erebrospinal fluid (CSF) is produced by the choroid plexus of the lateral third and
fourth ventricles at a rate of 0.35 mL/min. The CSF flows into the subarachnoid space
and is absorbed by the arachnoid villi in the sagittal sinus. Normal CSF pressure is 5
to 15 cm H2O. Neurologic symptoms may occur when CSF pressure reaches more
than 15 to 20 cm H2O.1 Three concomitant factors are needed for CSF leakage: an osseous defect,
a meningeal disruption, and a pressure gradient.2
Cerebrospinal fluid rhinorrhea may be
classified as a function of its site, its cause,
and the intensity of intracranial pressure.
Nontraumatic fistulas with normal intracranial
pressure (4% of all fistulas) constitute
a challenge because of their unclear
pathophysiologic features.3 Some
authors have used the term spontaneous to
include CSF leaks due to a tumor, a delayed
CSF leak after head trauma, or CSF
leaks associated with congenital malformations
of the skull base. Currently, the
term spontaneous is associated with CSF
leaks without any known cause. For those
reasons, it seems preferable to use the term
idiopathic spontaneous CSF leak.4
Some risk factors of idiopathic, spontaneous
CSF rhinorrhea in the sphenoid
sinus have been described in the literature:
skull base malformation; overpneumatized
sphenoid sinus, particularly with
a lateral extension (present in 16%-27%
of adults); empty sella syndrome; and obesity.
Obesity is associated with an increase
of abdominal and thoracic pressures,
leading to cranial venous congestion
and permanent benign intracranial hypertension.
5-7
The main complications of persistent
CSF leakage are meningitis or brain abscess,
which are potentially fatal. For those
reasons, abnormalities must be repaired
surgically.8 During the last decade, the
management of CSF rhinorrhea has been
changed by the introduction of endoscopic
sinus surgery. However, most of the
recent publications on endonasal sinus surgery
for CSF rhinorrhea treatment report
inconsistent efficacy of the method varying
from 85% to 95% for all types of fistulas.
9 The aim of this article is to report
2 exceptional cases of spontaneous idiopathic
skull base fistula through the clivus
treated by the endoscopic approach. |
