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Diagnostic Imaging of the Nasolacrimal Drainage System. Part REVIEW ARTICLES e-ISSN 1643-3750 © Med Sci Monit, 2014; 20: 628-638 DOI: 10.12659/MSM.890098 Received: 2013.11.27 Accepted: 2014.01.16 Diagnostic imaging of the nasolacrimal drainage Published: 2014.04.17 system. Part I. Radiological anatomy of lacrimal pathways. Physiology of tear secretion and tear outflow Authors’ Contribution: ABCDEFG 1 Artur Maliborski 1 Department of Medical Radiology, Military Institute of Medicine, Warsaw, Poland Study Design A ABCG 2 Radosław Różycki 2 Department of Ophthalmology, Military Institute of Medicine, Warsaw, Poland Data Collection B Statistical Analysis C Data Interpretation D Manuscript Preparation E Literature Search F Funds Collection G Corresponding Author: Artur Maliborski, e-mail: [email protected] Source of support: Departmental sources Excessive watering of the eye is a common condition in ophthalmological practice. It may be the result of ex- cessive production of tear fluid or obstruction and insufficiency of efferent tear pathways. The differentia- tion between obstruction and insufficiency of the lacrimal pathways is still clinically questionable. In the -di agnostic process it is necessary to perform clinical tests and additional diagnostic imaging is often needed. Dacryocystography, with or without the extension of the dynamic phase or subtraction option, still remains the criterion standard for diagnostic imaging of the lacrimal obstruction. It may help to clarify the cause and exact place of the obstruction and provide information for further management, especially surgical treatment. Increasingly, new techniques are used in diagnostic imaging of the lacrimal tract, such as computed tomogra- phy, magnetic resonance, and isotopic methods. Adequate knowledge of the anatomy and physiology of the lacrimal system and the secretion and outflow of tears is the basis for proper diagnostic imaging. The purpose of this paper is to present the exact anatomy of the lacrimal system, with particular emphasis on the radiological anatomy and the current state of knowledge about the physiology of tear secretion and drainage. MeSH Keywords: Lacrimal Apparatus Diseases • Dacryocystitis – diagnosis • Lacrimal Apparatus – anatomy & histology Full-text PDF: http://www.medscimonit.com/download/index/idArt/890098 5960 — 7 41 Indexed in: [Current Contents/Clinical Medicine] [SCI Expanded] [ISI Alerting System] This work is licensed under a Creative Commons [ISI Journals Master List] [Index Medicus/MEDLINE] [EMBASE/Excerpta Medica] Attribution-NonCommercial-NoDerivs 3.0 Unported License 628 [Chemical Abstracts/CAS] [Index Copernicus] Maliborski A. et al.: Diagnostic imaging of the nasolacrimal drainage system… REVIEW ARTICLES © Med Sci Monit, 2014; 20: 628-638 Background of the body of the maxilla, and the anterolateral part of the floor is filled by the orbital surface of the zygomatic bone and Epiphora is a common condition in ophthalmological practice. the posteromedial part by the orbital process of the palatine It may be the result of an excessive production of tear fluid, or bone. In the anteromedial part of the inferior wall, the supe- the obstruction or insufficiency of the efferent tear pathways. rior foramen of the nasolacrimal canal, running along the lat- Diagnosis of the latter problem, as well as differentiation be- eral nasal wall, can be found. The nasolacrimal duct, draining tween obstruction and insufficiency of lacrimal pathways, still tears from the lacrimal sac to the nasopharynx, passes through is clinically questionable. In the diagnostic process, it is neces- this bony canal. The inferior ostium of the canal is located on sary to investigate various causes of epiphora and perform ad- the surface of the inferior nasal concha. The vertically orient- ditional clinical tests. The ophthalmologist must have a thor- ed lateral wall of the orbit is formed by orbital surfaces of the ough knowledge of anatomy, physiology, and pathophysiology zygomatic bone and the greater wing of the sphenoid bone. of the lacrimal apparatus in order to make an adequate diag- The orbital roof is composed of the orbital part of the frontal nosis, determine the causes of excessive watering of the eye, bone and the lesser wing of the sphenoid bone. The depres- and to implement effective medical treatment. In doubtful cas- sion located in the anterolateral part of the roof is known as es it is necessary to perform additional tests, including radi- the fossa of the lacrimal gland, named after a gland that is ology and diagnostic imaging. Dacryocystography (DCG), per- situated there [1]. formed as a conventional radiology procedure with the use of contrast media, is considered to be the criterion standard in Pathological processes leading to the destruction of the bones the diagnosis of lacrimal tracts pathology. Supported by ad- forming the scaffold for the lacrimal pathways may cause their vanced image processing algorithms and high-quality modern blockage. Knowledge of the anatomy of the medial orbital wall contrast media, it