Changes in intracranial pulse pressure amplitudes after shunt implantation and adjustment of shunt valve opening pressure in normal pressure hydrocephalus

Summary Background  We have previously reported that the intracranial pulse pressure amplitudes were elevated in idiopathic normal pressure hydrocephalus (NPH) patients responding to shunt surgery. Whether or not shunt implantation or adjustment of the shunt valve opening pressure modifies the intracranial pulse pressure amplitudes in NPH patients remains to be established. This report summarises our observations. Patients and methods  Thirteen patients with NPH (idiopathic in nine and secondary in four) are presented in whom continuous intracranial pressure (ICP) monitoring was done before and after shunt implantation. In two, ICP monitoring was also done during adjustment of shunt valve opening pressure. The mean ICP and mean ICP wave amplitude (i.e. pulse pressure amplitudes) were determined in 6-s time windows. Results  After shunt implantation there was a fall in both mean ICP and mean ICP wave amplitude; the reduction in the two ICP parameters correlated significantly. However, mean ICP in the supine position was normal (i.e. <15 mmHg) in 12 of 13 patients before shunt placement, and remained normal after shunting. According to our criteria, the mean ICP wave amplitudes were elevated before shunting in 12 of 13 patients and became “normalised” the day after shunting in nine patients. The reduction in mean ICP wave amplitude after shunt was highly significant at the group level. Moreover, adjustment of shunt valve opening pressure modified the levels of mean ICP wave amplitudes. Conclusions  The present observations in 13 NPH patients indicate that shunt implantation reduces mean ICP wave amplitudes. Moreover, the level of reduction can be tailored by adjustment of the shunt valve opening pressure.     

Carotid endarterectomy: neurologic complications as related to surgical techniques.

Three hundred seventeen carotid endarterectomies performed on 240 consecutive patients in four Charleston hospitals were reviewed. The overall incidence of stroke was 10.7% and the mortality 3.2%. From these 317 operations a standardized series of 253 operations performed on neurologically stable patients was analyzed for neurologic complications as related to the use of an intra-operative shunt. Additional factors studied were length of time of carotid occlusion and degree of contralateral carotid stenosis. From the standardized series the incidence of stroke in 137 shunted cases was 9.5%, and in 116 non-shunted cases was 0.9%, a significant difference (p less than 0.01). Carotid artery occlusion times from 30 seconds to 12 minutes in the shunted group, and three minutes to 24 minutes in the non-shunted group had no relationship to the incidence of stroke. Significant contralateral carotid artery stenosis, present in 28/137 shunted cases and 30/116 non-shunted cases, had no predictive value in the development of a stroke. The use of an intra-operative shunt did not protect against stroke in these patients.     

Regional cerebral blood flow and oxygen metabolism in normal pressure hydrocephalus after subarachnoid hemorrhage

To clarify the pathophysiology of normal pressure hydrocephalus (NPH) after subarachnoid hemorrhage, the authors measured cerebral blood flow (CBF), cerebral oxygen metabolic rates (CMRO2), the cerebral oxygen extraction fraction (OEF), and cerebral blood volume (CBV) in eight normal volunteers, six SAH patients with NPH, and seven patients without NPH by 15O-labeled gas and positron emission tomography (PET). In the NPH group, PET revealed a decrease in CBF in the lower regions of the cerebral cortex and a diffuse decrease in CMRO2. The decrease in CBF in the lower frontal, temporal, and occipital cortices was significantly greater in the NPH than in the non-NPH group. Reduction of CMRO2 was also more extensive in the NPH group, and both CBF and CMRO2 were more markedly decreased in the lower frontal region. OEF was increased in all areas in both of the patient groups, but the increase was not significant in most areas. CBF, CMRO2 and OEF did not significantly differ between the non-NPH group and the normal volunteers. There was no significant difference in CBV among the three groups. These results indicate that NPH involves impairment of cerebral oxygen metabolism in the lower regions of the cerebral cortex, particularly in the lower frontal region.     

