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Current Practice in Neurosciences Idiopathic intracrnial hypertension -A surgeon's dilemma

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© 2018 Neurology India, Neurological Society of India | Published by Wolters Kluwer - Medknow 1
Current Practice in
Neurosciences
Idiopathic intracrnial
hypertension - A surgeon's
dilemma
George C. Vilanilam, Praksh Nair, Arun Gowda Keelara,
Easwer H. V.
Department of Neurosurgery, SreeChitra Tirunal
Institute for Medical Sciences and Technology,
Trivandru, India
JANUARY 2021
VOLUME 3, ISSUE 1
1
Vilanilam, et al:
Idiopathic intracranial
hypertension Introduction
Idiopathic intracranial hypertension (IIH), is a neurological disorder characterised by
raised intracranial pressure (ICP) that can cause papilloedema with no identifiable cause.[1-
3] Typically described in obese females, other atypical phenotypes are also susceptible. The
characteristic presentations include headaches, diplopia due to abducens nerve palsies,
pulse-synchronous tinnitus, and papilledema causing transient visual obscurations,
blurring, and field defects. Risk of blindness remains a potential threat which mandates
an early diagnosis and efficient management. Despite advances in imaging and diagnostic
modalities, IIH remains an enigma and continues to fascinate clinicians with a plethora
of pathophysiological theories and management options.
Quinke in 1893 first described IIH as ‘serous meningitis’.[1] The term Pseudotumor
cerebri (PTC) syndrome of primary origin was used synonymously with IIH and so
was Benign Intracranial hypertension. The prefix “Benign” was subsequently dropped
upon recognition of the potential risk of blindness in fulminant cases. A unique distinct
entity, IIH without papilledema, has been recently recognized and is characterized by
the presence of an abducens nerve palsy and MRI findings of elevated ICP like an empty
sella, inferior anterior bowing of the posterior globes, distention of the optic nerve CSF
sheaths, optic nerve kinking and tonsillar herniation, all in the absence of papilloedema.[4-6]
Terminology and Denitions
Idiopathic intracranial hypertension (IIH) refers to the syndrome of intracranial
hypertension with normal brain parenchyma but without ventriculomegaly, mass lesion,
or underlying infection or malignancy. Diagnostic criteria for idiopathic intracranial
hypertension have changed since the original Dandy criteria proposed in 1937.[7] The
modified Dandy criteria (1985) by Smith added Computerised Tomography (CT) scan
findings.[8] Digre and Corbett (2001) recommended the exclusion of secondary causes
of raised ICP with CT or MRI, especially venous sinus thrombosis with venography.[9]
Friedman et al.[10] prefer using the umbrella term PTC syndrome (PTCS) which can be
subdivided into primary and secondary PTC. IIH refers to the primary PTC category,
while the secondary PTC group would include other causes [Tables 1-5]. The updated,
modified Dandy criteria [1] and its further revision in 2013 are the commonly used criteria
at present.[5,6,11] (Figure 1). We will be using the term IIH throughout the article to refer
to primary PTC.
Fulminant IIH
Refers to patients having a precipitous decline in visual function within four weeks of
diagnosis of IIH.
Figure 1: MR features of IIH. (a) Vertical kinking of a tortuous optic nerve (arrow). (b) Globe attening and optic nerve
head protrusion (arrow). (c) Perioptic nerve sheath distension (arrow). (d) Partial empty sella (arrow)
d
c
b
a
Vilanilam, et al:
Idiopathic intracranial
hypertension
2
Atypical IIH
Patients meeting the diagnostic criteria of IIH but i) are not females, ii) not childbearing age
iii) who have a BMI below 30 kg/m2. These patients require more in-depth investigation
to rule out other underlying causes.
IIH without papilledema
Refers to a novel subtype of IIH seen in patients who meet all the criteria of definite IIH
but do not have papilledema. Intracranial pressures >25 cm CSF, ancillary evidence like
sixth nerve palsy and MRI imaging features indicating raised ICP are mandatory to make
a diagnosis of IIHwithout papilledema. [Table 1 and Figure 1].
IIH in ocular remission
Patients who have been diagnosed as IIH but in whom papilledema has resolved. These
patients may have ongoing morbidity from headache, but their vision is no longer at
risk as there is no papilloedema.
Table 1: Diagnostic criteria for IIH
Required for diagnosis of IIH
A. Papilledema
B. Normal neurologic examination except for cranial nerve abnormalities
C. Neuroimaging: Normal brain parenchyma without evidence of hydrocephalus, mass,
or structural lesion and no abnormal meningeal enhancement on MRI, with and without
gadolinium, for typical patients (female and obese), and MRI, with and without gadolinium,
and magnetic resonance venography for others; if MRI is unavailable or contraindicated,
contrast‑enhanced CT may be used
D. Normal CSF composition
E. Elevated lumbar puncture opening pressure (250 mm CSF in adults and 280 mm CSF in
children [250 mm CSF if the child is not sedated and not obese]) in a properly performed lumbar
puncture (lateral decubitus)
2. Diagnosis of IIH/without papilledema
In the absence of papilledema, a diagnosis of IIH/pseudotumor cerebri syndrome can be made
if
B‑E from above are satised, and in addition the patient has a unilateral or bilateral abducens
nerve palsy and in addition at least 3 of the following neuroimaging criteria are satised:
i. Empty sella
ii. Flattening of the posterior aspect of the globe
iii. Distention of the perioptic subarachnoid space with or without a tortuous optic nerve
iv. Transverse venous sinus stenosis
Denite IIH. Fullls criteria A‑E.
