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ANATOMY AND PHYSIOLOGY OF HEARINGLESIONS OF THE CEREBELLOPONTINE ANGLE, PETROUS APEX AND JUGULAR FORAMEN
Diagnosis history,
examination, imaging
Epidermoid cyst Cholesterol cyst
Pain, vertigo, V and VII
decits or infection
YesNo
Observation, rescan
Fit for surgery
Yes
Figure 23.2 Proposed management scheme for epidermoid and cholesterol cysts.
Non-Vestibular Schwannoma Tumours of the Cerebellopontine Angle
Anatomy
e CPA is an inverted, triangular subarachnoid space containing cranial nerves
•
(V–XI) and blood vessels bathed in cerebrospinal uid (CSF).
Relations include pons (medial), cerebellum (posterior), tentorium (superior) and pos-
•
terior temporal bone (lateral).
Extends into the petrous bone as the internal auditory canal (IAC); its medial aperture
•
is known as the porus acousticus.
Minimum symptoms only
No
Fit for surgery
Yes
V and VII decits
Yes
No
Serviceable hearing
No Yes
Yes
DrainageResection
Observation
rescan
No
Clinical Conditions
Vest ibular schwan nomas (VS) represent 80–90% of CPA tumours w ith the remaining 10–20%
a mixture of predominantly benign pathologies. e symptoms at presentation are normally
sensorineural hearing loss, tinnitus or vertigo. Other cranial nerves may be aected, causing
altered facial sensation, facial weakness/spasm and lower cranial nerve compromise. Larger
tumours may also cause brainstem compression.
e most common non-VS CPA lesions include:
Meningioma: ey form from clusters of epithelial cells at the tips of arachnoid villi.
•
ey may be well circumscribed or, more rarely, en plaque when their growth pattern
results in a at lesion. Bony inltration may result in hyperostosis. Typically they
displace or surround neurovascular structures. Histologically, meningiomas may be
graded from 1 to 3 according to the World Health Organization (WHO) grading
system (grade 1 and 2 benign, grade 3 malignant). Meningiomas occur in neurobromatosis and are associated with radiotherapy and hormone therapy. Watchful
waiting is less eective for meningiomas compared with VS due to tumour growth.
e treatment of choice for large or symptomatic tumours is surgery with removal of
the tumour, aected dura and bone. Surgical approaches are similar to that for VS.
Fractionated stereotactic radiotherapy and SRS have a high success rate in controlling tumour progression for small low-grade tumours.
128 e Ear
LESIONS OF THE CEREBELLOPONTINE ANGLE, PETROUS APEX AND JUGULAR FORAMEN
Epidermoid cyst: Epidermoids can occur in CPA as well as the PA. Surgery is the treat-
•
ment of choice for large or symptomatic cysts, and the aim of surgery is decompression of the cysts and removal of the lining if possible. Subtotal removal is advocated
to preserve neurovascular structures. Recurrence rate is high and revision surgery
may be required periodically. e retrosigmoid approach is the standard surgical
approach. Post-operative aseptic meningitis is not uncommon and is almost unique
to this condition.
Arachnoid cyst: ese are congenital malformations of the arachnoid histologically
•
characterised by a cyst wall that resembles arachnoid and a cystic space lled with
CSF. Eighty-ve percent of these cysts are asymptomatic and require neither treatment nor ongoing surveillance. For symptomatic cysts, microsurgical decompression
and fenestration via the retrosigmoid approach is the most commonly recommended
procedure.
Lipoma: ese are congenital malformations, which rarely grow. Almost always man-
•
aged conservatively, they oen do not need follow-up, but subtotal removal may be
considered for symptomatic lesions.
Facial nerve and lower cranial nerve schwannomas: ese are covered elsewhere.
•
Inammatory conditions: e CPA can be aected by autoimmune or idiopathic
•
pachymeningitis, tuberculosis and sarcoidosis.
Malignant lesions: ese are usually metastatic lesions from either intra-cranial or
•
extra-cranial sources (e.g. breast, prostate or lung). Diagnosis may be aided by lumbar
puncture and CSF cytology. Solitary metastases may be treated with surgical resection or with SRS. Melanomas and lymphoma can also occur at the CPA. Intra-axial or
intraventricular tumours may also invade the CPA and these include medulloblastomas, astrocytomas, ependymomas and gliomas.
