Benign Intracranial Hypertension
Case study & Discussion
05 November 2004
History
Ms LP
20 y.o. nurse
PHx Asthma
Smoker 20 / day
Initial Presentation
1995 aged 15
Hx 8/52 of tetracycline for acne
6/52 headaches
4/52 visual obscurations on bending, standing
5/7 diplopia
Examination
Acuity R 6/6 L 6/6
reduced colour vision
fields: increased blind spots
bilateral VIth nerve palsies
other CNs, UL, LL Ex normal
fundi ...
Imaging
MRI / CT Brain Normal
Cerebral venography, manometry, angio: no filling defect, no focal stenosis
SSS pressure 18mmHg, R Transverse sinus pressure prox 17mmHg, distal 6mmHg
Investigations
Lumbar Puncture:
opening pressure 50cmCSF
microscopy, 522 RBC, nil else
FBE, UEC, LFTs, TFTs, ACE normal
Dx: Idiopathic Intracranial Hypertension
Progress
Commenced on acetazolamide 250mg BD
1/12 r/v, headache, diplopia, obscurations all resolved
acuity 6/5 bilat, normal fields, mvmts
disc swelling decreased ..
1 yr r/v: asympt., bilat. 6/5, discs normal
2nd Presentation
4/00 developed episodic blurred vision
bilateral, intermittent, lasting minutes
assoc with coughing, straining
no diplopia, no headache, no tinnitus
no fever or sweats
drugs: salbutamol, flixotide for asthma
Examination
Visual Acuity R 6/5 L 6/5
colour vision normal
gross bilateral papilloedema
pupils, eye movements normal
wgt 93kg (prev 78kg)
field Ex enlarged blind spots
Investigations
LP, difficult
pressure 18cm CSF
CSF acellular, norm. protein & glucose
CT Brain: normal ventricles
no axial or extra-axial lesions
Management
commenced diamox 250mg tds
Review 2/52
less visual blurring, nil other symptoms
fundi, gross oedema R>L
Fields - enlarging blind spots, early arcuate deficits
2nd presentation with IIH
no obvious precipitant
worsening field deficit
no resolution of papilloedema with medical therapy
bilateral optic nerve fenestration
Follow-up
Ceased diamox
Review after 10 days
no diplopia or headache
eccentric pupils
VaR 6/6 VaL 6/6
fields improved
discs ...
Idiopathic Intracranial Hypertension
Raised ICP without explanation
usually obese young women
occasional males, older females
symptoms: headache, nausea, vomiting, visual obscurations
signs: papilloedema, VI nerve palsies
Definition
Modified Dandy Criteria:
1. Signs and symptoms of raised ICP
2. Elevated opening CSF pressure normal constituents
3. Normal neuro Ex (except VIth palsy)
4. Normal CT/MRI of the brain
Aetiology
Associated Factors
Obesity
pregnancy
medications: oral contraceptive pill
tetracyclines
vitamin A
steroid withdrawal
Investigation
In a patient with symptoms of raised ICP or newly diagnosed papilloedema:
urgent CT/MRI Brain and Orbit
Lumbar Puncture
Neuro-ophthal. evaluation
Computed Visual Fields
MRV / Venography
Journal of Neurophthalmology 2000 Mar 20(1); 12-13
review of MRV in 22 cases of IIH in young women
conclusion MRV added nthg to their evaluation, none had evidence of venous thrombosis
MRV of use in atypical cases (ie. Male or older female)
Natural History
Generally a self limiting process
Treatment indicated when:
1. Severe intractable headache
2. Evidence of progressive decrease in visual acuity or visual field loss
Severity of papilloedema doesnt allow severity of visual loss to be predicted
Once the papilloedema resolves the risk of visual loss is no longer a concern
Treatment
MEDICAL
1. Discontinue causative medication
2. Weight loss
3. Acetazolamide
4. Systemic steroids
SURGICAL
5. Optic nerve decompression
6. Lumboperitoneal shunt
7. Repeat LPs
Weight Loss or Diamox?
Johnson et al. Ophthalmology 1998;105:2313-2317
evaluated 48 patients with IIH and selected 15 who had no prev. surgery, or repeated LP
6% wgt loss was assoc with resolution of severe papilloedema
>wgt loss, >resolution of papilloedema
4 pts on diamox, no weight change had no resolution of papilloedema
one patient no diamox, complete resolution of papilloedema
need prospective study with greater power
Optic Nerve Fenestration
First described by de Wecker in 1872
early operations involved lateral orbitotomy
common approach is via the medial side of the globe
Review of ONSF
Kilpatrick et al. Clinical and Experimental Neurology 1980 (p162 - 168)
review of 14 patients post ONSF for IIH
11 bilateral, 3 unilateral
follow-up 4mths to 10yrs: 11 pts sympt free, 3 recurrences
2 recurrences of papilloedema > LP shunt
1 recurrence of headache > medical Mx
Mechanism for ONSF action:
A. local effect to reduce pressure within the subarachnoid space surrounding the optic nerve
B. persistent CSF leak though the optic nerve sheath window
not possible to say how long window remains open
Lumboperitoneal shunts for IIH
Burgett et al. Neurology 1997; 49:734-739
retrospective analysis of 30 patients who underwent LP shunt for IIH
symptoms improved 82%
acuity improved 71% (1 worsened)
perimetry improved 64% (none worse)
Serious complication rate low
30 patients required 126 shunt revisions
mean revision rate 4.2, not even distribution
one required 38 revisions
mean rate 2.5 if 4 outliers were excluded
Mx of Choice
Idiopathic intracranial hypertension given trial of diamox and wgt loss:
with progressive visual loss or field loss, treatment of choice is optic nerve decomp.
progressive visual/field loss and intractable headache treatment of choice is LP