The clinical effect of lumbar puncture in normal pressure hydrocephalus

Walking assessment after lumbar puncture in normal-pressure hydrocephalus: a delayed improvement over 3 days

OBJECTIVE The determination of gait improvement after lumbar puncture (LP) in idiopathic normal-pressure hydrocephalus (iNPH) is crucial, but the best time for such an assessment is unclear. The authors determined the time course of improvement in walking after LP for single-task and dual-task walking in iNPH. METHODS In patients with iNPH, sequential recordings of gait velocity were obtained prior to LP (time point [TP]0), 1-8 hours after LP (TP1), 24 hours after LP (TP2), 48 hours after LP (TP3), and 72 hours after LP (TP4). Gait analysis was performed using a pressure-sensitive carpet (GAITRite) under 4 conditions: walking at preferred velocity (STPS), walking at maximal velocity (STMS), walking while performing serial 7 subtractions (dual-task walking with serial 7 [DTS7]), and walking while performing verbal fluency tasks (dual-task walking with verbal fluency [DTVF]). RESULTS Twenty-four patients with a mean age of 76.1 ± 7.8 years were included in this study. Objective responder status moderately coincided with the self-estimation of the patients with subjective high false-positive results (83%). The extent of improvement was greater for single-task walking than for dual-task walking (p < 0.05). Significant increases in walking speed were found at TP2 for STPS (p = 0.042) and DTVF (p = 0.046) and at TP3 for STPS (p = 0.035), DTS7 (p = 0.042), and DTVF (p = 0.044). Enlargement of the ventricles (Evans Index) positively correlated with early improvement. Gait improvement at TP3 correlated with the shunt response in 18 patients. CONCLUSIONS Quantitative gait assessment in iNPH is important due to the poor self-evaluation of the patients. The maximal increase in gait velocity can be observed 24-48 hours after the LP. This time point is also best to predict the response to shunting. For dual-task paradigms, maximal improvement appears to occur later (48 to 72 hours). Assessment of gait should be performed at Day 2 or 3 after LP.

MR Elastography Demonstrates Increased Brain Stiffness in Normal Pressure Hydrocephalus

BACKGROUND AND PURPOSE

Normal pressure hydrocephalus is a reversible neurologic disorder characterized by a triad of cognitive impairment, gait abnormality, and urinary incontinence that is commonly treated with ventriculoperitoneal shunt placement. However, multiple overlapping symptoms often make it difficult to differentiate normal pressure hydrocephalus from other types of dementia, and improved diagnostic techniques would help patient management. MR elastography is a novel diagnostic tool that could potentially identify patients with normal pressure hydrocephalus. The purpose of this study was to assess brain stiffness changes in patients with normal pressure hydrocephalus compared with age- and sex-matched cognitively healthy individuals.

MATERIALS AND METHODS

MR elastography was performed on 10 patients with normal pressure hydrocephalus and 21 age- and sex-matched volunteers with no known neurologic disorders. Image acquisition was conducted on a 3T MR imaging scanner. Shear waves with 60-Hz vibration frequency were transmitted into the brain by a pillowlike passive driver. A novel postprocessing technique resistant to noise and edge artifacts was implemented to determine regional brain stiffness. The Wilcoxon rank sum test and linear regression were used for statistical analysis.

RESULTS

A significant increase in stiffness was observed in the cerebrum (P = .001), occipital lobe (P < .001), parietal lobe (P = .001), and the temporal lobe (P = .02) in the normal pressure hydrocephalus group compared with healthy controls. However, no significant difference was noted in other regions of the brain, including the frontal lobe (P = .07), deep gray and white matter (P = .43), or cerebellum (P = .20).

CONCLUSIONS

This study demonstrates increased brain stiffness in patients with normal pressure hydrocephalus compared with age- and sex-matched healthy controls; these findings should motivate future studies investigating the use of MR elastography for this condition and the efficacy of shunt therapy.

CSF tap test - Obsolete or appropriate test for predicting shunt responsiveness? A systemic review

OBJECTIVES

There is no accurate test for diagnosing normal pressure hydrocephalus or for screening for patients who will benefit from shunt surgery. Additional tests, such as cerebrospinal fluid tap test (CSF-TT), are often used in practice to provide further predictive value in detecting suitable patients for shunting. We performed a systematic review of the literature to evaluate the CSF-TT's effect on the outcome of main symptoms and on validity parameters in screening patients suitable for shunting.