Probable IIH.A‑D are met but the measured CSF pressure is lower than specied for a denite
diagnosis.
From: Friedman DI, Liu GT, Dirge KB. Revised diagnostic criteria for the pseudotumor cerebri syndrome in
adults and children. Neurology. 2013 Sep 24; 81 (13):1159‑65.
Table 2: Symptom prole
Headache (75‑94%)
Nausea with or without vomiting (72‑75%)
Photophobia, phonophobia, or both (42‑73%)
Transient visual obscurations (68‑72%)
Pulsatile tinnitus (52‑60%)
Back pain (53%)
Dizziness (52%)
Neck pain (42%)
Visual loss or blurring (32%)
Cognitive disturbances (20%)
Radicular pain (19% )
Horizontal diplopia (18% )
Uncommon manifestations
Facial (VII) nerve palsy, hemifacial spasm, or CSF rhinorrhea or otorrhea (conrmation of a
CSF leak in the presence of other supportive criteria highly suggests the diagnosis of PTCS).
Rarely, oculomotor (III) , trochlear (IV) nerve palsy, and generalized ophthalmoparesis
Vilanilam, et al:
Idiopathic intracranial
hypertension
3
Historical Perspective
It was first described by a German physician, Heinrich Quincke as “Meningitis serosain”
in 1893.[1] Nonne[12] in 1904 described a series of patients who presented as if they had an
intracranial mass and named this disease pseudotumor cerebri. In the pre-CT scan and
pre-MRI era, Davidoff and Dyke[13] in 1936 characterized IIH with a normal ventriculogram.
Foley was the first to label it as benign intracranial hypertension in 1955.[6, 11, 14, 15] In 1913,
Passot[16] postulated that IIH was caused by increased CSF volume and could be treated
by drainage of CSF via lumbar puncture. Dandy[7] reported a series of 22 patients in
Table 3: Visual function evaluation
Visual acuity Test each eye separately for the best corrected (with glasses) distance visual
acuity, using Snellen’s chart. Pinhole to correct error due to refractory error
Colour vision Test each eye individually with pseudoisochromatic plates, such as Ishihara’s plates
Pupil examination To exclude a relative afferent pupillary defect and oculosympathetic
palsy (Horner’s syndrome)
Visual eld assessment Assess visual elds (either a Humphrey’s or Goldmann’s), as
confrontational visual elds picks up only gross defects
Dilated fundus examination Document optic nerve head and macular ndings. This is important to
exclude intraocular inammation causing bilateral disc oedema. Slit lamp preferable.
Optical coherence tomography and retinal uorescein angiography can be used for evaluating the
extent of papilledema
Table 4: Secondary causes of raised ICP (Rule out before diagnosing IIH)
Cerebral venous abnormalities
Cerebral venous sinus thrombosis
Bilateral jugular vein thrombosis or surgical ligation
Middle ear or mastoid infection
Increased right heart pressure
Superior vena cava syndrome
Arteriovenous stulas
Decreased CSF absorption from previous intracranial infection or subarachnoid hemorrhage
Hypercoagulable states
Medications and exposures
Endocrine disorders
Addison disease Hypoparathyroidism, Cushing’s, Hypothyroidism
CSF hyperproteinaemia/hypercellularity (Example‑Spinal cord tumour/meningitis/Guillain‑Barré
syndrome/subarachnoid haemorrhage)
Hypercapnia
Sleep apnea
Pickwickian syndrome
Anemia
Renal failure
Turner syndrome
Down syndrome
Table 5: Drugs causing Pseudo‑tumor cerebri syndrome (secondary PTC)
Antibiotics Tetracycline, minocycline, doxycycline, nalidixic acid, Nitrofurantoin,
Sulphonamides, like trimethoprim
Vitamin A and retinoids Hypervitaminosis A, isotretinoin, all‑trans retinoic acid for promyelocytic
leukemia, excessive liver ingestion
Hormones Human growth hormone, thyroxine (in children), leuprorelin acetate,
levonorgestrel (Norplant system), anabolic steroids
Withdrawal from chronic corticosteroids
Lithium
Nitrofurantoin Beclometasone Sulphonamides, for example, trimethoprim Cimetidine Nalidixic
acid Lithium
Tamoxifen
Non‑steroidal anti‑inammatory drugs
Vilanilam, et al:
Idiopathic intracranial
hypertension
4
1937 with symptoms of increased intracranial hypertension. He proposed the earliest
diagnostic criteria and was struck by the normal ventricular volumes demonstrated on
ventriculography. He suggested intracranial pressure was due to increased intracranial
uid volume caused by increased CSF or increased intracranial blood.[14] In 1959 when
Sahs reported intracellular and extracellular cerebral edema in patients who had brain
biopsies and proposed that IIH was due to cerebral edema.[6, 11]
Epidemiology
The annual incidence in adults and children has been estimated to be 1.6– 2.22 and 0.5–0.95
per 1, 00 000, respectively. [2,10] In obese females the incidence rises to 13-19 per 100,000.
