Benign intracranial hypertension: I. Mastoiditis and lateral sinus obstruction

Factors affecting cerebrospinal fluid opening pressure in patients with spontaneous intracranial hypotension

OBJECTIVE

Spontaneous intracranial hypotension (SIH) is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid (CSF) pressure, some patients with SIH are observed to have normal pressure values. In this study, we aimed to confirm the proportion of patients with normal CSF opening pressure (CSF OP) and explore the factors affecting CSF OP in SIH patients.

METHODS

We retrospectively reviewed 206 consecutive SIH patients and analyzed their clinical and imaging variables (including demographic data, body mass index (BMI), duration of symptoms, and brain imaging findings). Univariate and multivariate analyses were performed to identify the potential factors affecting CSF OP.

RESULTS

In a total of 114 (55.3%) cases the CSF OP was ≤60 mmH₂O (1 mmH₂O=9.806 65 Pa), in 90 (43.7%) cases it was between 60 and 200 mmH₂O, and in 2 (1.0%) cases it was >200 mmH₂O. Univariate analysis showed that the duration of symptoms (P<0.001), BMI (P<0.001), and age (P=0.024) were positively correlated with CSF OP. However, multivariate analysis suggested that only the duration of symptoms (P<0.001) and BMI (P<0.001) were strongly correlated with CSF OP. A relatively high R² of 0.681 was obtained for the multivariate model.

CONCLUSIONS

Our study indicated that in patients without a low CSF OP, a diagnosis of SIH should not be excluded. BMI and the duration of symptoms can influence CSF OP in SIH patients, and other potential factors need further investigation.

A 17-year-old male with pseudotumor cerebri secondary to performance-enhancing steroids triggering venous thrombosis in the brain

This article is a case report of a 17-year-old male who presented with a headache and blurry vision. He subsequently was noted to have papilledema on a fundoscopic examination and an initial normal magnetic resonance imaging and computed tomography of his head; his condition was, therefore, diagnosed as pseudotumor cerebri. A subsequent magnetic resonance venography of his head revealed venous thrombosis, and other investigations revealed an elevated factor VIII level as well as a mutation at the MTHFR locus, consistent with an elevated risk for hypercoagulability. In addition, he admitted to steroid usage for purposes of performance enhancement in baseball. The patient's condition eventually improved with acetazolamide and serial lumbar punctures. Steroids have been linked to predisposition to hypercoagulable states, but there are no reports identified by these authors that link performance-enhancing steroids with pseudotumor cerebri as a result of a coagulation dyscrasia.

[Benign intracranial hypertension: history, definition, and physiopathology]

Benign intracranial hypertension (BIH) is a rare condition in which the pathophysiology remains unclear. Multiple theories have been proposed in the past to explain BIH. Today it is widely accepted that the condition occurs in situations where alteration of cerebrospinal fluid (CSF) reabsorption is encountered. The venous system is therefore involved and may be the common denominator of the pathophysiological theories. A distinction must be made between idiopathic benign intracranial hypertension and BIH resulting from drugs, other pathological conditions, or toxics (secondary BIH), which are reported in this paper. We emphasize the crucial role of exhaustive clinical, biological, and neuroradiological investigations aiming to establish the diagnosis of BIH.

Visual failure without headache in idiopathic intracranial hypertension

AIM

To determine the differences in outcome in a group of children with idiopathic intracranial hypertension (IIH) who do not present with headaches.

METHODS

Differences in epidemiological and aetiological factors, clinical presentation, and visual outcome were investigated in children with a diagnosis of IIH presenting with and without headaches to the Paediatric Neurology and Paediatric Ophthalmology Services at Guy's & St Thomas' Hospitals NHS Trust between 1997 and 2002.

RESULTS

Compared to the 29 children with headaches, the 12 children in the non-headache group were younger (7.3 v 9.5 years), presented with more neurological signs (33% v 10%), and were more likely to present with severe visual failure (33% v 4%), with a tenfold increased risk of an enlarged blind spot or field defects (50% v 5%). Permanent visual failure affected a third of all children in the non-headache group, but was rare in children presenting with headaches (33% v 3%), with one patient registered blind and two severely visually impaired.

