Estimated Incidence of Normal-pressure Hydrocephalus and Shunt Outcome
Estimated Incidence of Normal-pressure Hydrocephalus and Shunt Outcome
Object: The primary objective of this study was to estimate the prevalence of idiopathic normal-pressure hydrocephalus (NPH), both diagnosed and undiagnosed, among residents of assisted-living and extended-care facilities, by using a practical screening tool. A secondary objective was to evaluate prospectively the diagnosis and outcome of surgical treatment in a subset of patients residing in healthcare facilities who were at risk for idiopathic NPH.
Methods: A retrospective chart analysis was performed using the medical records from four nursing homes. The final analysis included 147 patient records. Symptomatology and comorbidity were evaluated, as was the ability to perform activities of daily living. In a subset of 17 patients residing in healthcare facilities, the authors applied a standard idiopathic NPH diagnostic and management protocol and followed up the patients 1 year after treatment.
The estimated incidence of suspected idiopathic NPH among all patients in the retrospective survey ranged from 9 to 14%, depending on the diagnostic criteria used. Among the cohort of 17 patients available for an in-hospital study and 1-year follow up, 11 received shunts and seven of these showed either transient or sustained improvement.
Conclusions: A valid and practical diagnostic method is needed to identify idiopathic NPH accurately before admitting patients to a healthcare facility. Data from a prospective study of 17 patients residing in healthcare facilities indicated that supplementary tests remain predictive of a positive response to shunt insertion but cannot predict whether a favorable outcome will be sustained in a population of patients who have been confined to a wheelchair for a prolonged period of time. This finding supports the notion of a finite window of opportunity for successful treatment of idiopathic NPH and the imperativeness of an early diagnosis.
The symptom triad of gait disturbance, urinary in continence, and dementia in combination with ventriculomegaly clinically defines idiopathic NPH. Abnormal gait is considered the predominant component of this diagnostic triad, and it is rare for a patient with idiopathic NPH to present without some form of gait disturbance. The characteristic gait is described as shuffling, wide-based, or ataxic. The incontinence associated with idiopathic NPH is characterized by urgency or frequent urination, and the dementia as faltering in short- or long-term memory. Although the disease was initially defined by Hakim and Adams in 1965, its precise origin remains elusive. The absence of a clearly established pathophysiology and the presence of possible confounding coexisting dementias or brain disorders with similar symptom patterns make it difficult to establish the clinical diagnosis of idiopathic NPH. As a result, it is frequently misdiagnosed or undiagnosed, and thus left untreated.
Normal-pressure hydrocephalus is subdivided into two main categories: idiopathic NPH and secondary NPH. The latter usually is caused by events such as subarachnoid hemorrhage, meningitis, head trauma, or stroke and can develop in patients of all ages. In contrast, there is no known origin for idiopathic NPH, and it is typically diagnosed in patients during their sixth or seventh decade of life, which suggests that age is a risk factor. Although the pathological mechanisms of idiopathic NPH are not fully understood, it is recognized as a disorder of CSF flow and absorption rather than formation. In fact, CSF flow can be disturbed by increased resistance to outflow, requiring a slightly higher pressure within the ventricles to maintain the production and balance of CSF; however, a disturbance in CSF circulation is not always indicative of idiopathic NPH. It has been postulated that a deficit in CSF absorption can cause dilation of the cerebral ventricles, but how this event leads to idiopathic NPH is not known. Data from studies in both animals and humans have shown that increased intraventricular CSF pressure caused by impaired CSF flow can result in ventricular enlargement. However, as the discrepancy between ventricular and convexity CSF pressures dissipates, episodic elevations in intraventricular CSF pressures appear to remain. Other mechanisms attributed to the development of idiopathic NPH include a reduction in blood flow and metabolism, an increase in transmantle pressure, and ischemic changes in white matter, altering the viscoelastic properties of brain parenchyma.
Although the pathophysiology of idiopathic NPH remains elusive, it is one of the few dementias considered treatable and reversible. The use of shunts to reduce intraventricular volume and pressure has demonstrated promising results in patients with idiopathic NPH if the shunts are placed before the onset of cognitive deterioration. Despite the numerous studies focused on the utility of surgical shunts in the treatment of this disorder, their placement is controversial because of the high rate of associated complications (30–40%). Nonetheless, authors of several studies have demonstrated that the predominant symptoms of idiopathic NPH (gait disturbance, incontinence, and dementia) improve following the surgical placement of shunts.
A lack of consensus remains regarding patient selection for optimal benefit from shunting. In a study of 18 patients with a diagnosis of idiopathic NPH, the clinical onset of the disease marked by dementia was predictive of an unfavorable outcome when assessing candidacy for shunting, whereas gait disturbance (either with or without urinary incontinence) correlated positively with functional recovery. Thus, patients treated in the early stages of symptom onset appear to have better outcomes from shunt surgery than patients who are diagnosed and treated in later stages of the disease.
The primary objective of this study was to estimate the prevalence of idiopathic NPH (diagnosed and undiagnosed) among residents of assisted-living and extended-care nursing homes in southeast Virginia by using a practical screening tool. A second goal was to determine the outcome of surgical management in a subset of residents in healthcare facilities who had met the criteria for suspected idiopathic NPH.