The incidence in males is much less, approximately 0.3 per 100,000. The male to female
ratio in the average incidence of IIH in adults is 1:8. About 60-70% of patients with IIH
have associated obesity. Women who are obese (Body mass index, BMI >30 kg/m2) and
in the child bearing age have a higher incidence (5·49 per 100 000). Mean age at diagnosis
ranges from 25-36 years. [2,4-6]
Pathophysiology
The pathogenesis of IIH has been unclear and elusive, thereby inexplicable by a unified
hypothesis. [6,11,14,17-20] Three mechanisms that are central to the theories are excessive CSF
production, impaired CSF absorption and venous hypertension.
a. CSF hypersecretion
Craniospinal CSF is about 150 ml in volume and is replaced about 3 to 4 times a day.
The choroid plexus is the key source of CSF production. CSF is produced through a
Na+ /K+ ATPase channel transporting Na+ to the CSF space with osmosis of water
through aquaporin-1 channels. Carbonic anhydrase enzyme is vital in the Na+ passage
through the production of protons and bicarbonate ions. The hypersecretion theory
was earlier supported by CSF infusion studies but later disproved by a larger series and
non-corroborative MRI findings.[3,18]
b. Impaired CSF drainage
The CSF ows through the natural ventricular pathway and is absorbed by the arachnoid
granulations. The glylymphatic system and the perivascular lymphatics contribute to the
CSF outow. In the arachnoid granulations, the CSF passes via ow dependent vacuoles
determined by the pressure-gradient.[6,11] An increased resistance to CSF absorption
impairs CSF outow. MRI dynamic phase contrast showed decreased jugular ow in
IIH along with altered spinal cord compliance.[17] With the prospects of decreased venous
ow, current research focuses on the pathology of the venous outow system.
c. Elevated venous pressure
IIH patients had a significantly higher incidence of bilateral sinus stenosis (or unilateral
sinus stenosis with a hypoplastic contralateral sinus). MRV is an acceptable test for venous
stenosis, yet a diagnostic angiogram and venogram is the gold-standard. Controversy
exists on whether venous stenosis is a primary cause of IIH or a secondary manifestation
of the IIH. Buell et al.[21] (using CSF manometry and venous sinus pressure measurements)
proved that the increased pressure gradient causes lower venous sinus-CSF gradient,
eventually resulting in decreased CSF resorption.[11,20]
d. Other theories and the role of obesity, hormones
Increased abdominal girth increases intra-abdominal pressure, subsequently increasing
the venous pressure in the spinal canal, is another postulation.[22,23] Another theory
proposes that IIH is a manifestation of the pro-inammatory effects of the cytokines
secreted by adipose tissue.[24] The increased inammation is postulated to scar the
arachnoid villi of the dura, resulting in overall decreased CSF absorption. Cytokines which
are specifically produced by adipose tissue and markers of inammation were present in
the CSF of patients with idiopathic intracranial hypertension, with the concentration of
chemokine (C-C motif) ligand 2 being significantly higher than that of controls. Added
proof was the detection of high concentrations of leptin, a product of the obesity gene
(Ob) which is involved in weight homoeostasis and appetite regulation in the CSF of
patients with IIH. [25]
Vilanilam, et al:
Idiopathic intracranial
hypertension
5
As women of childbearing age were more at risk for IIH, hormonal factors might play
a role in pathogenesis, although the evidence to support this hypothesis is currently
observational. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is an enzyme
that regulates local, tissue specific glucocorticoid availability by acting mainly as an
oxo-reductase, converting cortisone to active cortisol. This has been postulated to have
a role in obesity associated IIH as 11β-HSD1 activity is associated with a significant fall in
ICP, and a rise in CSF cortisone is associated with weight loss. [6,11,26,27] Venous hypertension
caused by hypercarbia has also been implicated in IIH associated with obstructive sleep
apnoea.[3,22] Similarly, excess of Vitamin A and retinoids can cause increased aquaporin
expression resulting in cerebral edema and thereby IIH.[5]
Symptom Prole
The common symptoms of IIH include headache, vomiting, photophobia and visual
blurring. Rarer symptoms are pulsatile tinnitus, back pain, dizziness, neck pain, cognitive
disturbances, radicular pain, and uncommon symptoms like CSF rhinorrhea, facial
paresis, and ophthalmoplegia [Table 2].
Based on symptom severity and visual dysfunction, patients may present in the following
manner:
a) Those who rapidly lose vision at diagnosis over days to weeks (rare but vital to
identify early);
b) Those whose disease resolves following diagnosis, over weeks to months, occasionally
after a single lumbar puncture (LP)(rare);
c) Those at lower risk of visual loss who develop chronic disease with small uctuations
in disease activity, frequently with weight changes (the majority); and
d) Those in disease remission and off treatment.
