Benign intracranial hypertension (BIH)

What is Benign intracranial hypertension?

Benign intracranial hypertension (BIH) is a disease of the brain. Benign intracranial hypertension is characterised by increased pressure in the brain without any evidence of any brain pathology by imaging studies. Benign intracranial hypertension is also characterised by normal cerebrospinal fluid (CSF - the fluid that surrounds the entire central nervous system, including brain and spinal cord) content.It is also known in different names, including:

Idiopathic intracranial hypertension (IIH)

Pseudotumour cerebri (PTC)

Statistics on Benign intracranial hypertension?

Benign intracranial hypertension is an extremely rare disease. Studies from various countries estimate that the annual incidence is at the figure of 0.9 per 100,000 of general population. This figure is increased in women after puberty and in women with their weight 20% or more of the ideal weight.

Risk Factors for Benign intracranial hypertension

Gender is a major risk factor for BIH. Before puberty, boys and girls are affected equally. After puberty, BIH affects women 9 times as often as men.Obesity is a risk factor as well, considering that the incidence rises sharply with women 20% or more above their ideal weight.

Progression of Benign intracranial hypertension

In short, the pathogenesis of benign intracranial hypertension is still uncertain despite the fact that it has been described more than 100 years ago. Benign intracranial hypertension is characterised by the following:

Increased intracranial pressure.

Lack of ventricular dilatation (ventricles are fluid filled cavities in the middle of the brain).

Predilection for young, obese women.

Induced by various medications, including tetracycliines, vitamin A and oral contraceptive pills.

The exact mechanism of benign intracranial hypertension is still under debate at the moment.With prolonged high pressure in the brain, eye changes and brain changes may occur.

Prognosis of Benign intracranial hypertension

Benign intracranial hypertension does not increase the death rate by itself, rather, the death rate is increased by morbid obesity which is a common association with benign intracranial hypertension.However, it does cause significant inconvenience to the patients. Eye changes can be a mortal complication of untreated benign intracranial hypertension, leading to permanent blindness. As many as 96% of the patients with benign intracranial hypertension has some degree of visual changes.General investigations:If a patient comes in with persistent headache and eye pathology, most likely a full physical examination will be necessary. These include looking at the blood function, kidney function, liver function, thyroid function, and the body's iron, vitamins and electrolytes level.

How is Benign intracranial hypertension Treated?

Treatment of benign intracranial hypertension needs multiple team approach, including neurologist, ophthalmologist, neurosurgeon and general practitioners.Below are the treatment strategies for BIH:

Diet and weight loss: This can either be achieved on patient self-discipline alone or with the help of medications and surgery. There have been positive improvement on signs and symptoms where patients have lost significant amount of weight.

Medications: Traditionally, diuretics (fluid tablets that removes water from the body) have been used. One such example is acetazolamide. However, it has significant side effects unpleasant taste with carbonated drinks, altered taste sensation, etc. Otherwise, other diuretics such as frusemide, thiazides, spironolactone, and triamterene can be used but with varying results.

Steroids can be used to reduce the pressure in the brain rapidly but they are not suitable for long-term use.

Supportive care: A persistent headache can be treated by standard pain relief medications.

Surgery: This is indicated for visual loss or worsening visual changes due to the disease. They aim to reduce the pressure that compresses on the nerve in the eye that is responsible for normal vision.

Benign intracranial hypertension References

[1] Durcan FJ, Corbett JJ, Wall M. The incidence of pseudotumor cerebri. Population studies in Iowa and Louisiana. Arch Neurol 1988;45:875-7[2] eMedicine: Pseudotumour cerebri [online]. 2005. [Cited 2005 October 25th]. Available from: URL: http://www.emedicine.com/NEURO/topic329.htm[3] Friedman DI. Pseudotumor cerebri. Neurol Clin 2004; 22(1): 99-131[4] Kesler A, Gadoth N. Epidemiology of idiopathic intracranial hypertension in Israel. J Neuroophthalmol 2001;21:12-4[5] Radhakrishanan K, Ahlskog JE, Cross SA, et al. Idiopathic intracranial hypertension (pseudotumor cerebri). Descriptive epidemiology in Rochester, Minn, 1976Ã¢â‚¬â€œ1990. Arch Neurol 1993;50:78-80[6] Radhakrishanan K, Sridharan R, Askhok PP, et al. Pseudotumor cerebri: incidence and pattern in north-eastern Libya. Acta Neurol (Napoli) 1986;25:117[7] Up to Date: Idiopathic intracranial hypertension (pseudotumor cerebri) in children [online]. 2005. [Cited 2005 October 25th]. Available from: URL: http://www.utdol.com/application/topic.asp?file=ped_neur/5164&type=P&selectedTitle=14~20