Brain oxygen extraction fraction as an indicator for shunting operation in normal pressure hydrocephalus]

It is still difficult for neurosurgeons to determine which patients with suspected idiopathic normal pressure hydrocephalus (NPH) should undergo shunting. We need to find a more accurate indicator to predict the effect of shunting. We introduced a new preoperative examination of brain oxygen extraction fraction (OEF) and examined whether preoperative OEF value is effective for prediction of the surgical results. Global brain OEF was calculated from oxygen contents of arterial blood (AO2) and jugular venous blood (VjO2) selectively sampled from the right jugular bulb using the Seldinger method: OEF = (AO2-VjO2)/AO2. Since June 1996 we have treated 9 patients suspected of idiopathic and 10 patients suspected of secondary NPH. OEF in non-NPH patients with dilated ventricle (n = 10) and in infarct patients (n = 85) were 0.33 +/- 0.02 and 0.38 +/- 0.06, respectively. In contrast, OEF increased both in idiopathic NPH (0.42 +/- 0.04) and secondary NPH (0.45 +/- 0.02), and the NPH patients with the higher preoperative OEF values showed the better symptomatic recovery. The present study suggests that brain function may be reversible when OEF can be increased and that OEF can be a useful indicator for predicting the effect of a shunting operation in NPH.     

Investigation of normal pressure hydrocephalus by 123I-IMP SPECT.

We evaluated N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) single photon emission computed tomography (SPECT) as a method for identifying normal pressure hydrocephalic (NPH) patients eligible for shunting procedures. 123I-IMP SPECT scans were taken before and after cerebrospinal fluid (CSF) taps in NPH cases. Post-subarachnoid hemorrhagic (SAH) patients showed apparent frontal blood flow reduction but non-SAH cases did not. The frontal blood flow increased in comparison with the temporal flow after CSF tapping in SAH cases who benefited most from shunting. Cerebral blood flow study before and after CSF removal is a potential method for classifying NPH patients likely to benefit from the shunting operation.     

Resistance to cerebrospinal fluid outflow and intracranial pressure in patients with hydrocephales after subarachnoid haemorrhage

Summary Resistance to CSF-outflow (R_out) and intracranial pressure (ICP) were measured in 33 patients with hydrocephalus after subarachnoid haemorrhage (SAH). Eleven patients examined between 10 to 30 days after SAH had high pressure hydrocephalus (HPH). Twenty-two patients had normal pressure hydrocephalus (NPH). All HPH-patients had ICP above 15 mmHg, plateau waves and B-waves, a median R_out of 59 mmHg×ml^–1×min^–1 (range 29–100). All NPH-patients had a normal ICP level, no plateau waves, but long periods of B-waves and a median R_out of 22 mmHg×ml^–1×min^–1 (range 6–47).Of the 11 patients with HPH six were shunted and five had temporary ventricular drainage. Five patients improved and six died. Of the five survivors only one went back to work. Of the 22 NPH-patients 18 were treated with a shunt, one refused shuntoperation and three had normal R_out. Seventeen improved after shunting. At followup 12 had a normal social life, 5 lived in a nursing home and 1 was dead.Thus, early development of hydrocephalus after subarachnoid haemorrhage is associated with a high R_out and a high ICP, whereas late (more than one month) hydrocephalus may be associated with normal ICP and high R_out. Patients with NPH and a high R_out have frequent B-waves and should be shunted. Patients with a long interval from subarachnoid haemorrhage to the diagnosis of hydrocephalus often have a normal ICP, low frequency of B-waves, normal CSF-dynamics and need no shunting.     

Preoperative spinal hydrodynamics versus clinical change 1 year after shunt treatment in idiopathic normal pressure hydrocephalus patients

Nineteen consecutive cases treated for idiopathic normal pressure hydrocephalus (iNPH) with ventriculo-peritoneal shunts were clinically followed prospectively. Change in clinical state one year after shunt surgery was assessed as change on a 15-3 score NPH Grade Scale. Preoperative spinal hydrodynamics were assessed using a constant-rate lumbar infusion test. The pressure recordings were stored as raw data files and analysed retrospectively with regard to the mean cerebrospinal fluid pressure (CSFP), as well as mean CSFP wave amplitudes. Changes in NPH score 1 year after shunt surgery correlated significantly with the levels of single CSFP wave amplitudes, but not with the lumbar resistance to CSF outflow (R(out)). Mean CSFP wave amplitude was thus, in this cohort, a better predictor of clinical change one year after shunt treatment than R(out).     

