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J Neurol Surg B Skull Base 2022; 83(06): 653-662
DOI: 10.1055/a-1933-3958
Review Article

Temporal Bone Skull Base Defects—The Value and Importance of Early Based Detection to Prevent Late Costly Morbidity and Mortality

Thomas Hendriks 
1   Department of Otolaryngology Head and Neck Surgery, Fiona Stanley Hospital, Murdoch, Australia
,
Claudia Kirsch 
2   Yale University School of Medicine Department of Radiology and Biomedical Imaging, New Haven, Connecticut, United States
3   Mount Sinai Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York City, New York, United States
4   Department of Clinical Dentistry, University of Sheffield, Sheffield, South Yorkshire, England
,
Daren Gibson
5   Department of Medical Imaging, Fiona Stanley Hospital Ringgold Standard Institution, Murdoch, Australia
,
Jafri Kuthubutheen
6   Department of Ear, Nose and Throat Surgery, Fiona Stanley Hospital Ringgold Standard Institution, Murdoch, Australia
7   Department of Otolaryngology and Head and Neck Surgery, Sir Charles Gairdner Hospital Ringgold Standard Institution, Nedlands, Australia
8   Department of Western ENT, South Perth Hospital, Como, Australia
9   School of Surgery, The University of Western Australia Ringgold Standard Institution, Perth, Australia
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Introduction

Acute bacterial meningitis is a devastating illness with high morbidity and mortality, involving leptomeningeal inflammation that may manifest as sudden onset fever, nuchal rigidity, and altered mental status.[1] [2] Common acquired causative pathogens in the community include Streptococcus pneumoniae and Neisseria meningitidis.[3] A high-grade bacteremia with central nervous system (CNS) invasion is the presumed transmission route in the majority of patients diagnosed with bacterial meningitis; however, upper airway mucosal infections and/or co-existent skull base bone defects can potentiate direct spread of bacteria into the CNS.[4] Examples of this are intracranial complications of otitis media (OM) requiring a prompt and accurate diagnosis to avoid significant disability.[5] Complicated OM is common both at a primary care level and as a predisposing factor in up to one-quarter of patients who develop acute bacterial meningitis.[6] The typical demographic affected by acute OM secondary to Streptococcus pneumoniae are pediatric patients under the age of two, or adults over 50 years.[7] An osseous tegmen defect can also potentially facilitate the spread of infection from the middle ear (ME) cleft to the middle cranial fossa (MCF). These defects can be congenital, such as incomplete partition, enlarged vestibular aqueducts, or persistent Hyrtl's fissure, posttraumatic or secondary to local erosive cholesteatomas, and in some cases iatrogenic following otological surgery. Approximately 5% of community-acquired meningitides are believed to be from anatomical skull base defects, with an increased risk of recurrent meningitis.[8] [9] Additionally, unfavorable prognostic outcomes associated with bacterial meningitis include pneumococcal infection and the presence of OM or sinusitis often co-existing with skull base defects.[2] Acquired skull base defects are an increasingly recognized condition related to spontaneous cerebrospinal fluid (sCSF) otorrhea. sCSF otorrhea has increased in incidence, almost doubling in the past decade, along with concomitant increases in obesity worldwide and benign intracranial hypertension (BIH), although the exact incidence and prevalence of sCSF from idiopathic intracranial hypertension (IIHT) and obesity remains unknown.[10] [11] In sCSF leakage, the CSF may extend through temporal bone defects into the ME and/or mastoid.[12] [13] Affected patients are typically obese middle-aged females presenting with unilateral aural fullness, conductive hearing loss, and occasionally frank otorrhoea.[10] [11] [14] [15] [16] Biochemical analysis of ME fluid for β-trace protein (BTP) and radiological temporal bone computed tomography (CT) or thin section T2-weighted magnetic resonance imaging (MRI) aid in identifying skull base bony defects and aberrant arachnoid granulations. Patients with skull base defects may be predisposed to risks of ascending intracranial sepsis and meningitis.[10] [11] [12] Prior published research by this group in a cohort of 28 sCSF patients, revealed two patients (7%) with otogenic meningitis presumed due to undiagnosed sCSF.[17] Additional literature has noted recurrent meningitis from temporal bone CSF leakage.[10] [18] [19] [20]

Because the incidence of sCSF is increasing, the goal of this value-based study was to retrospectively assess clinical and imaging features of bacterial meningitis with presumed otogenic etiology, compared with patients with sCSF. Currently, there is a paucity of detailed, published data quantifying the potential relationship between sCSF and risk of meningitis. This value-based study assessed 20 patients with acute otogenic meningitis, comparing clinical features to sCSF patients, for demographic features that may predispose to tegmen defects. Patients at risk of sCSF may benefit from workflows with early radiographic skull base and temporal bones assessment via temporal bone CT or MRI T2 thin section imaging evaluating for tegmen thinning, bony defects, or aberrant arachnoid granulations. In the ideal value-based health-care setting, earlier radiographic identification of tegmen defects with specialist ear, nose, and throat (ENT) treatment, may prevent progressing to acute otogenic meningitis and its associated increased morbidity and mortality.



Publication History

Received: 30 December 2021

Accepted: 24 August 2022

Accepted Manuscript online:
30 August 2022

Article published online:
12 November 2022

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