22. VESTIBULAR SCHWANNOMA
Jugular Foramen Lesions and Their Management
Anatomy
e JF is divided by intrajugular processes into a lateral compartment that contains
•
the sigmoid-jugular complex and a medial compartment that contains the inferior
petrosal sinus and cranial nerves IX, X and XI (Figure 23.3).
e superior and inferior petrosal sinuses, the occipital sinus and the mastoid and
•
condylar emissary veins drain into the sigmoid-jugular complex.
Clinical Conditions
Symptoms of JF lesions include paralysis of cranial nerves IX, X and XI (Vernet’s syndrome).
Cranial nerves VII and VIII may also be aected by pathology at the JF and venous involvement may rarely cause cavernous sinus syndrome or raised intracranial pressure. Pulsatile
tinnitus may be a feature of paragangliomas or jugular vein diverticulum. Otoscopy may
reveal a red lesion behind the eardrum in paragangliomas (rising sun sign) and a bluish
discolouration behind the eardrum may signify a high jugular bulb. Brown’s sign designates
blanching of the lesion with pneumatic otoscopy.
e most common conditions aecting the JF are paragangliomas, schwannomas and
meningiomas. Other conditions that aect this area include infections (e.g. complications of
otitis media or necrotising otitis externa) and malignancy (e.g. distant metastases).
e three most common tumours are briey described below and their management is considered together:
Temporal bone paragangliomas: Paraganglia are present in the adventitia of the jugular
bulb, along c ranial ner ves IX and X, and i n the middle ear i n association w ith Jacobsen’s
plexus. Up to 40% of patients with head and neck paragangliomas have a mutation
of the succinate dehydrogenase gene that makes them prone to developing multiple
paragangliomas, including intra-abdominal tumours with a higher propensity to
e Ear 129
ANATOMY AND PHYSIOLOGY OF HEARINGLESIONS OF THE CEREBELLOPONTINE ANGLE, PETROUS APEX AND JUGULAR FORAMEN
Figure 23.3 Basal view of the jugular foramen. View of the jugular foramen (right side) as shown
from below. 1, internal carotid artery; 2, internal jugular vein; 3, glossopharyngeal nerve; 4, inferior
petrosal sinus; 5, pha- ryngeal vein; 6, hypoglossal nerve; 7, vagus nerve; 8, spinal accessory nerve;
9, condylar emissary vein; 10, occipital con- dyle; 11, styloid process; 12, facial nerve.
secrete catecholamines. Patients should have their blood pressure checked and either
24-hour urinary catecholamine collection or an assay of plasma free metanephrines.
In addition to magnetic resonance imaging (MRI)/CT of the neck, assessment with
MR angiography, CT angiography or conventional angiography should be performed
as these tumours are highly vascular. Staging should be done with positron emission
tomography (PET) or MRI from the head to the pelvis. Fluorodeoxyglucose (FDG)
PET imaging can be used to indicate metabolic activity as evidenced by standardised
uptake value (SUV) max, which correlates with tendency to growth.
e Fisch classication of paragangliomas is as follows:
Class A: limited to the middle ear (mesotympanum)
•
Class B: middle ear (meso-and hypotympanum) and mastoid
•
Class C: involvement of infra-labyrinthine and apical compartments of temporal bone;
•
subclassication by degree of carotid canal erosion
Class D: tumours with intracranial extension; subclassication by presence and extent
•
of intradural extension
Schwannomas: ese develop from the Schwann cells in t he perineurium aecting cranial
nerves IX, X or XI in the medial part of the JF. e biological behaviour of schwannomas in the JF is similar to that in the CPA and is oen slow growing or apparently static.
Meningiomas: Basal meningiomas can penetrate the skull base through the JF.
Management includes:
Wait and see policy: Intervention in this area is fraught with danger to important neu-
•
rovascular structures. erefore conservative management is appropriate in patients
with minimal symptoms and non-growing tumours.
