Skip Navigation LinksHome > February 2007 - Volume 39 - Issue 1 > Normal Pressure Hydrocephalus
Journal of Neuroscience Nursing:
Article

Normal Pressure Hydrocephalus

Thynne, Kelly

Free Access
Article Outline
Collapse Box

Author Information

Questions or comments about this article may be directed to Kelly Thynne, MSN RN APN‐C, at kelthynne@aol.com. She is a nurse practitioner at Atlantic Neurosurgical Association in Morristown, NJ.

Collapse Box

Abstract

Normal pressure hydrocephalus (NPH) is a neurological disorder characterized by a triad of symptoms: gait disturbance, dementia, and urinary incontinence. To date, the treatment of choice is cerebrospinal fluid diversion with a shunt. Because the clinical presentation of NPH mimics other neurological disorders, or can be perceived by healthcare providers as a natural aging process, it can be misdiagnosed or go undetected for many years. Patients with NPH suffer from debilitating physiological impairments as well as psychological disturbances. There are many different healthcare concerns in this population, including quality‐of‐life and safety issues. To achieve a more expedient diagnosis and treatment plan, nurses must be educated about this disorder.

FH is a 75‐year‐old white male with a past medical history of diabetes mellitus, hypertension, myocardial infarction, and arthritis. His gait has been impaired for at least 2 years and has been characterized as widened, shuffled, and slowed. FH's primary physician attributed the impaired gait to arthritis and prescribed nonsteroidal antiinflammatory drugs (NSAIDs) and physical therapy.

Over the past year, in spite of physical therapy and NSAIDs, FH has not noticed any improvement in his gait, and now walks with a four‐point cane. FH's daughter also noticed that his memory was deteriorating, as he was unable to remember conversations and activities from one day to the next. He and his daughter attributed this to the natural aging process. FH also complained of urinary urgency and frequency, sometimes causing him to urinate every 2 hours. Because he thought this to be a secondary effect of taking a diuretic for hypertension, he had been taking the medication as soon as he awoke in the morning. However, even at bedtime FH continued to experience urinary frequency, sometimes becoming incontinent when he could not reach the bathroom in time.

An MRI scan of the brain was ordered, and FH was referred to a neurosurgeon because of his persistent complaints of gait instability, mild confusion, and urinary incontinence. During his initial visit with the neurosurgeon, FH reported his medical history and underwent a physical examination. His family history was significant for coronary artery disease, hypertension, and Alzheimer's disease. He stated that he did not drink alcohol and was a 20 pack‐year smoker, but had quit smoking 15 years prior. His wife was deceased, and he lived with his daughter and her husband in a two‐family home. He was taking 25 mg of hydrochlorothiazide orally with a potassium supplement once a day, 200 mg of metoprolol XL by mouth daily, 325 mg of aspirin daily, and 500 mg of glucophage by mouth twice a day. During his physical examination, FH was awake, alert, and oriented times three, but his memory recall was impaired. He was only able to recall 2 of the 5 items he had been shown several minutes earlier, and he was unable to remember what he had eaten for breakfast that morning. In addition, when asked to walk around the examination room, his gait was noticeably broadened and shuffling, and he could not perform tandem walking. He also complained of urinary incontinence.

After completing the physical examination, FH's brain MRI was reviewed and revealed ventriculogmegaly of the anterior and posterior horns, a broadened third ventricle, and an apparently normal fourth ventricle. The surrounding brain tissue was normal without evidence of atrophy. Magnetic resonance flow imaging (cine MRI) was ordered and revealed turbulent cerebrospinal fluid (CSF) flow in the third ventricle, indicating flow impedance. Given the MRI results and the patient's correlating signs and symptoms, a lumbar puncture (LP) was performed. Approximately 50 ml of CSF was drained during the LP. The opening pressure was 120 mm of water, and the CSF was clear and odorless. Protein, glucose, and cell counts were normal. After the procedure, the neurosurgeon asked FH to walk around the examination room once again. FH's gait was markedly improved, without a widened shuffle. He commented that it was the first time he had not wanted to use his cane for support. Based on the physical assessment findings and diagnostic test results, the neurosurgeon diagnosed normal pressure hydrocephalus (NPH) and recommended placing a permanent ventriculoperitoneal (VP) shunt.