Differential Diagnosis
A detailed evaluation is essential to rule out IIH mimicks like structural, endocrine,
nutritional, medicinal, and genetic disorders.[4,9,28,29] [Table 4]
Investigations
a. CSF manometry
A LP with an elevated CSF pressure is required for the diagnosis of definite PTCS.
CSF pressure on LP >250 mm water in adults and >80 mm of water in children
(250 mm CSF if the child is not sedated and not obese) is essential to establish the
diagnosis. The CSF manometry is prescribed in the lateral decubitus position and the
base of the manometer be level with the right atrium without sedation. A closing pressure
is also measured to document the reduction of intracranial pressure to a normal level.
A small volume of CSF should be sent for analysis to rule out abnormalities of routine
CSF parameters. [28,29]
If LP in presence of typical symptoms shows a normal or low opening pressure, a repeat
LP or continuous CSF pressure monitoring by a lumbar drain or ICP monitor—with
demonstration of B and plateau waves suggestive of elevated ICP may be needed to
confirm the diagnosis
b. Imaging
Imaging of the brain is crucial to rule out a structural pathology [Figure 1]. Additionally,
certain subtle signs of IIH are characteristic on MRI and help in confidently establishing
the diagnosis.[14, 17,20] These features include an empty sella, deformed pituitary gland
(occupying less than 50% of the fossa with an upper concavity), slit-like ventricles, vertical
tortuosity of the optic nerve tight sulcal and cisternal subarachnoid spaces, attening
of the posterior aspect of the optic globe with outward convexity of the globe in severe
cases, distension of the optic nerve sheath (width greater than 2 mm), enhancement of
the optic nerve and tonsillar herniation. Among these the most sensitive were optic nerve
sheath distention, pituitary compression, and globe attening at 66.7%, 53.3%, and 43.3%,
respectively, but the most specific were slit-like ventricles, optic nerve enhancement, and
empty sella at 100%, 98.2%, and 94.6%, respectively.[20] Focal narrowing of the dural venous
Vilanilam, et al:
Idiopathic intracranial
hypertension
6
sinuses typically near the junction of the transverse and sigmoid sinuses is reported
commonly on MRV. Additionally, MRV is performed to detect cerebral venous sinus
thrombosis in atypical patients. Recent reports have suggested narrowing of Meckel’s
cave and the cavernous sinuses on MRI and foramen ovale widening on CT.[14,20]
c. Visual assessment
Visual acuity, field, pupil, fundus assessment and optical coherence tomography (OCT)
are ideally done as part of the work up. [Table 3 and Figures 2, 3] OCT utilizes waveform
interference of reected low coherent light to create a 3D representation of the retinal
layers with an analysis of tissue thickness. It can be used to accurately measure the retinal
nerve fiber layer (RNFL) thickness around the optic disc. [30,31]
Treatment
Early diagnosis and effective therapy is the key to successful management of
IIH.[3,26,32-34] Treatment goals are primarily preservation of vision and symptom relief
[Table 5 and Figures 4-6].
Medical Management
The first-line treatment for IIH focuses on lifestyle changes and pharmacological
interventions. Weight loss and a low-sodium diet are a conservative method of reducing
symptoms. A modest reduction in weight in the range of 6% may cause good relief of
symptoms. Medical management consists of carbonic anhydrase inhibitors that reduce
CSF production, the most common being acetazolamide.[32] Frusemide can also be added
in selected cases if needed. Corticosteroids may also be given to initially quickly lower CSF
pressures, but long-term use is not recommended and there may be a rebound effect upon
discontinuation. Topiramate may be useful in those with side effects of acetazolamide
like fatigue, paresthesias, and kidney stones.[26,27]
Surgical Intervention
Surgical intervention should be considered for those who are at immediate risk of vision
loss and have medically refractory symptoms. Currently, the surgical options for IIH
are optic nerve sheath fenestration (ONSF), CSF diversion (lumboperitoneal shunt or
ventriculoperitoneal shunt), venous sinus stenting (VSS) and bariatric surgery.[36,37] The
choice of procedure is often dependent on local expertise and experience. Generally, CSF
shunts are recommended in cases where headaches are the dominant symptom, while
ONSF is advocated in patients in whom visual loss is the principal concern. Venous sinus
stenting is the most recently developed procedural option for the treatment of IIH and
Figure 2: Fundus photographs and Optical coherence tomogram (OCT). (a and b) Normal fundus and normal retina in
OCT. (c and d) Fundus showing papilledema and edematous retina in OCT. INF: Inferior, NAS: Nasal, RNFL: Retinal
nerve bre layer, SUP: Superior, TMP: Temporal
d
c
b
a
Vilanilam, et al:
Idiopathic intracranial
hypertension
7
has shown encouraging outcomes. Morbidly obese patients are regarded as candidates
for bariatric surgery.