SRS and fractionated radiotherapy (FRT): ese are associated with high rates of
•
tumour control and lower rates of cranial nerve palsy compared with surgery. SRS
has the advantage of being delivered in a single sitting. Consider this for small volume (<3cm) progressive disease and minimal symptoms, residual disease aer surgery, inoperable tumours and in patients of advanced age/poor physical condition.
Recovery of compromised nerves has been reported.
130 e Ear
24. TEMPORAL BONE TUMOURS
TEMPORAL BONE TUMOURS
Surgery: Considered in patients with significant symptoms, large tumours and
•
growing tumours. Pre-operative embolisation of feeding vessels 48 hours before
surgery is recommended for paragangliomas as well as vascular meningiomas (risk
of stroke <1%). Permanent balloon occlusion of the petrous carotid artery should
be performed if the artery is not salvageable. If carotid occlusion is not tolerated,
the artery can be reinforced with a covered stent or vascular bypass may be performed. The lateral transtemporal approach is commonly utilised. Transposition
of the facial nerve may be required depending on its relationship with the tumuor.
KEY POINTS
• The diagnosis for most PA lesions can be made radiologically (CT + MRI): active
treatment is not always required and ‘watchful waiting’ is often most appropriate.
• Paragangliomas, schwannomas and meningiomas are by far the most common lesions
found in the JF. There is no uniformity of opinion on the best therapeutic approach,
and the need for surgical treatment should be balanced with the considerable risk of
functional loss.
• Twenty percent of CPA tumours are not VS.
24. TEMPORAL BONE TUMOURS
Introduction
Primary temporal bone tumours are rare, with squamous cell carcinoma (SCC) representing the most common subtype. However, a myriad of less common benign and malignant
tumours can occur with varying biological behaviour and prognosis. is chapter provides
an overview of the presentation and management of temporal bone tumours.
Pathology and Epidemiology
e reported incidence of temporal bone SCC is fewer than six cases per million per year,
accounting for approximately 0.3% of all head and neck cancer. ere is a slight male sex
preponderance and a median age of presentation in the seventh decade. e epidemiological features of the rarer primary temporal bone tumours are dicult to establish given
their scarcity.
Risk Factors
Genetic: Some temporal bone tumours already have a known genetic predisposi-
•
tion, such as Von Hippel-Lindau (VHL) disease and endolymphatic sac tumours
(ESTs). Additionally, genetic syndromes predisposing patients to skin malignancies
have increased risk of cutaneous head and neck lesions with direct temporal bone
invasion.
Chronic suppurative otitis media (CSOM) and cholesteatoma: An aetiopathological
•
relationship has been postulated between SCC of the petrous temporal bone and
CSOM and cholesteatoma. In some series, up to 68% of SCC patients have a prior
history of either CSOM or cholesteatoma. e association between these two conditions is poorly understood. e current assumption is that chronic inammation
and cellular trauma can result in malignant transformation of the temporal bone
epithelium.
e Ear 131
ANATOMY AND PHYSIOLOGY OF HEARINGTEMPORAL BONE TUMOURS
Table 24.1 Presenting symptoms in temporal bone tumours
LE 115.1 Frequency of presenting symptoms (%)
Presenting symptoms in temporal bone tumours Frequency
Otalgia (52–74%)
Otorrhoea (45–84%)
Hearing loss (25–69%)
Headache and localised pain (23–42%)
Facial nerve palsy (13–30%)
Lower cranial nerve palsies (CNs IX–XII) (6–24%)
Cervical metastases (4–8%)
Trismus/temporomandibular joint dysfunction (16–31%)
Radiation: Radiation-induced malignancies are a known complication of both frac-
•
tionated radiation and radiosurgery. Dierentiating between primary, second primary, recurrent and radiation-induced malignancies is oen clinically challenging.
Lustig et al. 1997 developed a diagnostic criterion for dening radiation-induced
temporal bone tumours as follows:
Second neoplasm in irradiated eld
•
Latent period between radiation and malignancy diagnosis of several years
•
Previous histological and radiological conrmation of malignancy
•
Second neoplasm of diering histological subtype to primary malignancy
•
Ultraviolet (UV) light exposure: UV light exposure increases the risk of cutaneous skin
•
malignancies. Temporal bone involvement may occur due to direct inltration via
primary disease of the lateral external auditory canal (EAC) or pinna, or as a result
of advanced metastatic deposits within the parotid gland, which is the primary lymphatic drainage of much of the cutaneous head and neck.
