(BQ) Part 2 book Logan turner diseases of the ear, nose, and throat has contents: Anatomy and physiology, tests for hearing, tests for balance, diseases of the external ear, chronic otitis media, complications of otitis media,... and other contents.
III SECTION Ear 39 Anatomy and physiology LIAM M FLOOD Temporal bone 361 External ear 363 Tympanic membrane 364 Middle ear cleft 365 Ossicles 366 Eustachian tube 367 Inner ear 368 Cochlea 368 Physiology of hearing 369 External ear 369 Middle ear 369 Cochlea 370 Higher auditory pathways 372 Vestibular system 372 Conclusion 374 Key learning points 374 Further reading 374 This chapter provides an introduction to applied anatomy and physiology of the ear that is strictly of clinical relevance See the references at the end of this chapter for several excellent textbooks covering these topics in great detail The first challenge is to orientate the bone and confidently identify it as right or left The lateral surface is notable for: TEMPORAL BONE Osteology is a popular traditional examination topic and opens many temporal bone courses Some anatomists argue as to the four parts of the temporal bone, but they are best thought of as two that ossify in cartilage and two in membrane The former comprise the styloid process and the petromastoid, the latter the squamous temporal bone and tympanic ‘ring’ (a misnomer for what it is actually – a curved plate, like a gutter) ●● ●● ●● The bony external auditory canal, with the tympanic ring forming the floor as an incomplete semi-cylinder Note the sutures, the petrotympanic and tympanomastoid The squamous temporal bone and especially the temporal line, a landmark for the level of the middle cranial fossa dura when exploring The overlying muscle, the temporalis, is of less importance to ear, nose and throat (ENT) physicians than the covering layer of fascia, which is ideal graft material The mastoid process, which develops in infancy to progressively cover what is initially a very exposed stylomastoid foramen and facial nerve MacEwan’s triangle, with its spine of 361 362 Anatomy and physiology Henlé, is the surface landmark for the antrum, when starting to drill into a mastoid The posterior surface shows (Figure 39.1): ●● ●● ●● The internal auditory canal (IAC), divided into upper and lower segments by the transverse crest, but one has to gaze deep in to see it The upper segment is again divided by a small vertical partition That, not the horizontal division, is called Bill’s bar Anything nervelike that is anterior to it is the facial nerve, and posterior to it is the superior vestibular nerve, where vestibular schwannomas arise The cochlear aqueduct Directly below the IAC and passing in a similar plane is this much smaller canal, allowing communication between the cerebrospinal fluid (CSF) and cochlear perilymph (although there is great scepticism as to its patency in adults) Venous markings It is worth recognizing the inferior and superior petrosal sinuses, as they can challenge the neurosurgical approach to the IAC The grooves of the transverse and sigmoid sinuses and jugular foramen are more ●● obvious Their clinical relevance is in septic thrombosis secondary to chronic suppurative otitis media (CSOM) or the cranial neuropathies associated with glomus jugulare tumours (Figure 39.2) The cranial opening of the vestibular aqueduct Here lies the elusive endolymphatic sac, just awaiting ‘decompression’ The superior surface shows: ●● ●● ●● The groove of the middle meningeal artery, actually on the medial surface of the squamous bone and exposed to trauma The arcuate eminence, a dome that is an inconsistent landmark for the superior semicircular canal Various nerves escaping from the roof of the middle ear The most important is the hiatus for the greater superficial petrosal nerve Following this back is a way of finding the geniculate ganglion and facial nerve from the middle fossa This nerve is destined to stimulate lacrimation, hence the dry eye of Bell’s palsy 11 10 Figure 39.1 Posterior aspect of left temporal bone 1, Fossa subarcuata; 2, internal acoustic meatus; 3, groove for superior petrosal sinus; 4, groove for inferior petrosal sinus; 5, canaliculus cochleae (cranial opening of perilymphatic aqueduct); 6, styloid process; 7, fossa jugularis (jugular bulb); 8, mastoid process; 9, cranial opening of aqueduct of vestibule; 10, groove for transverse sinus; 11, mastoid foramen (for mastoid emissary vein) External ear 363 ●● ●● The great vessels, especially the carotid in front and internal jugular vein behind, passing from the posterior cranial fossa into the neck The bony eustachian tube If the physician looks closely, he or she can see a canal within a canal; the tendon for the tensor tympani passes this way also, all worryingly close to the carotid canal EXTERNAL EAR Figure 39.2 Magnetic resonance venography demonstrating flow through the upper midline (sagittal) sinus and through the lateral and sigmoid sinuses and internal jugular, on the right side of the image Thrombosis has prevented any flow on the corresponding opposite side ●● The roof of the petrous apex is probably the only feature of interest in what is a relatively ‘silent’ area, beyond the IAC It is marked by a depression, which makes up the floor of Dorello’s canal Its relevance is the proximity of the trigeminal and abducens nerve roots and the rare Gradenigo syndrome In those with highly pneumatized temporal bones, m astoid sepsis can extend to the petrous apex causing retro-orbital pain and diplopia (due to a lateral rectus palsy) with a discharging ear The inferior surface looks particularly daunting Structures worth noting include: ●● The digastric groove This is an anteroposterior dent in the undersurface of the mastoid giving attachment to the posterior belly of the digastric Follow it forward to the stylomastoid foramen, where the facial nerve exits the skull base In mastoid drilling, its reversed inner surface, now the digastric ridge (not groove), is a similarly useful landmark for the exit point of the descending facial nerve Most obvious is the auricle or pinna This is composed of skin-covered yellow elastic cartilage but for the lobule, which is purely fatty areolar tissue The relative safety of