Abstract and Introduction
Abstract
Object: The primary objective of this study was to estimate the prevalence of idiopathic normal-pressure hydrocephalus (NPH), both diagnosed and undiagnosed, among residents of assisted-living and extended-care facilities, by using a practical screening tool. A secondary objective was to evaluate prospectively the diagnosis and outcome of surgical treatment in a subset of patients residing in healthcare facilities who were at risk for idiopathic NPH.
Methods: A retrospective chart analysis was performed using the medical records from four nursing homes. The final analysis included 147 patient records. Symptomatology and comorbidity were evaluated, as was the ability to perform activities of daily living. In a subset of 17 patients residing in healthcare facilities, the authors applied a standard idiopathic NPH diagnostic and management protocol and followed up the patients 1 year after treatment.
The estimated incidence of suspected idiopathic NPH among all patients in the retrospective survey ranged from 9 to 14%, depending on the diagnostic criteria used. Among the cohort of 17 patients available for an in-hospital study and 1-year follow up, 11 received shunts and seven of these showed either transient or sustained improvement.
Conclusions: A valid and practical diagnostic method is needed to identify idiopathic NPH accurately before admitting patients to a healthcare facility. Data from a prospective study of 17 patients residing in healthcare facilities indicated that supplementary tests remain predictive of a positive response to shunt insertion but cannot predict whether a favorable outcome will be sustained in a population of patients who have been confined to a wheelchair for a prolonged period of time. This finding supports the notion of a finite window of opportunity for successful treatment of idiopathic NPH and the imperativeness of an early diagnosis.
Introduction
The symptom triad of gait disturbance, urinary in continence, and dementia in combination with ventriculomegaly clinically defines idiopathic NPH. Abnormal gait is considered the predominant component of this diagnostic triad, and it is rare for a patient with idiopathic NPH to present without some form of gait disturbance. The characteristic gait is described as shuffling, wide-based, or ataxic. The incontinence associated with idiopathic NPH is characterized by urgency or frequent urination, and the dementia as faltering in short- or long-term memory. Although the disease was initially defined by Hakim and Adams in 1965, its precise origin remains elusive. The absence of a clearly established pathophysiology and the presence of possible confounding coexisting dementias or brain disorders with similar symptom patterns make it difficult to establish the clinical diagnosis of idiopathic NPH. As a result, it is frequently misdiagnosed or undiagnosed, and thus left untreated.
Normal-pressure hydrocephalus is subdivided into two main categories: idiopathic NPH and secondary NPH. The latter usually is caused by events such as subarachnoid hemorrhage, meningitis, head trauma, or stroke and can develop in patients of all ages. In contrast, there is no known origin for idiopathic NPH, and it is typically diagnosed in patients during their sixth or seventh decade of life, which suggests that age is a risk factor. Although the pathological mechanisms of idiopathic NPH are not fully understood, it is recognized as a disorder of CSF flow and absorption rather than formation. In fact, CSF flow can be disturbed by increased resistance to outflow, requiring a slightly higher pressure within the ventricles to maintain the production and balance of CSF; however, a disturbance in CSF circulation is not always indicative of idiopathic NPH. It has been postulated that a deficit in CSF absorption can cause dilation of the cerebral ventricles, but how this event leads to idiopathic NPH is not known. Data from studies in both animals and humans have shown that increased intraventricular CSF pressure caused by impaired CSF flow can result in ventricular enlargement. However, as the discrepancy between ventricular and convexity CSF pressures dissipates, episodic elevations in intraventricular CSF pressures appear to remain. Other mechanisms attributed to the development of idiopathic NPH include a reduction in blood flow and metabolism, an increase in transmantle pressure, and ischemic changes in white matter, altering the viscoelastic properties of brain parenchyma.
Although the pathophysiology of idiopathic NPH remains elusive, it is one of the few dementias considered treatable and reversible. The use of shunts to reduce intraventricular volume and pressure has demonstrated promising results in patients with idiopathic NPH if the shunts are placed before the onset of cognitive deterioration. Despite the numerous studies focused on the utility of surgical shunts in the treatment of this disorder, their placement is controversial because of the high rate of associated complications (30–40%). Nonetheless, authors of several studies have demonstrated that the predominant symptoms of idiopathic NPH (gait disturbance, incontinence, and dementia) improve following the surgical placement of shunts.
A lack of consensus remains regarding patient selection for optimal benefit from shunting. In a study of 18 patients with a diagnosis of idiopathic NPH, the clinical onset of the disease marked by dementia was predictive of an unfavorable outcome when assessing candidacy for shunting, whereas gait disturbance (either with or without urinary incontinence) correlated positively with functional recovery. Thus, patients treated in the early stages of symptom onset appear to have better outcomes from shunt surgery than patients who are diagnosed and treated in later stages of the disease.
The primary objective of this study was to estimate the prevalence of idiopathic NPH (diagnosed and undiagnosed) among residents of assisted-living and extended-care nursing homes in southeast Virginia by using a practical screening tool. A second goal was to determine the outcome of surgical management in a subset of residents in healthcare facilities who had met the criteria for suspected idiopathic NPH.
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