Clinical Presentation and Examination Findings
e presentation of temporal bone tumours can oen be non-specic, therefore a clinician should look to exclude temporal bone tumours in any patients with recalcitrant
symptoms (Table 24.1). Tumour can extend via anatomical deciencies such as the fora-
men of Huschke, ssures of Santorini, tympanomastoid ssure and Eustachian tube into
the parotid, temporomandibular joint, skull base and nasopharynx. Cervical metastasis
may occur with malignancy; however, it is relatively uncommon. Unexplained lower cranial nerve (CN) dysfunction (CNs VII–XII) should always warrant a complete head and
neck and otological examination, in addition to imaging of the skull base and petrous
temporal bone.
Diagnostic Workup
Biopsy for histopathological examination: Biopsy can usually be performed trans-canal
•
under local anaesthetic. Tumours situated deep in the temporal bone, or patients who
have had previous non-diag nostic biopsies, may require biopsy under general anaesthetic.
Audiometry: Pure-tone audiometry should be performed in all patients and vestibular
•
assessment may be required depending on clinical presentation.
Multi-modality cross-sectional imaging: Physical examination alone is insucient to
•
characterise the extent of a patient’s disease, particularly in malignant conditions.
High-resolution computed tomography (CT) (axial and coronal) and gadoliniumenhanced magnetic resonance imaging (MRI) are complementary studies, allowing
assessment of the disease burden. Additionally, in malignant conditions, staging of
the neck and chest is oen appropriate to assess for metastatic disease.
132 e Ear
24. TEMPORAL BONE TUMOURS
TEMPORAL BONE TUMOURS
Figure 24.1 Anatomy of the left temporal bone in the coronal plane, showing the extent of a
lateral temporal bone resection (outlined in red) and an extended temporal bone resection (outlined in green).
Staging and multi-disciplinary team (MDT) discussion: Malignant tumours of the EAC
•
are oen classied via the modied Pittsburgh staging system (Figure 24.2). Whilst
several systems have been described, there is no established staging system for primary malignancy of the middle ear or petrous apex, likely due to the rare and varied
nature of the disease. Malignancies inltrating the temporal bone from a cutaneous
source are staged via the non-melanoma skin cancer (NMSC) AJCC TNM criterion
(Table 24.2). All malignant disease should be discussed within an MDT with expertise
in skull base surgery.
Table 24.2 Comparison of AJCC cutaneous malignancy tumour staging to modied Pittsburgh
staging system
AJCC 8th edition for
cutaneous malignancy
Stage Pittsburgh tumour staging system
T classication T1 Limited to the EAC without bony erosion or
evidence of soft tissue involvement
T2 Limited to the EAC with bone erosion (not full
thickness) or limited soft tissue involvement
(<0.5 cm)
T3 Erosion through the osseous EAC (full
thickness) with limited soft tissue involvement
(<0.5 cm), or tumour involvement in the
middle ear and/or mastoid
T4 Erosion of the cochlea, petrous apex, medial
wall of the middle ear, carotid canal, jugular
foramen or dura; with extensive soft tissue
involvement (>0.5 cm, such as involvement of
the TMJ or styloid process) or evidence of
facial paresis
of the head and neck
<2 cm
≥2 cm but <4 cm
≥4 cm or any size with
deep invasion or
perineural invasion or
minor bone erosion
T4a gross cortical bone/
marrow invasion
T4b skull base invasion
and/or skull base foramen
involvement
e Ear 133
ANATOMY AND PHYSIOLOGY OF HEARINGTEMPORAL BONE TUMOURS
Management
Benign Disease
A comprehensive discussion of the management of all benign tumours of the temporal bone is
beyond the scope of this chapter. e general treatment consensus in benign disease is complete
surgic al resection w ith narrow sur gical marg ins, unle ss the morbidity of resec tion is unaccept able.
