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

Abstract

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.

Are there modifiable risk factors to prevent a cerebrospinal fluid leak following vestibular schwannoma surgery?

“…1 Recently there has been growing evidence that obesity is also a risk factor for development of spontaneous temporal bone CSF leaks. 6,12,17,21 In contrast, little has been written regarding the possible association between obesity and the occurrence of a CSF leak following VS surgery. 8,14 Diaz Anadon et al studied 170 patients who had undergone surgery for tumors in the cerebellopontine angle (163 of whom had a VS) and found no relationship between CSF leaks and BMI.…”

A novel method for autograft placement during tegmen repair: The suture “pull‐through” technique

“…The use of a combined approach to repair the middle cranial fossa floor has advantages over either the transmastoid or subtemporal craniotomy approaches alone. Transmastoid approaches have commonly been employed for definitive exposure of defects that are small (<1 cm) and laterally located . As an extension of this approach, elevation within epidural space surrounding the defect and placement of an intracranial cartilage graft has been described .…”

“…However, a middle cranial fossa approach may offer improved visualization over the transmastoid approach alone, and the exposure provided by both a mastoidectomy and subtemporal craniotomy can be critical when repairing large, medially located, and/or multifocal defects . With particular regard to the latter, there is evidence to suggest that multiple defects can be encountered in >50% of cases, particularly in spontaneous encephaloceles or CSF leaks . Reliance on either approach alone may not allow for sufficient evaluation of the middle cranial fossa floor to identify and repair all defects.…”

“…In solitary lateral lesions, either a transmastoid or a middle cranial fossa approach may provide adequate visualization for repair. The combined transmastoid‐subtemporal middle cranial fossa approach for CSF fistula and encephalocele repair is commonly employed for large or medial tegmen defects, particularly those that involve the epitympanum and an intact ossicular chain . A variety of materials can be used to repair a defect, with an autologous multilayer reconstruction being preferred to a single layer or use of synthetic substrate .…”

Temporal Lobe Encephaloceles

“…Recent literature suggests that temporal lobe encephaloceles are associated with seizures in less than 5% of cases (4,5). However, the mere possibility of an epileptogenic encephalocele urges consideration of this etiology in patients with intractable seizures originating in the temporal lobe, especially when noting that durable seizure relief from encephalocele resection has been described (6Y8).…”