Keywords
intracranial hypertension - papilledema - pseudotumor cerebri - intracranial thrombosis
- endovascular procedures
Palavras-chave
hipertensão intracraniana - papiledema - pseudotumor cerebral - trombose intracraniana
- procedimentos endovasculares
Introduction
Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri, is
a syndrome with unknown etiology characterized by documented high opening pressure
of the cerebrospinal fluid (CSF) on lumbar puncture (initial pressure > 25 cm H2O).[1] The condition is associated with increased intracranial pressure (ICP), no localizing
focal neurological signs (with exception of abducens nerve palsy), together with neuroimaging
disclosing no cerebral abnormalities or hydrocephaly.[1]
The physiopathology of IIH is not fully understood, and a number of mechanisms have
been proposed to explain the condition, ranging from increased CSF production/reduced
CSF absorption, to increased cerebral venous pressure.[2] It has been acknowledged that patients with IIH often present unilateral or bilateral
stenosis of the transverse sinus.[3] Despite controversy over whether transverse sinus stenosis plays a role in the physiopathology
of IIH, angioplasty of the transverse sinus by stent placement can lower pre- and
poststenosis gradient pressure, reduce venous and intracranial pressures by improving
CSF reabsorption, and promote an improvement in symptoms.
In the present study, we report the case of a pediatric patient with IIH who underwent
venous sinus stenting with subsequent improvement in symptoms. We also discuss the
main aspects of this condition, based on a review of the literature.
Case Report
A previously healthy 12-year-old male patient presented with a 10-day history of headache
together with blurred vision, dizziness, nausea and vomiting. The patient's condition
declined, with worsening visual acuity, in the three days leading up to admission
to the Emergency Room. A consultation with the ophthalmologist resulted in a diagnosis
of papilledema on an ocular fundus exam.
Computed tomography (CT) and magnetic resonance imaging (MRI) scans of the head with
arterial and venous angiography ([Fig. 1]) revealed signs of intracranial hypertension and narrowing at the transition of
the transverse/sigmoid sinuses bilaterally. Given the suspected case of IIH associated
with bilateral stenosis of the venous sinuses, cerebral angiography with microcatheter
placement was performed to measure the pressure gradient and determine the need for
angioplasty.
Fig. 1 (A) Computed tomography (CT) without contrast revealing cerebrospinal fluid (CSF) distension
of the optic nerve sheath (white arrows). (B,C) T2-weighted axial and coronal sequences again showing CSF distension of the optic
nerve sheath (white arrows). (D) Fluid-attenuated inversion recovery (FLAIR) weighted axial sequence revealing hyperintensity
of the optic papilla (red arrows). (E,F,G,H) T2 driven equilibrium (DRIVE), diffusion-weighted imaging (DWI), T1 postcontrast
and FLAIR postcontrast sequences to assess orbits provide a clearer view of the CSF
sheath distension (blue arrows) and signs of bilateral papilledema (red arrows), displaying
hyperintensity in diffusion sequence, postcontrast intensity on T1 and FLAIR, with
the latter providing greater sensitivity. (I,J) Magnetic resonance angiography showing bilateral stenosis at the transition between
the transverse and sigmoid sinuses (green arrows).
Endovascular Procedure
The night prior to the procedure, clopidogrel 300 mg and acetylsalicylic acid (ASA)
200 mg were administered. The procedure commenced with puncture of the left femoral
artery and right common femoral vein with introduction of a 4F sheath using the Seldinger
technique. A 4F vertebral diagnostic catheter was advanced via the left for the cerebral
angiography study, which revealed severe stenosis of around 80% to 85% at the transition
of the sigmoid-transverse sinuses bilaterally ([Fig. 2A]). The study also showed redirecting of the supratentorial venous drainage to the
diploic veins, and from the scalp in the frontoparietal convexity bilaterally.
Fig. 2 (A-C) Front carotid angiogram disclosing: (A) bilateral stenosis at the transition of the transverse and sigmoid sinuses; (B,C) after venous angioplasty of the right transverse and sigmoid sinuses, with restoration
of the normal caliber; (D) final position of the stent at the topography of the transition between the right
transverse and sigmoid sinuses. A and B: with bone subtraction; C and D: without bone subtraction.
A Head-Hunter (Merit Medical OEM, Salt Lake City, UT, US) 4F catheter was then advanced
via the femoral vein, positioned at the right internal jugular vein, and, using coaxial
catheter placement, an Excelsior (Stryker Neurovascular, Fremont, CA, US) SL10 microcatheter
was advanced with the aid of a Transend Platinum (Stryker Neurovascular) microguide.