METHODS

In February 2015 we searched electronic databases from their inception to the current date, using the following key words: normal pressure hydrocephalus, idiopathic normotensive hydrocephalus, shunt operation, CSF tap test, predictive value, validity. The search retrieved 8 articles explicitly addressing the topic.

RESULTS

There was a very high positive predictive value of CSF-TT: 92% (range from 73% to 100%) but a low negative predictive value: 37% (18%-50%). Also, the CSF-TT has high specificity: 75% (33%-100%) but average sensitivity: 58% (26%-87%). The overall accuracy of the test was 62% (45%-83%).

CONCLUSIONS

This systematic review did not provide unambiguous validity of the CSF-TT in the screening of patients for shunting. The validity of the CSF-TT is good for patient inclusion for shunting due to the fact that the positive response to the test is very reliable. Unfortunately, the negative response to the test does not reliably make these patients ineligible for shunting. Further studies are needed to improve and standardize the methodology in order to optimize the detection power of the test.

Quantitative MRI for Rapid and User-Independent Monitoring of Intracranial CSF Volume in Hydrocephalus

BACKGROUND AND PURPOSE

Quantitative MR imaging allows segmentation of different tissue types and automatic calculation of intracranial volume, CSF volume, and brain parenchymal fraction. Brain parenchymal fraction is calculated as (intracranial volume - CSF volume) / intracranial volume. The purpose of this study was to evaluate whether the automatic calculation of intracranial CSF volume or brain parenchymal fraction could be used as an objective method to monitor volume changes in the ventricles.

MATERIALS AND METHODS

A lumbar puncture with drainage of 40 mL of CSF was performed in 23 patients under evaluation for idiopathic normal pressure hydrocephalus. Quantitative MR imaging was performed twice within 1 hour before the lumbar puncture and was repeated 30 minutes, 4 hours, and 24 hours afterward. For each time point, the volume of the lateral ventricles was manually segmented and total intracranial CSF volume and brain parenchymal fraction were automatically calculated by using Synthetic MR postprocessing.

RESULTS

At 30 minutes after the lumbar puncture, the volume of the lateral ventricles decreased by 5.6 ± 1.9 mL (P < .0001) and the total intracranial CSF volume decreased by 11.3 ± 5.6 mL (P < .001), while brain parenchymal fraction increased by 0.78% ± 0.41% (P < .001). Differences were significant for manual segmentation and brain parenchymal fraction even at 4 hours and 24 hours after the lumbar tap. There was a significant association using a linear mixed model between change in manually segmented ventricular volume and change in brain parenchymal fraction and total CSF volume, (P < .0001).

CONCLUSIONS

Brain parenchymal fraction is provided rapidly and fully automatically with Synthetic MRI and can be used to monitor ventricular volume changes. The method may be useful for objective clinical monitoring of hydrocephalus.

The Dynamic Gait Index in Evaluating Patients with Normal Pressure Hydrocephalus for Cerebrospinal Fluid Diversion

BACKGROUND

Diagnosing normal pressure hydrocephalus (NPH) remains challenging. Most clinical tests currently used to evaluate suspected NPH patients for shunt surgery are invasive, require inpatient admission, and are not without complications. An objective, noninvasive, and low-cost alternative would be ideal.

METHODS

A retrospective review was performed of prospectively collected dynamic gait index (DGI) scores, obtained at baseline and on every day of a 3- to 5-day lumbar cerebrospinal fluid (CSF) drainage trial on patients with suspected NPH at our institution.

RESULTS

Between 2003 and 2014, 170 patients were suspected to have primary NPH (166, 97.6%) or secondary NPH (4, 2.4%). Using responsiveness to lumbar CSF drainage and subsequent shunting as the reference standard, we found that a baseline DGI ≥ 7 was found to have significant ability in selecting patients for permanent CSF diverting shunt surgery: sensitivity of 84.2% (95% confidence interval [95% CI]: 75.6%-90.2%), specificity of 80.6% (95% CI 70.0%-88.0%), and diagnostic odds ratio of 22.1 (95% CI 9.9-49.3).

