MR imaging of pseudotumor cerebri

CSF hyperdynamics in rats mimicking the obesity and androgen excess characteristic of patients with idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a syndrome exhibiting elevated intracranial pressure (ICP), visual disturbances, and severe headache. IIH primarily affects young obese women, though it can occur in individuals of any age, BMI, and sex. IIH is characterized by systemic metabolic dysregulation with a profile of increased androgen hormones. However, the contribution of obesity/hormonal perturbations to cerebrospinal fluid (CSF) dynamics remains unresolved.

METHODS

We employed obese female Zucker rats and adjuvant testosterone to reveal IIH causal drivers. ICP and CSF dynamics were determined with in vivo experimentation and magnetic resonance imaging, testosterone levels assessed with mass spectrometry, and choroid plexus function revealed with transcriptomics.

RESULTS

Obese rats had undisturbed CSF testosterone levels and no changes in ICP or CSF dynamics. Adjuvant testosterone treatment of obese rats elevated the CSF secretion rate, although with no effect on the ICP, due to elevated CSF drainage capacity of these rats.

CONCLUSIONS

Obesity in itself therefore does not suffice to recapitulate the IIH symptoms in rats, but modulation of CSF dynamics appears with adjuvant testosterone treatment, which mimics the androgen excess observed in female IIH patients. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH and could potentially serve as a future therapeutic target.

Modelling idiopathic intracranial hypertension in rats: contributions of high fat diet and testosterone to intracranial pressure and cerebrospinal fluid production

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a condition characterized by increased intracranial pressure (ICP), impaired vision, and headache. Most cases of IIH occur in obese women of childbearing age, though age, BMI, and female sex do not encompass all aspects of IIH pathophysiology. Systemic metabolic dysregulation has been identified in IIH with a profile of androgen excess. However, the mechanistic coupling between obesity/hormonal perturbations and cerebrospinal fluid dynamics remains unresolved.

METHODS

Female Wistar rats were either fed a high fat diet (HFD) for 21 weeks or exposed to adjuvant testosterone treatment for 28 days to recapitulate IIH causal drivers. Cerebrospinal fluid (CSF) and blood testosterone levels were determined with mass spectrometry, ICP and CSF dynamics with in vivo experimentation, and the choroid plexus function revealed with transcriptomics and ex vivo isotope-based flux assays.

RESULTS

HFD-fed rats presented with increased ICP (65%), which was accompanied by increased CSF outflow resistance (50%) without altered CSF secretion rate or choroid plexus gene expression. Chronic adjuvant testosterone treatment of lean rats caused elevated ICP (55%) and CSF secretion rate (85%), in association with increased activity of the choroid plexus Na⁺,K⁺,2Cl^- cotransporter, NKCC1.

CONCLUSIONS

HFD-induced ICP elevation in experimental rats occurred with decreased CSF drainage capacity. Adjuvant testosterone, mimicking the androgen excess observed in female IIH patients, elevated the CSF secretion rate and thus ICP. Obesity-induced androgen dysregulation may thus contribute to the disease mechanism of IIH.

Isolated spontaneous cerebrospinal fluid rhinorrhoea as a rare presentation of idiopathic intracranial hypertension: Case reports with comprehensive review of literature

Isolated cerebrospinal fluid (CSF) rhinorrhoea as a sole presenting symptom of idiopathic intracranial hypertension (IIH) is extremely rare. IIH typically presents with headache, pulsatile tinnitus, dizziness, nausea, vomiting, and visual disturbance. We report two cases which presented with acute onset spontaneous CSF rhinorrhoea without any other symptom. In addition, we discuss in detail imaging features of IIH with review of its literature.

High Signal Intensity in the Dentate Nucleus and Globus Pallidus on Unenhanced T1-Weighted MR Images: Comparison between Gadobutrol and Linear Gadolinium-Based Contrast Agents

BACKGROUND AND PURPOSE

In view of the recent observations that gadolinium deposits in brain tissue after intravenous injection, our aim of this study was to compare signal changes in the globus pallidus and dentate nucleus on unenhanced T1-weighted MR images in patients receiving serial doses of gadobutrol, a macrocyclic gadolinium-based contrast agent, with those seen in patients receiving linear gadolinium-based contrast agents.

