Idiopathic intracranial hypertension within the ICF model: a review of the literature.
Subject: Intracranial hypertension (Care and treatment)
Intracranial hypertension (Research)
Author: Lehman, Cheryl A.
Pub Date: 10/01/2003
Publication: Name: Journal of Neuroscience Nursing Publisher: American Association of Neuroscience Nurses Audience: Professional Format: Magazine/Journal Subject: Health care industry Copyright: COPYRIGHT 2003 American Association of Neuroscience Nurses ISSN: 0888-0395
Issue: Date: Oct, 2003 Source Volume: 35 Source Issue: 5
Topic: Event Code: 310 Science & research
Accession Number: 110024682
Full Text: Abstract: Idiopathic intracranial hypertension (IIH) is an unusual disease, seen most often in women of childbearing age who are obese. If left untreated, IIH can cause chronic pain and blindness. Although IIH has been recognized by healthcare providers since the late 1880s, the cause is still not known and risk factors remain unclear. Treatment has not changed over the years. While professionals struggle to define, describe, and successfully treat IIH, persons with the disease are struggling to cope. Internet support ,group communications relate numerous personal stories of frustration, depression, pain, anxiety, and disability. The World Health Organization's International Classification of Functioning, Disability and Health (ICF) model provides an appropriate framework through which to view what is known and what is yet to be discovered about IIH. The ICF model was designed to complement the International Statistical Classification of Diseases and Related Health Problems, looking beyond mortality and disease by describing how people live with their health conditions. Applying this framework to IIH reveals many opportunities for nursing research within the ICF domains of health condition, body function and structure, ability and participation, and environmental and personal factors.

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Idiopathic intracranial hypertension (IIH) is an unusual disease. Seen most often in women of childbearing age who are obese, it has also been diagnosed in men and in children (Intracranial Hypertension Research Foundation [IHRF], 2003). If left untreated, IIH can cause pain and blindness. Although IIH has been recognized and diagnosed since the late 1880s, the cause of IIH is not known, risk factors are unclear, and treatment has not changed in more than 100 years (IHRF).

Review of the literature reveals ongoing attempts to describe IIH, including the causes, epidemiology, symptoms, and treatments. There is one glaring gap in the literature: The psychosocial aspects of the disease have not been systematically studied (Kleinschmidt, Digre, & Hanover, 2000). Conversations within several Internet support groups for IIH, however, abound with themes of anxiety, depression, frustration, unrelieved pain, marital difficulties, and disability (Bill Forum, 2003; BIH Web site, 2003; PTC Network, 2003).

This article reviews IIH within the framework of the International Classification of Functioning, Disability, and Health (ICF) model (World Health Organization [WHO], 2001). WHO sees the ICF model as a tool that can help "provide a scientific basis for consequences of health conditions; establish a common language to improve communications; and permit comparison of data across countries, healthcare disciplines, services, and time" (WHO, www.who.int/classification/icf/ intros/ICF-ENG-Intro.pdf, p. 5). Although ICF is an assessment tool used to elicit and record level of function and disability in an individual, the model can be a useful guideline for systematic review of a disease.

The ICF Model

As shown in Fig 1, the ICF model classifies information into two categories: function and disability (i.e., body structures and function, activities, and participation) and contextual factors (i.e., environmental and personal factors). Thus, the ICF model defines a person's level of function and disability in terms of a dynamic interaction between health conditions and contextual factors (WHO, 2001). ICF was designed to complement the International Statistical Classification of Diseases and Related Health Problems (ICD-10), by moving beyond mortality and disease to describe how people live with their health conditions.

[FIGURE 1 OMITTED]

Within the ICF model, body structures and functions are defined as the anatomical parts of the body and the physiological function of body systems. Impairments in body structure can involve anomaly, defect, or loss. Impairments are not the same as underlying pathology but are the manifestations of that pathology (WHO, 2001). Thus, brain damage resulting from a stroke would be a change in body structure, whereas hemiplegia would be the associated change in body function.

Activity is the execution of a task or action, whereas participation is involvement in a life situation. Limitations in activity are any difficulties that a person may have in performing activities, such as mobility, communication, or self-care. Restrictions in participation are problems that a person may experience ha involvement in life situations, such as domestic fife, interpersonal relationships, or community life (WHO, 2001). For example, the person who has hemiplegia resulting from a stroke might experience difficulty in ambulation (i.e., limitations) and also encounter marital problems resulting from the physical changes due to stroke (i.e., restrictions).