Middle Ear Adenomas (MEAs)
Middle ear adenomas (MEAs) represent a rare benign primary middle ear tumour,
•
thought to be derived from the middle ear mucosa. ese tumours lack the aggressive
features of malignancy such as bone erosion and are generally accepted to have a good
prognosis. Histologically and immunohistochemically, these tumours can display both
epithelial and neuroendocrine dierentiation. Surgical resection, without adjuvant
treatment, is the management of choice, although they have a high recurrence rate.
Endolymphatic SAC Tumours (ESTs)
ESTs are a primary tumour originating from the endolymphatic sac. Patients classi-
•
cally present similar to cerebellopontine angle (CPA) pathology with sensorineural
hearing loss, tinnitus and vertigo. Classically, they are associated with VHL disease.
Generally, surgical removal is recommended; however, similar to other CPA pathology,
radiation or observation may be appropriate if resection confers signicant morbidity.
Malignant Disease
e general management consensus for temporal bone malignancy is en bloc surgical resection followed by post-operative radiation therapy as described in Table 24.3.
Sleeve Resection
Sleeve resection, isolated resection of the so tissue of the EAC, can be appropriate for very
carefully selected small T1 tumours, which are laterally based in the EAC. Typically the so
tissue defect is reconstructed with a split-thickness skin gra.
Lateral Temporal Bone Resection
Tumours lateral to the tympanic membrane (T1 and T2) can be appropriately managed with
lateral temporal resection. A wide cortical mastoidectomy is performed, following the tegmen
anteriorly into the zygoma towards and up to the mandibular condyle. e facial ner ve is identied in the mastoid segment and traced through to the stylomastoid foramen. An extended
posterior tympanotomy is performed to isolate the bony EAC, sacricing the chorda tympani.
e incudostapedial joint is divided under direct vision. An osteotomy is introduced through
the posterior tympanotomy, and the bony EAC is fractured anteriorly o the bony carotid
canal to allow for en bloc delivery of the EAC. e tympanic membrane, middle ear mucosa,
incus and malleus are removed and the Eustachian tube is obliterated (Fig ure 24.1).
Table 24.3 Summary of management of malignant EAC lesions based on modied Pittsburgh staging
Stage Management Adjuvant therapy
T1 • Consider sleeve resection if very lateralised and
no aggressive features
• LTBR + parotidectomy
T2 • LTBR + parotidectomy • PORT
T3/T4 • ETBR + parotidectomy • PORT
N0 • Neck dissection if necessary for reconstruction • PORT if indicated for T stage
N+ • Neck dissection • PORT
Note: ETBR, extended temporal bone resection; LTBR, lateral temporal bone resection; PORT, post-
operative radiotherapy.
134 e Ear
• Consider PORT
24. TEMPORAL BONE TUMOURS
TEMPORAL BONE TUMOURS
Extended Temporal Bone Resection
Disease extending medially to the tympanic membrane (T3 or T4) mandates an extended
temporal bone resection. e specimen includes a lateral temporal bone resection, as
described previously, with extension to resect the inner ear, exposing the air cell of the
petrous apex. e facial nerve is resected at the internal auditory meatus. e procedure is
oen combined with resection of the head of the mandible.
Treatment of the Adjacent Nodal Basins
Parotidectomy
Supercial parotidectomy is oen performed for SCC, given it is the primary lymphatic
basin and in proximity to disease. For disease with more indolent behaviour, such as basal
cell carcinoma (BCC), parotidectomy is not necessary unless required for surgical margins.
Cervical Nodal Disease
Cervical nodal metastasis is uncommon in early tumours. In the absence of clinical neck
disease, surgical neck dissection may still be performed in selected cases, e.g. to facilitate
free ap reconstruction or to enable accurate neck staging in high-risk patients, such as those
who are immunosuppressed. e presence of clinical nodal disease mandates a comprehensive neck dissection.
Adjuvant Treatment
Post-operative radiotherapy (PORT), usually commencing 6–8 weeks after surgery, is
the accepted gold standard of management for temporal bone malignancy. The literature
suggests PORT improves disease-specific survival (DSS) and locoregional control (LRC).
In patients with tumour in an already radiated field, re-irradiation may be considered
if free vascularised tissue has been used to reconstruct the field. Palliative radiotherapy
may be offered to patients with non-resectable disease, or in patients whose comorbidities preclude surgery.