piercing the lobe, avoiding cartilage, is obvious to clinicians The tragus is anterior to the external meatus, a source of cartilage or perichondrium in tympanoplasty Above it is the one gap in the cartilage that allows the endaural incision The antihelix is, of course, the fold that can be lacking and augmented in pinnaplasty correction of bat ears The external canal in adults is about 2.5 cm long With the oblique lie of the tympanic membrane, the anterior canal is longer, passing into the acute tympanomeatal sulcus The outer one-third of the canal is cartilage and the medial two-thirds bony, but the two meet at an angle; hence the need for traction on the pinna to straighten the canal at otoscopy Only the outer third has wax glands and hair follicles, but defects in the floor, the fissures of Santorini, are notorious routes of infection from necrotizing otitis externa spreading to the parotid and skull base Deeper in the bony canal are two longitudinal sutures, a challenge to any surgeon in raising an intact tympanomeatal flap The tympanomastoid and, especially, a well-developed petrotympanic suture line can only be exposed by sharp dissection, if flaps are not to tear The innervation of the pinna and the external ear canal has some clinical relevance Cranial nerves V, VII, IX and X; the great auricular (C2 and 3); and the lesser occipital (C2) all contribute Hence the vesicles seen in Ramsay Hunt syndrome, the cough on stimulating the ear, the earache of tonsil cancer and the occasional numb pinna after parotidectomy 364 Anatomy and physiology 10 11 12 13 18 17 16 15 14 Figure 39.3 Vertical coronal diagrammatic section through right ear (After Brödel.) 1, External meatus, cartilaginous part; 2, middle cranial fossa; 3, attic; 4, malleus; 5, incus; 6, position of lateral semicircular canal; 7, position of posterior semicircular canal; 8, superior semicircular canal; 9, vestibule; 10, facial nerve; 11, vestibular nerve; 12, cochlear nerve; 13, cochlea; 14, eustachian tube; 15, stapes; 16, internal carotid artery; 17, bony part of external meatus; 18, cartilage The blood supply comes from the superficial temporal and post-auricular arteries, whilst the deep meatus is supplied by a deep auricular branch of the maxillary artery What is clinically important is how rich this supply is Thus a pinna can survive a combined endaural and post-aural incision, with only a worryingly narrow pedicle remaining inferiorly (Figures 39.3 and 39.4) TYMPANIC MEMBRANE Figure 39.4 Coronal computed tomographic scan Compare with diagram of ear anatomy in Figure 39.3 This is a conical-shaped membrane separating the external and middle ear Its diameter is approximately 1 cm and its area 85 mm2, of which only 55 mm2 is physiologically effective The otoscopic lateral view shows few features in health The pearly grey membrane of the pars tensa will show a light reflex unless inflamed but is generally too opaque to allow clear view of the ossicles, other than the handle of the malleus This runs almost vertically from the lateral process superiorly, down the manubrium to the umbo, in the centre of the Middle ear cleft 365 drumhead Retraction of the drum can produce a foreshortened appearance to the handle A few blood vessels will pass vertically, parallel to and immediately posterior to the handle in health The joint between the incus and the stapes lies deep to the posterosuperior segment but is rarely evident unless the drum is thinned or retracted onto it If it is visible, confirming its integrity is fundamental to evaluation of conductive losses In the same quadrant, the chorda tympani nerve passes from posteriorly, lateral to the long process of the incus and medial to the neck of the malleus It is at risk of trauma in elevating the membrane for any middle ear exploration, and taste disturbance in the ipsilateral tongue may result The membrane itself is said to show the elasticity of rubber and is made up of three layers Superficially is keratinizing squamous epithelium, a curious finding in an area not expected to experience wear and tear A failure of migration of this keratin is the basis of diseases such as keratosis obturans or cholesteatoma The middle layer, the lamina propria, shows radiating and circular fibres Atrophic loss of this layer weakens the drumhead and allows retraction pockets and adhesions Conversely, hyaline degeneration and calcification produce the characteristic white plaques of tympanosclerosis The inner layer is the expected mucous epithelium of the middle ear The tympanic fibrocartilaginous annulus encircles the membrane edge and sits in the corresponding bony sulcus Elevating and separating these is the basis of raising a tympanomeatal flap Superiorly, the middle layer is deficient (but not absent), forming the pars flaccida, easily overlooked by the novice otoscopist but the origin of many a cholesteatoma Above the level of its superior bony margin, but deeply in the attic, lies the bulk of the ossicular chain, the heads of the malleus and the incus Unless there is significant bony marginal erosion of the outer attic wall or scutum, these are invisible to the examiner MIDDLE EAR CLEFT This is a complex, air-filled structure running posteriorly, from the bony eustachian tube through the tympanic cavity (what most call ‘the middle ear’) and the aditus, a small connection with the mastoid antrum (itself a single large cavity), and then connected to a variable number of mastoid air cells Indeed, air cells can extend well beyond the mastoid to the petrous apex or into the root of the zygoma, with obvious implications in disease The cavity is lined with a modified respiratory mucosa that undergoes a transition passing posteriorly In health, only the most anterior and inferior portions show typical mucociliary epithelium with goblet cells The majority show a flat, squamous but non-keratinizing lining Chronic middle ear sepsis profoundly alters this distribution The relationships of the cleft are best considered for their clinical relevance Superiorly lies the temporal lobe in the middle cranial fossa, separated from the upper middle ear, the ‘epitympanum’ or attic, by a thin plate of bone, the tegmen Deficiency can lead to dural/cerebral herniation and even CSF