Skull Base, Petrous Apex, Tumors

Skull Base, Petrous Apex, Tumors

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The petrous apex lies at the anterior superior portion of the temporal bone. [1] Access to this region is difficult and often requires special surgical skills. The region is associated with severe life-threatening complications of otitis media. Improvements in antibiotic therapy, surgery for chronic otitis media, and the development of tympanostomy tubes have decreased incidence of suppurative petrous apicitis. Neoplastic and inflammatory lesions are the most common pathologic processes in the petrous apex. Imaging studies have greatly increased the ability to diagnose these lesions, especially in view of the often-vague symptomatology associated with these lesions. A number of the processes are diagnosed as incidental findings, and consultation is sought to determine the appropriate diagnosis and therapeutic plan. See the image below.

Classic studies detailing the anatomy of the apex and development of improved surgical techniques, including the operating microscope and facial nerve monitor, permit access to the region while lowering the morbidity and mortality associated with surgery. Stereotactic radiation is a relatively new therapeutic tool that offers nonsurgical hope for treating some tumors. Diagnostic evaluation and treatment plan determination for the lesions are dynamic processes that have changed significantly over the past 20 years, and they should change significantly over the next 20 years.

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Petrous apex lesions were primarily diagnosed as complications of chronic otitis media. Sophisticated imaging techniques, such as CT scanning and MRI, were not yet available, and the diagnosis was based on clinical findings, oftentimes correlating with a severe life-threatening scenario. Tympanostomy tubes, antibiotics, operating microscopes, drills, facial nerve monitors, and electroencephalography were not yet available. Pediatric wards were filled with children with intracranial complications secondary to chronic otitis media, including petrous apicitis. These lesions of the apex were evaluated by a careful history coupled with a thorough physical examination. Standard radiography, including Towne and Stenver views, coupled with polytomography permitted evaluation of the apex. Clinical suspicions were correlated with autopsy findings in fatal cases. The advent of improved imaging studies, such as CT scanning and MRI, allowed accurate diagnosis of lesions of the petrous apex.

Infectious lesions can cause meningitis, brain abscess, cranial nerve disorders, and other severe life-threatening problems. The infection must be treated promptly and aggressively to prevent adverse sequelae. In some cases, antimicrobial therapy alone is sufficient to resolve the infection. In most cases, however, surgical drainage of the abscess cavity facilitates recovery. Skull base osteomyelitis is a severe infection of the temporal bone that requires an extended course of antibiotics. Immunocompromised individuals are most susceptible to these severe infections, but these infections can occur in people with healthy immune systems.

Inflammatory lesions generally produce symptoms through the mass effect of the tumor. The apex hosts or borders several important structures discussed in Relevant Anatomy. If these lesions continue to expand, function is progressively sacrificed.

Neoplastic lesions, although rarely malignant, produce symptoms by mass effect and through direct invasion. The natural history of the disease must be thoroughly understood in order to make the correct clinical decisions. Vascular lesions produce symptoms by interrupting blood supply, by bleeding, or by producing a mass effect from the aneurysm or blood.

Lesions of the petrous apex are classified as infectious, inflammatory, neoplastic, and vascular abnormalities. The natural history of these disease processes can cause significant morbidity and mortality. The lesions most commonly observed in the petrous apex are listed below.

Inflammatory or congenital conditions

Cholesterol granuloma

Cholesteatoma

Mucocele

Infectious conditions

Petrous apicitis

Skull base osteomyelitis

Neoplastic conditions

Chordoma

Chondrosarcoma

Meningioma

Schwannoma (trigeminal acoustic, jugular foramen)

Metastasis

Glomus tumor

Nasopharyngeal carcinoma

Intrapetrous carotid artery aneurysm

Normal variants that may simulate pathologic conditions

Asymmetric bone marrow

Giant air cell

Lesions of the petrous apex remain relatively rare. Infectious causes are decreasing because of improved antibiotic therapy, improved techniques in chronic ear surgery, earlier and more frequent placement of tympanostomy tubes, and improved imaging studies leading to earlier diagnosis, ie, before the apex is affected. Inflammatory tumors remain infrequent, and major referral centers report few cases over several years. Neoplastic tumors of the apex also occur only rarely. Some neurootologists do not encounter a chordoma over the course of years of busy clinical practice. Skull base osteomyelitis secondary to otitis externa is common in elderly people who are immunocompromised, especially those with diabetes mellitus. Younger individuals who are immunocompromised also experience this disorder. Vascular tumors are extremely rare, with fewer than 50 cases reported in the literature.