CONCLUSIONS

A baseline DGI ≥ 7 appears to provide an objective, low-cost, noninvasive measure to select patients with suspected NPH for a positive response to CSF diversion with high sensitivity, specificity and diagnostic odds ratio.

Improvement in executive subfunctions following cerebrospinal fluid tap test identifies idiopathic normal pressure hydrocephalus from its mimics

BACKGROUND AND PURPOSE

Patients with idiopathic normal pressure hydrocephalus (iNPH) present cognitive deficits that overlap with other neurological conditions such as Parkinson's disease or vascular dementia, therefore mimicking iNPH. This prospective study aimed to compare cognitive performances between iNPH and iNPH mimics before and after cerebrospinal fluid (CSF) tapping.

METHODS

A total of 57 patients with suspicion of iNPH (75.84 ± 6.42 years; 39% female) were included in this study (37 iNPH and 20 iNPH mimics). Neuropsychological assessments were performed before and 24 h after CSF tapping of 40 ml. Multivariate logistic regressions were used to examine the association between iNPH and cognitive functions, adjusted for age, education, baseline cognitive assessment and disease duration.

RESULTS

Both groups presented the same baseline cognitive performances. After CSF tapping, iNPH patients improved their semantic (P = 0.001) and phonemic verbal fluencies (P = 0.001), whereas iNPH mimics presented similar performances to before CSF tapping. The phonemic verbal fluency (odds ratio 1.43, 95% confidence interval 1.05; 1.96) and the Color Trails Test (odds ratio 0.10, 95% confidence interval 0.01; 0.76) improvements were the two discriminative cognitive tests that identified iNPH from iNPH mimics.

CONCLUSION

Improvement in executive subfunctions after CSF tapping identified iNPH patients from other neurological conditions that mimic iNPH. These findings respond to clinical issues encountered on a daily basis and would improve the diagnostic process of iNPH.

Idiopathic normal pressure hydrocephalus: cerebral perfusion measured with pCASL before and repeatedly after CSF removal

Pseudo-continuous arterial spin labeling (pCASL) measurements were performed in 20 patients with idiopathic normal pressure hydrocephalus (iNPH) to investigate whether cerebral blood flow (CBF) increases during the first 24 hours after a cerebrospinal fluid tap test (CSF TT). Five pCASL magnetic resonance imaging (MRI) scans were performed. Two scans were performed before removal of 40 mL CSF, and the other three at 30 minutes, 4 hours, and 24 hours, respectively after the CSF TT. Thirteen different regions of interest (ROIs) were manually drawn on coregistered MR images. In patients with increased CBF in lateral and frontal white matter after the CSF TT, gait function improved more than it did in patients with decreased CBF in these regions. However, in the whole sample, there was no significant increase in CBF after CSF removal compared with baseline investigations. The repeatability of CBF measurements at baseline was high, with intraclass correlation coefficients of 0.60 to 0.90 for different ROIs, but the median regional variability was in the range of 5% to 17%. Our results indicate that CBF in white matter close to the lateral ventricles plays a role in the reversibility of symptoms after CSF removal in patients with iNPH.

Changing cerebral blood flow in normal pressure hydrocephalus after the tap test can predict clinical improvement

BACKGROUND

We studied the role of cerebrospinal fluid (CSF) tap test at idiopathic normal pressure hydrocephalus (INPH) in improving cerebral blood flow velocity indices by transcranial Doppler (TCD) sonography.

METHODS

Twelve patients with assumed INPH were included in the study. The CSF tap test and INPH grading score was carried out according to the standard protocol. TCD was performed before and after the tap test for assessing blood flow in middle cerebral and anterior cerebral arteries.

RESULTS

Five INPH patients (41.7%) had clinical improvement as defined by at least one point reduction in INPH grading scale. The baseline TCD parameters of the middle cerebral artery were significantly higher compared with the control, and those parameters were decreased after tap test in those who improved.

CONCLUSION

Our study showed that improvement in INPH grading score after CSF tap test might correlate with changing in TCD parameter in MCA and TCD parameter might be useful for shunt response in these patients.