Environmental factors interact with all the components of functioning and disability. These factors can help or hinder the effects of the physical, social, and attitudinal worlds on the individual (WHO, 2001). Environmental factors include the presence of ramps in public buildings, attitudes of healthcare workers, or funding for employment training. The person with stroke might not have funding for a wheelchair or may be unable to return to work due to an inaccessible workplace.

Personal factors vary with cultural and social settings. Coping skills, self-esteem, communication skills, and life goals are all examples of personal factors that may affect functioning and disability.

Idiopathic Intracranial Hypertension

IIH has been known by many other names. The most common names, actually misnomers, are pseudotumor cerebri and benign intracranial hypertension. Because "pseudo" and "benign" connote a trivial sort of diagnosis, clinicians are currently supporting the name idiopathic intracranial hypertension (Corbett, 2000).

Confusion about the name of the disease stems from the fact that there are two forms of intracranial hypertension: primary, or idiopathic, intracranial hypertension, in which increased intracranial pressure (ICP) occurs spontaneously, without a known cause, and secondary intracranial hypertension, which is the outcome of a known underlying condition (IHRF, 2003). Clinicians add to the confusion by routinely using the terms pseudotumor cerebri and benign intracranial hypertension interchangeably in both IIH and secondary intracranial hypertension.

The incidence of IIH has been found to vary from population to population. The numbers most frequently quoted in the literature are from a study done in Louisiana and Iowa in 1988 (Durcan, Corbett, & Wall, 1988). This study found that the annual incidence in the general population in Iowa was 0.9/ 100,000. The incidence for women 20-44 years old who were 10% or more heavier than their ideal weight was 13/100,000 in Iowa, and 14.3/100,000 in Louisiana. The incidence became 19.3/100,000 for those women in the same age range who were 20% or more heavier than their ideal weight. The female to male ratio was 8:1 in Iowa and 4.3:1 in Louisiana. The mean weight was 38% above ideal weight for height. The authors noted that they could have underestimated the incidence because of the research design. These numbers were not age adjusted.

Age-adjusted incidence in Rochester, MN, was found to be 0.9/100,000 in the general population, 1.6/100,000 in the female population, and 7.9/100,000 in females 15-44 years old whose body mass index (BMI) was greater than 26 (Radhakrishnan, Ahlskok, Cross, Kurland, & O'Fallon, 1993). The crude annual incidence rate in Libya was found to be 2.2/100,000, and 21.4/100,000 in obese females 15-44 years old (Radhakrishnan, Thacker, Bohlaga, Maloo, & Gerryo, 1993). Incidence is not related to gender in the pediatric population (Digre & Corbett, 1988).

The current incidences of IIH could be different from those found in 1988. Obesity in America has been increasing, and because IIH is closely related to obesity, the incidence of IIH may be higher than expected. There are now 60 million obese persons in the United States. Between 1988 and 1994, 23% of Americans were considered obese. In 1999-2000, this increased to 30.5%. During the same time period, 69.6% of African Americans, 73.4% of Mexican Americans, and 62.3% of whites were considered overweight (i.e., BMI [greater than or equal to] 25). and 39% of African Americans, 34.4% of Mexican Americans, and 28.7% of whites were considered obese (i.e., BMI [greater than or equal to] 30; American Obesity Association, 2002).

Although the medical literature is rich with studies about women with IIH, few studies on the male population have been published. Although the incidence of IIH is lower in men, there is a similar age distribution, and signs and symptoms are similar in both sexes. Men may be more likely to require surgery for vision loss, and African American males may be at greater risk for vision loss. Males with IIH may also be less likely to be obese than women (Digre & Corbett, 1988).

Conditions and diseases that have been confirmed as being associated with IIH are gender (i.e., female), reproductive age group, menstrual irregularity, obesity, and recent weight gain. Unconfirmed conditions include endocrine dysfunction (e.g., hypothyroidism, Cushing's disease, adrenal insufficiency, hypoparathyroidism), medications (e.g., minocycline, tetracycline, cimetadine corticosteroids, lithium, Norplant, human growth hormone, vitamin A), chronic renal failure, and systemic lupus erythematosus (Radhakrishnan, Ahlskog, Garrity, & Kurland, 1994). White women with IIH have been found to be younger at onset of menses, to experience change in menstrual pattern at onset, have a higher presence of hypertension, and have a higher prevalence of first-degree relatives with hypertension, diabetes, and obesity (Ireland, Corbett, & Wallace, 1990). There is also a possible association between anticardiolipin antibodies (ACL-Ab) and IIH; the incidence of ACL-Ab has been found to be higher in persons with IIH than in the general population (Shin & Balcer, 2001).