However, incidental findings are becoming more common because the routine use of CT and MRI. The increased quality of these imaging studies and the ability to get details previously unavailable oftentimes finds abnormalities in the petrous apex. The etiology of the lesion requires a careful evaluation with occasional use of serial imaging studies to determine whether the lesion is growing.

Infectious petrositis generally is secondary to eustachian tube dysfunction causing chronic otitis media, with or without cholesteatoma. Infectious petrositis is also secondary to acute otitis media with subsequent extension to an aerated petrous apex. The pathogens are assumed to be identical to those causing otitis media.

Cholesterol granulomas are believed to be secondary to chronic otitis media. A giant cell reaction ensues, and hemoglobin is broken down to form cholesterol debris.

Congenital cholesteatomas are secondary to trapped or misplaced ectoderm. Acquired cholesteatomas are secondary to eustachian tube dysfunction that cause retraction or to abnormal epithelial migration from tympanic membrane perforations or retractions.

Skull base osteomyelitis is secondary to a severe otitis externa, most commonly in patients who are immunocompromised.

The remaining disorders in the apex are idiopathic.

Petrous apicitis is a bacterial infection secondary to chronic otitis media, with or without cholesteatoma. This disease process is secondary to poor eustachian tube function. The process occurs after the air in the middle ear space is resorbed and a relative vacuum occurs. A bacteria-infected effusion follows and spreads to the apex through air cell tracts connecting the apex to the middle ear or mastoid.

With cholesteatomas, the tympanic membrane becomes retracted from the negative pressure. The retraction becomes deeper, squamous epithelium accumulates in the retraction pocket, and enzymes in the leading edge of the cholesteatoma erode bone. Bacteria through the middle ear colonize the pocket, and suppuration occurs. Skull base osteomyelitis is a severe complication of otitis externa in immunocompromised patients.

Inflammatory lesions are often secondary to eustachian tube dysfunction. Congenital cholesteatomas are from retained ectoderm.

The pathophysiology of neoplastic lesions is uncontrolled growth with invasion or pressure on the surrounding structures. The etiology of nasopharyngeal carcinoma is associated with the Epstein-Barr virus.

The presenting symptoms of lesions of the petrous apex can be specific, readily directing attention to the apex, or these symptoms can be vague and nonspecific, not clearly calling attention to the skull base. Some lesions are diagnosed as incidental findings on imaging studies for nonrelated symptoms. Symptoms related to the apex are attributable to the mass effect of an expansile lesion.

In 1904, Gradenigo described a syndrome of abducens nerve palsy, pain secondary to gasserian ganglion inflammation, and facial nerve palsy from suppurative otitis media. [2] The abducens nerve is affected as it passes inferior to the petroclinoid ligament.

Facial pain or disturbance of the trigeminal nerve distribution occurs secondary to involvement of the trigeminal nerve at the Meckel cave. Facial paralysis is secondary to inflammation of the facial nerve in the temporal bone. Pain, usually around the eye, is an early symptom that is followed by the cranial neuropathies.

Several other symptoms from lesions of the petrous apex are common. Hearing loss occurs secondary to an effusion from eustachian tube dysfunction, ossicular erosion from chronic otitis media, or sensorineural hearing loss secondary to invasion of the otic capsule or the cochleovestibular nerve. Tinnitus and vertigo can also occur along with or independent of hearing loss. Facial paralysis occurs secondary to pressure on the facial nerve anywhere throughout its course in the temporal bone, especially near the geniculate ganglion. Headaches occur from distortion of the dura near the lesion. The headaches are primarily retro-orbital or at the vertex. Syncope, stroke, or amaurosis fugax occur secondary to carotid artery occlusion. Other cranial neuropathies occur with posterior lesions that affect cranial nerves VIII through XII or with anterior lesions that affect cranial nerves II-VI.

