Spontaneous Skull Base Meningoencephaloceles and Cerebrospinal Fluid Fistulas

Abstract

Cerebrospinal fluid (CSF) fistulas are characterized by the egress of CSF from the intracranial cavity through an osteodural disruption between the subarachnoid space and a pneumatized structure within the skull base. Depending on the cause, CSF fistulas are classified as acquired or congenital, and acquired fistulas are further classified as traumatic, nontraumatic, or spontaneous. Spontaneous CSF fistulas are considered to result from a multifactorial process and have been postulated to represent a variant of idiopathic intracranial hypertension. However, an anatomic predisposition involving thinning of the cranial base, such as pneumatization of the sinus walls, must also be present. This process creates areas of structural weakness that act as potential pathways for CSF leaks, which most commonly occur in the ethmoid roof, sphenoid sinus, and temporal bone. Because CSF leaks may be overlooked, a result of their asymptomatic or subtle, intermittent course, a high level of suspicion is crucial in making an early diagnosis. However, CSF fistulas may be well seen at computed tomography (CT), which depicts bone defects, and magnetic resonance cisternography, which reveals the contents of herniated tissue. Knowledge of the location and size of the bone defect and herniated contents is crucial for the selection of surgical approach and grafting material.

Small temporal pole encephalocele: A hidden cause of “normal” MRI temporal lobe epilepsy

“…38 Furthermore, as shown in some of our patients, CT scans with thin coronal reformatted images, can provide further information by showing the bone defects along the middle fossa surface of the temporal bone. 39 In conclusion, our findings show that STPE can present with recognizable clinicoradiologic features in a subgroup of patients with temporal lobe epilepsy in whom the initial MRI review is considered as normal. Identification of this lesion might alter significantly the surgical approach, prompting more targeted resections and hopefully leading to better outcomes.…”

Transmastoid Cartilage Graft-Meningocele Temporal: Surgical Approach

“…and they do not change diagnoses or therapy compared with CT. β 2 -transferrin tests can be done in cases of difficult diagnosis [4].…”

“…The most expected symptoms are: unilateral conductive hearing loss with middle (secondary to reduce ossicular mobility), ear effusion on at patients older than 40 years-old, headache, pulsatile tinnitus or cerebrospinal fluid leak [4], those symptoms must be specially alarming if patient underwent recent trauma or surgery. It can also be presented with recurrent episodes of meningitis, and rarely associated with epilepsy of the temporal lobe [3].…”

“…However, the colorless characteristic of the fluid can lead to a normal otoscopy diagnosis in most of the cases. An audiometry may also show a unilateral conductive hearing loss [4].…”

Endoscopic pedicled nasoseptal flap repair of spontaneous sphenoid sinus cerebrospinal fluid leaks

“…It is of spontaneous aetiology if unrelated to trauma, surgery, malformation, tumour or radiotherapy, and may be associated with a current or previous history of benign intracranial hypertension (BIH) 1. Without intervention, 10% of patients are at risk of developing meningitis annually and up to 40% in the long term 2. Accordingly, surgical repair is the preferred form of management.…”