CONCLUSION

The management of IIH is difficult in the absence of headache. Visual surveillance is vital. These children were treated with an aggressive management programme to reduce cerebrospinal fluid pressure by repeated lumbar puncture, medication, and early surgical intervention if required. Non-invasive monitoring techniques might contribute to a better understanding of the natural history of IIH, improved management, and visual outcome.

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.

Physiologic effects of externally applied continuous negative abdominal pressure for intra-abdominal hypertension

BACKGROUND

To determine the ability of an externally applied continuous negative abdominal pressure device (CNAP) to reverse the effects of elevated intra-abdominal pressure on the central nervous and cardiovascular systems.

METHODS

Anesthetized, ventilated swine had catheters placed for measurement of intra-abdominal (IAP), intracranial (ICP), central venous, pulmonary artery, pulmonary artery occlusion, mean arterial, peak inspiratory, inferior vena cava, and femoral vein pressures. After the animals stabilized, baseline measurements were obtained. IAP was increased by incrementally instilling an isosmotic polyethylene glycol solution into the peritoneal cavity until it was 25 mm Hg above baseline. IAP was maintained at 25 mm Hg above baseline for 2 hours. CNAP was then applied for 2 hours. All parameters were remeasured 30 minutes after each increase in IAP, at 2 hours after attaining maximum IAP, and lastly at 2 hours after abdominal decompression. Cardiac index was maintained near baseline by volume expansion.

RESULTS

Elevation of IAP to 25 mm Hg above baseline for 2 hours caused increases (p<0.05) in central venous pressure (10.3+/-0.9 to 15.2+/-1.7), inferior vena cava pressure (13.0+/-1.0 to 29.5+/-1.5), femoral vein pressure (13.5+/-0.5 to 33.3+/-1.3), ICP (10.6+/-1.5 to 21.0+/-1.5), and peak inspiratory pressure (18.3+/-0.3 to 34.2+/-1.0). The mean arterial pressure (106.3+/-3.5 to 125.8+/-3.4), pulmonary artery pressure (24.3+/-2.3 to 31.3+/-1.7), and pulmonary artery occlusion pressure rose (12.3+/-0.9 to 17.5+/-3.5), but not significantly. Cardiac index (3.3+/-0.5 to 3.4+/-0.4) remained essentially unchanged. CNAP significantly (p<0.05) decreased IAP (30.7+/-1.3 to 18.2+/-1.3), central venous pressure (15.2+/-1.7 to 12.4+/-2.1), inferior vena cava (29.5+/-1.5 to 19.2+/-1.3), and ICP (21.0+/-1.5 to 16.2+/-1.3). Pulmonary artery occlusion pressure (17.5+/-3.5 to 15.0+/-3.1) and peak inspiratory pressure (34.2+/-1.0 to 29.7+/-1.1) decreased, but not significantly.

CONCLUSION

Acutely elevated IAP causes a significant increase in ICP and impaired cardiovascular and pulmonary function. Abdominal decompression remains the standard of care for abdominal compartment syndrome. However, in patients in whom an increased IAP does not require surgical decompression, the results of this study suggest that externally applied CNAP may be of value.

A proposed relationship between increased intra-abdominal, intrathoracic, and intracranial pressure

OBJECTIVES

To determine the effect of acutely increased intra-abdominal pressure on pleural pressure, intracranial pressure, and cerebral perfusion pressure, and to clarify the relationship between these parameters.

DESIGN

Nonrandomized, controlled study.

SETTING

Laboratory at a university medical center.

SUBJECTS

Yorkshire swine, weighing 15 to 20 kg.

INTERVENTIONS

Anesthetized, ventilated swine had a balloon inserted into the peritoneal cavity and catheters placed for measurement of intracranial pressure, pleural pressure, central venous pressure, pulmonary artery occlusion pressure, and mean arterial pressure. Following baseline measurements, intra-abdominal pressure was increased by incrementally inflating the intraperitoneal balloon. All parameters were remeasured 30 mins after each increase in intra-abdominal pressure. Two groups were studied: a) group 1 (n = 9) animals had intra-abdominal pressure increased to 25 mm Hg above baseline, then released; b) group 2 (n = 3) animals underwent sternotomy and pleuropericardotomy to prevent an increase in pleural pressure with increasing intra-abdominal pressure.