Interpreting indications for treating these lesions involves a careful risk and benefit analysis based on the symptoms, extent of disease, and natural history of the disease. Options for treating these lesions include observation, medical therapy, surgical therapy, and stereotactic radiation. Each disease process behaves differently, and specific treatment options for each lesion are discussed.

The 4 parts of the temporal bone are the petrous, squamous, tympanic, and mastoid portions. The petrous portion (ie, petrosa) is a 4-sided (ie, quadrilateral) pyramid with its apex anteromedial and its base posterolateral. The clivus anteromedially and the otic capsule posterolaterally border the apex.

The anterosuperior or cerebral portion of the apex forms the floor of the middle cranial fossa. Landmarks on the floor of the middle fossa are as follows:

Depression for the diverticulum of dura and arachnoid, known as the Meckel cave, which houses the gasserian ganglion of the trigeminal nerve

Facial hiatus where the greater superficial petrosal nerve carries preganglionic parasympathetic fibers to the sphenopalatine ganglion and afferent fibers to the lacrimal gland

Arcuate eminence formed by the arch of the superior semicircular canal

Tympanic canaliculus where the lesser superficial petrosal nerve carries preganglionic parasympathetic fibers to the otic ganglion

The posterosuperior surface or cerebellar aspect of the petrous bone is vertical and faces the posterior cranial fossa. It has bony landmarks as follows:

Internal meatus of the internal auditory canal

Orifice of the vestibular aqueduct

Groove for the superior petrosal sinus

Groove for the inferior petrosal sinus

The abducens, or sixth cranial nerve, travels with the inferior petrosal sinus and enters the cavernous sinus through a dural fold between the petroclival ligament and a notch in the petrosphenoid joint called the Dorello canal.

The posterior rim lies in a horizontal plane that articulates with the occipital bone to form the jugular foramen, near the opening of the cochlear aqueduct. The anterior rim articulates with the sphenoid bone and houses the anterior orifice of the carotid canal medially.

In the late 1930s and early 1940s, Lindsay performed several temporal bone studies examining the various tracts between the mastoid and petrous apex. [3, 4] He also examined the comparative anatomy of the apex. The petrous apex can be extensively pneumatized or unpneumatized, with bone marrow that fills the bone. [5] About 20-30% of apices are pneumatized. Most apices are relatively symmetric between the right and left side, essentially having the same amount of pneumatization or marrow formation. Asymmetric marrow formation can be mistaken for tumor.

The base of the apex contains the otic capsule or the inner ear. Air cells from the middle ear cleft invade the apex in varying degrees through tracts described by Lindsay. The pneumatization tracts from the mastoid and middle ear cleft to the apex are as follows:

The infralabyrinthine tract from the middle ear cleft inferior to the otic capsule to the apex [6]

The posteromedial tract of Lindsay extending along the posterior fossa anterior to the internal auditory canal to the apex

The subarcuate tract that follows the subarcuate artery through the arch of the superior semicircular canal to the apex

The anterior tract between the middle ear anterior to the cochlea and posterior to the carotid canal to the apex

The superior tract from the mastoid superior to the superior semicircular canal and superior to the internal auditory canal to the apex

An extensive 3-dimensional understanding of the anatomy of the temporal bone is absolutely necessary to surgically address disorders of the petrous apex. This region is filled with critical structures that are unforgiving to subtle mistakes in surgical technique or to those not intimately acquainted with the anatomy.

With the exception of petrous apicitis and skull base osteomyelitis, all lesions of the petrous apex are best treated surgically. Stereotactic radiation with increased dosage at the tumor and less to the surrounding brain promises a role in treating neoplastic lesions of the apex. Combined therapy with surgery followed by stereotactic radiation are undergoing several controlled studies to determine its efficacy in treating both primary and metastatic lesions.

Dublin AB, Bhimji SS. Anatomy, Head, Face, Temporal Region. 2018 Jan. [Medline]. [Full Text].

Gradenigo G. Sulla leptominingite circiscritta e sulla paralisi dell’ abducente di origine otitica. G Acad Med Torino. 1904. 10:59.