NPH can be treated with CSF diversion. This article discusses the triad of signs and symptoms associated with NPH, addresses the appropriate diagnostic workup and management of these patients, and helps the reader identify those at high risk for developing NPH.

Back to Top | Article Outline

Epidemiology

NPH is a rare condition. According to Krauss and Halve (2004), the annual incidence of NPH is approximately 1.8 cases per 100,000 people. However, these estimates are based on patients considered for surgical treatment, so the true incidence of NPH is higher. There is no racial or gender propensity associated with NPH, but NPH is diagnosed more frequently in people in their sixth and seventh decades of life (Wilson, 2004). As the population ages, NPH will become increasingly prevalent, forcing healthcare providers to be more acutely aware of the disorder. Diagnosis of this complex neurological disorder is often missed because its presentation is similar to other neurological disorders. Patients with NPH can suffer for months or years with symptoms before a proper diagnosis is made. A better understanding of NPH provides for a more rapid diagnosis and an improved quality of life for these patients.

Back to Top | Article Outline

Pathophysiology

The disorder is characterized by a decreased absorption rather than an overproduction of CSF (Verrees & Selman, 2004). NPH develops insidiously—as absorption is gradually blocked, CSF slowly accumulates. Because the ventricles enlarge slowly, the fluid pressure in the brain may not be as high as in other types of hydrocephalus (Dalvi, 2004). The term normal pressure hydrocephalus can be misleading because there are transient rises in intracranial pressure noted during intracranial monitoring of these patients. As the ventricles enlarge, pressure is applied to different areas of the brain parenchyma, causing various symptoms. NPH is characterized by ventricular enlargement, a normal opening pressure on LP, and the triad of signs and symptoms.

NPH has no known cause, but has been attributed to fibrosed arachnoid villi. Arachnoid villi are finger‐like projections that help absorb CSF. Other theories posed for idiopathic NPH are fibrosing meningitis and periventricular ischemia. Both are thought to result in weakened, dilated ventricles (Hebb & Cusimano, 2001).

Controversy exists over the role of periventricular ischemia in NPH. Bradley (2001) identified two theories. One theory is that ventricular enlargement increases interstitial pressure in the periventricular region, leading to deep white matter ischemia. The other hypothesis describes an increased venous resistance, secondary to arteriosclerosis, from deep white matter ischemia, which leads to further ventricular enlargement and symptoms (Bradley, 2001). Ischemic lesions in the brain are associated with hypertension, coronary artery disease, stroke, decreased high‐density lipoproteins, and diabetes mellitus, all of which occur more commonly with advanced age. A comprehensive medical history includes identification of these comorbidities as possible contributing factors.

Back to Top | Article Outline

Presentation

A triad of signs and symptoms characterizes NPH: gait disturbance, dementia, and urinary incontinence. Gait disturbance results from ventricular enlargement encroaching on motor fibers, which innervates the legs (Dalvi, 2004). It is often the first and most significant presenting problem, prompting patients to seek medical attention. In NPH patients, the gait is commonly characterized as wide‐based, short stepped, shuffling, and bradykinetic. These patients have trouble picking up their feet, which makes stairs and curb‐walking difficult. Falls are frequent, so safety issues are paramount when assessing these patients. Medical histories should incorporate questions such as whether patients have experienced falls or near falls, whether they live alone or have help at home, whether there is someone who can help with chores and errands, and whether there are stairs at home. Other pertinent information may include whether anyone is dependent upon the patient for care and whether there are throw rugs at home. Because gait instability can occur with other diseases, such as Parkinson's disease (PD), NPH is sometimes misdiagnosed as PD and treated inappropriately. Differentiating the two disorders is important. Rigidity, tremors, and slowing of rapid alternating movements are classic symptoms of PD but are less commonly observed in patients with NPH. Patients with NPH will not respond to medications used for PD. Nurses play a vital role in understanding and identifying signs and symptoms in these patients. They must anticipate safety barriers and alter the environment to allow for a safe hospital stay. In addition, after patients are discharged, it is important that nurses work with the discharge planner to devise an appropriate plan of home care.