Chemotherapy
ere is little evidence to support the use of pre- or post-operative chemotherapy in temporal bone tumours. Palliative systemic therapies, including chemotherapy, may be given in
advanced or metastatic disease.
Immunotherapy
Whilst there is no evidence supporting immunotherapy in primary temporal bone tumours,
there is emerging evidence supporting checkpoint inhibitor therapy for advanced cutaneous
tumours. ese therapies include hedgehog signalling pathway inhibitors in BCC, and PD-1/
PD-L1 inhibitors in SCC. ese are currently used primarily on a trial basis in unresectable
or metastatic disease.
Treatment Outcomes and Prognosis
Benign Disease
Collectively, benign disease oen has a good prognosis when amenable to complete surgical
resection. Adjuvant treatment is usually not necessary.
Malignant Disease
e prognosis of malignant disease depends on its biological behaviour. Given that SCC
is the most common tumour of the temporal bone it will form the focus of this section.
Prognosis is favourable in early (T1/T2) tumours with 5-year survival rates between 80 and
100% in most series. Survival with advanced disease (T3/T4) is variable but generally confers
a worse prognosis, with 5-year survival rates between 28 and 86% reported in the literature.
Poor prognostic factors include facial nerve, internal carotid or dural/brain parenchymal
inltration, poorly dierentiated tumours, positive surgical margins and advanced disease.
e Ear 135
ANATOMY AND PHYSIOLOGY OF HEARINGTEMPORAL BONE TUMOURS
KEY POINTS
• Tumours of the temporal bone are rare.
• Consider temporal bone tumours in patients with refractory otological presentations
or in patients with CN dysfunction.
• Given the complexity of temporal bone tumour management, malignancy should be
managed in an MDT with skull base expertise.
Further Reading
Arriaga, M., et al. Staging proposal for external auditory meatus carcinoma based on pre-
operative clinical examination and computed tomography ndings. Ann Otol Rhinol
Laryngol. 1990; 99(9 Pt 1):714–721.
Lustig LR, Jackler RK, Lanser MJ. Radiation-induced tumors of the temporal bone. Am J
Otol. 1997; 18(2):230–235.
Masterson L , Rouhani M, Donnelly NP, et al. Squamous cell carcinoma of the temporal bone:
clinical outcomes from radical surgery and postoperative radiotherapy. Otol Neurotol.
2014; 35(3):501–508. doi:10.1097/MAO.0000000000000265.
136 e Ear
SECTION
2
RHINOLOGY AND FACIAL
PLASTIC SURGERY
25. ANATOMY OF THE NOSE AND PARANASAL SINUSES
Introduction
is chapter outlines paranasal sinus development, neurovascular and anatomical structures of the external nose, nasal cavity and nasal septum. A surgically relevant approach to
sinus anatomy is discussed.
Development of the Nose and Paranasal Sinus
Maxillary Sinus
e maxillary sinus appears between the 7th and 10th weeks of gestation with rapid growth
until the age of 7, and reaches nal size by 17–18 years. Any disruption in development may
result in maxillary sinus aplasia or hypoplasia.
Ethmoid Sinus
e ethmoid sinus is present at birth and develops from four to ve folds called ethmoturbinals. ese dene a series of lamella that must be removed to pass from the anterior sinonasal
cavity to the sphenoid sinus. ese include the following:
1 Agger nasi (ascending portion) and uncinate process (descending portion)
2 Bulla ethmoidalis
3 Basal lamella of the middle turbinate
4 Superior turbinate
5 Supreme turbinate if present
e furrows between ethmoturbinals develop into nasal meatuses. e rst furrow (between
the rst and second ethmoturbinal) becomes the middle meatus (hiatus semilunaris), while
the second furrow becomes the superior meatus.
Sphenoid and Frontal Sinus
Pneumatisation of sphenoid sinus begins at the age of 3 with three described patterns:
Sellar (pneumatisation posterior to the sella turcica, 90%)
•
Pre-sellar (pneumatisation up to the anterior sella, 9%)
•
Conchal (shallow bowl with minimal sphenoid pneumatisation, 1%)
•
Rhinology and Facial Plastic Surgery 137
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