MATERIALS AND METHODS

This was a retrospective analysis of on-site patients with brain tumors. Fifty-nine patients received only gadobutrol, and 60 patients received only linear gadolinium-based contrast agents. Linear gadolinium-based contrast agents included gadoversetamide, gadobenate dimeglumine, and gadodiamide. T1 signal intensity in the globus pallidus, dentate nucleus, and pons was measured on the precontrast portions of patients' first and seventh brain MRIs. Ratios of signal intensity comparing the globus pallidus with the pons (globus pallidus/pons) and dentate nucleus with the pons (dentate nucleus/pons) were calculated. Changes in the above signal intensity ratios were compared within the gadobutrol and linear agent groups, as well as between groups.

RESULTS

The dentate nucleus/pons signal ratio increased in the linear gadolinium-based contrast agent group (t = 4.215, P < .001), while no significant increase was seen in the gadobutrol group (t = -1.422, P = .08). The globus pallidus/pons ratios followed similarly, with an increase in the linear gadolinium-based contrast agent group (t = 2.931, P < .0001) and no significant change in those receiving gadobutrol (t = 0.684, P = .25).

CONCLUSIONS

Successive doses of gadobutrol do not result in T1 shortening compared with changes seen in linear gadolinium-based contrast agents.

Pseudotumor Cerebri and Glymphatic Dysfunction

In contrast to virtually all organ systems of the body, the central nervous system was until recently believed to be devoid of a lymphatic system. The demonstration of a complex system of paravascular channels formed by the endfeet of astroglial cells ultimately draining into the venous sinuses has radically changed this idea. The system is subsidized by the recirculation of cerebrospinal fluid (CSF) through the brain parenchyma along paravascular spaces (PVSs) and by exchanges with the interstitial fluid (IF). Aquaporin-4 channels are the chief transporters of water through these compartments. This article hypothesizes that glymphatic dysfunction is a major pathogenetic mechanism underpinning idiopathic intracranial hypertension (IIH). The rationale for the hypothesis springs from MRI studies, which have shown many signs related to IIH without evidence of overproduction of CSF. We propose that diffuse retention of IF is a direct consequence of an imbalance of glymphatic flow. This imbalance, in turn, may result from an augmented flow from the arterial PVS into the IF, by impaired outflow of the IF into the paravenous spaces, or both. Our hypothesis is supported by the facts that (i) visual loss, one of the main complications of IIH, is secondary to the impaired drainage of the optic nerve, a nerve richly surrounded by water channels and with a long extracranial course in its meningeal sheath; (ii) there is a high association between IIH and obesity, a condition related to paravascular inflammation and lymphatic disturbance, and (iii) glymphatic dysfunction has been related to the deposition of β-amyloid in Alzheimer's disease. We conclude that the concept of glymphatic dysfunction provides a new perspective for understanding the pathophysiology of IIH; it may likewise entice the development of novel therapeutic approaches aiming at enhancing the flow between the CSF, the glymphatic system, and the dural sinuses.

Transverse Sinus Stenosis Is the Most Sensitive MR Imaging Correlate of Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE

Patients with idiopathic intracranial hypertension have transverse sinus stenosis on gadolinium-bolused MRV, but other MR imaging signs are less consistently seen. Our aim was to demonstrate that transverse sinus stenosis could be identified on conventional MR imaging, and this identification would allow improved diagnostic sensitivity to this condition.

MATERIALS AND METHODS

MR imaging and MRV images from 63 patients with idiopathic intracranial hypertension and 96 controls were reviewed by using 3 independent procedures. MRV images were graded for the presence and degree of stenosis of the transverse sinus. Postgadolinium coronal T1-weighted sequences were evaluated independent of MRV. The dimensions of the proximal and distal transverse sinus were measured from the MRV examinations, and the cross-sectional area of the transverse sinus was calculated. Correlation among the 3 modes of evaluation of the transverse sinus was conducted by using Wilcoxon/Kruskal-Wallis, Pearson, and Spearman ρ nonparametric statistical techniques.

RESULTS

Transverse sinus stenosis was identified bilaterally on MRV in 94% of patients with idiopathic intracranial hypertension and in 3% of controls. On coronal T1 postgadolinium MR images, transverse sinus stenosis was identified in 83% of patients with idiopathic intracranial hypertension and 7% of controls. Previously described MR imaging signs of intracranial hypertension were identified in 8%-61% of patients with idiopathic intracranial hypertension. Correlation among the 3 modes of evaluation was highly significant (P < .0001).

CONCLUSIONS

Even without the assistance of an MRV sequence, neuroradiologists can validly identify bilateral transverse sinus stenosis in patients with intracranial hypertension more reliably than other previously described MR imaging findings in this condition. We conclude that transverse sinus stenosis is the most useful and sensitive imaging indicator of this disease state.