Clinical characteristics and indications for shunting in patients with idiopathic normal pressure hydrocephalus with brain atrophy (atypical idiopathic normal pressure hydrocephalus)

PURPOSE: To clarify clinical characteristics of atypical idiopathic normal pressure hydrocephalus (AINPH) and indications for shunt operations. SUBJECTS AND METHODS: Subjects examined in the present study included 65 patients who satisfied the following 4 diagnostic criteria of AINPH and underwent V.P shunt with Medos type shunt system; set pressure: epidural standard pressure x 13.6 - 20 mmH2O (omission of a figure in the first place). The diagnostic criteria were: 1) no apparent history of intra- or extra-cranial disease; 2) dementia was present as a main complaint; 3) the presence of moderate to severe cerebral atrophy and ventricular enlargement and PVL around the anterior horn on CT scans; 4) normal cerebrospinal pressure and filling of ventricles or subarachnoid space with contrast medium at 24 hours on cisternography. The patients were aged 49-83 with the mean age of 62.9 years; the ratio of male to female was 37:28. They were categorized as shunt-effective (group E: 36 cases) or non-shunt-effective (group NE: 29 cases), and the following parameters in both groups were compared: 1. clinical characteristics: 2. the presence or absence of pressure wave (PW) during preoperative continuous epidural pressure measurement (EDPM) 3. CSF outflow resistance (Ro) 4. preoperative serum alpha-1-antichymotrpsin (alpha-1-ACT) 5. cerebral arteriovenous difference of oxygen content (c-AVDO2) before and after surgery 6. mean cerebral blood flow (mCBF; 99mTc-HMPAO-SPECT) before and after surgery. RESULTS AND CONCLUSIONS: 1. Group E had a shorter duration between symptom onset and hospital visit (within 16 months and showed hyporoluntary and hyporeactivity as their main complaints associated with gait disturbance; the time course of symptoms was classified as suddenly progressing and fluctuating in many cases. Group NE had a relatively longer duration between symptom onset and hospital visit and showed activeness, wandering, nervousness and quick temper as their main complaints; the time course of symptoms was classified as progressing in many cases. 2. PW-positive cases were all included in group E. but some PW-negative cases were also observed in group E. 3. Ro was significantly higher in group E (p < 0.01), and cases with a Ro value over 20 mmHg/ml/min. were all included in group E. 4. alpha-1-ACT was significantly lower in group E (p < 0.05), and cases with an alpha-1-ACT value over 55 mg/dl were all included in group NE. 5. Although preoperative c-AVDO2 was significantly higher in group E (p < 0.05), cases with a c-AVDO2 value over 8.5 ml% were all included in group NE. c-AVDO2 values were within 5-8.5 ml% in all cases of group E. 6. mCBF significantly increased after surgery in group E (p < 0.001). 7. It was confirmed that cerebral atrophy in group E on AINPH is caused by a cerebral circulation disturbance defined as a cerebral blood flow of penumbra or more due to cerebral arteriosclerosis, etc. 8. A flowchart of indications for shunt surgery for AINPH was prepared based on the results of the present study.     

Efficacy and some complications of programmable pressure valve

Twenty-five patients with hydrocephalus were treated using Sophy programmable pressure valve. The valve pressure is adjustable percutaneously with a magnet. This valve was very useful for management cases presenting overdrainage and high-risk cases of shunt dysfunction such as aqueductal stenosis and idiopathic normal pressure hydrocephalus. It was also useful for hydrocephalus after subarachnoid hemorrhage because it was difficult to know the most adequate pressure before the shunt operation. Two patients developed acute subdural hematoma of arterial origin after the shunt operation. The causative factor appeared to be low intracranial pressure and rupture of small arterial branches. This complication may be more frequent in cases using this system than in cases using other systems. We must pay attention to this complication and it is necessary to improve the shunt system. One bed-ridden patient developed necrosis of the skin because of this valve, and it had to be removed. We should place this valve so that it is at the anterior of the chest.     