MEASUREMENTS AND MAIN RESULTS

Increase of intra-abdominal pressure to 25 mm Hg above baseline caused significant (p < .05) increases in intracranial pressure (7.3 +/- 0.6 [SEM] to 16.4 +/- 1.9 mm Hg), pleural pressure (4.3 +/- 1.3 to 11.8 +/- 1.9 mm Hg), pulmonary artery occlusion pressure (9.0 +/- 0.6 to 14.3 +/- 0.8 mm Hg), and central venous pressure (6.6 +/- 0.7 to 10.7 +/- 0.9 mm Hg). The cardiac index (3.4 +/- 0.3 to 1.6 +/- 0.1 L/min/m2) and cerebral perfusion pressure (75.6 +/- 3.6 to 62.0 +/- 6.8 mm Hg) deceased significantly (p < .05), whereas mean arterial pressure (82.8 +/- 3.2 to 78.4 +/- 6.6 mm Hg) remained essentially constant. Sternotomy and pleuro-pericardotomy negated all effects of increased intra-abdominal pressure except the decreased cardiac index (1.6 +/- 0.1 to 2.5 +/- 0.2 L/min/m2).

CONCLUSIONS

Acutely increased intra-abdominal pressure causes a significant increase in intracranial pressure and a decrease in cerebral perfusion pressure. Increased intra-abdominal pressure appears to produce this effect by augmenting pleural and other intrathoracic pressures and causing a functional obstruction to cerebral venous outflow via the jugular venous system. It is possible that the same phenomenon may be why persons with chronically increased intra-abdominal pressure, such as the morbidly obese, suffer from a high frequency rate of idiopathic intracranial hypertension.

Idiopathic intracranial hypertension in children: the Iowa experience

Idiopathic intracranial hypertension is an uncommon condition in children and is seen only about once a year in a large referral hospital. Sex incidence is equal, and obesity is a feature in about one third of patients. This article reviews the 30-year experience in an institution where idiopathic intracranial hypertension in adults has been extensively studied. Symptomatic causes of intracranial hypertension and both medical and surgical therapeutic options are reviewed.

Eosinophilic granuloma of the occipital bone presenting as intracranial venous hypertension

Intracranial venous sinus thrombosis is an uncommon cause of pseudotumor cerebri. The diagnosis is often not confirmed on the rationale that treatment will not be altered. We report a case presenting a pseudotumor cerebri where the underlying pathology disclosed dural sinus thrombosis resulting from compression by an eosinophilic granuloma of the occipital bone. Routine CT of the head and Technetium-99m brain scan initially demonstrated neither tumor nor thrombosis. Plain skull x-rays subsequently revealed a lytic lesion of the occiput. When reinvestigated with CT using bone density windows the tumor was revealed. Excision of the tumor and a short course of cobalt therapy was curative. Special techniques in nuclear scanning, CT and MRI designed to improve the sensitivity for diagnosing venous sinus thrombosis are described. This case illustrates the importance of establishing a definitive diagnosis and shows the importance of pre-test consultation between clinicians and radiologists to ensure that specific investigative techniques are properly utilized.

Idiopathic intracranial hypertension (pseudotumor cerebri) in pediatric patients

Improved evaluation of visual features of idiopathic intracranial hypertension in pediatric patients has resulted in the demonstration of optic neuropathy which may be reversible. A wide variety of etiologic associations should be investigated to provide definitive therapy; however, nonspecific means often will be required to lower intracranial pressure. It is hoped that a double-blind controlled trial of medical therapies and another for surgical therapies will be conducted to elucidate optimum management of this condition.

Benign intracranial hypertension caused by mastoiditis and lateral sinus obstruction: the value of computerized tomography in diagnosis

A case of benign intracranial hypertension occurring in an 11-year-old boy, and due to lateral sinus obstruction, is reported. Computerized tomographic scan was conclusive, revealing a normal ventricular system and no evidence of a neoplastic lesion. Disappearance of the mastoid air cells and disruption of the trabecular pattern were also shown on the affected side. The diagnosis was confirmed at operation, and the course was favourable. In accordance with other studies cited, our findings suggest that patients suspected of benign intracranial hypertension can be spared invasive neuroradiological procedures if the computerized tomographic scan of the head is normal.

Extraneural metastases of a cerebral astrocytoma

Extraneural spread of a cerebral glioma has been described infrequently. The present case provides an example of this unique mode of metastasis.