A computerized neuropsychological test battery designed for idiopathic normal pressure hydrocephalus

Background

A tool for standardized and repeated neuropsychological assessments in patients with idiopathic normal pressure hydrocephalus (INPH) is needed. The objective of this study was to develop a computerized neuropsychological test battery designed for INPH and to evaluate its reliability, validity and patient’s ability to complete the tests.

Methods

Based on a structured review of the literature on neuropsychological testing in INPH, the eight tests most sensitive to the INPH cognitive profile were implemented in a computerized format. The Geriatric Depression Scale (GDS) was also included. Tests were presented on a touch-screen monitor, with animated instructions and speaker sound. The battery was evaluated with the following cohorts: A. Test-retest reliability, 44 healthy elderly; B. Validity against standard pen and pencil testing, 28 patients with various cognitive impairments; C. Ability to complete test battery, defined as completion of at least seven of the eight tests, 40 investigated for INPH.

Results

A. All except the figure copy test showed good test-retest reliability, r = 0.67-0.90; B. A high correlation was seen between conventional and computerized tests (r = 0.66-0.85) except for delayed recognition and figure copy task; C. Seventy-eight percent completed the computerized battery; Patients diagnosed with INPH (n = 26) performed worse on all tests, including depression score, compared to healthy controls.

Conclusions

A new computerized neuropsychological test battery designed for patients with communicating hydrocephalus and INPH was introduced. Its reliability, validity for general cognitive impairment and completion rate for INPH was promising. After exclusion of the figure copy task, the battery is ready for clinical evaluation and as a next step we suggest validation for INPH and a comparison before and after shunt surgery.

Trial registration

ClinicalTrials.org NCT01265251.

Cognitive functions after spinal tap in patients with normal pressure hydrocephalus

Normal pressure hydrocephalus (NPH) is characterised by gait disturbance, urinary incontinence and dementia. Even though dementia is a cardinal symptom of NPH, there is few data available concerning cognitive functioning. The aim of this observational case-control study was to evaluate the use of neuropsychological (NPSY) tests prior and after spinal tap test, which might be helpful for diagnosis, treatment and as a prognostic factor for shunt surgery. 15 patients with NPH and 18 controls were examined with eleven different tests covering all neuropsychological domains on two consecutive days. The second examination in NPH patients was 1 day after a spinal tap of 30-50 ml cerebrospinal fluid. A significant difference between NPH and controls in the change between baseline and 1 day after spinal tap was only observed in MMSE. In the domains of visuo-constructive function and attention, controls performed slightly better at day one compared to baseline, which could be interpreted as a learning effect, but after adjusting for multiple testing none of the P values were significant. In contrast to other reports, the MMSE seems to provide a sensitive evaluation of the response to spinal tap in NPH patients and might therefore be included into the routine work up of NPH patients. All other NPSY tests showed less prominent changes within 1 day after spinal tap.

Normal pressure hydrocephalus: a qualitative study on outcome

OBJECTIVE

To describe the natural history and shunt outcome in patients with normal pressure hydrocephalus (NPH) and the variables that influence both.

METHOD

Motor and cognitive parameters of 35 patients with NPH, as well as shunt surgery status, were registered at two time points (T0 and T1).

RESULTS

Thirteen patients underwent shunt surgery. Favorable outcome in gait function occurred in 5 of 35 patients and was related to younger age, absence of cardiovascular risk factors (CVRF) and white matter lesions (WML), and shunt surgery. Cognitive outcome was favorable in 9 of 35 patients and associated with shunt surgery (trend level). Of the patients subjected to surgery, favorable outcome in motor function was related to younger age at T0 and absence of CVRF and WML (trend level).

CONCLUSION

Shunt surgery had a significant effect on gait and less on cognition. Favorable outcome in gait was also associated with younger age and absence of CVRF and WML.