There are no established evidence-based guidelines regarding the surgical treatment
options for IIH. Prospective studies and systematic reviews on surgical treatment options
Figure 5: Endoscopic right optic nerve sheath fenestration. The sheath is being cut with scissors
Figure 3: Perimetry for eld charting. (a) Humphrey perimetry –Showing left nasal eld cut and right enlarged blind
spot in an IIH patient. (b) Goldmann’s perimetry showing asymmetric central eld loss and enlarging blind spot in IIH
b
a
Figure 4: Venogram. (a) Stenosis at transverse-sigmoid junction (arrow). (b) Resolution of stenosis post stenting
(arrowheads)
b
a
Vilanilam, et al:
Idiopathic intracranial
hypertension
8
for IIH are scant and only three systematic reviews have been published so far.[35-37] One
RCT in the US is currently enrolling patients (ClinicalTrials.gov Identifier: NCT02513914),
results of which are awaited.[38] A systematic review of the surgical interventions for
IIH published by Kalyvas et al in 2020 is the most recent and comprehensive review on
surgical options for IIH.[35] This systematic review draws data from 109 observational
studies including 3 prospective, 75 retrospective studies and 31 case reports.
a. CSF diversion procedures
These are often the surgical therapy of the first choice in the event of failed medical therapy
and rapid visual deterioration. Serial lumbar punctures have been used for symptomatic
control but often as a temporary measure. The most common form of CSF diversion in
IIH is CSF shunting through either a Lumboperitoneal/Thecoperitoneal shunt (LPS) or a
Ventriculoperitoneal shunt (VPS). The slit-like ventricles make VP shunts technically difficult
but with lower failure rates than LPS. VPS malfunction rates range from 20%-40%.[35,37] Up
to 82% of patients can have a resolution of increased ICP symptoms and improvement in
visual acuity can be noted in up to 71% of patients. [39] Revision rates for LPS are higher.[35,37]
b. Optic nerve sheath fenestration (ONSF)
ONSF aims to prevent the most serious morbidity, visual loss. A window or a series of
small slits are made in the retrobulbar optic nerve sheath to drain CSF and decrease the
optic nerve edema to prevent visual loss. [Figure 4] This can be performed by an open
front orbital /pterional craniotomy or an endoscopic approach. When performed in a
single eye, the contralateral eye has been shown to have an improvement in papilledema
suggesting that the primary physiology might involve local decompression of the
subarachnoid space. Though meant primarily for the preservation of ophthalmologic
function, it has also shown to the improvement of headache in more than 50% of
patients.[36] At one-year and three-year follow-up, ONSF has significant failure rates of
34% and 45%, respectively.[35, 37, 39] Adverse events include hemorrhage, retinal artery
occlusion, neuropathy, or ophthalmoplegia. Fonesca et al.[39] compared ONSF (n=14)
with CSF diversion (n=19) in a retrospective chart review of patients with IIH. No
significant difference in visual acuity grades was recorded between the groups, but
the visual field grades were significantly better in the CSF-shunted patients than in
the ONSF group.
Figure 6: Management algorithm
Vilanilam, et al:
Idiopathic intracranial
hypertension
9
Table 6: Treatment outcomes in IIH
Treatment Author (year),
number of
patients
Visual Outcome Symptoms/Signs
outcome
Adverse events
Acetazolamide Wall
et al (2016)
IIH treatment
trial 165
Improved Improvement in CSF
opening pressure and
papilledema
Fatigue, paresthesias,
renal stones
Lumbo
peritoneal shunt
Sinclair
et al (2011) 53
Improved in 90% Headache
improved ‑ 71%
Papilledema
improved ‑ 90%
Infection, malfunction
Optic Nerve
sheath
fenestration
Alsuhaibani
et al (2011) 78
Bilateral
improvement
in unilateral
procedures, but
short lived
Headache also
relieved (43%)
Optic nerve injury
Venous sinus
stenting
Dinkin
et al (2019)
(Meta‑analysis)
808
Improved in 74% Papilledema
improvement ‑ 49%
Stent thrombosis,
migration
Bariatric
Surgery
(Laparoscopic
gastric banding
or bypass)
Fridley
et al (2011) 126
Visual
improvement in
90%
Signicant relief of
papilledema
Anastomotic leak
The SIGHT trial is an ongoing randomized control trial with three treatment arms:
medical therapy with diet and acetazolamide, ONSF plus medical and diet therapy, and
VP shunting with medical and diet therapy.[38]
c. Venous sinus stenting
Stenting of dural venous sinus stenosis [Figure 5] is an alternative or adjunct to CSF
shunting and optic nerve sheath fenestration in medically refractory IIH patients
with vision loss debilitating symptoms. Venous stenosis was first described by King
et al. in 1995 using venography and manometry in IIH.[40] Higgins et al. did the first
venous stenting in 2002 in a young female with refractory IIH.[41] The pathophysiology
involves improved CSF resorption through the arachnoid villi after a decrease in venous
stenosis. Bilateral transverse sinus stenosis is prevalent in 90% of IIH patients.[6,11]
Normal gradients between the superior sagittal sinus (SSS) and the jugular bulb range
between 0 and 3 mm Hg in healthy patients. Those with ‘favourable’ outcomes had a
higher mean pre-stent trans-stenosis gradient (TSG) of 22.8 mm Hg (vs 17.4 mm Hg
in those with unfavourable results) and a higher chance in the TSG of 19.4 mm Hg
(vs 12.0 mm Hg).[42,43]
d. Other adjunct procedures
Bariatric surgery could be used to treat IIH due to resultant weight loss and possible
reduction of cerebral venous pressures due to decreased intra-abdominal pressures.[44]
Since the positive effects of bariatric surgery take time to manifest, it would not be an
effective first-line option in patients with rapid visual dysfunction. In addition, there
are risks associated with bariatric surgery including band migration, anastomosis leak,
gastric stenosis, dumping syndrome and malnutrition.[27,35,44]
Special Situations
Pregnancy
Acetazolamide is best avoided in the first trimester though it is not known to be
teratogenic. The weight gain during the pregnancy is 5-9 kg (0.22 kg/week in the
second and third trimester) in those with a starting BMI of ≥30 kg/m2. There is no
contraindication due to IIH for a normal vaginal delivery. [2-4] When there is compromised
optic nerve function, a prolonged second stage of labour is best avoided. Epidural and
spinal anaesthetic during labour (even with a shunt in situ) is permissible. Serial LPs
Vilanilam, et al:
Idiopathic intracranial
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10
can be done as a temporizing measure in the first trimester till CSF diversion is planned
in the second.