Treatment of normal pressure hydrocephalus with low versus medium pressure cerebrospinal fluid shunts

In a retrospective study, 39 patients received a low pressure (20 to 50 mm H2O) shunt and 33 received a medium pressure (55 to 85 mm H2O) shunt for the treatment of normal pressure hydrocephalus (NPH). Pre- and postoperative computed tomographic scans were obtained in 32 patients, permitting us to determine the influence of shunt pressure on ventricular size. A reduction in 3rd ventricle width was found to correlate with clinical improvement and was observed more frequently after the placement of a low pressure shunt than after the placement of a medium pressure shunt. When results were evaluated in patients who did not have advanced NPH or develop postoperative complications, gait was markedly improved in 60% of those receiving a low pressure shunt as opposed to 23% of those receiving a medium pressure shunt (P less than 0.05).     

Subdural hematoma after cerebrospinal fluid shunt for hydrocephalus following subarachnoid hemorrhage-report of two cases (author's transl)

Post-shunt subdural hematoma was found in two patients with hydrocephalus due to subarachnoid hemorrhage. The first case was a 46-year-old man with two episodes of subarachnoid hemorrhage from anterior communicating aneurysm. Two weeks after neck-clipping for the aneurysm, a ventriculo-peritoneal shunt with Pudenz's system was performed since hydrocephalus with moderately increased pressure had been found. He did well for one month, then soon after mild head injury, disorientation and right hemiparesis developed. Cerebral angiogram revealed avascular space in the left parietotemporal region. After the ligation of the shunt tube, subdural hematoma was removed. The symptoms improved in two weeks. The second case was a 62-year-old man with an aneurysm at the trifurcation of the right middle cerebral artery. One month after successful clipping of the aneurysm, he received a ventriculoperitoneal shunt with Pudenz's system for normal pressur hydrocephalus. One and a half years after the operations he hit his head against the ground during his convulsive seizure. Since then, disorientation, urinary incontinence and gait disturbance appeared. After cerebral angiogram, the subdural hematoma was removed and the shunt tube was ligated. He became free of these symptoms in two weeks. The cerebrospinal fluid shunt is recommended for hydrocephalus induced by subarachnoid hemorrhage, but careful follow-up is necessary since these patients might develop post-shunt subdural hematoma, especially after head trauma as shown in our cases.     

Adjustable valves in normal-pressure hydrocephalus: a retrospective study of 218 patients

OBJECTIVE: We sought to assess the value of adjusting shunt valve opening pressure, complications, and outcomes with the use of an adjustable shunt valve in the treatment of patients with normal-pressure hydrocephalus (NPH). METHODS: In a single-center retrospective study, 231 adjustable valves (range, 30-200 mm H(2)O) were the first shunt implantations in 147 patients with idiopathic NPH (INPH) and 71 patients with secondary NPH (SNPH). The effect of adjustment on gait disturbance, cognitive impairment, urinary incontinence and other symptoms were evaluated, and an improvement index was created. RESULTS: In the INPH group, 138 adjustments were performed in 49.0% of the patients (average, 0.94 adjustments/patient). For the SNPH group, 49 adjustments were performed in 32.4% of the patients (average, 0.69 adjustments/patient). The reasons for adjustment were overdrainage in 48 patients (25.7%), underdrainage in 98 patients (52.4%), subdural hematoma in 37 patients (19.8%), and other reasons in 2 patients (2.1%). Clinical status improved after 56 (49.1%) of all 114 adjustments, whereas 23 (42.6%) of 54 minor (< or =20 mm H2O) and 33 (66.0%) of 50 larger adjustments improved the patient's clinical status. The correlation of the improvement index with the size of the individual adjustments was not significant. Complications occurred in 43 (19.7%) of 218 patients, valve malfunction occurred in 3 patients (1.3%), infection occurred in 14 patients (6.4%), and nontraumatic subdural effusion occurred in 15 patients (6.9%; 8 were treated by adjustment alone). The 5-year shunt survival rate was 80.2%. Outcomes were excellent or good in 71 (78.9%) of 90 patients with INPH and in 30 (69.8%) of 43 patients with SNPH. CONCLUSION: Noninvasive, particularly consecutive, minor or single larger adjustments to the valve opening pressure can further improve outcome in patients with NPH who undergo shunting.     