Benign intracranial hypertension vs. intracranial arteriovenous malformation: a possible CT dilemma

A nine-year-old boy, presenting only with signs of increased ICP, underwent computerized tomography. This examination demonstrated no abnormalities in the precontrast scan. Following C. E., it showed scattered areas of blood-like density in both hemispheres, as well as a presumedly abnormal vessel in the left occipital region and dilated vein of Galen, sinus rectus, and tentorial veins. The presumptive diagnosis of left occipital AVM was not confirmed by angiography, which also ruled out obstructions of the intracranial sinuses. The possible mechanism responsible for this atypical CT picture is briefly discussed in the light of pertinent literature. It is suggested that careful consideration should be given to the indications for angiography in similar cases, in the presence of a "hypervascular" aspect of the postcontrast CT scan, particularly if a considerable amount of contrast medium has been used.

Pseudotumor cerebri

Pseudotumor cerebri is a clinical syndrome in which signs and, sometimes, symptoms of raised intracranial pressure are present but in which mental and neurological function are unaffected. Therefore, the diagnosis is reached after mass and other structural causes of raised pressure have been excluded. Many causes of pseudotumor have been suggested, not all of them well documented. Pathogenesis, however, includes cerebral edema, increased cerebral blood volume, and decreased cerebro spinal fluid (CSF) absorption. Except for the risk of vision in a minority of cases, the prognosis is excellent.

Hydrocephalus caused by increased intracranial venous pressure: a clinicopathological study

A child developed progressive communicating nonobstructive hydrocephalus as a result of increased intracranial venous pressure. The child had been treated for congenital heart disease at age 3 weeks by surgical creation of an anastomosis between his superior vena cava and right pulmonary artery. Although his cardiac symptoms were alleviated, intracranial venous hypertension resulted, giving rise to progressive head enlargement and other signs of hydrocephalus. Postmortem examination at age 3 years disclosed no other lesions that could have caused the hydrocephalus. Increased intracranial venous pressure can lead to either pseudotumor cerebri or hydrocephalus, the former in children 3 years or older, the latter in infants 18 months or less. Possible mechanisms accounting for these differences are discussed.

Papilloedema associated with respiratory failure

A case of papilloedema secondary to respiratory failure is reported which caused considerable diagnostic difficulty and led to extensive neurological investigation. Neurological complaints of headache and visual impairment overshadowed respiratory symptoms and were associated with gross haemorrhagic papilloedema. The case is compared with previous reports and the pathogenesis of papilloedema in respiratory failure is reviewed briefly. The similarity between the pathogenesis of this condition and benign intracranial hypertension is discussed.

Dural posterior fossa AVM producing raised sagittal simus pressure. Case report

A patient with raised intracranial pressure secondary to a dural arteriovenous malformation (AVM) of the posterior fossa is presented. Direct shunting of arterial blood into the transverse sigmoid sinus caused a considerable increase of the sagittal sinus pressure (SSP) and elevation of intracranial pressure (ICP). Both ICP and SSP returned to normal values following obliteration of the dural AVM by selective embolization.

Hydrocephalus resulting from superior vena cava thrombosis in an infant. Case report

The authors report an unusual case of superior vena cava thrombosis in an infant who subsequently developed communicating hydrocephalus; they also review previously reported cases of dural sinus hypertension, and separate them into two groups. Patients in the first group develop hydrocephalus and those in the second develop a pseudotumor-like syndrome. The former patients tend to have generalized increase in intracranial venous pressure while the latter have a normal pressure in some major intracranial venous structure(s). The absence of venous cushioning of the choroid plexus pulse wave is proposed as the cause of ventricular enlargement in the former group. In addition, patients in the large-ventricle group were younger than patients in the small-ventricle group.

Benign intracranial hypertension following corticosteroid withdrawal in childhood

In an 18-month period seven children who were treated for a variety of neurological and non-neurological diseases, and in whom the corticosteroid or corticotrophin dosage was reduced, developed a syndrome indistinguishable from "benign intracranial hypertension." The total duration and rate of reduction of corticosteroid dosage and perhaps an underlying susceptibility to cerebral oedema appear to be important factors in this syndrome. Usually patients can be treated without the need for special neuroradiological studies. Possibly mild forms of this condition are not uncommon, but its pathogenesis is still uncertain.