Pediatric IIH
Childhood IIH is commoner after the age of 7 years where it is twice as common in girls
and more so in the overweight and obese. Obesity has been associated with more than
80% of cases aged 12–15 years.[45] The incidence increases eightfold from that in 1–6
years to that in 12–16 years.[19, 45, 46] Dysregulation of glucocorticoid signalling can alter
ICP dynamics and cause elevation of ICP in obese children.[47] The mechanisms of IIH in
non-overweight younger children remains unclear. Recent diagnostic criteria have been
established specifically for children with IIH, including a different normal range of ICP in
children. Treatments may include weight loss, carbonic anhydrase inhibitors, or surgical
procedures.[18, 19] The visual prognosis of children treated appropriately is generally good.
Spontaneous CSF leaks and IIH
Spontaneous CSF rhinorrhea or otorrhoea should raise a high index of suspicion of IIH.
CSF diversion procedures and venous sinus stenting have been reported to have cured
spontaneous CSF leaks without other reparative procedures.[33]
Prognosis and Outcome
Visual fields are typically involved first while color vision and acuity are not affected
until later [Table 6]. [5,11,32,47] Color vision was impaired in 17% and abnormal acuity was
seen in 14% of patients with IIH.[35,38] Severe visual impairment or blindness involving at
least one eye is present in 25% of patients on long-term follow-up.[4,6,27]
Nonverbal memory, executive function, visual-spatial processing, attention, motor skills,
problem-solving, and information processing speed are impaired and do not improve
much with treatment.[4,6]
A large systematic review of surgical outcomes showed papilledema improving in 95%
of cases following CSF diversion. LP and VP shunting resulted in improvement in visual
fields in 71% and 69% of cases, respectively, and papilledema improved in 91% and 90%
of cases, respectively.[35] Improvement in headache occurred in 41% of cases treated with
ONSF compared with 96% and 93% of those treated with LPS and VPS, respectively.
Recurrence is reported in 15% to 67% of cases.
Conclusions
Early diagnosis and prompt effective treatment are crucial in the management of
Idiopathic Intracranial hypertension. No single theory describes its pathophysiology
appropriately and therefore, treatment options are varied. The aim of early therapy
is to preserve vision and control debilitating symptoms. There are no established
guidelines or Level 1 evidence to give an edge to any particular surgical procedure in
IIH. Multi-disciplinary care involving the neurologist, ophthalmologist, neurosurgeon
and radiologist, is the key to efficient management.
The simple and ubiquitous LP shunt offers remarkable symptom relief with headaches
and visual dysfunction. ONSF is effective for those with predominantly visual symptoms,
as an adjunctive procedure or those with failed CSF diversion. Good prognosis for visual
recovery has been seen in 60-80% patients with early diagnosis and effective treatment.
Venous sinus stenting at the transverse sigmoid junction is the new evolving therapy
with early promising results.
Our Approach to Patients with Suspected IIH
We confirm the diagnosis of IIH with a detailed clinical evaluation and workup, involving
CSF manometry, visual evaluation and imaging. Medical management and weight loss
is the preferred first option, to stabilize the symptoms and preserve vision in a vast
majority of patients. Surgical options are considered for patients with medically refractory
headache, without/with progressive visual loss or those with only progressive visual
symptoms [Table 7].
Vilanilam, et al:
Idiopathic intracranial
hypertension
11
Lumbo peritoneal shunt is the preferred first option for those with debilitating headaches
without/with progressive visual loss. VP shunts are reserved for those with recurrent
LP shunt malfunctions. If visual dysfunction predominates (over headache), then ONSF
(endoscopic, bilateral) is done additionally, on follow up. For progressive visual loss after
LP shunts, ONSF is considered after ruling out a shunt malfunction. At our centre, one
patient underwent a combined LP shunt and ONSF at the same setting, due to fulminant
progressive visual dysfunction . There was remarkable recovery of visual function.