Dementia may result from distortion of the periventricular limbic system (Dalvi, 2004). The limbic system is responsible for setting the emotional tone of the mind, filtering external events through internal states, storing highly charged emotional memories, modulating motivation, controlling appetite and sleep cycles, and promoting interaction (Holman, Chandak, & Garada, 1995). Patients may experience mild dementia or a moderate cognitive slowing, including forgetfulness, difficulty dealing with routine tasks, and short‐term memory loss (Goodman & Meyer, 2001). These signs and symptoms are usually less severe than with other dementias, but can be easily misdiagnosed by healthcare practitioners as early onset Alzheimer's disease, or they may be overlooked by the primary care physician or family as an inevitable consequence of aging. Similar symptoms are also observed with multiple infarcts from cerebral vascular disease, however symptoms of expressive or receptive aphasia are not observed in NPH patients (Goodman & Meyer).

Urinary incontinence is usually present in advanced NPH patients, occurring as a result of pressure from dilated ventricles on periventricular pathways to the bladder center (Wilson, 2004). This results in a decreased inhibition of bladder contractions and, consequently, instability of bladder detrusors. More commonly, NPH patients suffer from urinary frequency, which may be easily misdiagnosed as prostate disease in males.

Back to Top | Article Outline

Diagnosis

Diagnosis of NPH is challenging. Beyond the signs and symptoms already discussed, there is a lack of one “gold standard” test to confirm the clinical diagnosis of NPH (Luetmer et al., 2002). A CT scan of the brain is usually the first test done. In NPH, a CT reveals ventricular enlargement. Radionuclide cisternography may be used to determine the presence of NPH. A radioactive isotope is injected intrathecally by LP, and the flow of CSF is monitored by taking sequential pictures over a period of hours or days. In patients with NPH, impaired reabsorption of CSF is observed, which leads to early visualization of ventricles (Soudry & Ahn, 1993). This test has fallen out of favor because abnormalities have not correlated well with shunt surgery, and a normal cisternogram is not useful in ruling out NPH (Hebb & Cusimano, 2001).

MRI demonstrates ventriculomegaly with normal cerebral parenchyma (Verrees & Selman, 2004), and cine MRI may reveal turbulent flow in the posterior third ventricle and within the aqueduct of Sylvius, indicating a flow void, which helps to differentiate NPH from brain atrophy present in Alzheimer's disease (Verrees & Selman). This abnormality of CSF flow is highly correlated with not only the preoperative diagnosis of NPH but with shunt‐responsive NPH as well (Bradley, 2001).

An LP may also be performed, and this allows for CSF analysis and measurement of pressure. In order to yield an accurate diagnostic result, 30‐50 cc of CSF must be collected. The physician assesses the patient's gait directly before and after the LP. An improved gait after the LP may be a positive predictor that a patient will respond to a more permanent CSF diversion device, such as a VP shunt (Krauss & Halve, 2004).

Fig 1
Fig 1
Image Tools

A temporary lumbar drain is a thin, flexible catheter inserted in the lumbar cistern, which may be used in lieu of an LP. This allows for continuous or intermittent removal of CSF over several days to simulate the effect of a more permanent device such as a shunt. With intermittent drainage, 10 cc of CSF may be drained at the beginning of every hour, enabling the patient to be mobile in between drainage periods. Demonstrated improvement in gait following 5‐6 days of CSF diversion proved 100% effective in predicting a positive shunt outcome in a pilot study (Verrees & Selman, 2004). However, some patients with a negative result from external lumbar drainage still experienced improved symptoms after a shunt (Walchenbach, Geiger, Thomeer, & Vanneste, 2002). Documentation of improved symptoms during this trial period is crucial; patients with NPH would show an improved gait, decreased episodes of urinary incontinence, and an improvement in concentration and memory. Nurses must also complete a thorough assessment of the spinal fluid (i.e., color, clear or cloudy appearance), and take the patient's temperature and vital signs. Anticipating possible signs or symptoms of infection should be included in the plan of care; nurses should monitor for elevated temperature, cloudy appearing CSF, change in mental status, and nuchal rigidity.