Lindsay JR. Suppuration of the petrous apex. Ann Otol Rhinol Laryngol. 1938. 47:3-36.

Lindsay JR. Petrous pyramid of temporal bone: Pneumatization and roentgenologic appearance. Arch Otolaryngol. 1940. 31:231-235.

Malone A, Bruni M, Wong R, Tabor M, Boyev KP. Pneumatization Patterns of the Petrous Apex and Lateral Sphenoid Recess. J Neurol Surg B Skull Base. 2017 Dec. 78 (6):441-6. [Medline].

Jacob CE, Rupa V. Infralabyrinthine approach to the petrous apex. Clin Anat. 2005 Sep. 18(6):423-7. [Medline].

Jackler RK, Parker DA. Radiographic differential diagnosis of petrous apex lesions. Am J Otol. 1992 Nov. 13(6):561-74. [Medline].

Wachter D, Behm T, Gilsbach JM, Rohde V. Neurosurgical strategies and operative results in the treatment of tumors of or extending to the petrous apex. Minim Invasive Neurosurg. 2011 Apr. 54(2):55-60. [Medline].

Yang J, Ma SC, Fang T, Qi JF, Hu YS, Yu CJ. Subtemporal transpetrosal apex approach: study on its use in large and giant petroclival meningiomas. Chin Med J (Engl). 2011 Jan. 124(1):49-55. [Medline].

Montgomery MM. Cystic lesions of the petrous apex: transphenoidal approach. Ann Otol. 1977. 86:429-435.

Fucci MJ, Romanczuk BJ, Bell RD. Superior sagittal sinus thrombosis after radical neck dissection. Skull Base Surgery. 1994. 4(1):41-45.

Negm HM, Singh H, Dhandapani S, Cohen S, Anand VK, Schwartz TH. Landmarks to Identify Petrous Apex Through Endonasal Approach Without Transgression of Sinus. J Neurol Surg B Skull Base. 2018 Apr. 79 (2):156-60. [Medline].

Giddings NA, Brackmann DE, Kwartler JA. Transcanal infracochlear approach to the petrous apex. Otolaryngol Head Neck Surg. 1991 Jan. 104(1):29-36. [Medline].

Eytan DF, Kshettry VR, Sindwani R, et al. Surgical outcomes after endoscopic management of cholesterol granulomas of the petrous apex: a systematic review. Neurosurg Focus. 2014 Oct. 37(4):E14. [Medline].

Leonetti JP, Anderson DE, Marzo SJ, Origitano TC, Schuman R. The preauricular subtemporal approach for transcranial petrous apex tumors. Otol Neurotol. 2008 Apr. 29(3):380-3. [Medline].

Sweeney AD, Osetinsky LM, Carlson ML, et al. The Natural History and Management of Petrous Apex Cholesterol Granulomas. Otol Neurotol. 2015 Dec. 36 (10):1714-9. [Medline].

Goiney C, Bhatia R, Auerbach K, Norenberg M, Morcos J. Intraosseous schwannoma of the petrous apex. J Radiol Case Rep. 2011. 5(11):8-16. [Medline]. [Full Text].

Lesion

Bone Erosion

Eroded Margin

Contralateral Apex

Contrast Enhancement

Cholesterol granuloma

+

Smooth

Highly pneumatized

Cholesteatoma

+

Smooth

Often not pneumatized

Petrous apicitis

+

Irregular

Variable

Effusion

Usually pneumatized

Bone marrow asymmetry

Variable

Carotid aneurysm

+

Smooth

Variable

+

Neoplasia

+

Variable

Variable

+

*From Jackler RK and Parker D: The radiographic differential diagnosis of petrous apex lesions. AJO 1992;13:561-574 [7]

Lesion

T1 Images

T2 Images

T1-Gadolinium

Cholesteatoma

Hypo

Hyper

No enhancement

Cholesterol granuloma

Hyper

Markedly hyper

No enhancement

Petrous apicitis

Hypo

Hyper

Rim enhancement

Effusion

Hypo

Hyper

Mucosal enhancement

Bone marrow asymmetry

Hyper

Hypo

No enhancement

Neoplasia

Hypo

Hyper

Enhancing

Carotid aneurysm

Hypo

Mixed

Rim enhancement

*From Jackler RK and Parker D: The radiographic differential diagnosis of petrous apex lesions. AJO 1992;13:561-574 [7]