MRI in the Evaluation of Acute Visual Syndromes

Acute visual symptom emergencies occur commonly and present a challenge to both clinical and radiologic facets. Although most patients with visual complaints routinely require clinical evaluation with direct ophthalmologic evaluation, imaging is rarely necessary. However, there are highly morbid conditions where the prompt recognition and management of an acute visual syndrome (AVS) requires an astute physician to probe further. Suspicious symptomatology including abrupt visual loss, diplopia, ophthalmoplegia, and proptosis/exophthalmos require further investigation with advanced imaging modalities such as magnetic resonance imaging and magnetic resonance angiography. This review will discuss a variety of AVSs including orbital apex syndrome, cavernous sinus thrombosis, cavernous carotid fistula, acute hypertensive encephalopathy (posterior reversible encephalopathy syndrome), optic neuritis, pituitary apoplexy including hemorrhage into an existing adenoma, and idiopathic intracranial hypertension. A discussion of each entity will focus on the clinical presentation, management and prognosis when necessary and finally, neuroimaging with emphasis on magnetic resonance imaging. The primary purpose of this review is to provide an organized approach to the differential diagnosis and typical imaging patterns for AVSs. We have provided a template for radiologists and specialists to assist in early intervention in order to decrease morbidity and provide value-based patient care through imaging.

Idiopathic Intracranial Hypertension: Diagnostic Accuracy of the Transverse Dural Venous Sinus Attenuation on CT Scans

Idiopathic intracranial hypertension (IIH) is a clinical disorder of unknown etiology. It may exhibit several non-specific imaging findings. We observed that patients with intracranial hypertension demonstrate intracranial venous sinus attenuation with changes in the contour and caliber of the distal transverse sinus. This can be seen on routine non-contrast sagittal reformatted CT images of the brain. We have termed this the venous attenuation sign (VAS). This study evaluated the VAS as a marker for IIH assessing the transverse sinuses on sagittal reformatted non-contrast CT for the presence of a VAS in 25 patients with IIH and 24 control patients. Scans were independently assessed in a blinded fashion by three readers. The readers identified the VAS in 96% of patients with IIH; 83.3% of the control patients were negative for VAS. Our study supports the VAS as an additional imaging marker which may be incorporated into the evaluation of patients suspected to have this condition.

Update on intracranial hypertension and hypotension

PURPOSE OF REVIEW

The aim of this article is to review recent findings on the pathophysiology of idiopathic changes in intracranial pressure. The review will focus on idiopathic intracranial hypertension (IIH) and spontaneous intracranial hypotension (SIH).

RECENT FINDINGS

Substantial evidence indicates that IIH is associated with delayed absorption of cerebrospinal fluid (CSF). Stenoses of the transverse sinus are common in IIH, but their clinical significance has not been entirely clarified. Despite the observed efficacy of endovascular treatment in some IIH patients, a correlation between the extent of observed stenoses and the clinical course of the disease could not be demonstrated. The underlying cause of SIH is a spontaneous CSF leakage into the epidural space. Conservative treatment and the epidural blood patch remain the treatment of choice for this rare syndrome.

SUMMARY

Recent clinical evidence indicates that IIH is probably a result of CSF outflow abnormality rather than of CSF production. Further research is needed to elucidate the causes of elevated intracranial pressure and the mechanism leading to visual loss. Prospective randomized clinical trials are needed to clarify a possible therapeutic potential of endovascular treatment. Research efforts on SIH should focus further on associated connective tissue disorders predisposing to CSF leaks.

Detection of nerve fiber atrophy in apparently effectively treated papilledema in idiopathic intracranial hypertension

BACKGROUND

Since papilledema in idiopathic intracranial hypertension is a passive event not primarily affecting the visual tract, resolution with restitution ad integrum is expected if intracranial pressure is rebalanced. Retinal nerve fiber swelling due to papilledema in the acute phase and possible axon loss after long-lasting elevated intracranial pressure was investigated in a controlled cross-sectional study by scanning laser polarimetry.

METHODS

A cohort of 23 patients with idiopathic intracranial hypertension according to the modified Dandy diagnostic criteria, and 23 controls matched for age and gender were investigated. All patients received neurological and ophthalmologic examination including scanning laser polarimetry (GDx VCC). Patients were divided into groups depending on the presence of a papilledema (group 1) or the regression of the papilledema after initiation of therapy (group 2). Therapy was based on recommendations of the German Society of Neurology.

