Standardization of the diagnostic process for idiopathic intracranial hypertension (IIH)

In light of a recent consensus article on idiopathic intracranial hypertension (IIH) published in The Journal of Headache and Pain, we spoke to the corresponding authors, Jan Hoffmann and Alex Sinclair. They gave us insights into the main findings of the article, how they aim to help patients with idiopathic intracranial hypertension, and why this disease is so important to study.

Could you please give us a short summary of the most important areas of the consensus article on idiopathic intracranial hypertension?

Headache is an extremely disabling aspect of idiopathic intracranial hypertension (IIH) that dramatically reduces quality of life for these patients over many years.

There is a growing realization that medication overuse is a significant issue in IIH and that the headache phenotype is typically migrainous. Despite the high levels of morbidity from IIH headache, there has been no research into underlying mechanisms or treatment for headache in IIH. This document highlights this important area of morbidity and starts to establish pragmatic steps to improve headaches.

Another important aspect of the guideline is that it provides a clear diagnostic algorithm. Sometimes the diagnostic workup is incomplete, in particular in ruling out secondary causes of elevated intracranial pressure, and may rely on novel methods without considering their limitations or include an un-evidenced practice such as repetitive lumbar punctures without a clear diagnostic or therapeutic strategy. The article aims to standardize and streamline the diagnostic process to improve the time to and the quality of the diagnosis of IIH.

The guideline… shows the need for an interdisciplinary diagnostic approach and therapeutic management in order to tackle IIH.

Thirdly, the guideline aims at providing a clear strategy regarding the therapeutic management of IIH. A vast amount of studies have been published regarding interventional treatments (i.e. stenting of stenoses, CSF diversion, optic nerve sheath fenestration, etc.) without providing the clinician a clear overview of their limitations or a strategy.

Finally the guideline helps the clinician to manage particularly difficult situations where objective studies remain scarce, such as in IIH during pregnancy, where treatment options are very limited.

Why was the consensus article developed? What benefits will it bring to physicians and patients, and what do you hope it will accomplish? 

Diagnosis and management of IIH varies widely internationally and often involves physicians from a number of specialties including neurology, ophthalmology, and neurosurgery. As the incidence of IIH is rising in line with global obesity rates, this condition is presenting more frequently to these physicians. This guideline was developed to help diagnose IIH accurately and standardize the management of patients with IIH, hence improving quality of care.

Another aspect of the guideline is that it highlights the complexity of the disease as well as the highly variable clinical picture and thereby showcases the need for an interdisciplinary diagnostic approach and therapeutic management in order to tackle IIH.

What treatment options are available in idiopathic intracranial hypertension? What current challenges are there?

Currently the only disease modifying treatment in IIH is weight loss. However, this is challenging for patients to achieve and maintain.

A lack of realistic, efficient methods of treatment show that novel approaches and drugs are urgently needed in this disease.

Other options include pharmacological agents such as acetazolamide, which aim to reduce the secretion of cerebrospinal fluid (CSF) in order to lower intracranial pressure. However, the Cochrane review on IIH reported insufficient evidence for the efficacy of these existing drugs. For example, acetazolamide has been shown to be effective in those with mild visual loss, but many patients do not respond to this pharmacological therapy. Furthermore, the drug’s side effects are problematic, with some trials reporting 48% of patients withdrawing from acetazolamide therapy. Novel approaches and drugs are urgently needed in this disease.

For those with rapidly declining fulminant visual loss, CSF diversion surgery can prevent blindness; however, the current CSF shunting techniques have a high revision rate (30-50% per annum) and can lead to additional morbidity from low pressure headaches in up to 30% of patients. Another option is optic nerve sheath fenestration, or venous stenting, but the lack of randomized trials and long-term data results in many uncertainties about the efficacy and safety of these interventions.

What areas of ambiguity does this guideline discuss?

The cut off for lumbar puncture (LP) pressure has been debated in the literature. The diagnostic criteria have a cut off of 25 cm CSF but describe a “grey zone” with pressure between 25 and 30 cm CSF which can be pathological but can also be normal in some individuals.

The ambiguity arises as some patients are found to have slightly elevated CSF pressure, but don’t fulfill the rest of the diagnostic criteria for IIH, and so the elevated CSF pressure can be a coincidental finding. Although there is a cut off value of 25 cm CSF, pressures above this can be normal in some individuals. Therefore, we advise caution when interpreting LP pressure between 25- 30 cm CSF  (and make sure the optic nerve findings are true papilloedema as opposed to pseudopapilloedema) to avoid over-diagnosing IIH.

Tell us more about the process and efforts of getting this document together, who was involved?

This EHF consensus was the result of a cross European collaboration by key opinion leaders in the IIH field with multidisciplinary input. All authors on this consensus paper are either neurologists or ophthalmologists specialized in this condition.

Corresponding Authors:

Jan Hoffmann is a Clinical Senior Lecturer and Honorary Consultant in Neurology, Basic and Clinical Neuroscience at the Institute of Psychiatry, Psychology and Neuroscience, King’s College London, UK

Alex Sinclair is an NIHR Clinician Scientist and Honorary Neurology consultant at the Institute of Metabolism and Systems Research, University of Birmingham, UK

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