Michael J Fucci, MD Medical Director, Arizona Hearing and Balance Center

Michael J Fucci, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Otolaryngology-Head and Neck Surgery, American Medical Association, Arizona Medical Association, American Neurotology Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Gerard J Gianoli, MD Clinical Associate Professor, Departments of Otolaryngology-Head and Neck Surgery and Pediatrics, Tulane University School of Medicine; President, The Ear and Balance Institute; Board of Directors, Ponchartrain Surgery Center

Gerard J Gianoli, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Neurotology Society, American Otological Society, Society of University Otolaryngologists-Head and Neck Surgeons, Triological Society

Disclosure: Nothing to disclose.

Arlen D Meyers, MD, MBA Professor of Otolaryngology, Dentistry, and Engineering, University of Colorado School of Medicine

Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American Head and Neck Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Cerescan;RxRevu;Cliexa;Preacute Population Health Management;The Physicians Edge<br/>Received income in an amount equal to or greater than $250 from: The Physicians Edge, Cliexa<br/> Received stock from RxRevu; Received ownership interest from Cerescan for consulting; for: Rxblockchain;Bridge Health.

Douglas D Backous, MD Director of Listen for Life Center, Department of Otolaryngology-Head and Neck Surgery, Virginia Mason Medical Center

Douglas D Backous, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Auditory Society, American College of Surgeons, American Laryngological Rhinological and Otological Society, American Medical Association, Association for Research in Otolaryngology, North American Skull Base Society, Society for Neuroscience, and Washington State Medical Association

Disclosure: Nothing to disclose.

Skull Base, Petrous Apex, Tumors

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Skull Base, Petrous Apex, Infection

Skull Base, Petrous Apex, Infection

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The petrous portion of the temporal bone lies in a complicated anatomic position and has critical relationships to important neural and vascular structures. Consequently, infections arising within or spreading to the petrous apex can result in severe clinical sequelae.

Before the advent of antibiotics in the 1940s, infections of the petrous apex, termed petrous apicitis, commonly progressed to meningitis, brain abscess, cavernous sinus thrombosis, and death. Since the introduction of antibiotics, the prevalence of such serious complications has been drastically reduced. By the late 1950s, experienced clinicians already noted this decreasing prevalence; DeWeese cautioned physicians to remain vigilant of petrous apicitis, “Lest we forget that this condition still occurs.” [1]

DeWeese’s admonition is still valid. Patients still occasionally present with petrous apicitis, and the clinician needs to be wary of the condition’s presenting features to prevent possible life-threatening complications.

An image depicting skull base anatomy can be seen below.

Gradenigo syndrome, ie, petrous apicitis in combination with the clinical triad of headache, abducens nerve (cranial nerve [CN] VI) palsy, and otorrhea, is named after Giuseppe Gradenigo. In 1904, Gradenigo related his experience with this disorder in a manuscript entitled “Uber circumscripte Leptomeningitis mit spinalensymptomen und über Paralyse des N. Abducens otitischen Ursprungs,” in the Archiv für Ohrenheilkunde. [2] In the paper, Gradenigo summed up the disease process through its 3 principal symptoms, which “… dearly and mutually cohere: acute inflammation of the middle ear, continuing pain in the temporal and parietal area, and paralysis the N Abducens, which is indicated usually by the patient himself.”

Throughout the early 1900s, in the absence of antibiotics, various surgical procedures were developed to treat petrous apicitis. Procedures usually included a mastoidectomy with or without a labyrinthectomy. In 1930, Almour and Kopetsky describe following fistulous tracts into the petrous apex via a mastoidectomy with or without a labyrinthectomy. [3] Ramadier introduced the radical petrous apicectomy in 1933. [4]

In 1937, Lempert described the mastoidotympanoapicectomy, which is now the classic operation for exenteration of the anterior petrous apex. [5, 6] This radical operation required glenoid fossa exposure and dissection along the carotid canal within the skull base. Because of the morbidity associated with the operation, many other surgeons rejected it during this period. In 1973, Hendershot and Wood advocated the extradural middle fossa approach. [7]

In the 1930s, Profant and Lindsay described the drainage pathways of the petrous apex through several air cell tracts along with the routes whereby infection may come to involve the petrous apex. [8, 9]

Between the 1940s and the 1960s, the incidence of petrous apicitis was dramatically reduced, which is evidenced by the paucity of clinical manuscripts on the topic. This reduction was primarily due to the introduction of antibiotics. Most reports since this time are based on single clinical cases or very small clinical series.