enables accurate diagnosis of pathology in is particularly important for the radiologist conducting the as- small structures such as the lacrimal duct with fewer adverse sessment of the lacrimal pathways. Its anterior part is formed effects. Both dacryocystography and modern diagnostic meth- by the posterior surface of the frontal process of maxilla and ods, which are more commonly used in the lacrimal pathway the lacrimal bone, while the posterior part is formed by the imaging, can not only provide answers to questions crucial in orbital plate of the ethmoid bone and the lateral surface of choosing the appropriate treatment method, but also signifi- the sphenoid bone. The lacrimal bone, which is the smallest cantly impact the scope of possible surgical treatment. However, bone of the facial skeleton (viscerocranium), plays an impor- the radiologist must have a broad knowledge on this partic- tant role in the construction of the anterior part of the medi- ular ailment, be able to select an adequate imaging method, al orbital wall. Its orbital surface is divided into 2 parts by the have appropriate skills and experience to perform diagnos- vertical posterior lacrimal crest. The smooth posterior com- tic procedures, and closely cooperate with the clinician. Good poses the orbital wall. Located in the anterior part, the ver- knowledge of radiographic anatomy of the orbit and lacrimal tical lacrimal sulcus (which, with the similar lacrimal sulcus pathways, as well as the physiology of tears outflow, is an es- of the frontal process of maxilla, forms the fossa of the lac- sential factor in proper interpretation of test results. rimal sac), has an average length of 16 mm, width of 8 mm, and depth of 2–4 mm. This depression is usually slightly less narrow in women than in men [2]. The lacrimal sac is located Radiographic Anatomy of the Orbit and in the superior part of the fossa, while the initial section of Lateral Nasal Wall the nasolacrimal duct is in the inferior part of the fossa. The posterior nasal crest divides the inferior margin of the lacri- The normal anatomical structure of an organ usually deter- mal bone into 2 parts: the posterior part is connected to the mines its physiological efficiency. The visual organ, located orbital process of maxilla, and anterior part descends lower mainly within the facial skeleton, consists of an eye and ac- and is connected to the lacrimal process of the inferior na- cessory organs. The eye is made up of the eyeball, placed in a sal concha. Due to that latter connection, the lacrimal bone 4-sided pyramid known as the orbit, and an optic nerve, which helps form the nasolacrimal canal (the bony scaffold for the is the only connection between this sense organ and the en- nasolacrimal duct, which begins on the medial orbital wall, cephalon. The system of accessory organs is formed by orbital runs along the lateral wall of the nasal cavity and enters the fasciae, eyelids, conjunctiva, the lacrimal apparatus, and mus- inferior nasal meatus just behind the anterior end of the in- cles of the eyeball. The volume of the orbit is usually about 30 ferior nasal concha. The nasolacrimal canal is formed lateral- ml, of which the eye occupies only 6–7 ml. ly and anteriorly by the lacrimal sulcus of the frontal process and the body of maxilla, and is formed medially and posteri- In each orbit, 4 walls, the inlet of the orbit, and its apex, di- orly by the lacrimal sulcus of the lacrimal bone and the lac- rected medially and posteriorly, can be identified. The floor rimal process of the inferior nasal concha. The lacrimal part (inferior wall) of the orbit is formed by the orbital surface of the orbiculus oculi muscle attaches to the posterior nasal Indexed in: [Current Contents/Clinical Medicine] [SCI Expanded] [ISI Alerting System] This work is licensed under a Creative Commons [ISI Journals Master List] [Index Medicus/MEDLINE] [EMBASE/Excerpta Medica] Attribution-NonCommercial-NoDerivs 3.0 Unported License 629 [Chemical Abstracts/CAS] [Index Copernicus] Maliborski A. et al.: REVIEW ARTICLES Diagnostic imaging of the nasolacrimal drainage system… © Med Sci Monit, 2014; 20: 628-638 Figure 1. Le Fort fracture, type II scheme. Based on RosarioVanTulpe scheme. of the viscerocranium with the zygomatic and nasal bones is detached from the cranium as a whole. In Lefort II fractures, injuries of the inferior walls and inferior margins of the orbits near the zygomaticomaxillary sutures, lacrimal bones, nasal bridge, fractures of the frontal processes of maxilla, and lat- eral walls of the maxillary sinuses occur. Shadowing of the maxillary sinus can also be seen on radiograms. This type of fracture can lead to posttraumatic obstruction of the lacri- mal pathways (Figures 1 and 2) [5–9]. Fractures of the medial wall of the orbit are also concomitant with direct injuries of the nasal bone. The fractures are also Figure 2. Le Fort fracture, type II. CT volume reconstruction. the effects of blowout trauma, in which a large, round object (e.g., a ball) hits the eyeball directly with great force.
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