A clinical study of posttraumatic hydrocephalus

From 1989 to 1998, 721 patients with head injury were admitted to our department and 22 (3.1%) of them developed posttraumatic hydrocephalus. These patients included 16 males and 6 females, ranging in age from 17 to 86 years (mean age, 66 yrs) with peak incidence in the eighth decade. CT scan on admission immediately after head injury showed subarachnoid hemorrhage (SAH) in 18 cases. The other 4 cases without SAH had once suffered head injuries severe enough to give rise to consciousness disturbance. The typical clinical symptoms of hydrocephalus were observed in only 5 (23%) patients, and in the other 17 cases prolonged or deteriorated of consciousness disturbance were the main symptoms. Hydrocephalus was diagnosed between 1 and 3 months in 15 cases and in 7 cases after 4 months. Clinical improvement has been seen in 17 (77%) cases and marked recovery of consciousness was achieved in 12 cases after V-P shunt, but 5 cases with severe disturbance of consciousness revealed no improvement of clinical signs even after decrease of ventricular size. These results indicate that elderly patients with traumatic SAH should be followed up for at least 4 to 5 months, paying attention to development of hydrocephalus, and V-P shunt would be effective to improve consciousness disturbance in most of the cases.     

Is the placement of shunts in patients with idiopathic normal-pressure hydrocephalus worth the risk? Results of a study based on continuous monitoring of intracranial pressure

OBJECT: Data from many studies have demonstrated that shunt insertion in patients with idiopathic normal-pressure hydrocephalus (NPH) is associated with high morbidity and a lack of significant improvement; however, the use of strict diagnostic and treatment protocols can improve the results of surgery in these patients. The primary aim in this prospective study was to analyze the results of shunt placement in 43 patients with idiopathic NPH. A secondary aim was to determine the relationship between several clinical and neuroimaging factors, and patient outcome after surgery. METHODS: Thirty men and 13 women with a mean age of 71.1 +/- 6.9 years participated in this study. All patients underwent clinical, neuropsychological, and radiological assessment before and 6 months after surgery. In all patients continuous monitoring of intracranial pressure was performed using a fiberoptic extradural sensor. In 31 patients cerebrospinal fluid dynamics were also determined. Eighty-six percent of patients showed clinical improvement after shunt insertion, 11.6% showed no change, and 2.3% exhibited some worsening. Gait improved in 81.4% of the patients, sphincter control in 69.8%, and cognitive dysfunction in 39.5%. There was no treatment-related death. Early or late postsurgical complications occurred in six patients (14%), although all of these complications were minor or were satisfactorily resolved. The complete clinical triad, cortical sulci size, and periventricular lucencies were related to outcome, whereas patient age, symptom duration, ventricular dilation, and the degree of presurgical dementia were unrelated to outcome. CONCLUSIONS: Given the correct diagnosis, shunt insertion can produce marked improvement in patients with idiopathic NPH syndrome, causing few deaths and few clinically relevant complications.     

Laparoscopic management of abdominal complications in ventriculoperitoneal shunt surgery.

Ventriculoperitoneal (VP) shunts are among the most frequently performed operations in the management of hydrocephalus. Abdominal complications, though rare, are reported to occur in 5-47%. VP shunt obstruction or malfunction leads to raised intracranial pressure, which requires immediate intervention. Recently we have used the laparoscope to manage abdominal complications of VP shunt in two patients. The first patient had hydrocephalus secondary to tubercular meningitis. She developed recurrent intraabdominal cerebrospinal fluid (CSF) pseudocysts, possibly due to subtle peritoneal infection. In the second patient, who developed hydrocephalus following subarachnoid haemorrhage, the lower end of the shunt was malfunctioning due to retraction into the extraperitoneal tissues. The distal end of the VP shunt was revised in both patients with the help of a laparoscopically assisted technique. Thus, a conventional laparotomy, along with its various associated postoperative problems, was avoided without compromising the quality of surgery.     