Documentation of improved symptoms during this trial period is crucial; patients with NPH would show an improved gait, decreased episodes or urinary incontinence, and an improvment in concentration and memory.

Neuropsychological testing may also be performed to determine NPH. A physician, neuropsychologist, or a nurse practitioner can complete this evaluation. Neuropsychological tests are standardized and can be administered orally or as a written examination. The written tests require looking at a picture and selecting a response, whereas the oral test involves asking the patient to respond to a question or perform a skill, such as putting items in order. This testing may help differentiate Alzheimer's dementia from NPH dementia. Patients in early stages of NPH have cognitive impairment predominately in the frontosubcortical area, which contrasts markedly with patients with Alzheimer's disease, who have posterior cortical brain damage (Iddon et al., 1999). A Mini Mental State Examination is one test that can be used to assess for dementia, but this test alone cannot differentiate between the dementia associated with NPH and the dementia associated with Alzheimer's disease (Iddon et al.). A more sensitive neuropsychological test such as the Cambridge Neuropsychological Test (a series of computerized tests completed by patients through a touch screen) may be more specific (Iddon et al.).

Back to Top | Article Outline

Operative Choices

The most common operative choice for NPH is CSF diversion with a shunt, but no definitive algorithm or test exists for the prediction of shunt responsiveness (Verrees & Selman, 2004). A patient presenting primarily with gait instability, incontinence, and mild dementia of short duration, accompanied by imaging showing ventricular dilation but a preserved cortical mantle, has a reasonable likelihood of benefiting from VP shunting (Verrees & Selman).

VP shunting remains the most common therapy for NPH (Verrees & Selman, 2004). The shunt is surgically inserted anteriorly or posteriorly. The anterior approach, which is most commonly used, involves a total of three surgical incisions. The first incision is made in the frontal area at the point where the parasagittal line passes through the pupil crossing the coronal suture. The second incision is made behind the ear (retroauricular), and the third incision is made in the peritoneal cavity where the CSF is drained. The catheter is tunneled underneath the skin and lies freely in the peritoneal cavity. Postoperative nursing assessment and documentation should include observation of a patient's mental status, vital signs, and incisional dressings. The abdomen should also be assessed for softness and presence of bowel sounds. Incisional tenderness should be anticipated and properly medicated with analgesics, but a rigid abdomen with absent bowel sounds and an elevated temperature warrants immediate intervention, including notification of the surgeon.

A lumboperitoneal shunt may also be considered as a therapy for NPH. A lumboperitoneal shunt is inserted into the lumbar intrathecal space; the distal end is tunneled under the skin to the peritoneal cavity, much like the VP shunt (Drake & Sainte‐Rose, 1995). Although it is an enticing alternative to some patients because it does not require entry into the brain, studies have shown the revision rate to be high (Karabatsou, Quigley, Buxton, Foy, & Mallucci, 2004). Other complications of the lumboperitoneal shunt include migration of the abdominal end of the shunt, infection, and hindbrain herniation (Karabatsou et al., 2004). Given these risks, most surgeons have opted to use VP shunts rather than lumboperitoneal shunts (Karabatsou et al.).

