases Percentage 

3.1 Descriptive anatomy of membrane SCCs

+ Position of membrane SCCs in bony SCCs

Table 3.8: Position of membrane SCCs in bony SCCs (n = 32)

Position Cases Percentage %