Symptoms of IIH include headache, pulsatile intracranial noises, double vision, neck pain, shoulder and back pain, radicular pain, photophobia, nausea, vomiting, transient visual obscurations, and vision loss. Signs include papilledema and associated vision loss, along with 6th cranial nerve palsy (Friedman & Jacobson 2002). Not all people have all signs and symptoms; no will they have the same signs and symptoms to the same degree. Nearly 50% of all patients with this disease will have some vision or visual field loss (Skorin, 1999). Women with 1114 report other symptoms, including mental confusion, ear pain, food cravings, and memory loss, as well as a change in ability to accurately spell, read, and write (PTC Network, 2003).

IIH is typically a diagnosis of exclusion. Once the patient presents with symptoms, other diseases, such as tumor or structural defect, are ruled out. IIH is diagnosed according to the "modified Dandy's Criteria," which are as follows:

* Patient shows signs and symptoms of increased ICP.

* Patient is awake and alert.

* There are no localizing neurologic signs other than abducens nerve paresis.

* Neuroimaging studies are normal except for small ventricles or empty sella.

* Although increased pressure is documented (>201 mm [H.sub.2]O in nonobese and >250 mm H20 in the obese patient), there is a normal composition of cerebrospinal fluid

* No other cause of intracranial hypertension is present (Radhakrishnan, Ahlskog, et al., 1993).

Friedman and Jacobson (2002) recommended the following diagnostic criteria:

* If signs and symptoms are present, they may only reflect those of generalized intracranial hypertension or papilledema.

* Elevated ICP (>250 mm [H.sub.2]O) measured in the lateral decubitus position is documented.

* Cerebrospinal fluid (CSF) composition is normal.

* There is no evidence of hydrocephalus, mass, structural, or vascular lesion on magnetic resonance imaging (MRI) or contrast-enhanced computed tomography (CT) for typical patients (obese healthy women of childbearing age), and MRI and MR venography for all others (men, children, and the elderly).

* No other cause of intracranial hypertension is identified (Friedman & Jacobson, 2002).

Because chronically elevated ICP can cause edema of the optic nerve, with resulting necrosis of the nerve and vision loss, treatment for IIH is aimed primarily at preventing blindness through management of the increased ICE This is typically through pharmaceutical or mechanical means. Persons without visual signs and symptoms (e.g., papilledema and/or visual changes) are commonly treated with medications. These include diuretics such as acetazolamide, hydrochlorothiazide, and furosemide to reduce ICP; digoxin; and, in rare instances, corticosteroids. Once visual signs and symptoms appear, mechanical options are recommended, including short-term serial lumbar punctures, insertion of lumbar-peritoneal or ventricular-peritoneal shunts, or optic nerve sheath fenestration. For persons with obesity, weight reduction programs are recommended and, in the most extreme cases, surgery to reduce the size of the stoma& and induce weight loss (Goodwin, 2002; Radhakrishnan et al., 1994).

Body Functions

Within the ICF model, body functions are defined as the physiological and psychological functions of body systems. It is important to understand both normal and abnormal body function.

Physiological Functions

Normally, CSF is produced by the choroid plexus of the lateral ventricles. The body produces between 400 and 500 cc of CSF per day, keeping the actual volume of CSF at any one time at 125-150 cc. Production normally equals absorption. CSF flows freely over the convexities of the brain and along the spinal canal, helping to keep the brain cushioned and afloat. It is drained by the arachnoid villi via a pressure-dependent process through the superior and lateral sinuses, into the venous circulation. ICP is determined by cerebral arterial pressure, cerebral venous pressure, the production and absorption of CSF, the elastic properties of the brain and blood vessels, and the capacity of the cranial and subarachnoid space to expand. Normal CSF pressure is 150-180 mm H20 (Hickey, 2003; Hyman-Newman Institute, 2003; The Ventricular System and CSF, 2003).

Functionally, IIH has been defined as ICP above 200-250 mm [H.sub.2]O. This increased ICP is not due to structural changes, although structural changes can result from increased ICP. It has been postulated, but not proven, that IIH could be due to three different functional changes: (a) increased resistance to CSF absorption, (b) increased production of CSF without increased absorption, or (c) increased venous sinus pressure (Digre, 2002). Physiological changes in body functions resulting from chronically increased ICP may include chronic pain, visual changes such as loss of visual fields, blurring, or visual acuity, or permanent vision loss. Women with IIH also have reported changes in hearing and more peripheral edema than age--and weight-matched group (Kleinschmidt et al., 2000).