RESULTS

Scanning laser polarimetry showed an increase of nerve fiber thickness in group 1, and a decrease of the nerve fiber thickness in group 2 compared to controls. Ten of 13 patients showed signs of a regional axon loss in the deviation map of the GDx report, and six had a Nerve Fiber Index above 30. All patients with regressive papilledema and coincidence of visual field damage and pale optic disc appearance had a pathologic result in the GDx examination, but only four of ten patients with a pathologic GDx examination showed coincidence of pale optic disc appearance and visual field damage as sign of underlying optic disc atrophy.

CONCLUSION

In patients with apparently effective treatment of clinical symptoms and a regression of papilledema in idiopathic intracranial hypertension, a retinal axon loss was detected by scanning laser polarimetry. Axon loss was even present in patients without clinical evidence of optic nerve atrophy.

Magnetic resonance imaging changes in idiopathic intracranial hypertension in children

To evaluate the usefulness of neuroimaging in children with idiopathic intracranial hypertension, brain magnetic resonance imaging (MRI) scans of children with idiopathic intracranial hypertension and age-matched controls were reviewed. Compared with controls, patients with idiopathic intracranial hypertension had flattening of the posterior sclera in 61% versus 40% of cases, distension of perioptic subarachnoid space in 65% versus 35%, intraocular protrusion of pre-laminar optic nerve in 17% versus 0%, tortuosity of optic nerve in 30% versus 5%, and an empty sella in 26% versus 5% of cases. The presence of 3 or more of the MRI features is 95% specific in predicting idiopathic intracranial hypertension. The observed general anesthetic effect on these neuroimaging features are also minimized when multiple features are taken into account. Magnetic resonance imaging features can assist in suspecting the diagnosis of idiopathic intracranial hypertension in children, provided caution is applied when interpreting imaging performed under a general anesthesia.

The importance of toxoplasma gondii infection in diseases presenting with headaches. Headaches and aseptic meningitis may be manifestations of the Jarisch-Herxheimer reaction

Worldwide, approximately 2 billion people are chronically infected with T. gondii with largely unknown consequences. This review presents clinical symptoms, differential diagnosis, triggering factors, treatment, and pathomechanisms responsible for idiopathic intracranial hypertension, pseudotumor cerebri, and aseptic meningitis. Literature cited in this work illustrates that immune state and other biologic mediator imbalances due to various endogenous and exogenous triggering factors may markedly affect latent central nervous system T. gondii infection/inflammation intensity, and cause reactivation of cerebral toxoplasmosis (CT). Irregularities in pro- and anti-inflammatory processes may markedly disturb the host and/or T. gondii defense mechanisms important for immune control of the parasite thereby manifesting as a wide range of neurologic symptoms and signs observed in some patients with migraine, epilepsy, celiac disease, Henoch-Schönlein purpura, and other brain disorders. This is consistent with reactivation of CT in mice after treatment with dexamethasone associated with depression of type T(H)1 immune response, and development of CT after administration of etanercept or other bioproducts. It seems that various types of headaches, epilepsy, aseptic meningitis, systemic adverse reactions to drugs or other substances represent the Jarisch-Herxheimer reaction due to apoptosis of T. gondii tachyzoites. Also development of some brain tumors, such as ependymoma and glioma may be associated with a chronic course of CT. Thus, all these patients should be tested for T. gondii infection.

Macrocephaly, increased intracranial pressure, and hydrocephalus in the infant and young child

Macrocephaly, increased intracranial pressure, and hydrocephalus are common related conditions that lead to cross-sectional imaging of the infant and young child. Imaging plays a central role in establishing the diagnosis and guiding disposition and treatment of these patients. In this review, a general overview is provided, and the more common causes of hydrocephalus are presented, including posthemorrhage, postinfection, developmental malformations, and masses. Imaging guidelines are also outlined for initial evaluation and follow-up, along with a discussion of the imaging features of shunt malfunction.

Diffusion tensor imaging of benign intracranial hypertension: absence of cerebral oedema

Cerebral oedema, it has been suggested, may have a role in the pathophysiology of benign intracranial hypertension (BIH). We applied diffusion tensor MR imaging (DTI), a technique able to detect cerebral oedema, to the study of patients with BIH. A quantitative regional analysis of diffusion parameters (trace and relative anisotropy) was conducted by comparing five BIH patients and six healthy controls. A small but significant increase in anisotropy accompanied by a small but significant decrease in trace was found in the putamen and head of the caudate nucleus. No significant changes were demonstrated in the thalamus, cerebral white matter or cortical regions. Our findings support other recent work that suggests cerebral oedema is not a factor in the pathogenesis of BIH.