Shunt-responsive idiopathic normal pressure hydrocephalus patient with delayed improvement after tap test

The cerebrospinal fluid tap test (CSFTT) is recommended as a key step in the diagnosis of idiopathic normal pressure hydrocephalus (iNPH). While there is no generally accepted evaluation period for ascertaining a CSFTT responder, a substantial number of patients are evaluated only once within 24 hours of the test for improvement in gait. We report an iNPH patient with a favorable response to shunt surgery, who was first judged a non-responder by this standard, though subsequently was judged a responder in virtue of repetitively testing gait over 7 days. A 68-year-old man presented with progressive impairment of gait, balance, and memory. He was diagnosed as iNPH with an Evans' ratio of 0.35. At first hospitalization, change in gait was evaluated 24 hours after the CSFTT. He didn't show any significant improvement and was judged as a non-responder. However, at the second CSFTT, we repetitively tested his change in gait over seven days. Forty-eight hours after the tap, he showed significant improvement in his gait. He was then confirmed as a responder. After the operation, the gait difficulties were almost fully resolved. Further studies developing the standard procedure of the CSFTT should be considered.

Pulsatility in CSF dynamics: pathophysiology of idiopathic normal pressure hydrocephalus

BACKGROUND

It is suggested that disturbed CSF dynamics are involved in the pathophysiology of idiopathic normal pressure hydrocephalus (INPH). The pulsatility curve describes the relationship between intracranial pressure (ICP) and the amplitude of cardiac related ICP pulsations. The position of baseline ICP on the curve provides information about the physiological state of the CSF dynamic system. The objective of the study was to investigate if shunt surgery modifies the pulsatility curve and the baseline position on the curve, and how this relates to gait improvement in INPH.

METHODS

51 INPH patients were investigated with lumbar CSF dynamic investigations preoperatively and 5 months after shunt surgery. During the investigation, ICP was measured at baseline, and then a CSF sample was removed, resulting in pressure reduction. After this, ICP was regulated with an automated infusion protocol, with a maximum increase of 24 mm Hg above baseline. The pulsatility curve was thus determined in a wide range of ICP values. Gait improvement was defined as a gait speed increase ≥0.1 m/s.

RESULTS

The pulsatility curve was unaltered by shunting. Baseline ICP and amplitude were reduced (-3.0±2.9 mm Hg; -1.1±1.5 mm Hg; p<0.05, n=51). Amplitude reduction was larger for gait improvers (-1.2±1.6 mm Hg, n=42) than non-improvers (-0.2±0.5 mm Hg, n=9) (p<0.05) although mean ICP reduction did not differ.

CONCLUSIONS

The pulsatility curve was not modified by shunt surgery, while the baseline position was shifted along the curve. Observed differences between gait improvers and non-improvers support cardiac related ICP pulsations as a component of INPH pathophysiology.

Gait dysfunction in Parkinson's disease and normal pressure hydrocephalus: a comparative study

Our objectives were to characterize gait dysfunction in Parkinson's disease (PD) and normal pressure hydrocephalus (NPH) patients, in a comparative analysis. We used a walking test to determine gait velocity (GV), stride length (SL), stride cadence and the presence of frontal (FG) and sub-cortical hypokinetic gait (SHG) features. Equilibrium was tested with the shoulder tug test (STT). These variables were used in cluster analysis, to classify subjects according to gait dysfunction. PD patients were assessed with the Unified Parkinson's Disease Rating Scale (UPDRS) and Hoehn and Yahr (HY) scale. NPH patients were reassessed after high volume lumbar puncture (LP). NPH (n = 35) and PD (n = 40) patients had lower SL, GV and STT scores than controls (n = 30). NPH patients had worse results in SL, GV and STT than PD and a higher frequency of both FG and SHG features, compared to PD and the control groups. We found a severe/moderate gait dysfunction cluster, formed by 33 NPH patients and 11 PD patients, and a normal/mild dysfunction cluster, comprising 2 NPH, 29 PD patients and all control subjects. PD patients in the first cluster had worse UPDRS (except for tremor) and HY scores. In NPH patients, all gait variables improved after LP, although not to the controls level. PD and NPH gait was similarly characterized by loss of balance, slowness and small steps, although NPH patients performed worse. In PD patients, gait dysfunction comparable to that of NPH patients was associated with worse motor stage and the akinetic-rigid variant.

