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Idiopathic Intrancranial Hypertension
Last updated 5th November 2024
Clinical Features
- Predominantly affects obese young women
- Annual incidence 2-3/100,000, but could be as high as 20/100,000 in obese young women
- Usually presents with progressive headache
- Often with transient darkening of vision and pulsatile tinnitus
- Occasionally leads to permanent loss of vision
Diagnostic Criteria
- Papilloedema
- Normal neuro exam (except 6th nerve)
- Normal neuroimaging (should exclude venous thrombosis)
- Normal CSF constituents
- Elevated LP CSF pressure ≥ 25cm
Ophthalmology Review
- All patients should have dilated fundal examination to grade the severity of the papilloedema and exclude ocular causes for disc swelling
- An assessment should also be made of the imminent risk to their visual function.
- The following should be recorded in the presence of papilloedema:
- visual acuity
- pupil examination
- intraocular pressure to exclude hypotony, a rare cause for disc swelling)
- formal visual field test perimetry
- Ophthalmology are happy to see these patients and advise that we phone the ophthalmology clinic on 33511 for an urgent (usually same day) appointment
Lumbar Puncture
- Following normal imaging and assessment by ophthalmology all patients should have LP to check opening pressure and ensure contents are normal (samples should be sent for routine biochemistry and cell count)
- LP opening pressure should be measured in lateral decubitus position without sedation
- Following needle insertion into CSF space the pressure recording should be made with legs extended. It may take a significant time for pressure equilibration to occur.
- Click here for link to Lumbar Puncture and Neuroaxonal Anaesthesia if patient is taking an antiplatelet or antithrombotic drug as it is important to stop these (apart from aspirin) before undertaking LP.
Increasing Likelihood of Pathologically Raised ICP
Best Way to Induce Remission?
- Weight loss is the only disease modifying therapy
- All patients with BMI >30kg/m2 should be referred to a weight management programme
- The amount of weight required for remission is not known for certain but is probably at least 15%
Best Drug Treatment for Symptoms?
- Acetazolamide (carbonic anhydrase inhibitor) shown to improve headache at 6 months in IIH Treatment Trial,
- Usual starting dose is 250-500mg bd, titrating up to 2g bd if tolerated
- Up to 50% discontinue drug due to side effects eg fatigue, nausea, diarrhoea
May Have More Than One Type of Headache
- Headache attributed to IIH
- Migraine type headache in 2/3 patients
- Medication overuse headache
- Tension type headache
- Headache due to low CSF pressure
- Headache due to iatrogenic Arnold-Chiari malformation secondary to CSF shunting
Role of Therapeutic LP
- Therapeutic serial LPs are not advocated as a long-term treatment strategy for IIH.
- Most patients require an opening pressure measurement only to aid in diagnosis and not removal of CSF. Relief from removing 25mls CSF is short lived as CSF is secreted by choroid plexus at rate of 25ml/hour.
- Despite temporary relief of headache in 75% cases, LPs are associated with significant anxiety in many patients and can lead to acute and chronic back pain.
- In the short term, LP may have a role as a temporary measure to preserve vision in patients with fulminant IIH awaiting a CSF diversion procedure.
How to Arrange LP
- Anaesthetics provide an LP service for challenging lumbar punctures. We advise that medical middle graders do not attempt LP on morbidly overweight young women in AMU.
- Unless vision threatened then it is best to defer LP until a date, time and an operator have been agreed.
- Arrange Ophthalmology review prior to LP unless the diagnosis of papilloedema is very clear or this is a very urgent LP with documented loss of vision / visual fields.
- Check patient is not receiving any oral anticoagulants or anti-platelet treatments which need to be stopped before the procedure (aspirin does not need to be stopped). Please ring anaesthetic dept for advice if in doubt.
- Arrange LP by emailing Anaesthetic Secretaries ([email protected], Ext 33622). In the email please state the reason for LP and any relevant investigations (CT/MRI scans, ophthalmology review). The Secretaries will then liaise with Dr Niranjali Yatiwelle, Consultant Anaesthetist, and contact the patient with a date and time for LP in theatre.
- NB the correct position for obtaining CSF pressure is lateral decubitus with legs extended. If the patient is sitting up or in the lateral decubitus position with the legs curled up there will be a falsely high reading.
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If an LP is required urgently in an inpatient (for example loss of vision / visual fields) contact the on-call anaesthetic team to ask for help.
Links
Idiopathic Intracranial Hypertension: Consensus Guidelines on Management Mollan SP et al. J Neurol Neurosurg Psychiatry 2018; 89: 1088-1100 [pdf]