What is new about idiopathic intracranial hypertension? An updated review of mechanism and treatment

Idiopathic intracranial hypertension (IIH) is the syndrome of raised intracranial pressure without clinical, laboratory or radiological evidence of intracranial pathology. IIH is a relatively rare disease but rapidly increasing incidence is reported due to a global increasing incidence of obesity. Disease course is generally said to be self-limiting within a few months. However, some patients experience a disabling condition of chronic severe headache and visual disturbances for years that limit their capacity to work. Permanent visual defects are serious and not infrequent complications. The pathophysiology of IIH is still not fully understood. Advances in neuroimaging techniques have facilitated the exclusion of associated conditions that may mimic IIH. No causal treatment is yet known for IIH and existing treatment is symptomatic and rarely sufficient. The aim of this review is to provide an updated overview of this potentially disabling disease which may show a future escalating incidence due to obesity. Theories of pathogenesis, diagnostic criteria and treatment strategies are discussed.

Idiopathic intracranial hypertension

Idiopathic intracranial hypertension is common in obese women and can lead to significant visual impairment. First described more than 100 years ago, the cause of the disorder remains unknown. Despite a multitude of proposed links, the aetiology has never been established. Impairment of cerebrospinal-fluid reabsorption is the most likely underlying pathophysiological cause of the raised pressure, but this notion has yet to be proven. Cerebral venous sinus abnormalities associated with the disorder need further exploration. Although the major symptoms of headache and visual disturbance are well documented, most data for disease outcome have been from small retrospective case series. No randomised controlled trials of treatment have been done and the management is controversial. The importance of weight loss needs clarification, the role of diuretics is uncertain, and which surgical intervention is the most effective and safe is unknown. Prospective trials to examine these issues are urgently needed.

Cranial venous outflow obstruction and pseudotumor Cerebri syndrome

The pathophysiology of PTS including idiopathic intracranial hypertension or 'BIH', remains controversial. The older literature frequently referred to pathology in the cerebral venous drainage but more modern imaging techniques (CT and early MR) failed to reveal gross venous pathology. The role of impaired cranial venous outflow has recently been re-examined in the light of new methods of investigation (advanced MR venography and direct microcatheter venography with manometry) and of treatment (venous sinus stenting). Venous sinus obstruction in PTS is a more common factor in the pathogenesis of the condition than previously recognised. Venous obstruction may be primary, that is, it is the underlying aetiological factor in PTS. Venous sinus obstruction may also be secondary to raised CSF pressure which may exacerbate problems with intracranial compliance and raised CSF pressure. Early experience with venous stenting suggests that it may be a helpful treatment for patients with PTS but more experience and longer follow-up is required to define the subgroups of patients for whom it is most appropriate.

Idiopathic intracranial hypertension

OBJECTIVE

The history, diagnosis, and therapy of idiopathic intracranial hypertension (IIH) (pseudotumor cerebri) are reviewed. Theories of pathogenesis are considered, the clinical presentation is described, and potential diagnostic and therapeutic challenges are explored.

METHODS

An extensive literature review of IIH and related conditions (secondary pseudotumor syndromes) was performed. The history of and rationale for the diagnosis and medical and surgical approaches to treatment are reviewed. Available outcome studies are presented.

RESULTS

Diagnosis of IIH requires that the modified Dandy criteria be satisfied. Multiple potential contributing causes of intracranial hypertension must be identified or excluded. The clinical presentation most often includes headaches and papilledema, but many other findings have been described. The most important goal of therapy is to prevent or arrest progressive visual loss. Medical therapies include alleviation of associated systemic diseases, discontinuation of contributing medications, provision of carbonic anhydrase inhibitors, and weight loss. Surgical therapies include lumboperitoneal shunting, ventriculoperitoneal shunting, and optic nerve sheath fenestration. On the basis of the advantages and disadvantages of these treatment modalities, a suggested treatment paradigm is presented.

CONCLUSION

Idiopathic intracranial hypertension is the term to be adopted instead of pseudotumor cerebri. IIH remains an enigmatic diagnosis of exclusion. However, prompt diagnosis and thorough evaluation and treatment are crucial for preventing visual loss and improving associated symptoms.