Role of Endoscopic Third Ventriculostomy and Ventriculoperitoneal Shunt in Idiopathic Normal Pressure Hydrocephalus

BACKGROUND:

Currently, the most common treatment for idiopathic normal pressure hydrocephalus (INPH) is a ventriculoperitoneal shunt (VPS), generally with programmable valve implantation. Endoscopic third ventriculostomy (ETV) is another treatment option, and it does not require prosthesis implantation.

OBJECTIVE:

To compare the functional neurological outcome in patients after 12 months of treatment with INPH by using 2 different techniques: ETV or VPS.

METHODS:

Randomized, parallel, open-label trial involving the study of 42 patients with INPH and a positive response to the tap test, from January 2009 to January 2012. ETV was performed with a rigid endoscope with a 30° lens (Minop, Aesculap), and VPS was performed with a fixed-pressure valve (PS Medical, Medtronic). The outcome was assessed 12 months after surgery. The neurological function outcomes were based on the results of 6 clinical scales: mini-mental, Berg balance, dynamic gait index, functional independence measure, timed up and go, and normal pressure hydrocephalus.

RESULTS:

There was a statistically significant difference between the 2 groups after 12 months of follow-ups, and the VPS group showed better improvement results (ETV = 50%, VPS = 76.9%).

CONCLUSION:

Compared with ETV, VPS is a superior method because it had better functional neurological outcomes 12 months after surgery.

The value of the cerebrospinal fluid tap test for predicting shunt effectiveness in idiopathic normal pressure hydrocephalus

BACKGROUND

The cerebrospinal fluid (CSF) tap test (TT) has been regarded as an important test for the prediction of shunt effectiveness in patients with suspected idiopathic normal pressure hydrocephalus (iNPH). Although its specificity and sensitivity are reportedly high, there remains some disagreement over this point. Herein, the TT as a test for predicting shunt effectiveness was investigated in our multicenter prospective study named SINPHONI and strategies to increase its predictability were examined.

METHODS

One hundred suspected iNPH patients with the following entry criteria were enrolled in the study: (1) 60 to 85 years old, (2) one or more of the NPH triad signs, (3) ventriculomegaly (Evans index > 0.3), (4) high convexity tightness in coronal-section MRI, and (5) no antecedent disorders. Changes in NPH triad symptoms were assessed using the iNPH grading scale and other measures before and after removal of 30 ml lumbar CSF. A positive response to TT was pre-defined by specific improvements on the grading and other scales. A ventriculoperitoneal shunt was performed with a programmable valve. The sensitivity and specificity of the TT was calculated with a contingency table. A decision tree analysis was performed to increase the predictability of the TT.

RESULTS

Among 100 patients, 80 were shunt responders. A statistically-significant variable between shunt responders and non-responders was CSF pressure. The changes in single variables in the iNPH grading scale after TT showed high specificity with low sensitivity. In contrast, change of the total score in the iNPH grading scale showed a relatively high sensitivity of 71.3% with specificity of 65%. A decision tree analysis revealed that using the iNPH grading scale total score and pre-shunt CSF pressure ≥ 15 cmH20, sensitivity increased to 82.5%, without a decrease in specificity.

CONCLUSIONS

The sensitivity and specificity of the TT for predicting shunt responsiveness were optimum when improvement on any iNPH grading scale was combined with CSF pressure ≥ 15 cmH20. To increase the sensitivity of the TT, further effort is necessary.

TRIAL REGISTRATION

This study is registered with ClinicalTrials.gov, with the number NCT00221091.

Ten years of clinical experience in the use of fixed-pressure versus programmable valves: a retrospective study of 159 patients

AIM

The aim of this study was to present our 10-year experience with the use of fixed-pressure and programmable valves in the treatment of adult patients requiring cerebrospinal fluid (CSF) diversion.

MATERIAL AND METHODS

Patients (n = 159; 89 male and 70 female) suffering from hydrocephalus of various causes underwent CSF shunt implantation. Forty fixed-pressure and 119 programmable valves were initially implanted.

RESULTS

The observed revision rate was 40% in patients with fixed-pressure valves. In 20% of these patients, a revision due to valve mechanism malfunction was undertaken, and the initial valve was replaced with a programmable one. The revision rate in the adjustable-pressure valve subgroup was 20%. The infection rate for the fixed-pressure and programmable valve subgroups were 3%, and 1.7%, respectively. Similarly, subdural fluid collections were noticed in 17% and 4% of patients with fixed-pressure valves and programmable valves, respectively.