Venous sinus stenting is currently used very sparingly, only after a failed LP shunt and
ONSF, and provided intrinsic venous sinus stenosis has been documented. Based on the
available expertise, experience, and best practice evidence, every centre should establish
its protocol to effectively care for patients with IIH.
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Table 7: Merits and demerits of different surgical options
Option Clinical indications Merits Demerits
CSF diversionHeadache and
progressive bilateral
visual loss
Easily available,
ubiquitous
procedure
Shunt malfunction, infection
Difcult ventricular cannulation (VP
shunt)
ONSF Vision loss predominant
symptom
Asymmetric papilledema,
Failed CSF diversion
Good improvement
of visual symptoms
Headache also
improves
Endoscopic technique‑Steep
learning curve
Venous Sinus
stenting
Failed CSF diversion
and ONSF (with sinus
stenosis and trans sinus
gradient)
Good symptom
relief with intrinsic
sinus stenosis
Expensive hardware
Need for anti‑coagulation
Procedural learning curve
Bariatric
surgery
Adjunct procedure for
morbid obesity (Not a rst
line primary procedure
for IIH)
Improves other
obesity related
morbidities
Laparoscopic procedures‑Steep
learning curve,
Not easily available at peripheral
centres.
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Article
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There is increasing evidence and appreciation of idiopathic intracranial hypertension (IIH) in medicine. The pathological processes underlying raised intracranial pressure are being studied, with new insights found in both hormonal dysregulation and the metabolic neuroendocrine axis. These will potentially lead to novel therapeutic targets for IIH. The first consensus guidelines have been published on the investigation and management of adult IIH, and the International Headache Society criteria for headache attributable to IIH have been modified to reflect our evolving understanding of IIH. Randomized clinical trials have been published, and a number of studies in this disease area are ongoing.
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Idiopathic intracranial hypertension is a condition of raised intracranial pressure of unknown cause. Features include new onset headache, which is frequently non-specific; papilloedema is present, visual disturbances are common; and there may be sixth nerve palsy. Diagnosis includes brain imaging with venography to exclude structural causes and venous sinus thrombosis. Lumbar puncture reveals pressure greater than 250 mmCSF with normal constituents. Treatments aim to modify the disease, prevent permanent visual loss and manage headaches. These include weight loss. For those with rapid visual decline, urgent surgical intervention is essential. For most, this is a chronic condition characterised by significantly disabling headaches.
Article
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Article
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Idiopathic intracranial hypertension (IIH) is a functionally limiting disorder secondary to increased intracranial pressures (ICPs) with a prevalence of one per 100,000 persons. It is estimated to cost >$400 million per year in productively. Symptoms classically consist of chronic headaches, papilledema, and visual loss. The pathophysiology is unknown but postulated to involve increased resistance to cerebrospinal fluid (CSF) absorption. Traditional treatments involve weight loss, acetazolamide, CSF diversion, or optic nerve fenestration. More recent technology has allowed exploration of venous sinus stenosis. Through venous sinus stenting (VSS), the ICPs and venous sinus pressures decrease. After treatment, >75% exhibit an improvement in headaches, ~50% improvement in tinnitus, and ~50 % improvement in ophthalmologic testing. Complications are rare but involve stent stenosis, femoral pseudoaneurysm, and hemorrhages. Future studies will look into controlled studies for VSS as well as expansion to other venous structures of the intracranial circulation.
Article
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Article
Idiopathic intracranial hypertension (IIH) is a condition in which elevated pressure in the cerebrospinal fluid can lead to optic nerve head (ONH) dysfunction and subsequent visual impairment. Physicians are currently limited in their ability to monitor and manage this condition, as clinical symptoms and exam findings are often delayed in response to changes in intracranial pressure. In order to find other biomarkers of disease, researchers are using imaging modalities such as optical coherence tomography (OCT) to observe microscopic changes in the eye in this condition. OCT can create 2-dimensional and 3-dimensional high definition images of the retina of the ONH and has been used to study various conditions such as glaucoma and multiple sclerosis. Numerous studies have used OCT in IIH as well, and they have shown that certain retinal layers and the ONH change in thickness and shape in both the short and long term with intracranial pressure changes. OCT is a promising modality for clinical and scientific evaluation of IIH as it is a noninvasive and practical tool to obtain in depth images. This review will discuss how OCT can be used to assess a patient with IIH, both before and after treatment, along with its limitations and future applications.