Association of the Adult Chiari Malformation and Idiopathic Intracranial Hypertension: more than a coincidence

There are significant similarities between the Adult Chiari Malformation (ACM) and Idiopathic Intracranial Hypertension (IIH). They include similar demographics, clinical presentation, and response to treatment. There is an eightfold increase in the incidence of significant tonsillar herniation in patients with IIH. Based on these findings and our observation in a subgroup of patients with failed ACM decompression, we suggest that these disorders are interrelated in a group of patients. The physiopathology is that of craniocephalic disproportion, i.e., a disproportion between the skull and the brain, due to a small skull or posterior fossa (like in ACM) and/or an engorged brain (like in IIH). This will occasionally lead to tonsillar ectopia. The craniocephalic disproportion will alter the brain compliance and lead to the symptomatology.

Ventricular size in pseudotumor cerebri and the theory of impaired CSF absorption

The purpose of this theoretical study is to determine whether the absence of ventricular enlargement in pseudotumor cerebri (PTC) is consistent with the theory that PTC is caused by reduced absorption of cerebrospinal fluid (CSF), either from increased outflow resistance at the arachnoid villi or from obstruction of the dural venous sinuses. We model the brain as a thick spherical shell of parenchyma, enclosing a CSF-filled ventricular system, and surrounded by a thin cerebral subarachnoid space (CSAS). We treat the parenchyma as a porous solid matrix, filled with interstitial fluid and blood vessels. We subject the model to a uniform increase in CSF pressure (CSFP) and solve the equations of poroelasticity for the resulting displacements of parenchymal tissue. The effect of a rise in CSFP on ventricular size depends on the response of the cerebral blood vessels and the degree to which the pia is tethered to the dura. If the cerebral vessels decrease in caliber with increasing CSFP, a rise in CSFP causes the ventricles to contract and the CSAS to expand if the pial surface is free to move inward, but causes slight ventricular enlargement if the pia is tethered to the dura. If, instead, the vessels dilate, the ventricles contract and the CSAS becomes effaced. Small, normal, or slightly enlarged ventricles in PTC are consistent with the theory of reduced CSF absorption.

Idiopathic intracranial hypertension: orbital MRI

The case is reported of a patient with idiopathic intracranial hypertension examined with magnetic resonance imaging. Marked enhancement of the optic nerve heads was found, which might be related to blood-retinal barrier breakdown related to a sudden rise in intracranial cerebrospinal fluid pressure.

Childhood pseudotumor cerebri: clinical and intracranial pressure response to acetazolamide and furosemide treatment in a case series

The purpose of this study was to investigate the efficacy of combined therapy with acetazolamide and furosemide in normalizing intracranial pressure in children with pseudotumor cerebri. The role of repeated lumbar cerebrospinal fluid pressure monitoring in evaluating the response to therapy is also demonstrated. Continuous 1-hour lumbar cerebrospinal fluid pressure monitoring was done in eight children with pseudotumor cerebri on admission and at weekly intervals until the baseline pressure had normalized. (One child had two episodes of pseudotumor cerebri). All patients were treated with oral acetazolamide and furosemide until papilledema had cleared. Raised intracranial pressure was present on admission in all nine episodes of pseudotumor cerebri. Six children had an increased baseline cerebrospinal fluid pressure, whereas raised intracranial pressure was diagnosed in three children on account of an abnormal pulse wave and/or pressure waves. The mean baseline pressure was significantly lower after the 1st week of treatment than on admission (P = .007) and normalized in all patients within 6 weeks of start of therapy. All children had a rapid clinical response. Combined therapy with acetazolamide and furosemide is an effective first-line method of treating raised intracranial pressure in children with pseudotumor cerebri. The good correlation found between the clinical response and normalization of baseline cerebrospinal fluid pressure suggests that clinical monitoring of treatment is adequate in most children with this condition.

Magnetic resonance imaging in pseudotumor cerebri

The pathophysiology of pseudotumor cerebri is unclear, but may relate to an abnormality in water transport in the brain. The authors performed MR imaging in seven children with pseudotumor cerebri; the signal intensity in the white matter was normal in all patients. These data suggest that periventricular brain water content is not increased markedly in children with pseudotumor cerebri. The authors speculate that this may relate to the establishment of an equilibrium between increased resistance to cerebrospinal fluid outflow and increased brain stiffness, occurring as a consequence of increased cerebral blood-volume and/or interstitial pressure.