At a glance
- Contents
- Meninges and CSF only
- Cranial sites
- Cribriform plate, sphenoid lateral recess, tegmen, calvarium
- Presentation
- CSF rhinorrhoea/otorrhoea, meningitis, mass
- Diagnosis
- β2-transferrin; thin-section CT; T2 MRI
- Repair
- Multilayer reconstruction, endoscopic where possible
Overview
A meningocele is a protrusion of the meninges filled with CSF through a defect in the skull or spine, without neural tissue. When brain tissue is included it is a meningoencephalocele (see Encephalocele). Spinal meningoceles, part of the spina bifida spectrum, are distinct from myelomeningoceles, in which the spinal cord is included. Cranial meningoceles can be congenital (occipital, frontoethmoidal, basal) or acquired after trauma, surgery or chronic intracranial hypertension.
Clinical presentation
Congenital calvarial meningoceles present as a soft, skin-covered swelling that transilluminates and may enlarge with crying. Skull-base meningoceles present with CSF rhinorrhoea, otorrhoea or middle-ear effusion, and with recurrent meningitis; they can also be found incidentally on imaging. Skull-base defects in adults are often associated with raised intracranial pressure[1].
Imaging and work-up
Thin-section CT identifies the bony defect, and T2-weighted MRI confirms that the sac contains only CSF. Beta-2 transferrin confirms that a fluid leak is CSF. In spinal lesions, MRI of the whole neuraxis looks for tethering, a Chiari II malformation and hydrocephalus. In adults with skull-base defects, look for signs of raised intracranial pressure.
Surgical management
Repair follows the same principles as for encephaloceles: reduce or excise the sac, close the dural defect and reconstruct the skull base in layers. Anterior skull-base and sphenoid defects are usually repaired endoscopically, using free mucosal or fascial grafts for small defects and a vascularised nasoseptal flap for large ones[2]. Temporal-bone defects are repaired through a middle-fossa or transmastoid approach. Congenital calvarial meningoceles are excised and the dura closed, with management of any associated hydrocephalus. Intracranial hypertension should be treated to prevent recurrence[1].
Outcomes
Isolated meningoceles have an excellent prognosis after repair, because no neural tissue is involved. Recurrence of skull-base leaks is related mostly to untreated raised intracranial pressure and to the size of the defect.
Take-home
Surgical pearls
- Confirm on T2 MRI that no brain is in the sac; this changes the counselling and the repair.
- A spontaneous adult skull-base meningocele suggests raised intracranial pressure.
- Match the reconstruction to the defect size: free graft for small, vascularised flap for large.
Related
References
- 1.Kenning TJ, Willcox TO, Artz GJ, Schiffmacher P, Farrell CJ, Evans JJ. Surgical management of temporal meningoencephaloceles, cerebrospinal fluid leaks, and intracranial hypertension: treatment paradigm and outcomes. Neurosurg Focus. 2012;32(6):E6.
- 2.Hadad G, Bassagasteguy L, Carrau RL, et al. A novel reconstructive technique after endoscopic expanded endonasal approaches: vascular pedicle nasoseptal flap. Laryngoscope. 2006;116(10):1882-1886.
General education for medical professionals. It summarises published literature and is not advice for any individual patient or a substitute for supervised surgical training.