Petrous apicitis is a rare infection of the petrous apex of the temporal bone that occurs as an extension of a middle ear or mastoid infection.

Petrous apicitis was commonly encountered before the introduction of antibiotics. It now appears quite rarely. Most reports on petrous apicitis in the literature are single clinical cases, and determining its frequency is difficult.

In a retrospective review of petrous apicitis cases occurring over a 40-year period, Gadre and Chole found that six out of 44 patients with the condition (13.6%) had Gradenigo syndrome. [10]

Petrous apicitis is believed to result when organisms, typically pseudomonads, become trapped within the complex air cell system of the petrous apex. Blockage of this air cell system may result from acute or chronic inflammation or mechanical blockage from an obstructing lesion.

Direct extension of infection from the mastoid and middle ear through pneumatized air cell tracts into the petrous apex is thought to be the etiology of petrous apicitis, which can occur as a rare complication of acute or chronic otitis media. [11, 12] An undetected and poorly drained infected air cell of the petrous apex must trail through small air cell tracts into the middle ear and mastoid. These cell tracts consist of the infralabyrinthine air cell tract, the retrofacial tract, and the peritubal air cells superior to the eustachian tube.

Because of the extensive pneumatization and presence of rich bone marrow within the petrous apex, it is susceptible to infection or inflammation, typically in combination with mastoiditis. The proximity of the venous sinuses to the petrous apex is the reason for the historically high incidence of venous sinus thrombosis associated with petrous apicitis. The inflammation may extend into the Dorello canal, which transmits CN VI and the gasserian ganglion (CN V). Inflammation of the canal produces the triad of symptoms recognized by Gradenigo: lateral rectus (CN VI) palsy, retroorbital pain, and otorrhea.

Pseudomonads are most often responsible for petrous apicitis. In rare cases, tuberculosis has been identified as the cause, primarily in individuals younger than 20 years. Rare cases of fungal petrous apicitis have also been described including aspergillosis and blastomycosis infections.

Petrous apicitis may follow an acute or a chronic course. [13]  The acute form typically develops rapidly and is caused by sudden obstruction of a normally pneumatized petrous apex air cell system. This obstruction can be caused by mechanical blockage from a lesion within the mastoid or by acute mastoid inflammation.

Chronic apicitis has a more indolent course and typically follows months to years of otorrhea. Patients may not appear acutely ill compared with those patients with acute petrositis. Chronic apicitis may result from chronic mastoid inflammation, or it may occur after a mastoid operation has led to blockage of the air cell system.

The triad of retroorbital pain, lateral rectus (CN VI palsy), and otorrhea is pathognomic for petrous apicitis. However, the presence of this triad is uncommon, since antibiotics typically halt the disease process before it involves dural structures. The presence of both otorrhea and deep pain should lead the examining physician to suspect petrous apicitis.

The anatomic relationship at the petrous tip may explain some of the symptoms of petrous apicitis. If the bony cortex of the anterior petrous apex is involved by the extension of infection, the infection may cause an epidural abscess in the region or damage nearby cranial nerves. On the superior aspect of the petrous tip lies the trigeminal or gasserian ganglion. Damage or irritation to the ganglion may explain the deep facial pain in some patients with apicitis. The petroclinoid ligament extends from the tip of the petrous apex to the clinoid is the petroclinoid ligament. The abducens nerve travels below the petroclinoid ligament in a small canal called the Dorello canal. The inflammation may extend into the Dorello canal, which transmits CN VI and the gasserian ganglion (CN V). Inflammation of the canal produces the triad of symptoms recognized by Gradenigo: lateral rectus (CN VI) palsy, retroorbital pain, and otorrhea.