Normal pressure hydrocephalus in children and young adults

Normal pressure hydrocephalus (NPH) is generally considered to be a disorder of adult and geriatric patients. We report four patients who are children or young adults with chronic neurological disorders, recent deterioration of their levels of function, normal cerebrospinal fluid (CSF) pressures, and ventricular enlargement. All four patients improved after the placement or revision of a ventriculoperitoneal shunt. Frequent symptoms and signs included irritability (three patients), vomiting (three patients), and abnormal limb posturing (two patients). Correct diagnosis was hampered by two factors: (a) Multiple or prolonged recordings of CSF pressures were invariably well within the normal ranges with respect to age, and (b) the patients had chronic neurological deficits. After ventriculoperitoneal shunting, subjective and objective improvement was seen in all cases. Young patients with large ventricles may benefit from shunting procedures despite low CSF pressures. These patients may be clinically identified by symptoms of new neurological dysfunction in cases of previously static neurological disease or acceleration of slowly progressive neurological dysfunction. Some of these underlying neurological disorders may predispose children and young adults to NPH.     

Intracranial pulse pressure amplitude levels determined during preoperative assessment of subjects with possible idiopathic normal pressure hydrocephalus

Summary Background. It was previously reported that the intracranial pulse pressure amplitudes were elevated in idiopathic normal pressure hydrocephalus (iNPH) patients responding to shunt surgery. In this study, pulse pressure amplitudes were determined in all patients referred for tentative iNPH, and patients were selected for shunt surgery based on the determination of their threshold levels of intracranial pulse pressure amplitudes. Patients and methods. All patients referred to our department for tentative iNPH during a 12 months time period were included. Using intracranial pressure (ICP) monitoring the intracranial pulse pressure amplitudes were determined as the mean wave amplitude in consecutive 6-seconds time windows. Intracranial pulse pressure amplitudes were defined as being elevated when the mean wave amplitudes were either ≥4 mmHg in ≥70%, ≥5 mmHg in ≥40% or ≥6 mmHg in ≥10% of the ICP recording time. Shunt treatment was offered to those with elevated mean wave amplitudes. Clinical state was assessed by using a NPH Grading Scale and the Stein-Langfitt scale before ICP monitoring, and then repeated after 12 months. Results. Among the 40 iNPH patients included during the 12 months period, the mean wave amplitudes were elevated in 24 patients (60%), while not being elevated in 16 (40%). Neither pre-operative clinical state, radiological ventricular size nor co-morbidity differed between patient groups with elevated or non-elevated mean wave amplitudes. In the shunted patients who had pre-operatively elevated mean wave amplitudes, 91% had very significant clinical change after 12 months (median change in NPH score +4). In those with non-elevated amplitudes and no shunt, clinical state was somewhat worse after 12 months (median change in NPH score −1). Conclusions. In this one-year material, mean wave amplitudes were elevated in 60% of iNPH patients. In those with elevated mean wave amplitudes who were treated with shunt, 91% had a significant clinical response.     

Normal pressure hydrocephalus found after anesthesia--a case report

Normal pressure hydrocephalus (NPH) is characterized by insidious onset and gradual development of the triad of gait disturbance, dementia, and urinary incontinence. Nausea, vomiting, and signs of increased intracranial pressure do not occur. A 71-year-old male patient was scheduled for total knee replacement due to osteoarthritis of right knee joint. No neurological symptoms and signs except mild forgetfulness were detected during physical examination following admission. Due to operational mistakes, the anesthesiologist was informed that the surgery was cancelled just after completion of induction of general anesthesia. The patient was allowed to emerge from anesthesia. Unfortunately, his consciousness became drowsy the next morning. After a series of examinations, he was at last diagnosed as a case of NPH principally by the brain computed tomography scan. So he was scheduled again but this time for vetriculoperitoneal (V-P) shunt. The patient regained consciousness after V-P shunt. From this case, we learned that NPH may remain in concealment in the patients we contacted in our daily practice. A vigilant physician should keep in mind that the presentation of gait disturbance, dementia, and urinary incontinence in a patient may indicate the likelihood of NPH.     

