We identified references for this Review through searches of PubMed from Jan 1, 1955, to March 16, 2015, with the terms “idiopathic intracranial hypertension”, “pseudotumor cerebri”, “intracranial hypertension”, “papilledema”, “idiopathic intracranial hypertension without papilledema”, “spontaneous intracranial hypotension”, “CSF hypovolemia”, and “CSF leak”. We identified additional references by manually searching journals and relevant articles. We only reviewed articles published in English
ReviewHeadache arising from idiopathic changes in CSF pressure
Introduction
New-onset headache can have various causes, including disorders of intracranial pressure (ICP).1 Headache is the most common—and often the presenting—symptom of both intracranial hypertension and intracranial hypotension syndromes. These syndromes can be either symptomatic or idiopathic, with no clear identifiable cause. Most causes of intracranial hypertension are life-threatening (panel 1), so clinical investigations are always urgent, including those for patients presenting with isolated headaches. In symptomatic intracranial hypertension or hypotension, treatment of the underlying disease often results in improvement of headaches, the specific management of which is not addressed in this Review. Sometimes, the only identified cause of headache is an idiopathic change in CSF pressure: an increase in CSF pressure, in association with papilloedema, is used to define idiopathic intracranial hypertension, while a decrease in CSF pressure defines spontaneous intracranial hypotension. Diagnosis of these conditions can be challenging. Many cases present with isolated headaches, normal examination—except for papilloedema in the case of idiopathic intracranial hypertension—and normal brain imaging.
If left untreated, idiopathic intracranial hypertension and spontaneous intracranial hypotension can reduce quality of life and cause serious complications, including blindness for idiopathic intracranial hypertension and coma for spontaneous intracranial hypotension. In this Review, we describe the pathological mechanisms, clinico-radiological features, and management of headache arising from CSF pressure changes related to idiopathic intracranial hypertension and spontaneous intracranial hypotension.
Section snippets
Physiology of intracranial pressure and CSF
Pressure within the brain parenchyma is equal to the pressure in the intracranial extra-axial spaces, including the ventricular and subarachnoid spaces, which contain CSF. Normal CSF pressure is equal to ICP, varies from 60 to 250 mm H2O in healthy adults, and fluctuates during the day because of many factors. According to the Monro-Kellie doctrine,2 because bone is rigid, the volume of the intracranial and spinal canal spaces must remain constant: a volume change in one constituent must be
Pathological mechanisms of changes in CSF pressure
Volume increase of any intracranial constituent (eg, brain parenchyma, blood, or CSF) above the threshold of compensatory mechanisms will result in increased ICP (panel 1). Similarly, CSF hypovolaemia reduces ICP.5 Uncompensated ICP changes can cause headache through traction on pain-sensitive structures, including intracranial large blood vessels and nerves.
Potential pathological mechanisms of idiopathic intracranial hypertension have been reviewed previously.6 Classic mechanisms include
Suspected headache secondary to change in CSF pressure
Most patients presenting with headache as the chief complaint have a primary headache disorder, such as migraine or tension-type headache, the diagnosis of which relies on strict diagnostic criteria in the absence of any objective marker.1 Secondary headache disorders manifest as new-onset headaches that arise in close temporal association with the underlying cause.1 Secondary headache should be suspected in any patient without a history of primary headache who reports a de-novo headache and in
Measurement of CSF pressure
The gold standard for ICP measurement is placement of an intraventricular catheter connected to an external pressure transducer, which is an invasive procedure used in intensive care units.31 The classic, less invasive method to reliably estimate ICP is lumbar puncture (panel 2).31, 34, 38
Although the definition of normal CSF opening pressure is still debated, results from studies have shown that the upper limit of CSF opening pressure in healthy individuals should be regarded as 250 mm H2O in
Characterisation and classification
Idiopathic intracranial hypertension is characterised by increased ICP of unknown cause,46 in the absence of any intracranial process, venous sinus thrombosis, or meningeal process (panel 1). Patients with high ICP secondary to specific drugs or cerebral venous stenosis are still classified as having idiopathic intracranial hypertension. Suggestions have been made that the older term pseudotumour cerebri could be used again,33 but we prefer the term idiopathic intracranial hypertension, which
Demographics, predisposing factors, and associated disorders
Spontaneous intracranial hypotension has been reported in patients aged from 2 to 86 years,81, 82 but occurrence peaks between 35 and 42 years and the disorder is most common in women.44, 82, 83, 84 Spontaneous intracranial hypotension is probably not as rare as is generally thought, as shown by the large number of patients (338) from the same institution who were retrospectively included in a study during a 9 year period.85 Incidence is estimated to be two to five cases per 100 000 people per
Conclusions
Idiopathic changes in CSF pressure are rare causes of secondary headaches that are treatable. Despite the widespread availability of diagnostic tests, misdiagnosis of idiopathic intracranial hypertension and spontaneous intracranial hypotension remains common. If untreated, these disorders cause highly disabling headaches and threaten vision, hearing, and, in rare cases, brain function and life. Improvements in the overall strategy for the diagnosis of headaches will be needed to improve the
Search strategy and selection criteria
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