rhinorrhoea (leakage down the eustachian tube) The dura frequently dips even lower laterally, over the external canal, tending to drive the unguarded surgeon progressively lower in drilling and towards the descending facial nerve Inferiorly, equally thin bone, which can indeed be dehiscent, protects the bulb of the internal jugular vein from the myringotome, passing deep to the vestibular system More anteriorly, the carotid passes anteromedially, deep to the cochlea The anterior wall is pierced by the eustachian tube and the canal for the tensor tympani, and laterally lies the tympanic membrane and outer attic wall The posterior wall shows landmarks of greater surgical relevance The aditus leads into the antrum, but most importantly guides one to that essential surgical landmark, the prominence of the lateral semicircular canal, immediately medial to the short process of the incus The pyramidal eminence lies on the posterior wall below the aditus and is there to allow the stapedius tendon to insert into the stapes neck It is, however, also a landmark dividing two vertical grooves, fundamental to the evolution of mastoid surgery The stapedius muscle is innervated by the facial nerve, and so the trunk, in its descending portion just deep to the pyramid, forms a vertical ridge Anything lateral to that and deep to the drum margin, the bony annulus, is the facial 366 Anatomy and physiology Figure 39.5 Axial section of temporal bone showing: 1, basal turn of cochlea; 2, posterior semicircular canal; 3, sinus tympani; 4, facial canal and pyramid/stapedius tendon; 5, facial recess recess Disease here was traditionally accessed by a ‘canal wall down’ technique, to take away the bony annulus and leave an open cavity The later intact canal wall approach uses a ‘posterior tympanotomy’, a transmastoid approach directly into the facial recess, between the facial and chorda tympani nerves Unfortunately, there is a second groove deep to the pyramid and facial nerve, the sinus tympani, of varying depth and relatively inaccessible (Figure 39.5) The medial wall is what the exploring surgeon encounters and what separates the middle from the inner ear To allow sound passage, it is pierced by the oval and round windows The first accommodates the stapes footplate, the latter, below it, is less obvious The true round window membrane lies oblique to the view at tympanotomy, within a deep round window niche Mucosal folds within this cavity are easily mistaken for the membrane itself, especially by the credulous, when seeking a perilymph fistula Anterior to both windows is a distinct convex bulge, created by the basal turn of the cochlea, the promontory The smooth surface may show superficially the nerves of the tympanic plexus or Jacobson’s nerve Tympanic neurectomy here has long been an option in attempts to reduce salivation stimulation, for example in Frey’s syndrome (Figure 39.6) Familiarity with the course of the facial nerve here is indispensable A consistent landmark for the geniculate ganglion is the processus cochlearformis, especially as it is relatively resistant to erosion (Cochleariform means ‘hooked’ and has nothing to with the hearing part of the inner ear.) The tensor tympani, having travelled up the eustachian tube, here gives off its tendon, which turns laterally to insert into the neck of the malleus All books agree on its value in finding the entry point of the facial nerve; few accurately describe how the two relate The geniculate ganglion is immediately superior to this bony process Lying in a bony tunnel, it must be slightly more medial than the processus cochlearformis Do not confuse this with medial to; it is just above The facial nerve then passes in the horizontal or fallopian canal, which rarely lacks some dehiscence, especially above the oval window Passing posteriorly and slightly downwards, it courses superior to the stapes footplate, hopefully not so dehiscent as to challenge footplate surgery It will now pass inferior to the lateral semicircular canal, towards its second turn or genu Erosion of the lateral canal by disease is commonly associated with facial nerve exposure (and resulting paralysis) at just this point Just as the lateral semicircular canal is curving back into the labyrinth, at its posterior end, the facial nerve takes that right angle turn into its descending portion Clinicians have seen its branch then pass to the stapedius Approximately 5 mm from its exit point, the stylomastoid foramen, it also gives off the chorda tympani, which passes all the way back up to the tympanic membrane OSSICLES The malleus is attached to the tympanic membrane by its handle and umbo; it has well-developed anterior and posterior ligaments and various suspensory folds, all of which stabilize it Its head lies in the attic but is often removed in surgery of CSOM by division at its neck The stapes is secured by the stapedius tendon and the annular ligament, which, unless obliterated by oto- or tympanosclerosis, allows it to still vibrate in the margins of the oval window It is the smallest bone in the body; its weight is that of an adult mosquito at 2.5 mg, and it Middle ear cleft / Eustachian tube 367 10 11 12 13 14 15 Figure 39.6 Relations of the left tympanic cavity and the facial nerve 1, Cerebral cortex; 2, subarachnoid space; 3, canal for tensor tympani; 4, eustachian tube; 5, internal carotid artery; 6, jugular bulb; 7, dura mater; 8, aditus; 9, lateral semicircular canal; 10, oval window; 11, pyramid; 12, promontory; 13, mastoid process; 14, facial nerve; 15, round window is remarkably like a true stirrup with its footplate, two crura and head The incus is less stable, almost floating between its two companions It articulates with the malleus head via a synovial joint and with the stapes via its long process, and its posterior short process provides further ligament support Skull trauma causing conductive loss usually indicates incus dislocation, however The tenuous blood supply to the incudo-stapedial joint (ISJ; those tiny vessels have far to go to pass up the crura and down the long process to its tip, the lenticular process) is easily compromised by chronic sepsis, and ISJ erosion is common The heads of the ossicles are surrounded by eponymous