The prognostic value of clinical characteristics and parameters of cerebrospinal fluid hydrodynamics in shunting for idiopathic normal pressure hydrocephalus

Summary Background. It is difficult to predict which patients with symptoms and radiological signs of normal pressure hydrocephalus (NPH) will benefit from a shunting procedure and which patients will not. Risk of this procedure is also higher in patients with NPH than in the overall population of hydrocephalic patients. The aim of this study is to investigate which clinical characteristics, CT parameters and parameters of cerebrospinal fluid dynamics could predict improvement after shunting. Methods. Eighty-three consecutive patients with symptoms and radiological signs of NPH were included in a prospective study. Parameters of the cerebrospinal fluid dynamics were measured by calculation of computerised data obtained by a constant-flow lumbar infusion test. Sixty-six patients considered candidates for surgery were treated with a medium-pressure Spitz-Holter valve; in seventeen patients a shunting procedure was not considered indicated. Clinical and radiological follow-up was performed for at least one year postoperatively. Findings. The odds ratio, the sensitivity and specificity as well as the positive and negative predictive value of individual and combinations of measured parameters did not show a statistically significant relation to clinical improvement after shunting. Conclusions. We conclude that neither individual parameters nor combinations of measured parameters show any statistically significant relation to clinical improvement following shunting procedures in patients suspected of NPH. We suggest restricting the term normal pressure hydrocephalus to cases that improve after shunting and using the term normal pressure hydrocephalus syndrome for patients suspected of NPH and for patients not improving after implantation of a proven well-functioning shunt. An erratum to this article is available at .     

Management of idiopathic normal-pressure hydrocephalus: a multiinstitutional study conducted in Japan.

OBJECT: A cooperative study was undertaken to identify factors that could be used to predict a favorable outcome after extracranial cerebrospinal fluid (CSF) diversion (shunting) in patients with suspected idiopathic normal-pressure hydrocephalus (NPH). METHODS: Questionnaires concerning patients with suspected idiopathic NPH were sent to 14 members of the Committee for Scientific Research on Intractable Hydrocephalus, sponsored by the Ministry of Health and Welfare of Japan. After the questionnaires were returned, a retrospective analysis of the responses was undertaken. To be included in the study, patients had to be 65 years of age or older and had to have undergone surgery between October 1995 and October 1998. Clinical measures included degrees of gait disturbance, dementia, and urinary incontinence as evaluated before. 3 months after, and 3 years after shunt placement. Diagnostic tests in various combinations included lumbar puncture in which CSF was withdrawn; intracranial pressure monitoring; measurements of CSF outflow resistance, level of serum alpha-1-antichymotrypsin, cerebral arteriovenous differences of oxygen content, and cerebral blood flow; and computerized tomography cisternography. In this study, 120 patients were identified as having idiopathic NPH and these patients underwent placement of shunts. A ventriculoperitoneal shunt with a programmable valve was used in two thirds of the patients. At the end of 3 months (early assessment), there was an 80% overall rate of clinical improvement, which dropped to 73.3% of the 105 patients who could be evaluated at the end of the 3-year study. Of the three variables, gait disturbance was most improved, both at early and late testing periods. Shunt complications occurred in 22 (18.3%) of the patients. CONCLUSIONS: Patients suspected of having idiopathic NPH did not form a homogeneous group, making it difficult to select those who would most likely respond to CSF diversion. Of the diagnostic studies, the most reliable result was improvement in clinical symptoms following a lumbar puncture in which CSF was withdrawn. The use of a programmable valve is recommended because it offers advantages in preventing problems of over- and underdrainage.