Symptoms of petrositis are usually subtle. Typically, a patient who has had previous mastoid surgery complains of persistent infection and deep facial pain. Chole and Donald found that the most common presenting symptoms in petrous apicitis, as found in 22 patients from 1976-1995, were as follows:

Deep pain and headache – 13 patients (59%)

Otalgia – 16 patients (72%)

Otorrhea – 13 patients (59%)

Fever – 5 patients (22%)

Coma – 2 patients (9%)

Cranial nerve paralysis

Nerve V – 15 patients (68.2%)

Nerve VI – 4 patients (18.2%)

Nerve VII – 6 patients (27.3%)

Nerve VIII – 9 patients (40.9%)

Nerve IX – 1 patient (4.5%)

Nerve X – 1 patient (4.5%)

Another study, the aforementioned report by Gadre and Chole, found that out of 44 patients with petrous apicitis, 24 (54.5%) had severe retroorbital pain, 27 (61.4%) had otitis media (including 16 [36.4%] with purulent otorrhea) at the time of presentation, 37 (84.1%) had facial pain along with otitis media, eight (18.2%) had fever, and seven (15.9%) had abducens nerve palsy. [10]

Indications for surgical drainage of the petrous apex in patients with petrous apicitis include failure to respond to medical (antimicrobial) therapy, the development of CN deficits as a result of extension of the infection, development of a petrous apex, epidural or parenchymal brain abscess, and the development of another life-threatening complication as a result of the infection.

Wedged between the occipital bone and the greater wing of the sphenoid, the petrous portion of the temporal bone is shaped like a 3-sided pyramid. The pyramid’s base is the medial wall of the middle ear. Two of the sides of the pyramid constitute the anterior floor of the middle cranial fossa and the anterolateral wall of the posterior fossa. The jugular bulb and inferior petrosal sinus line the inferior aspect of the petrous bone.

Anterior and superior to the petrous apex lie CN V and the gasserian ganglion. CN VI traversing through the Dorello canal also lies in this region. At its apex lie the carotid artery and cavernous sinus.

Air cells within the petrous portion of the temporal bone communicate with the eustachian tube and nasopharynx via the middle ear, providing a route of pressure equalization and drainage. In 1931, Profant described 2 separate air cell tracts within the temporal bone, an epitympanic tract leading from the antrum and a hypotympanic tract traveling beneath the cochlea. [8]  A study by Lee et al suggested that pneumatization of the petrous apex may not be influenced by major temporal bone structures but may instead be primarily impacted by the anterior saccule of the saccus medius. [14]

The petrous apex is the most surgically inaccessible portion of the temporal bone. A coronal plane through the internal auditory canal may arbitrarily bisect the apex. This plane divides the apex into anterior and posterior portions. The anterior apex, which is pneumatized in 9% of patients, is a peritubal area anterior and medial to the cochlea. The carotid artery traverses the anterior petrous apex. The posterior petrous apex, which is pneumatized in 30% of patients, is a perilabyrinthine area just medial to the semicircular canals.

If the patient is medically unstable and unable to tolerate general anesthesia, high-dose IV antibiotics may be attempted to eradicate the infection in place of surgery.

DeWeese D. Four unusual cases of temporal bone disease. Laryngoscope. 1958 Jun. 68(6):1028-35. [Medline].

Gradenigo G. Uber circumscripte leptomeningitis mit spinalensymptomen und paralyse des n. Abducens otitischen ursprungs. Archiv f?enheilkunde. 1904. 62:255-270.

Kopetzky S, Almour R. Suppuration of the petrous pyramid: symptomatology, pathology and surgical treatment. Ann Otol Rhinol Laryngol. 1931. 40:396-414.

Ramadier J. Exploration de la pointe du rocher par la voie du canal carotidien. Ann d’Oto-laryngol. 1933. 4:422-444.

Lempert J. Complete apicectomy (mastoidotympanoapicectomy). Arch Otolaryngol. 1937. 25:144-177.