folds and spaces (such as the notch of Rivinius, the pouch of von Troeltsch and Prussak’s space), but quoting them is less important than recognizing that cholesteatoma may either stay lateral to the ossicles or pass medially, with major implications for surgical prognosis EUSTACHIAN TUBE The eustachian tube passes from the nasopharynx to the tympanic cavity, upwards, backwards and laterally (as it must, to run from a midline structure to the lateral temporal bone) It is 36 mm long in the adult, with the child’s tube being shorter, wider, more horizontal and less efficient It is the reverse of the external ear canal, being one-third bony and two-thirds cartilaginous This reflects its role as a dynamic, moving and complex structure, not a simple conduit In cross section proximally, it is described as a cartilaginous shepherd’s crook, an inverted J or a fishhook Its lateral cartilage-free margin is membranous It is normally closed but opens owing to the contractions of the tensor and levator palati, unless of course there is a congenital abnormality, as in cleft palate Distally, the bony tube is separated from the medially lying internal carotid canal by what may, at most, be a thin bony 368 Anatomy and physiology partition Attempts at dilatation and intubation of the canal have raised the spectre of breaching this, with unfortunate consequences INNER EAR The physiology of the inner ear is of greater clinical import to most surgeons than its structure, as few will venture there There is a bony labyrinth containing a floating membranous labyrinth, following its every twist and turn The bony labyrinth has an endosteal lining, and in erosive disease (e.g cholesteatoma) a fistula is usually walled off by this delicate membrane, so, hopefully, perilymph will not pour out if one lifts the matrix (Figure 39.7) Anteriorly is the cochlea with its two-and-onehalf spiral turns The vestibule is the connection between this and the posterior and slightly higher vestibular apparatus with its three semicircular canals The vestibule is the site of sound entry through the oval window, with the round window membrane also piercing its lateral wall The medial wall of the vestibule allows nerves to pass from the internal auditory canal but also, with the cochlear aqueduct, allows CSF and perilymph to communicate The vestibule contains the saccule 10 Figure 39.7 Membranous labyrinth (right side, lateral view) 1, Superior semicircular canal; 2, utricle; 3, saccule; 4, cochlea; 5, ductus reuniens; 6, endolymphatic sac; 7, endolymphatic duct; 8, posterior semicircular canal; 9, lateral semicircular canal; 10, crus commune and the utricle, with the former immediately deep to the stapes footplate and at risk in stapedotomy The remaining vestibular apparatus comprises the three semicircular canals, each with its ‘ampullated end’, the part that contains the sensory end organ, anteriorly Each canal then passes in its own orientation (superior, posterior and lateral or horizontal) in a large arc to pass back to the vestibule once more As the superior and inferior canal meet, just before regaining the vestibule, there are only five orifices into the cavity The ampullated end of the inferior canal is deep to the descending facial nerve, with obvious risks in osseous labyrinthectomy The arc of the posterior canal is at risk in approaches to the endolymphatic sac, whilst the horizontal canal is important as a surgical landmark for the facial nerve The endolymphatic sac at the end of its duct acts as a site of surgery for Ménière’s disease COCHLEA The ascending spiral takes its two-and-one-half turns around the central bony modiolus The stairway in the middle allows nerves to ascend Getting stimulating electrodes close to these in cochlear implantation led to the design of the modiolus hugger A projecting bony plate follows off this central pillar in the spiral canal, winding back down again Now the nerves can pass to the membranous labyrinth and things get complicated Essentially, three soft tissue tubes are joined together The upper is the scala vestibuli, so called because it runs from the vestibule, where the stapes footplate is located The lowermost is the scala tympani, its name reflecting that it is heading back down to the round window membrane (or ‘tympanum’) Both contain perilymph, essentially modified CSF; they meet at the apex of the spiral, the helicotrema, allowing sound transmission from one to the other Then comes the scala media, the mysterious third space that contains endolymph, far more like intrathan extra-cellular fluid Dilatation of this space, ‘endolymphatic hydrops’, is suggested as the basis for Ménière’s disease, and consequent membrane rupture, allowing endolymph and perilymph to meet, has profound otoneurological consequences At its simplest, the scala media is almost an isosceles triangle in cross section, its floor the basilar Salivary glands / Inflammation 677 MR sialography performed with heavily T2-weighted images is a useful non-invasive method of evaluation of the salivary ductal system INFLAMMATION Sialadenitis Figure 70.35 Ultrasound image shows a hyperechoic calculus (arrow) in the proximal submandibular duct with acoustic shadowing (small arrows) CT is the most sensitive method for visualization of calculi in the ducts and salivary glands and is the method of choice for evaluation of postobstructive inflammation and abscess formation (Figure 70.36) Acute inflammatory sialadenitis is seen as diffuse swelling of the involved gland with inflammation of the surrounding fat Abscesses in the gland are seen as unilocular or multilocular areas of fluid density showing peripheral enhancement on post-contrast CT or MRI There is atrophy and scarring of the gland with focal dilatation of the intraglandular ducts in chronic sialadenitis Sjogren’s syndrome Multiple well-defined areas of hypoechogenicity are seen in the salivary glands on ultrasound in Sjögren’s syndrome On CT these glands show a honeycomb appearance (Figure 70.37) MRI shows multiple rounded areas of fluid signal thought to be retained saliva Histological evaluation of solid lesions is important as there is a known association with lymphomas Lyphoepithelial lesions Lymphoeithelial lesions are seen in