Demographic Comparison of Patients Undergoing Repair of Anterior versus Lateral Spontaneous Skull Base Meningoencephaloceles

Introduction: The correlation of spontaneous meningoencephaloceles and obesity has been well described in the literature. Yet it is unclear if patient demographics vary between patients with spontaneous meningoencephaloceles occurring in the anterior versus lateral skull base. It would seem that many of the presenting characteristics and defining features are similar between these two groups suggesting that there may be a type of continuum with regard to this particular entity. Specifically, these defects often present in obese, female patients and patients with signs and symptoms of idiopathic intracranial hypertension. It is not known whether there are larger patterns relating anatomic location of the meningoencephalocele, patient demographics, comorbid conditions, and treatment outcomes. The purpose of this study is to review and compare demographic and treatment data of patients presenting with spontaneous meningoencephaloceles in the anterior versus lateral skull base.

Methods: A search for all patients with CPT codes 62121, craniotomy for repair of encephalocele, and 61591, infratemporal post-auricular approach to middle cranial fossa, between January 2005 and December 2014 at our institution was performed. Meningoencephalocele etiologies were separated as spontaneous, iatrogenic, traumatic, and tumorogenic. Anterior meningoencephaloceles were defined as those occurring in the ethmoid, medial and lateral sphenoid, frontal and frontoethmoid regions. Lateral meningoencephaloceles were defined as those occurring in the temporal region and middle ear. Patient information including age at presentation, gender, BMI, presenting symptoms, comorbidities, repair type, complications, and recurrence were collected.

Results: A total of 81 patients were identified. Of these patients, 38 were determined to have spontaneous meningoencephaloceles. Thirty two (84%) of the 38 patients were female. Twenty-nine of these patients (76%) presented with anterior skull base meningoencephaloceles, and 9 (24%) presented with lateral meningoencephaloceles. The average BMI of those patients presenting with anterior meningoencephaloceles was 34.13, compared with 34.52 for those presenting with lateral meningoencephaloceles. Average BMI of those patients presenting with meningoencephaloceles from other etiologies was 31.9, which was significantly less than the average BMI of the spontaneous group overall (p = 0.023). Common presenting symptoms of those with anterior meningoencephaloceles including headache and rhinorrhea, compared with symptoms of hearing loss and otorrhea in patients with lateral meningoencephaloceles. Five (17%) of the 29 patients with anterior meningoencephaloceles experienced recurrence requiring surgical revision, while 1 (11%) of the 9 with lateral meningoencephaloceles required revision.

Conclusions: Our patient series appears to confirm that patient’s presenting with spontaneous meningoencephaloceles along both the anterior and lateral skull base are predominately obese and female, with many presenting with signs and symptoms of idiopathic intracranial hypertension. It is unclear what factors may predispose a patient to presenting with lateral defects as opposed to anterior defects, and further work is necessary to determine whether the location of meningoencephalocele occurrence is due to anatomic variations, larger demographic characteristics, or a combination of these factors.