Back to Top | Article Outline

Complications

Shunts have complications including obstruction, under‐ and overdrainage, and infection. The effects of gravity on CSF flow through the shunt can lead to drainage of an excessive amount of CSF. This phenomenon is commonly known as siphoning (Bergsneider, Yang, Hu, McArthur, Cook & Boscardin, 2004). Siphoning is associated with headaches, nausea, and vomiting when the patient is in the upright position (Bergsneider et al.). In severe cases, the disruption of blood vessels between the brain and skull caused by overdrainage can lead to subdural hematoma (Bergsneider et al.). To counteract this problem, valve mechanisms have been designed that incorporate antisiphon and gravitycompensating mechanisms to prevent overdrainage with position changes (Bergsneider et al.). Some internal valves can also be adjusted externally using magnetic programmers or adjustment tools, allowing the shunt to be fine‐tuned without the need for additional surgery (Drake & Sainte‐Rose, 1994).

Underdrainage of CSF is characterized by an inadequate decrease of the ventricular size after shunt placement and persistent neurological symptoms (Rohde, Mayfrank, Ramakers, & Gilsbach, 1998). Adjustment of a programmable valve would preclude the need for surgery; otherwise, surgical revision of the valve is necessary.

Other complications include obstruction of the tip of a VP shunt in the choroid plexus. Distal obstruction in the peritoneal portion of the catheter may also be caused by progressive accumulation of debris (Drake & Sainte‐Rose, 1995).

Shunt infection can also occur; clinical features depend on the site of infection (Drake & Sainte‐Rose, 1995). Patients with meningitis or ventriculitis can present with fever, headache, nuchal rigidity, and irritability (Drake & Sainte‐Rose). Patients with peritonitis present with fever, anorexia, abdominal rigidity, hypoactive bowel sounds, and abdominal pain. The shunt may be tapped to determine whether infection is present; blood and urine cultures may also be obtained. An abdominal X ray or ultrasound may be ordered for patients presenting with abdominal signs and symptoms (Drake & Sainte‐Rose). A CT scan is also ordered to assess for ventricular enlargement. Hardware removal and intravenous antibiotic therapy allow the best chance for eradication of infection (Drake & Sainte‐Rose). A temporary external ventricular drain may be inserted after a shunt is removed, which allows the CSF to be examined to determine sterility after intravenous antibiotic treatment and can serve as a route for antibiotic administration directly into the ventricular system if needed (Drake & Sainte‐Rose).

Shunt fractures are another complication. Patients exhibit similar neurological signs and symptoms as those seen prior to shunt insertion. Radiographs of the skull, chest, and abdomen (for VP shunts) and abdomen only (for lumboperitoneal shunts) may be ordered to assess the position and detect a disconnection of tubing. A CT scan of the head may be ordered to assess ventricular size. Nurses play an important role in anticipating and identifying possible shunt complications. They are usually the first healthcare providers to recognize subtle changes in mental status and are able to identify possible shunt complications.

After a permanent shunting device has been inserted and the patient has been discharged, it is imperative for patients and family members to be taught how to identify possible postoperative complications of shunts, such as infection and drainage from the incision. Patient education should also incorporate possible shunt complications such as obstructions and fractures. The signs and symptoms of shunt complication are similar to the patient's preshunting baseline. For example, patients may complain of a decline in mental status, a worsening gait, or increasing episodes of urinary incontinence.

Back to Top | Article Outline

Case Resumed

After an extensive conversation with the neurosurgeon and his daughter, FH elected to undergo an insertion of a VP shunt. He was discharged from the hospital 2 days after insertion. After 2 weeks, he walked without any assistive devices. Over the subsequent weeks, FH and his daughter noticed an improvement in his memory and a decrease in the episodes of urinary incontinence. He was in better spirits and felt his quality of life had greatly improved.

Back to Top | Article Outline

Summary

Normal pressure hydrocephalus is a neurological disorder diagnosed by a triad of symptoms along with radiographic findings. NPH patients treated with CSF diversion have seen positive results. It is important for healthcare providers to be vigilant when assessing these high‐risk patients. Identifying the onset and duration of signs and symptoms, as well as their progression, are crucial to the diagnosis of NPH.

The diagnosis of NPH can be challenging for healthcare providers. Other neurological disorders such as Parkinson's disease or Alzheimer's disease include similar symptoms as NPH and can contribute to the delay of diagnosis and treatment. The lack of a diagnostic “gold standard” further complicates appropriate diagnosis. Further studies are needed to identify a specific cohort of patients who will benefit most from shunt surgery.