acquired immune deficiency syndrome (AIDS) patients Figure 70.36 Axial CT image shows a right submandibular duct calculus (arrow) with proximal dilatation (small arrows) Figure 70.37 Ultrasound image of submandibular gland shows multiple small hypoechoic areas in keeping with Sjögren’s syndrome 678 ENT head and neck radiology Figure 70.38 Ultrasound image shows a welldefined, lobulated, hypoechoic pleomorphic adenoma (arrow) with posterior acoustic enhancement (small arrows) and are seen as multiple small, well-defined cystic and solid lesions diffusely distributed in one or both parotid glands Tonsillar hyperplasia and bilateral cervical lymphadenopathy are often associated NEOPLASMS Pleomorphic adenoma (benign mixed tumour) Figure 70.39 Coronal MRI image shows a pleomorphic adenoma (arrow) involving superficial and deep lobes FDG on PET scanning Warthin’s tumour shows increased uptake of 99mTc-pertechnetate Mucoepidermoid carcinoma Pleomorphic adenomas are more common in the parotid and are seen on ultrasound as well-defined, lobulated, hypoechoic lesions showing posterior acoustic enhancement (Figure 70.38) On MRI they are well-defined, lobulated lesions showing low signal on T1 and heterogenous high signal on T2 images MRI is used for surgical planning and can demonstrate the involvement of the deep lobe of parotid (Figure 70.39) Mucoepidermoid carcinomas occur predominantly in the parotid and demonstrate variable appearance on imaging depending on their histological grade (Figure 70.40) Low-grade tumours demonstrate well-defined margins and are cystic, while high-grade tumours are ill-defined, infiltrative, enhancing lesions Lymphadenopathy is noted within the parotid and in the ipsilateral level group Warthin’s tumour Adenoidcystic carcinoma Warthin’s tumours are usually seen in the tail of the parotid and are identified on ultrasound as well-defined, hypoechoic or cystic lesions MRI shows well-defined lesions with small areas of cystic change showing high signal and solid components showing intermediate signal on T2 images Warthin’s tumour shows increased uptake of Adenoidcystic carcinomas have a higher incidence in submandibular, sublingual and minor salivary glands and have a strong tendency for spread by vasculature and lymphatics Appearances can range from well-defined to ill-defined infiltrating mass lesions Contrast-enhanced MRI may demonstrate perineural infiltration along the facial nerve Mandible 679 Figure 70.41 Sagittal oblique CT image shows a radicular cyst around the apex of a molar tooth Figure 70.40 Axial T1 MRI image shows an ill-defined mass involving superficial and deep lobes of the left parotid Lymphoma Lymphomas have an increased incidence in patients with Sjögren’s syndrome Lymphomatous lesions of the parotid and submandibular glands are more commonly seen secondary to nodal involvement in the neck Metastases Lymph nodal metastases from cutaneous squamous cell carcinomas and melanomas are the most common cause of intraparotid metastases Haematogenous metastases may also arise from lung, breast, kidney and prostate tumours MANDIBLE An orthopantomogram is often the first investigation performed to evaluate lesions of the mandible Figure 70.42 Orthopantomogram shows a dentigerous cyst associated with the crown of the unerupted third molar tooth Further evaluation with CT or MRI is useful for characterization Radicular cyst is the most common cyst in the mandible and is seen as a welldefined lucent lesion around the apex of a tooth (Figure 70.41) Dentigerous cysts are seen as welldefined, unilocular cysts related to the crown of an unerupted tooth (Figure 70.42) Odontogenic keratocysts are multilocular, cystic, expansile lesions associated with an unerupted tooth Amelo blastomas are seen as expansile, multilocular, cystic lesions with thinning of the bony cortex and possible extension into the surrounding soft tissue (Figure 70.43) 680 ENT head and neck radiology Dermoids are seen as well-defined heterogeneous lesions showing fat, fluid and calcification on CT and MRI (Figure 70.44) Lymphangioma Lymphangiomas are unilocular or multilocular cystic lesions involving submandibular or sublingual spaces They are seen extending across fascial planes without mass effect While they can be identified on ultrasound as cystic lesions, CT or MRI is usually required to delineate the true extent of the lesion Ranula Figure 70.43 Axial CT image of the mandible shows an ameloblastoma seen as an expansile, multiloculated, cystic lesion with bony erosion ORAL CAVITY DEVELOPMENTAL Lingual thyroid Ranulas are retention cysts of sublingual salivary gland They are well-defined and show fluid contents There is minimal enhancement of the wall with contrast They may extend posteriorly and inferiorly into the submandibular space when they are called diving ranulas (Figure 70.45) INFLAMMATION Sublingual and submandibular abscess Ectopic thyroid tissue is often seen in the floor of mouth or base of tongue as a well-defined mass in the midline It shows high attenuation on noncontrast CT in keeping with high iodine content and shows avid enhancement with contrast Radionuclide scan with iodine-123 or technetium99m pertechnetate show increased uptake of tracer by the mass Abscesses are seen as ring-enhancing fluid collections Abscesses involving sublingual space are seen superior and medial to the mylohyoid muscle Abscesses involving submandibular space are seen inferolateral to the mylohyoid muscle and may cross the midline to form a horseshoe-shaped collection Infections can cross fascial planes, with involvement of several adjacent spaces in the neck CT and MRI are helpful in delineating the full extent (Figure 70.46) Dermoid and epidermoid Tonsillitis and peritonsillar abscess These are developmental inclusion cysts containing epithelial elements in case of epidermoid and a mixture of epithelial and dermal elements in case of dermoid They are commonly seen in the floor of the mouth Epidermoids are well-defined lesions showing fluid characteristics on CT and MRI Acute and chronic tonsillitis have a non-specific appearance on CT Peritonsillar abscess is seen as a peripherally enhancing fluid collection adjacent to the tonsils (Figure 70.47) Larger abscesses may