CONCLUSIONS

The revision and over-drainage rates were significantly lower when using programmable valves, and thus, this type of valve is preferred whenever CSF has to be diverted.

Shunt surgery in patients with hydrocephalus and white matter changes

Object

Patients with idiopathic normal pressure hydrocephalus (iNPH) often present with impaired gait and cognition together with ventricular enlargement and normal intracranial pressure. Many have vascular risk factors as well as periventricular and deep white matter changes on MR imaging. Abnormal CSF dynamics, that is, high resistance to outflow or improvement after CSF drainage, indicate good effects of shunt surgery.

The authors examined whether the worst-case iNPH patients with extensive vascular white matter disease and normal CSF dynamics would benefit from shunt surgery. These patients also fulfilled the criteria for Binswanger disease. Therefore, a randomized controlled double-blind study was performed.

Methods

Fourteen consecutive patients fulfilling the above criteria were randomized to receive either open or closed shunts. At 3 months after surgery, the patients with initially ligated shunts had their shunts opened. Clinical evaluation consisting of 7 quantitative psychometric and 6 continuous gait tests was performed preoperatively and 3 and 6 months after surgery.

Results

Patients randomized to receive open shunts had improved motor (30% increase) and psychometric (23% increase) scores 3 months after shunt placement. There were no significant changes between the 3- and 6-month follow-up in these same patients. Conversely, those with initially ligated shunts were unchanged during the first 3-month period, although they improved in both motor (28%) and cognitive (18%) functions following removal of the ligature.

Conclusions

Patients with enlarged ventricles, hydrocephalic symptoms, and extensive vascular white matter changes benefit from shunt surgery.

Pattern recognition of overnight intracranial pressure slow waves using morphological features of intracranial pressure pulse

This study aimed to develop a new approach to detect intracranial pressure (ICP) slow waves based on morphological changes of ICP pulse waveforms. A recently proposed Morphological Clustering and Analysis of ICP Pulse (MOCAIP) algorithm was utilized to calculate a set of metrics that characterize ICP pulse morphology. A regularized linear quadratic classifier was used to test the hypothesis that classification between ICP slow wave and flat ICP could be achieved using features composed of mean values and dispersion of 24 MOCAIP metrics. To optimize the classification performance, three feature selection techniques (differential evolution, discriminant analysis and analysis of variance) were applied to find an optimal set of MOCAIP metrics under different criteria. In addition, we selected three sets of metrics common to those found by combination of two selection methods, to be used as classification features (differential evolution and analysis of variance, discriminant analysis and analysis of variance, and combination of differential evolution and discriminant analysis). To test the approach, a total of 276 selections of ICP recordings corresponding to two patterns without waves and containing slow waves were obtained from overnight ICP studies of 44 hydrocephalus patients performed at the UCLA Adult Hydrocephalus Center. Our results showed that the best classification performance of differentiation of slow waves from the ICP recording without slow waves was obtained using the combination of metrics common to both differential evolution and analysis of variance methods; achieving an accuracy of 89%, specificity 96%, and sensitivity 83%.

Cognitive and motor improvement after retesting in normal-pressure hydrocephalus: a real change or merely a learning effect?

Object

The test-retest method is commonly used in the management of patients with normal-pressure hydrocephalus (NPH). One of the most widely used techniques in the diagnosis of this condition is evaluation of the patient's response to CSF evacuation by lumbar puncture (a so-called tap test or spinal tap). However, interpretation of improved results in subsequent evaluations is controversial because higher scores could reflect a real change in specific abilities or could be simply the result of a learning effect.

Methods

To determine the effect of testing-retesting in patients with NPH, the authors analyzed changes documented on 5 neuropsychological tests (the Toulouse-Pieron, Trail Making Test A, Grooved Pegboard, Word Fluency, and Bingley Memory tests) and several motor ability scales (motor performance test, length of step, and walking speed tests) in a series of 32 patients with NPH who underwent the same battery on 4 consecutive days. The same tests were also applied in 30 healthy volunteers. In both groups, the authors used the generalized least-squares regression method with random effects to test for learning effects. To evaluate possible differences in response depending on the degree of cognitive impairment at baseline, the results were adjusted by using the Mini-Mental State Examination scores of patients and controls when these scores were significant in the model.

