Case report
A 53-year-old woman, who had been suffering from serous rhinorrhea for
several years, with no specific medical conditions except for obesity
with a body mass index of 41 kg/m2, presented
emergently to the neurological department with high fever and impaired
consciousness. Cerebrospinal fluid (CSF) examination by lumbar puncture
revealed a diagnosis of bacterial meningitis. Only an accumulation of
fluid with air was noted in the right sphenoid sinus through brain
computed tomography (CT) taken at 4-mm slice thickness (Figure 1A) and
magnetic resonance imaging (MRI) (Figure 1B). There were no other
findings that could be considered a focus of inflammation. She was
referred to the otorhinolaryngological department to investigate whether
the right sphenoid sinus was the focus of the meningitis.
High-resolution (HR) CT images were taken with 0.5-mm slice thickness,
and coronal and sagittal sections were reconstructed (Figure 2A1-3).
HRCT revealed a skull base fistula at the lateral wall of the right
sphenoid sinus and arachnoid pits at the middle cranial fossa. In
addition, the fluid in the right sphenoid sinus, draining into the nasal
cavity via the natural ostium of the right sphenoid sinus (Figure 3A),
was collected and measured for glucose, and was found to be similar to
the CSF from the lumbar region. Therefore, we diagnosed the patient with
spontaneous CSF leakage due to fistula of the middle cranial fossa and
an ascending bacterial infection spilled over into the cranium via the
fistula. After improvement of the meningitis by medical treatment, an
interdisciplinary team of otorhinolaryngologists and neurosurgeons
performed reconstruction of the skull base.
An otolaryngologist and a neurosurgeon performed the reconstruction
surgery. First, right endoscopic sinus surgery was performed to open the
sphenoid sinus via the ethmoid sinus (Figure 4A). The base of the right
sphenoid sinus was observed with a 70-degree telescope, and a fistula
was identified on the lateral wall of the right sphenoid sinus (Figure
4B, 4C). Subsequently, bilateral sphenoid sinuses were opened using a
transseptal approach (Figure 4D, 4E). To secure a wide surgical field
and sufficient field of view, a rescue incision was made to the natural
ostium of the right sphenoid sinus, parallel to the nasal floor, at the
area where the olfactory epithelium did not exist (Figure 4F). The
sphenoid crest was removed, and the surgical field was developed
laterally so that the floor of the right sphenoid sinus could be fully
manipulated (Figure 4G, 4H). The blood vessels and nerves in the right
palatovaginal and Vidian canals were cauterized, and the surgical field
was further expanded laterally to enable manipulation of the lateral
wall of the right sphenoid sinus. The arachnoid mater was identified in
the fistula after removal of the right sphenoid sinus mucosa (Figure
5A). A collagen matrix (DuraGenTM Dural Graft Matrix
[Integra Life Sciences, Plainsboro, NJ, USA]) was inserted into the
fistula and laid against the dura mater (Figure 5B, 5C, 5D). The vomer
bone was shaped into a pile and fitted into the fistula for rigid
reconstruction of the skull base (Figure 5E, 5F, 5G). A multilayer
reconstruction was performed by covering the outermost layer with a
pedicle nasoseptal mucosal flap (Figure 5H).
At 6-month follow-up, no recurrence of CSF leakage or resorption of the
inserted bone pile was observed (Figure 2B1-3, 3 B). There were no
complications, such as olfactory disturbances or nasal septal
perforation, due to surgical invasion. There were no findings of
intracranial infection or sinusitis.