Temporal bone encephalocele and cerebrospinal fluid fistula repair utilizing the middle cranial fossa or combined mastoid–middle cranial fossa approach

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Object

The goals of this study were to report the clinical presentation, radiographic findings, operative strategy, and outcomes among patients with temporal bone encephaloceles and cerebrospinal fluid fistulas (CSFFs) and to identify clinical variables associated with surgical outcome.

Methods

A retrospective case series including all patients who underwent a middle fossa craniotomy or combined mastoid–middle cranial fossa repair of encephalocele and/or CSFF between 2000 and 2012 was accrued from 2 tertiary academic referral centers.

Results

Eighty-nine consecutive surgeries (86 patients, 59.3% women) were included. The mean age at time of surgery was 52.3 years, and the left side was affected in 53.9% of cases. The mean delay between symptom onset and diagnosis was 35.4 months, and the most common presenting symptoms were hearing loss (92.1%) and persistent ipsilateral otorrhea (73.0%). Few reported a history of intracranial infection (6.7%) or seizures (2.2%).

Thirteen (14.6%) of 89 cases had a history of major head trauma, 23 (25.8%) were associated with chronic ear disease without prior operation, 17 (19.1%) occurred following tympanomastoidectomy, and 1 (1.1%) developed in a patient with a cerebral aqueduct cyst resulting in obstructive hydrocephalus. The remaining 35 cases (39.3%) were considered spontaneous. Among all patients, the mean body mass index (BMI) was 35.3 kg/m2, and 46.4% exhibited empty sella syndrome. Patients with spontaneous lesions were statistically significantly older (p = 0.007) and were more commonly female (p = 0.048) compared with those with nonspontaneous pathology. Additionally, those with spontaneous lesions had a greater BMI than those with nonspontaneous disease (p = 0.102), although this difference did not achieve statistical significance.

Thirty-two surgeries (36.0%) involved a middle fossa craniotomy alone, whereas 57 (64.0%) involved a combined mastoid–middle fossa repair. There were 7 recurrences (7.9%); 2 patients with recurrence developed meningitis. The use of artificial titanium mesh was statistically associated with the development of recurrent CSFF (p = 0.004), postoperative wound infection (p = 0.039), and meningitis (p = 0.014). Also notable, 6 of the 7 cases with recurrence had evidence of intracranial hypertension. When the 11 cases that involved using titanium mesh were excluded, 96.2% of patients whose lesions were reconstructed with an autologous multilayer repair had neither recurrent CSFF nor meningitis at the last follow-up.

Conclusions

Patients with temporal bone encephalocele and CSFF commonly present with persistent otorrhea and conductive hearing loss mimicking chronic middle ear disease, which likely contributes to a delay in diagnosis. There is a high prevalence of obesity among this patient population, which may play a role in the pathogenesis of primary and recurrent disease. A middle fossa craniotomy or a combined mastoid–middle fossa approach incorporating a multilayer autologous tissue technique is a safe and reliable method of repair that may be particularly useful for large or multifocal defects. Defect reconstruction using artificial titanium mesh should generally be avoided given increased risks of recurrence and postoperative meningitis.

Abbreviations used in this paper:BMI = body mass index; CPAP = continuous positive airway pressure; CSFF = cerebrospinal fluid fistula.

Article Information

Address correspondence to: George B. Wanna, M.D., Department of Otolaryngology–Head and Neck Surgery, The Bill Wilkerson Center for Otolaryngology & Communication Sciences, 7209 Medical Center East, South Tower, 1215 21st Ave. S., Nashville, TN 37232-8605. email: george.wanna@vanderbilt.edu.

Please include this information when citing this paper: published online July 26, 2013; DOI: 10.3171/2013.6.JNS13322.

© AANS, except where prohibited by US copyright law.

Headings

Figures

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    Sagittal (upper) and axial (lower) T2-weighted MR images demonstrating empty sella syndrome, with herniating arachnoid of the suprasellar cistern filling the majority of the sella turcica, resulting in downward compression of the pituitary gland.

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    A–C: Coronal temporal bone CT scans demonstrating a left-sided superior semicircular canal dehiscence (white arrows) in a patient with a tympanic cavity encephalocele. D: Coronal CT scan demonstrating coincident left-sided encephalocele and labyrinthine segment facial nerve dehiscence (black arrow). Note the thin bony covering of the contralateral facial nerve (white arrow) for comparison.

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    A: Following a left-sided mastoidectomy, a large encephalocele (white arrow) can be seen filling the mastoid antrum. B: A small middle fossa craniotomy (black arrow) is centered over the tegmen defect that was identified during mastoidectomy. C: The dura is carefully elevated and a large dehiscence (black arrow) is identified on the middle cranial fossa floor. D: A multilayer repair incorporating fascia and an autologous bone plate (black arrow) is performed. EAC = external auditory canal; M = mastoid; T = tegmen.

  • View in gallery

    A and B: Following a right-sided mastoidectomy and middle fossa craniotomy, the dura is elevated, and the temporal lobe is gently retracted, revealing multiple defects involving the tegmen tympani and mastoideum (black arrows). C: After adequate exposure is gained, a large composite graft (black arrow) incorporating fascia, bone plate, and collagen dural substitute is placed over the multiple areas of bony dehiscence. D: Inspection of the tegmen from the mastoid vantage point ensures that all bony defects have been adequately covered and there is no active CSF leak. Finally, bone pâté is placed over the tegmen mastoideum (black arrow) to provide additional reinforcement of the repair. TL = temporal lobe.

  • View in gallery

    A: Coronal CT scan of a right temporal bone demonstrating an occult epitympanic encephalocele (white arrow) that was discovered after the patient was diagnosed with a right temporal lobe abscess. B and C: Coronal postcontrast T1-weighted and axial T2-weighted MR images demonstrating a 2.2-cm ring-enhancing lesion (white arrows) in the right inferior temporal lobe, with surrounding vasogenic edema.

  • View in gallery

    Axial CT scans demonstrating sequential right (upper) and left (lower) middle cranial fossa encephalocele repair using a multilayer technique incorporating autologous calvarial bone (black arrows) fixed in place with titanium miniplates and screws to prevent displacement.

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