Krisht KM, Shelton C, Couldwell WT. Early Conquest of the Rock: Julius Lempert’s Life and the Complete Apicectomy Technique for the Treatment of Suppurative Petrous Apicitis. J Neurol Surg B Skull Base. 2015 Mar. 76 (2):101-7. [Medline]. [Full Text].

Hendershot EL, Wood JW. The middle fossa approach in the treatment of petrositis. Arch Otolaryngol. 1973 Dec. 98(6):426-7. [Medline].

Profant HJ. Gradenigo’s syndrome. Arch Otolaryngol. 1931. 13:347-378.

Lindsay J. Suppuration in the petrous pyramid. Ann Otol Rhinol Laryngol. 1938. 47:3-36.

Gadre AK, Chole RA. The changing face of petrous apicitis-a 40-year experience. Laryngoscope. 2018 Jan. 128 (1):195-201. [Medline]. [Full Text].

Valles JM, Fekete R. Gradenigo syndrome: unusual consequence of otitis media. Case Rep Neurol. 2014 May. 6(2):197-201. [Medline]. [Full Text].

Choi KY, Park SK. Petrositis with bilateral abducens nerve palsies complicated by acute otitis media. Clin Exp Otorhinolaryngol. 2014 Mar. 7(1):59-62. [Medline]. [Full Text].

Jensen PV, Hansen MS, Moller MN, Saunte JP. The Forgotten Syndrome? Four Cases of Gradenigo’s Syndrome and a Review of the Literature. Strabismus. 2016. 24 (1):21-7. [Medline].

Lee DH, Kim MJ, Lee S, Choi H. Anatomical Factors Influencing Pneumatization of the Petrous Apex. Clin Exp Otorhinolaryngol. 2015 Dec. 8 (4):339-44. [Medline]. [Full Text].

Montgomery W. Cystic lesion of the petrous apex: transsphenoid approach. Trans Am Otol Soc. 1977. 65:32-39.

Chole RA, Donald PJ. Petrous apicitis. Clinical considerations. Ann Otol Rhinol Laryngol. 1983 Nov-Dec. 92(6 Pt 1):544-51. [Medline].

Andrea H Yeung, MD Assistant Clinical Professor, Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco

Andrea H Yeung, MD is a member of the following medical societies: Alpha Omega Alpha, Phi Beta Kappa

Disclosure: Nothing to disclose.

Lawrence R Lustig, MD Howard W Smith Professor and Chair, Department of Otolaryngology-Head and Neck Surgery, Columbia University College of Physicians and Surgeons, NewYork-Presbyterian/Columbia University Irving Medical Center

Lawrence R Lustig, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Auditory Society, American College of Surgeons, American Neurotology Society, American Otological Society, Association for Research in Otolaryngology, North American Skull Base Society, Society for Neuroscience, Society of University Otolaryngologists-Head and Neck Surgeons

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Gerard J Gianoli, MD Clinical Associate Professor, Departments of Otolaryngology-Head and Neck Surgery and Pediatrics, Tulane University School of Medicine; President, The Ear and Balance Institute; Board of Directors, Ponchartrain Surgery Center

Gerard J Gianoli, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Neurotology Society, American Otological Society, Society of University Otolaryngologists-Head and Neck Surgeons, Triological Society

Disclosure: Nothing to disclose.

Arlen D Meyers, MD, MBA Professor of Otolaryngology, Dentistry, and Engineering, University of Colorado School of Medicine

Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American Head and Neck Society

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Cerescan;RxRevu;Cliexa;Preacute Population Health Management;The Physicians Edge<br/>Received income in an amount equal to or greater than $250 from: The Physicians Edge, Cliexa<br/> Received stock from RxRevu; Received ownership interest from Cerescan for consulting; for: Rxblockchain;Bridge Health.

Douglas D Backous, MD Director of Listen for Life Center, Department of Otolaryngology-Head and Neck Surgery, Virginia Mason Medical Center

Douglas D Backous, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Auditory Society, American College of Surgeons, American Laryngological Rhinological and Otological Society, American Medical Association, Association for Research in Otolaryngology, North American Skull Base Society, Society for Neuroscience, and Washington State Medical Association

Disclosure: Nothing to disclose.

Skull Base, Petrous Apex, Infection

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