Manometry of the intracranial venous sinuses was then performed, disclosing pre- and
poststenosis pressure gradients, as described in [Table 1].
Table 1
Values obtained by intracranial sinus manometry, before and after angioplasty
|
SITE
|
PREANGIOPLASTY MANOMETRY
|
POSTANGIOPLASTY MANOMETRY
|
|
Right internal jugular vein
|
10 mmHg
|
9 mmHg
|
|
Left internal jugular vein
|
10 mmHg
|
10 mmHg
|
|
Right sigmoid sinus
|
11 mmHg
|
10 mmHg
|
|
Left sigmoid sinus
|
11 mmHg
|
10 mmHg
|
|
Right transverse sinus
|
22 mmHg
|
10 mmHg
|
|
Left transverse sinus
|
22 mmHg
|
11 mmHg
|
|
Torcula
|
23 mmHg
|
11 mmHg
|
Angioplasty with right stent placement was performed, because the left sinuses exhibited
hypoplasia. The jugular-vein catheter was removed, and the short 4F sheath was replaced
by a long NeuroMax (Penumbra, Inc., Alameda, CA, US) 8F sheath. With the aid of a
Neuron Select (Penumbra, Inc.) 6F catheter and hydrophilic 0.035” stiff guidewire,
the NeuroMax (Penumbra, Inc.) 8F sheath was advanced up to the right transverse sinus
beyond the stenosis site. A 9 × 40 mm Carotid Wallstent (Boston Scientific Corporation,
Marlborough, MA, US) was then advanced and deployed to cover the transition of the
right sigmoid-transverse sinuses ([Fig. 2]). An Excelsior (Stryker Neurovascular) SL10 microcatheter was then advanced with the aid of a Transend Platinum (Stryker Neurovascular) microguide, and manometry of the intracranial venous sinuses
was performed (data shown in [Table 1]).
The endovascular procedure was performed under general anesthesia and systemic heparinization.
In the first 24 hours after the procedure, the patient reported an improvement in
the headache. The blurring of vision gradually improved over the ensuing days. The
patient was discharged from hospital on the third postoperative day, and was prescribed
clopidogrel 75 mg/day for 3 months and ASA 100 mg/day for 1 year. A 3-month follow-up
MRI confirmed improvement in the signs of intracranial hypertension ([Fig. 3]).
Fig. 3 (A,B): T2-weighted axial and coronal sequences showing distension of the optic nerve sheath,
which was stable relative to a previous study. (C,D) FLAIR and DWI-weighted axial sequence revealing slight protrusion of the optic papilla,
characterized by a slight hypersignal on the FLAIR sequence (white arrows), lower
than that of the previous study, but not exhibiting hypersignal on the diffusion sequence
(white arrows). (E,F,G) Magnetic resonance angiography showing stenosis at the transition between the left
transverse and sigmoid sinuses (white arrows), stable relative to that of the previous
study, highlighting material characterizing artefact with magnetic susceptibility
contralaterally consistent with the stent (white arrow).
Discussion
The annual incidence of IIH is of approximately 1 case for every 100,000 people, reaching
up to 20 cases per 100,000 people when the population is constrained to obese women
aged between 20 and 44 years.[4]
[5]
For many years, IIH was interpreted as “intracranial hypertension secondary to arterial
hypertension”, and regarded as a manifestation of brain edema due to a variety of
different pathologies, including obstructive sleep apnea, chronic kidney disease,
or connective tissue disorders.[6] Another theory involves impairment of CSF absorption due to overuse of vitamin A
derivatives, antibiotics, and hormonal contraceptives.[7] Other studies highlight the importance of obesity in compromising intracranial venous
drainage as a result of elevated intra-abdominal and right atrial venous pressures.
These increases in pressure hamper cerebral venous return flow, increasing cerebral
venous pressure.[8]
Unlike the cases typically found in the literature, in which around 86% of the patients
with IIH are adult females with an average body mass index (BMI) > 30 kg/m2,[9] the case herein reported is of a boy with normal BMI. However, recent recommendations
do not support the use of BMI as a predictive factor for venous sinus stenosis.[10] Thus, BMI should not be employed as a criteria to select patients for complementary
investigations using angiography by catheter.
In IIH patients, MRI studies reveal empty sella turcica, cerebellar tonsillar herniation,
meningoceles, CSF fistula, and venous stenoses of the sigmoid-transverse sinuses.[11] In the case herein reported, the patient presented distension of the optic nerve
sheath and hyperintensity of the optic papilla. The main goals of the treatment include
reducing the ICP to alleviate the symptoms of headache and preserve vision.[11] Persistent papilledema can develop with progressive optic atrophy, visual disability,
and blindness.