extend into the parapharyngeal, masticator and retropharyngeal spaces Oral cavity / Inflammation 681 (a) (b) Figure 70.44 Sublingual dermoid showing high signal on coronal T1 MRI image (a) with reduction in signal on fat suppressed STIR coronal image (b) in keeping with fatty contents Figure 70.45 Coronal MRI image shows a diving ranula extending into the submandibular space (arrow) from the sublingual space (small arrow) Figure 70.46 Coronal CT scan image shows abscess in the right sublingual space (arrow) and right submandibular space (small arrow) 682 ENT head and neck radiology in extension of the infection inferiorly into the mediastinum (Figure 70.48) Hence it is important to evaluate the mediastinum in patients with suspected retropharyngeal abscess Neoplasm MRI is the modality of choice for local staging of primary malignancies in the tongue, oral cavity and oropharynx CT may be useful in the elderly, patients with claustrophobia and patients with contraindications to MRI Malignant lesions are frequently squamous cell carcinomas from the floor of mouth, tonsillar fossa or the base of tongue (Figure 70.49) They are seen as illdefined, infiltrative lesions showing high signal on T2 images and enhancement on post-contrast T1 images Tumour infiltration of the lingual septum, extrinsic muscles and neurovascular bundle can be identified Tumour extension into the parapharyngeal, carotid and prevertebral spaces is important for staging and can be delineated accurately Lymph node metastases, commonly to level nodes, are seen on CT or MRI as enlarged nodes Figure 70.47 Axial CT image shows a left peritonsillar abscess Retropharyngeal abscess CT is the modality of choice for evaluation of retropharyngeal abscess, which is seen as a peripherally enhancing fluid collection pushing the posterior pharyngeal wall anteriorly Pockets of gas may be seen within the collection Rupture of the alar fascia in the retropharyngeal space can result (a) (b) Figure 70.48 Axial CT images show large retropharyngeal abscess (a) with extension inferiorly into the mediastinum (b) Hypopharynx / Developmental 683 Figure 70.49 Coronal MR image shows a malignant left tonsillar mass (arrow) with a metastatic left cervical node (small arrow) with central areas of necrosis Ultrasound with high-resolution transducers has a high sensitivity and specificity in characterization of cervical lymph nodes Metastatic nodes appear hypoechoic with loss of normal fatty hilum on ultrasound Ultrasound-guided fine-needle aspiration is often used as a problem-solving tool to characterize enlarged lymph nodes that cannot be accurately characterized on CT or MRI HYPOPHARYNX DEVELOPMENTAL Figure 70.50 Bilateral pharyngoceles (arrows) seen on a barium swallow Pharyngeal pouch (Zenker’s diverticulum) Pharyngeal pouches are seen as posterior mucosal protrusions identified at the level of the Killian’s dehiscence on barium swallow (Figure 70.51) Pooling of barium may be seen in large pouches Pharyngeal web Pharyngeal webs are thin membranes seen arising from the anterior aspect of the hypopharynx, causing narrowing of the lumen These are best seen on the lateral cine images on barium swallow (Figure 70.52) Pharyngocele Infection and inflammation Pharyngoceles are mucosal outpouchings from the piriform sinus They are seen as broad-based outpouchings coated with barium on the frontal view of a barium swallow (Figure 70.50) Imaging is rarely performed in infectious and inflammatory conditions of the hypopharynx Thickening of the epiglottis may be seen in epiglottitis on a lateral x-ray of the neck 684 ENT head and neck radiology Figure 70.51 Barium swallow showing a pharyngeal pouch (arrow) with a narrow neck Malignancy Hypopharyngeal tumours are most commonly squamous cell carcinomas and may be staged with CT or MRI Tumours may arise from the piriform sinus, posterior pharyngeal wall or post-cricoid region (Figure 70.53) Tumours can extend into the aryepiglottic fold, paraglottic space or carotid space Lymph node involvement is often seen at level in the neck on CT and MRI Equivocal nodes may be evaluated further with ultrasound-guided fine-needle aspiration Figure 70.52 Barium swallow showing a pharyngeal web (arrow) causing partial obstruction to the flow of barium images of CT or MRI Internal laryngoceles are seen in the paraglottic space and are contained laterally by the thyrohyoid membrane External laryngoceles penetrate the thyrohyoid membrane and extend into the soft tissue of the neck LARYNX DEVELOPMENTAL Laryngocele Laryngoceles are thin-walled areas containing air or fluid communicating with the laryngeal ventricle They can be identified on axial or coronal Figure 70.53 Axial CT image shows an enhancing mass lesion in the right piriform sinus Larynx / Developmental 685 Laryngeal cyst Laryngeal cysts are usually seen as incidental abnormalities on CT or MRI They are well defined and show fluid density on CT On MRI they show high signal on T2 and low to high signal on T1-weighted images depending on the protein content Inflammation Narrowing of the subglottic lumen (Steeple sign) may be seen on a frontal x-ray of the neck in laryngo-tracheitis This is seen in less than 50 per cent of patients, and hence x-rays are not routinely performed CT scan is the modality of choice for investigation of chronic laryngeal or tracheal stenosis secondary to previous inflammation or intervention Laryngeal malignancy Squamous cell carcinomas are the most common tumours in the larynx While tumours can be staged with CT or MRI, CT is the preferred modality as its shorter examination time reduces artefacts due to swallowing and movement MRI is more sensitive in detection of early cartilaginous invasion PET-CT is used in post-surgical patients to differentiate recurrence from post-surgical scarring Tumours are seen as enhancing, nodular, infiltrative lesions involving the epiglottis, aryepiglottic fold, true or false cord Lesions involving the epiglottis may extend anteriorly to involve the pre-epiglottic space, which cannot be evaluated clinically and is best seen on sagittal images on MRI or CT Infiltration of the paraglottic fat may be seen in tumours of the true or false cord (Figure 70.54) Sclerosis of the arytenoid