Idiopathic intracranial hypertension (IIH) is a syndrome of unknown cause that is increasing in frequency. Patients who are typically women of childbearing age and obese present with headaches and may also present with visual changes that may become chronic. The purpose of this review is to describe the possible mechanisms for this disease and also to illustrate the ever increasing role of imaging in the diagnosis of this disorder. In addition, the various methods of treatment including medical and surgical will be reviewed. The fact that idiopathic intracranial hypertension has undergone many name changes over the years serves as a reminder that the underlying mechanism is still not well understood. Although there are only several possible mechanisms that can cause increased intracranial pressure, it is still not certain which of these mechanisms is involved. The role of imaging has significantly changed in the evaluation of patients with possible IIH. First, it is involved in ruling out secondary causes of increased intracranial pressure. In addition, there is now ample evidence that the previously held belief that imaging of patients with IIH should be normal is incorrect but rather that there are several subtle findings that radiologists need to look for. These findings include a partially empty sella, flattening of the posterior globe, cupping of optic disks and distension of the optic nerve sheaths. In addition, the role of intracranial venography is playing an ever increasing role due to the finding that a very high percentage of patients have dural venous sinus stenoses. It is becoming clear that there is potentially true morbidity associated with idiopathic intracranial hypertension. The earlier the disease can be diagnosed, the earlier treatment can be started to minimalize permanent visual changes including blindness. Treatment varies from institution to institution due to the fact that multiple specialists with different perspectives treat these patients. Knowledge of subtle imaging features associated with idiopathic intracranial hypertension can help radiologists establish the diagnosis earlier and potentially prevent complications of this disorder. However imaging has not as of yet been shown to be beneficial in managing patients with idiopathic intracranial hypertension.
Article
Background and purpose Idiopathic intracranial hypertension (IIH) is positively associated with obesity, mostly in young women. The global increase in obesity may influence the burden of IIH. Methods Using PubMed, Embase, Medline and Web of Science databases a meta‐analysis and systematic review of epidemiological studies of IIH were performed up to June 2017. Temporal changes in IIH incidence were measured and incidence rates of IIH were correlated with country‐specific World Health Organisation obesity rates. Prevalence data and shunting rates of IIH were recorded. The quality of epidemiological studies was assessed using the STandards of Reporting Of Neurological Disorders (STROND) criteria. Results In 15 identified studies there were 889 patients (87% women), mean age 29.8 years. The incidence of IIH ranged from 0.03 to 2.36 per 100,000 per year. Pooled incidence of IIH was 1.20 per 100,000/year although there was very high heterogeneity (I² 98%). The incidence rates of IIH were correlated with country‐specific prevalence of obesity (Spearman's correlation 0.82, p <0.01). Prevalence of IIH was rarely recorded. A shunting procedure was reported in 8% of patients. STROND criteria were variably reported, median of 26.5 of 43 (range 16 to 35). Conclusions IIH is a public health concern as increased obesity prevalence is associated with increased incidence of IIH. Better quality of epidemiological studies is required to improve understanding of IIH and inform health policy for IIH management. This article is protected by copyright. All rights reserved.
Article
We report a case in which an intracranial dural arteriovenous fistula (DAVF) developed after endovascular treatment of a patient with idiopathic intracranial hypertension with venous sinus stenting (VSS). The pathogenesis may involve hemodynamic alterations secondary to increased poststenting venous sinus pressure, which may cause new arterial ingrowth into the fistulous sinus wall without capillary interposition. Despite administration of dual antiplatelet therapy, there may also be subclinical cortical vein thrombosis that contributed to DAVF formation. In addition to the aforementioned mechanisms, increased inflammation induced by VSS may upregulate vascular endothelial growth factor and platelet-derived growth factor expression and also promote DAVF pathogenesis. Since VSS has been used to obliterate DAVFs, DAVF formation after VSS may seem counterintuitive. Previous stents have generally been closed cell, stainless steel designs used to maximize radial compression of the fistulous sinus wall. In contrast, our patient’s stent was an open cell, self-expandable nitinol design (Protégé Everflex). Neurointerventionalists should be aware of this potential, although rare complication of DAVF formation after VSS.
Article
Introduction: Headaches, visual problems and tinnitus are symptoms of Idiopathic Intracranial Hypertension (IIH) which resolve with reduction of CSF pressure. Impaired cranial venous outflow has been implicated in the pathogenesis and there is evidence of good treatment results in IIH using venous sinus stenting. We are currently initiating a multi-centre randomised controlled trial, the VISION study (Venous Intervention versus Shunting in IIH for Optic Disc Swelling) comparing radiological (venous sinus stenting) to surgical intervention (CSF shunting). As part of the preparations for VISION we made a basic questionnaire available to members of the website IIH UK (www.iih.org.uk). Methods: 10-point questionnaire pertaining to IIH diagnosis, symptoms and management using www.surveymonkey.com. Results: 250 questionnaires were returned. 95.6% of respondents were female, mostly ≤40 years of age. 70% were diagnosed in the last 5 years, but only 35% were diagnosed less than a year after onset of symptoms. 59.4% of patients had not undergone any radiological/surgical intervention, 34.9% had had CSF diversion, 3.6% venous stenting and 2.0% had stent plus shunt. 16.8% indicated their lives were most affected by tinnitus and 18.1% by visual problems, but 49.6% said they were most affected by their headaches. 81% of patients indicated they would be happy to participate in a randomised trial comparing the two treatment options of venous stenting and CSF shunting. Conclusion: IIH patients want to be actively involved in their treatment and are favourably disposed towards clinical research. Variation exists in treatment modalities offered. There are individual differences regarding impact of symptoms.