The classic approaches for the management reported in the literature include weight
loss, treatment using a carbonic anhydrase inhibitor (acetazolamide), and serial lumbar
taps, traditionally considered auxiliary measures in the treatment of select cases.[12]
[13] Patients with refractory IIH can be treated by fenestration of the optic nerve sheath
or CSF shunts (ventriculoperitoneal or lumboperitoneal CSF shunting). These procedures,
however, are associated with high rates of complication and recurrence.[12]
Recently, impaired venous drainage systems due to bilateral focal stenosis of cerebral
venous sinuses (generally at the transverse-sigmoid transition) have become the focus
of attention as a possible cause of IIH. Bilateral stenosis of venous sinuses is commonly
associated with the occurrence of IIH, found in more than 50% of the patients. Most
of these cases fail to respond to initial the weight-loss and acetazolamide therapy.
The rates can reach 100% among patients refractory to the initial procedures.[11]
[13]
[14] Whether venous stenosis is a cause or consequence of IIH remains unclear, but studies[11]
[13] show that reducing cerebral venous pressure by implanting stents within the narrow
venous segment is an effective approach to resolve the signs and symptoms of IIH.
In fact, decreasing the intraluminal pressure of the venous system promotes greater
CSF absorption in the arachnoid granulations, in turn reducing the ICP.[11]
[14] This notion was confirmed by Ding et al.[15] in 2014, who showed a reduction in ICP after venous sinus stenting in a patient
with IIH. Akin to the case herein reported, most previous studies[4]
[11]
[16] show pre- and poststenosis sinus pressure gradients. Some reports[4]
[11]
[16] demonstrate the importance of a pressure gradient ≥ 8 mmHg as a criteria for an
indication of sinus stenting – as applied in the case herein presented. Patients with
a pressure gradient between 4 mmHg and 7 mmHg can show some benefit from stenting
in specific cases.[4]
[11]
[16]
Stenosis of the transverse/sigmoid sinus can be classified into two types: intrinsic
discrete stenosis, with clearly demarcated intraluminal narrowing, secondary to arachnoid
granulations, fibrous septa. or fat deposits; and long stenosis narrowing with normal
arachnoid granulations on imaging, secondary to extrinsic compression from swollen
brain parenchyma.[16] Patients with IIH generally present the latter pattern of transverse/sigmoid sinus
stenosis, the same pattern seen in the case reported in the current study.[16]
This stenosis causes a slowing of venous outflow, resulting in venous hypertension.
Consequently, CSF reabsorption is decreased, and ICP is further increased. External
compression of the sinus then increases, with progressive collapse of its walls and
further stenosis, exacerbating venous and intracranial hypertension via a feedback
mechanism.[4]
[13]
The use of venous stents is associated with a significant reduction in venous pressure
gradient across the stenosis site before and after the procedure, as evidenced in
the case herein presented ([Table 1]). Consequently, stent deployment can interrupt the feedback mechanism described
and result in relief of the IIH symptoms.[17]
Currently, there is no evidence suggesting that one type of stenting is superior to
another to treat venous sinus stenosis. Similarly, the benefits of bilateral versus
unilateral stent implantation in transverse sinuses remain unclear. In the present
case, unilateral venous stent implant was performed in the dominant transverse/sigmoid
segment only.[18]
Adjuvant antiplatelet therapy can be administered before stent implantation and maintained
for 3 to 6 months, although there is no consensus on the optimal length of treatment.[11]
[18]
[19] No data are available to support the inferiority of single versus dual antiplatelet
therapy, but thromboembolic complications have been reported with the use of aspirin
alone.[17]
Some complications with the technique have been reported (venous sinus perforation,
stent migration, intra-procedural stent thrombosis, subdural hemorrhage, and development
of further stenoses immediately proximal or distal to the stent), although no complications
were observed in the case herein presented.[12]
[13]
Conclusion
Venous sinus stent implantation is increasingly used for the management of IIH in
the presence of bilateral stenosis of the cranial sinuses. Stent implantation can
widen the narrowed sinus and facilitate venous drainage, thereby reducing intracranial
hypertension. Although long-term follow-up is necessary, several studies show that
stent placement for the management of symptomatic stenoses of transverse-sigmoid sinuses
may be a safe and durable treatment that provides symptom relief in IIH patients.