cartilage on CT is suspicious of infiltration by the tumour Involvement of anterior commissure and extension into the contralateral side can be identified on axial images of CT or MRI Superior and inferior extension of the tumour can be identified on coronal images Chondrosarcoma of larynx Chondrosarcomas most commonly arise from the cricoid cartilage and are seen as an expansile Figure 70.54 Coronal CT image shows a malignant mass involving the left false cord, laryngeal ventricle and left true cord soft-tissue mass eroding the cricoid with characteristic popcorn-like chondroid calcification on CT (Figure 70.55) Figure 70.55 Axial CT image shows soft tissue mass causing destruction of the left lateral aspect of the cricoid with chondroid calcification (arrows) 686 ENT head and neck radiology SUPERFICIAL NECK LUMPS Ultrasound is usually the first choice of investigation for evaluation of neck lumps Depending on the findings on ultrasound, further evaluation with CT or MRI and ultrasound-guided fineneedle aspiration may be performed for further characterization BRANCHIAL CYST Type branchial cysts are the most commonly identified branchial cleft cysts (Figure 70.56) They can be identified on ultrasound as well-defined, unilocular cysts with clear fluid in the posterior submandibular space, anterior and medial to the sternomastoid Infected branchial cysts may show echogenic contents On CT and MRI, a beak pointing medially between the external and internal carotid arteries may be seen, which is pathognomonic Infected cysts show enhancement of the wall on CT or MRI Type branchial cysts are seen as well-defined, unilocular cysts in the preauricular region adjacent to the external auditory canal or in the parotid space A beak-like projection or sinus may be seen extending posteriorly to the anterior wall of the external auditory canal at the junction of the cartilaginous and bony segments on MRI Type branchial cysts are rare and are noted in the posterior triangle as well-defined unilocular cysts CT or MRI may demonstrate a sinus or fistula extending medially into the piriform sinus Type branchial cysts are unilocular thinwalled cysts found in close relation to the left lobe of the thyroid or the thyroid cartilage THYROGLOSSAL CYST Thyroglossal cysts (Figure 70.57) are seen on ultrasound as thin-walled cysts with anechoic or echogenic contents in the midline of the neck extending deep to the strap muscles Enhancement of the cyst wall is seen on contrast-enhanced CT or MRI in case of infected cysts LYMPHANGIOMA Appearance of lymphangiomas may vary from large, well-defined cystic spaces to the presence of multiple tiny cystic areas Lymphangiomas are seen to extend across fascial planes with no significant mass effect While ultrasound is usually the first modality of investigation, MRI is the modality of choice for delineating the true extent of lymphangiomas Lymphangiomas show high signal on T2-weighted images (Figure 70.58) Lymphangiomas can be differentiated from haemangiomas by the lack of enhancement on post-contrast T1 images HAEMANGIOMA Haemangiomas are seen commonly in the buccal space and masticator spaces as well-defined, lobulated, hypoechoic lesions with variable vascularity on ultrasound CT can demonstrate the presence of phleboliths and remodelling of adjacent bone MRI is useful in delineating the extent of haemangiomas showing high signal on T2-weighted images and variable enhancement on the post-contrast images (Figure 70.59) LYMPH NODAL MASS Figure 70.56 Axial CT image shows a right type 2 branchial cyst medial to the sternomastoid muscle Reactive lymphadenitis is the most common cause of lymph nodal enlargement, especially in children On ultrasound these nodes are enlarged but maintain their normal ovoid shape and show the presence of normal fatty hilum Superficial neck lumps / Lymph nodal mass 687 (a) (b) Figure 70.57 Axial (a) and sagittal (b) MR images show a midline thyroglossal cyst closely related to base of tongue and extending inferiorly Figure 70.59 Axial T2 STIR image shows a lobulated haemangioma in the left buccal space showing high signal Figure 70.58 Axial T2 MRI image shows bilateral large lymphangiomas showing high signal Suppurative lymph nodes are seen as enlarged nodes with focal areas of reduced echogenicity in the centre Confluence or rupture of lymph nodes can lead to development of an abscess Contrast-enhanced CT or MRI is helpful in delineating the extent of an abscess The abscess is visualized as central irregular area of fluid density with enhancement of the surrounding wall (Figure 70.60) Tuberculous lymphadenitis presents as a painless nodal mass in the neck Findings on ultrasound 688 ENT head and neck radiology Figure 70.60 Axial post-contrast MRI image shows a confluent left tuberculous abscess with peripheral enhancement (arrowheads) and an enhancing left cervical node (arrow) or CT include enlarged nodes with central areas of necrosis, abscess formation and presence of multiple foci of calcification Associated changes in the pulmonary parenchyma may be evident Metastatic nodes in the neck arise commonly from primary squamous cell carcinomas involving the pharynx or larynx On ultrasound, metastatic nodes are enlarged, rounded and diffusely hypoechoic with absence of normal fatty hilum Contrast-enhanced CT or MRI may show the presence of central areas of necrosis in squamous cell carcinoma metastases (Figure 70.61) Extracapsular spread from metastatic nodes is seen as irregularity of the nodal margins with infiltration of the surrounding fat Metastatic nodes in the neck are also noted in primary tumours involving the lung, breast, oesophagus and melanoma Enlarged nodes in lymphoma are seen on ultrasound as multiple, enlarged, diffusely hypoechoic nodes with no evidence of necrosis Contrastenhanced CT or MRI can better delineate the extent of nodal involvement in the neck (Figure 70.62) PET-CT is usually performed for pre-treatment staging and follow-up of lymphoma after chemotherapy Figure 70.61 Coronal MRI image shows a metastatic left cervical node with focal area of necrosis superiorly (arrow) Primary lesion in the base of tongue is also seen (arrowheads) CAROTID BODY PARAGANGLIOMA A carotid body tumour is seen on