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Idiopathic Intracranial Hypertension

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Within This Document

Introduction
Incidence
Clinical assessment
Investigations
Causes of secondary intracranial hypertension
Management Algorithm
Treatment
Follow up

Introduction 

Idiopathic intracranial hypertension (IIH), formally known as pseudo tumour cerebri and benign intracranial hypertension, is a disorder of raised intracranial pressure of unknown cause. It commonly presents with headache and clinical findings of papilloedema and elevated cerebrospinal fluid opening pressure (CSF-OP).

This guideline is intended to assist in the appropriate diagnosis and management of children and adolescents with IIH and to help clinicians distinguish those children with secondary causes of intracranial hypertension or other causes of headache, such as migraine.

Incidence

Idiopathic intracranial hypertension is rare with an incidence of 0.5-1.5/100 000 in the paediatric population. Obese pubertal teenage girls have the greatest risk, however younger patients and those with a normal BMI can also be affected.

Clinical assessment

History

The history in any child with suspected IIH should include:

Headache (91%)  o Daily, diffuse, non-pulsatile headache
o Severe in the morning
o Exacerbated by lying flat, valsalva and cough 
Note: Headache is often less prominent in prepubertal children and may be of any type
Visual symptoms  o Diplopia, blurred vision 
o Transient visual obscurations, particularly if precipitated by change in position
o Retro-orbital pain and pain with eye movement 
o Reduced visual acuity and visual field loss are late signs requiring URGENT intervention 
Nausea, vomiting  
Tinnitus (45%)  
Learning/cognitive difficulties, irritability  
Recent rapid weight gain   
Medication history  
Check for symptoms of obstructive sleep apnoea  
Rarely o Hyposmia 
o Rhinorrhea, otorrhea

Examination 

Height, weight, BMI  
Blood pressure  
Pubertal status  
Detailed neurological examination including o Visual acuity
o Eye movements for a unilateral or bilateral lateral rectus (CN VI) palsy
o Visual fields
o Direct fundoscopy

Investigations

Ophthalmology review

A formal ophthalmology review is recommended in all patients suspected of having IIH.

Ophthalmology review should include assessment of visual acuity, formal visual field testing, colour vision, fundoscopic examination and optic disc photos when possible. Visual field defects are present in up to 90% of children at presentation, while up to 30% will have reduced visual acuity.

Papilloedema is difficult to diagnose with 100% certainty using direct fundoscopy alone as optic nerve drusen, optic neuritis and other pathology can have a very similar appearance.

B-scan ultrasonography can be used to detect drusen (although with less sensitivity in the paediatric population) and measure the diameter of the optic nerve sheath. Optical coherence tomography (OCT) and fundus autofluoresence can also detect drusen. These additional modalities should be considered in a child with bilateral papilloedema and few other features to support a diagnosis of IIH.

Imaging

Imaging is required prior to undertaking a lumbar puncture to rule out other causes of increased intracranial pressure and support the diagnosis of IIH.

MRI with MRV is the preferred modality, as cerebral venous sinus thrombosis can present in a similar manner.

MRI findings seen in IIH include:

Lumbar puncture with opening pressure

  1. Preparation
    Involve Play Specialist to prepare patient where possible. Consider analgesia and sedation requirements well ahead of time.
    Location should be low stimulus. Ensure access to a digital disposable manometer where possible
  2. Analgesia
    Suggested process of care is:
    1. Ametop - 45 min prior - clinician to select likely puncture location ahead of time
    2. Infiltrate with generous amount of lignocaine, at least to depth of spinous process. Infiltration of lignocaine can be painful - see Starship guideline on local anaesthesia for minor procedures for a range of techniques to reduce this pain
    3. If lignocaine infiltration is not tolerated, then the use of Entonox during infiltration is suggested
  3. Lumbar puncture
    The child should be in the lateral decubitus position with legs extended if possible. If Entonox has been required for lignocaine infiltration then wait 15 min before performing LP.
    Sedation, including nitrous oxide, general anaesthesia and ketamine may increase opening pressure. Crying and hyperventilation will also increase opening pressure.
    Preferred sedation options include clonidine and midazolam.

    Reference values (90th centile CSF opening pressure)
      Opening Pressure
    Obese child ≥ 28cm H2O
    Sedated child ≥ 28cm H2O
    Non-obese, non-sedated child ≥ 25cm H2O

    A single lumbar puncture with opening pressure should be interpreted with caution as CSF opening pressure values vary minute to minute. There is some evidence that a sub-group of children with opening pressures of 20-28cm H2O AND other clinical features strongly supportive of idiopathic intracranial hypertension (papilloedema, classic headaches, visual symptoms, VIth nerve palsy and/or MRI features) also benefit from treatment. A repeat lumbar puncture, intracranial pressure monitoring, or trial of medication should be considered in these children.

    If the opening pressure is elevated CSF should be removed until it reaches 20-25cm H2O. CSF should be routinely sent for cell count, protein and microscopy +/- cytology.

Causes of secondary intracranial hypertension

Causes of secondary intracranial hypertension include:

Other causes of intracranial hypertension or conditions associated with IIH include:

Medications associated with raised intracranial pressure:


Recommended blood tests (to exclude secondary causes)

Management algorithim

IIH Algorithm
Treatment

Follow-up

References

Document last reviewed: June 2018

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