Idiopathic intracranial hypertension

Dhungana S, Sharrack B, Woodroofe N. Idiopathic intracranial hypertension.
Acta Neurol Scand: 2010: 121: 71–82.
© 2009 The Authors Journal compilation © 2009 Blackwell Munksgaard. Idiopathic intracranial hypertension (IIH) is a condition which affects predominantly overweight women and is characterized by raised intracranial pressure without any identifiable pathology in the brain and with normal cerebrospinal fluid (CSF) composition. The cause of IIH is unclear and as such it remains a diagnosis of exclusion. Although the pathophysiology of IIH remains elusive, some observations have recently been added to our understanding of this, including the presence of transverse sinus stenosis on many patients and the possible role of leptin and inflammation in the disease pathogenesis. Headache is the most common symptom and papilloedema is the major clinical finding. Choices of medical treatment are limited to the use of diuretics particularly acetazolamide and encouragement of weight loss. Surgical therapies such as CSF diversion procedures and fenestration of the optic nerve may be necessary in some cases with persistent symptoms or progressive visual deterioration. While not life‐threatening, IIH has a significant morbidity with up to 25% of patients developing visual impairment from optic atrophy. Visual surveillance is therefore vital. Long‐term follow‐up is recommended as the disease may worsen after an initial period of stability.     

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.     

Zoster-associated intracranial hypertension

A 14-year-old female presented with headache, vomiting, and a rash. She was found to have papilledema and herpes zoster. Examination of the cerebrospinal fluid revealed pleocytosis and an elevated protein concentration. Varicella-zoster virus deoxyribonucleic acid was detected in the cerebrospinal fluid by polymerase chain reaction. Intracranial hypertension was treated by repeated lumbar puncture and with acetazolamide. This case represents an unusual complication of the reactivation of varicella-zoster virus.     

Benign intracranial hypertension

Benign intracranial hypertension (BIH) is characterized by an elevation of the intracranial pressure not associated with an intracranial process or hydrocephaly, and with normal cerebrospinal fluid (CSF) contents. The elevation of the intracranial pressure is isolated; therefore, diseases such as cerebral venous thrombosis or dural fistulas should not be considered as etiologies of BIH. The exact definition of BIH remains debated, and other terms such as "pseudotumor cerebri" or "idiopathic intracranial hypertension" are often used in the literature. Although we agree that BIH is usually not a so benign disease, we suggest that BIH is still the most appropriate term to describe this entity which should be classified as "secondary BIH" or "idiopathic BIH" depending on whether there are precipitating factors for the development of BIH or not. We also propose new diagnostic criteria emphasizing the need for investigations for the diagnostic of secondary and idiopathic BIH. The management of patients with BIH depends mainly on the presence and severity of ocular symptoms and signs on which the prognostic of the disease is based. Repeated lumbar punctures associated with acetazolamide and weight loss are usually efficient enough. However a surgical treatment (optic nerve sheath fenestration or lumboperitoneal shunt) is required when appropriate medical management does not prevent progressive alteration of vision (visual loss or visual field defect), or when the patients complains of severe, refractory headaches. Careful follow-up with repeated formal visual field testing may help preventing a devastating visual loss in these patients.     

Idiopathic intracranial hypertension

Although the cause of IIH remains obscure, loss of visual function is common, and patients may progress to blindness. Diagnosis should adhere to the modified Dandy criteria. Recent case-control studies cast doubt on the validity of many frequently cited conditions associated with IIH. Valid associations include obesity, recent weight gain, female sex, vitamin A intoxication, and steroid withdrawal. Management should include serial perimetry using a sensitive disease-specific strategy so the proper therapy can be selected and visual loss prevented or reversed.     

Paroxysmal intracranial hypertension

We present the case of a man who presented with headache and severe papilloedema which was caused not by chronic intracranial hypertension but by paroxysms of raised intracranial pressure, and we speculate what relationship this disorder has to idiopathic intracranial hypertension.     

Idiopathic intracranial hypertension.

The syndrome of intracranial hypertension without structural brain or cerebrospinal fluid abnormalities and without identifiable cause, now most appropriately termed idiopathic intracranial hypertension, was described over a century ago. Although the pathogenesis of this condition remains unknown, diagnostic and therapeutic developments during the past two decades have substantially advanced patient management.     

Doxycycline and intracranial hypertension

The authors report seven patients from six neuro-ophthalmology referral centers who developed pseudo-tumor cerebri during treatment with doxycycline. All four female patients and one of three male patients were obese. Vision was minimally affected in most patients, but two had substantial visual acuity or visual field loss at presentation. Discontinuation of doxycycline, with or without additional intracranial pressure-lowering agents, yielded improvement, but permanent visual acuity or visual field loss occurred in five patients.     

Management of intracranial hypertension

Effective management of intracranial hypertension involves meticulous avoidance of factors that precipitate or aggravate increased intracranial pressure. When intracranial pressure becomes elevated, it is important to rule out new mass lesions that should be surgically evacuated. Medical management of increased intracranial pressure should include sedation, drainage of cerebrospinal fluid, and osmotherapy with either mannitol or hypertonic saline. For intracranial hypertension refractory to initial medical management, barbiturate coma, hypothermia, or decompressive craniectomy should be considered. Steroids are not indicated and may be harmful in the treatment of intracranial hypertension resulting from traumatic brain injury.