ultrasound as a well-defined solid mass splaying the internal and external carotid arteries at the carotid bifurcation with extensive vascularity (Figure 70.63) Contrast-enhanced CT shows the presence of an intensely enhancing mass lesion at the carotid bifurcation On MRI, carotid body tumours show serpentine vascular flow voids within the tumour Intense enhancement is seen on post-contrast T1-weighted images Preoperative embolization of the tumour can be performed to reduce blood loss during surgery THYROID THYROIDITIS Thyroiditis is seen on ultrasound as diffuse enlargement of the thyroid with multiple ill-defined foci Thyroid / Thyroid nodules 689 Figure 70.62 Enlarged left submandibular nodes (arrow) and left posterior cervical node (small arrows) in a patient with non-Hodgkin’s lymphoma Figure 70.64 Fused PET-CT image shows diffuse fludeoxyglucose uptake in both lobes of thyroid (arrows) in keeping with diffuse thyroiditis of hypoechogenicity Increased vascularity is seen on colour Doppler imaging It is not possible on ultrasound to differentiate between Hashimoto thyroiditis and Graves’ disease Diffusely increased radionuclide uptake is noted on 99m Tc-pertechnetate and iodine-123 radionuclide imaging Diffusely increased FDG uptake may also be noted incidentally on PET-CT scans done for other indications (Figure 70.64) THYROID NODULES Figure 70.63 Sagittal CT image shows an enhancing carotid body tumour at the carotid bifurcation Nodules of the thyroid are very common and are seen in up to 40 per cent of individuals having ultrasound of the thyroid Up to 10 per cent of nodules in multinodular goitre and around 10 per cent of solitary nodules turn out to be malignant Ultrasound is often the initial test used for detection and characterization of thyroid nodules (Figure 70.65) The nodules are evaluated based on their margins, shape, echogenicity, vascularity and calcification Solid nodules are more likely to be malignant than cystic nodules Nodules with ill-defined or lobulated margins have a higher 690 ENT head and neck radiology Figure 70.65 Ultrasound image shows a welldefined colloid nodule with areas of cystic degeneration in the periphery Figure 70.66 Sagittal CT image shows a large thyroid nodule extending inferiorly into the retrosternal space of the mediastinum incidence of malignancy While peripheral calcification is seen in benign nodules, central calcification is associated with an increased incidence of malignancy Malignant nodules of the thyroid are more likely to be solid, have ill-defined margins, infiltrate into the surrounding parenchyma and have Figure 70.67 Axial CT image shows a malignant thyroid mass with ill-defined margins and central necrosis cervical lymphadenopathy However, the majority of nodules cannot be reliably distinguished as benign or malignant on ultrasound Hence ultrasound-guided fine-needle aspiration is performed for accurate characterization of nodules CT scan may be performed for large multinodular goitres with suspected retrosternal extension before surgery to delineate the full extent (Figures 70.66 and 70.67) Radionuclide imaging with Tc99m pertechnetate or I123 is used evaluate the functional status of a thyroid nodule Hot nodules on scintigraphy are more likely to be benign Medullary thyroid carcinoma takes up octreotide (111-In-pentreotide) or I-131- MIBG (meta iodobenzyl guanidine) Nodules that are FDG avid on PET-CT scans done for other indications have to be evaluated with ultrasound-guided fine-needle aspiration as the incidence of malignancy in FDG avid nodules is up to 40 per cent KEY LEARNING POINTS ●● ●● Ultrasound is a very good first investigation for evaluation of pathologies in the superficial organs of the neck CT or MRI is often needed to evaluate the full extent of involvement in infections and tumours the Nose, Throat and Ear: Head and Neck Surgery covers the whole of otolaryngology in 70 chapters This classic textbook has been completely updated and expanded to reflect the increasing sophistication of diagnostic and management skills All subspecialties are covered with the content grouped into five major sections: • Rhinology • Head and Neck • Otology • Paediatric Otorhinolaryngology • Radiology Each chapter in this new edition includes key learning points, up-todate references, and suggestions for further reading.The contributors are leaders in their respective fields – a virtual list of ‘who’s who’ of British otolaryngology head & neck surgery ABOUT THE EDITOR FRCS(ORL-HNS), FRCP(Ed), is a Consultant ENT Surgeon and Honorary Professor of Otolaryngology at Ninewells Hospital and the University of Dundee School of Medicine in Dundee, UK He has been a member of both the UK Higher Surgical Training Committee (SAC in Otolaryngology) and the Intercollegiate Specialty Examination Board in Otolaryngology Professor Hussain has examined for the Board (FRCS ORL), the Royal College of Surgeons of Edinburgh (FRCS Ed) and the ELEVENTH EDITION S Musheer Hussain, MBBS, MSc(Manc), FRCS(Ed & Eng), ELEVENTH EDITION LOGAN TURNER’S First published over 100 years ago, Logan Turner’s Diseases of DISEASES OF THE NOSE, THROAT AND EAR SURGERY, OTORHINOLARYNGOLOGY Intercollegiate Diploma in Otolaryngology (DOHNS) LOGAN TURNER’S DISEASES OF THE NOSE, THROAT AND EAR HEAD AND NECK SURGERY Hussain edited by S Musheer Hussain K18615 an informa business w w w c r c p r e s s c o m K18615_Cover_mech.indd All Pages 6000 Broken Sound Parkway, NW Suite 300, Boca Raton, FL 33487 711 Third Avenue New York, NY 10017 Park Square, Milton Park Abingdon, Oxon OX14 4RN, UK ISBN: 978-0-340-98732-2 90000 780340 987322 7/29/15 1:23 PM ... (Figure 39.11) The utricle and saccule These lie in the vestibule, the former orientated in the plane of the horizontal canal, the latter in the vertical plane The receptor organs are the maculae As in the. .. to tear The innervation of the pinna and the external ear canal has some clinical relevance Cranial nerves V, VII, IX and X; the great auricular (C2 and 3); and the lesser occipital (C2) all contribute... clear view of the ossicles, other than the handle of the malleus This runs almost vertically from the lateral process superiorly, down the manubrium to the umbo, in the centre of the Middle ear