Psychological Functions

One recent study on the effect of IIH on depression, anxiety, and quality of life found that persons with IIH had higher levels of anxiety and depression than age--and weight-matched groups. They also reported a greater number of adverse health problems and were more affected by hardships associated with health problems than the other two groups. Obesity alone did not explain the higher levels of depression and lower levels of quality of life (Kleinschmidt et al., 2000). Coffey (2000) postulated that IIH could be the result of changes in endocrine function following a major depressive episode. Women with IIH also report stress and depression, as well as frustration when dealing with the medical community (PTC Network, 2003).

Body Structure

ICF defines body structures as anatomical parts of the body, such as organs and limbs and their components. By the strictest definition, IIH is not caused by a heretofore discovered change in body structures--hence the name, idiopathic.

Researchers have postulated that obesity is closely associated with IIH. Several studies related findings of an improvement in symptoms of IIH with weight loss, although many persons with IIH who communicate through online support groups refute these findings (Kupersmith et al., 1998; PTC Network, 2003; Sugarman, Felton, Salvant, Sismanis, & Kellum, 1995). The mechanism of obesity's relation to IIH seems to be an elevation of intra-abdominal pressure, which increases pleural pressure and cardiac filling pressure, which slows venous return from the brain, leading to chronic increased intracranial venous pressure and increased ICP. This theory has not been proven and does not explain IIH in people who fall within normal weight ranges.

IIH also can cause structural changes in the body. These include papilledema (swelling of the optic disc), necrosis of the optic nerve, and scarring and nerve damage from repeated procedures such as lumbar punctures or surgical procedures. Insertion of a shunt, either lumbar-peritoneal or ventricular-peritoneal, causes unseen changes in internal body structure and function, and can also cause visible, external changes in body structure.

Activity and Participation

ICF defines activity as the execution of a task and participation as the involvement in life's activities. Impairment in these areas often remains a hidden problem in IIH.

One recent article in the literature is related to these areas of ICF, although recent communications in the Internet support groups for IIH abound with the concerns and frustrations of people with IIH about activity and participation. Kleinschmidt et al. (2000) found that women with IIH reported more fatigue and sleep loss than age--and weight-matched groups. Women with IIH in this study also reported less of an ability to meet daily demands.

Women communicating via Internet support groups revealed restrictions in activity and participation. Causes of decreased activity and participation are numbness, muscle spasms, back pain, headaches, vision loss, fatigue, dizziness, and depression. They related their inability to hold a job, take care of household chores, and participate in family life. Some related marital difficulties caused by their "invisible illness," and some shared tips on how to access Social Security disability and on the Family Medical Leave Act (FMLA; PTC Network, 2002).

Environmental Factors

Environmental factors make up the physical, social, and attitudinal environment in which people live and conduct their lives (WHO, 2001). They include external influences on functioning and disability.

These factors have not been explored in the IIH population, although they certainly could affect outcomes. Women with IIH who communicate via the Internet support groups revealed concerns about attitudes of physicians, employers, and family who do not understand their disease or symptoms. They talked about attitudes of medical workers toward their weight, pain, coping, and symptoms. Some reported difficulties with employers, sick leave, and FMLA and concerns about money; others shared tips on alternative care options such as chiropractic care, massage, and herbal therapies. Suggestions on managing procedures and requesting appropriate equipment, such as spinal needles and radiologic guidance for lumbar punctures, were given (PTC Network, 2003).

IIH has the potential to be an expensive disease. Vision assessments, lumbar punctures, medications, radiological procedures, and surgical procedures are costly. Insurance, or lack thereof, has the ability to affect the outcome of the disease. In fact, conversation on the British Benign Intracranial Hypertension (BIH) support group's Internet site revealed differences in access to care between the UK's National Health Plan and those insured or uninsured in the United States (BIH Forum, 2003).

Personal Factors

Personal factors are those internal influences on functioning and disability. They may include self-efficacy, self-esteem, culture, ethnicity, gender, and age. Other than gender and age, personal factors and their effect on disability in persons with IIH have not been reported in the literature.

Summary

Figs 2 and 3 illustrate what is known about IIH and identify opportunities for further study. Even after more than 100 years, there are multiple opportunities for medical and psychosocial research in the population of persons with |TH. Epidemiology, causes, risk factors, treatments, symptoms, psychological factors, and sociological factors related to IIH remain unclear, as do the activity limitations and limitations in participation. Environmental and personal factors affecting the course and outcomes of the disease have not been studied. Research to date has focused on medical issues--it is now important to expand research with personal input from those with the disease.

[FIGURES 2-3 OMITTED]

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Questions or comments about this article may be directed to: Cheryl A. Lehman, MSN RN CRRN-A, by phone at 409/772 1071 or by e-mail at clehman@utmb.edu. She is a clinical nurse specialist in medical-surgical nursing at the University of Texas Medical Branch at Galveston, Galveston, TX.
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