Nurses play a vital role in assessing the signs and symptoms of NPH and educating patients and families. With prompt diagnosis and treatment, patients with NPH are able to have an improved quality of life.

Back to Top | Article Outline

References

Bergsneider, M., Yang, I., Hu, X., McArthur, D., Cook, S., & Boscardin, W. (2004). Relationship between valve opening pressure, body position, and intracranial pressure in normal pressure hydrocephalus: Paradigm for selection of programmable valve pressure setting. Neurosurgery, 55(4), 851-859.

Bradley, W. G. (2001). Normal pressure hydrocephalus and deep white matter ischemia: Which is the chicken, and which is the egg? American Journal of Neuroradiology, 22, 1638-1640.

Dalvi, A. (2004). Normal pressure hydrocephalus. Retrieved February 25, 2005, from www.emedicine.com/neuro/topic277.htm.

Drake, J., & Sainte-Rose, C. (1995). The shunt book. Boston: Blackwell Science.

Goodman, M., & Meyer, W. (2001). Dementia reversal in post-shunt normal pressure hydrocephalus predicted by neuropsychological assessment. American Geriatrics Society, 49(5), 685-686.

Hebb, A., & Cusimano, M. D. (2001). Idiopathic normal pressure hydrocephalus: A systematic review of diagnosis and outcome. Neurosurgery, 49(5), 1166-1186.

Holman, B., Chandak, P., & Garada, B. (1995). Atlas of brain perfusion SPECT. Retrieved March 17, 2005, from http://brighamrad.harvard.edu/education/online/BrainSPECT/.

Iddon, J., Pickard, J., Cross, J., Griffiths, P. D., Czosnyka, M., & Sahakian, B. (1999). Specific patterns of cognitive impairment in patients with idiopathic normal pressure hydrocephalus and Alzheimer's disease: A pilot study. Journal of Neurology, Neurosurgery, and Pyschiatry, 67, 723-732.

Karabatsou, K., Quigley, G., Buxton, M., Foy, P., & Mallucci, C. (2004). Lumboperitoneal shunts: Are the complications acceptable? Acta Neurochirurgica, 146, 1193-1197.

Krauss, J., & Halve, B. (2004). Normal pressure hydrocephalus: Survey on contemporary diagnostic algorithms and therapeutic decisionmaking in clinical practice. Acta Neurochirurgica, 146, 379-388.

Luetmer, P., Huston, J., Friedman, J., Dixon, G., Petersen, R., Jack, C., et al. (2002). Measurement of cerebrospinal fluid flow at the cerebral aqueduct by use of phase-contrast magnetic resonance imaging: Technique validation and utility in diagnosing idiopathic normal pressure hydrocephalus. Neurosurgery, 50(3), 534-543.

Rohde, V., Mayfrank, L., Ramakers, V., & Gilsbach, J. (1998). Fouryear experience with the routine use of the programmable Hakim valve in the management of children with hydrocephalus. Acta Neurochirurgica, 140, 1127-1134.

Soudry, G., & Ahn, C. (1993). Cysternography in normal pressure hydrocephalus. Case presentation. Retrieved February 25, 2005, from www.med.harvard.edu/JPNM/TF93_94/Oct12/WriteUpOct12.html.

Verrees, M., & Selman, W. (2004). Management of normal pressure hydrocephalus. American Family Physician, 70(6), 1071-1078.

Walchenbach, R., Geiger, E., Thomeer, R., & Vanneste, J. (2002). The value of temporary external lumbar CSF drainage in predicting the outcome of shunting on normal pressure hydrocephalus. Journal of Neurology, Neurosurgery, and Psychiatry, 72, 503-506.

Wilson, J. (2004). Normal pressure hydrocephalus. Retrieved February 25, 2005, from www.emedicine.com/radio/topic479.htm.

© 2007 American Association of Neuroscience Nurses

Login

Article Level Metrics