Results

In patients with NPH there were no statistically significant differences in any of the neuropsychological or motor tests performed over the 4 consecutive days, except in the results of the Toulouse-Pieron test, which were significantly improved on Day 3. In contrast, healthy volunteers had statistically significant improvement in the results of the Toulouse-Pieron test, Trail Making Test A, and Grooved Pegboard test but not in the remaining neuropsychological tests. Patients in the healthy volunteer group also exhibited statistically significant improvement in the motor performance test but not in step length or walking speed.

Conclusions

No learning effect was found in patients with NPH on any of the neuropsychological or motor tests. Clinical improvement after retesting in these patients reflects real changes, and this strategy can therefore be used in both the diagnosis and evaluation of surgical outcomes.

Upper extremity motor measures of Tap Test response in Normal Pressure Hydrocephalus

OBJECTIVE

The Tap Test (TT) is a commonly used method for predicting shunt responsiveness in patients with Normal Pressure Hydrocephalus (NPH). The present study investigates whether measures of upper extremity motor function are useful for assessing response to spinal fluid drainage.

METHODS

42 subjects undergoing evaluations for idiopathic NPH (iNPH) participated in this study. A standardized gait evaluation, a neuropsychological battery, and objective tests of upper extremity motor functions were administered. A Neurologist skilled in NPH assessment independently rated patients as TT Responders (n=26) or Non-Responders (n=16) based on clinical impression of change 2-4h after 40-50 cm(3) drainage of spinal fluid by lumbar puncture (LP). In the subset of subjects who underwent shunt placement, operative outcome was also evaluated.

RESULTS

TT Responders improved significantly more than TT Non-Responders in Upper Extremity Coordination/Speed tasks (p<.001). The groups did not differ on other neuropsychological measures post-LP. A possible association was observed between pre- and post-TT changes in Upper Extremity Coordination/Speed and post-shunt improvement. Among Upper Extremity Coordination/Speed measures, Line Tracing displayed the greatest sensitivity (76%) to change post-LP.

CONCLUSIONS

Our data suggest that measures of upper extremity motor functions may be useful as measures of Tap Test response in patients with iNPH. These upper extremity motor tasks can be rapidly administered (<5 min) in clinical practice and may provide an additional dimension beyond gait and cognition for evaluating response to LP.

Normal pressure hydrocephalus: Diagnostic and predictive evaluationon

In typical cases, normal pressure hydrocephalus (NPH) manifests itself with the triad of gait disturbance, which begins first, followed by mental deterioration and urinary incontinence associated with ventriculomegaly (on CT or MRI) and normal cerebrospinal fluid (CSF) pressure. These cases present minor diagnostic difficulties and are the most likely to improve after shunting. Problems arise when NPH shows atypical or incomplete clinical manifestations (25–50% of cases) or is mimicked by other diseases. In this scenario, other complementary tests have to be used, preferentially those that can best predict surgical outcome. Radionuclide cisternography, intracranial pressure monitoring (ICP) and lumbar infusion tests can show CSF dynamics malfunction, but none are able to confirm whether the patient will benefit from surgery. The CSF tap test (CSF-TT) is the only procedure that can temporarily simulate the effect of definitive shunt. Since the one tap CSF-TT has low sensitivity, it cannot be used to exclude patients from surgery. In such cases, we have to resort to a repeated CSF-TT (RTT) or continuous lumbar external drainage (LED). The most reliable prediction would be achieved if RTT or LED proved positive, in addition to the occurrence of B-waves during more than 50% of ICP recording time. This review was based on a PubMed literature search from 1966 to date. It focuses on clinical presentation, neuroimaging, complementary prognostic tests, and differential diagnosis of NPH, particularly on the problem of selecting appropriate candidates for shunt.

Reversible grasp reflexes in normal pressure hydrocephalus

We present two cases of normal pressure hydrocephalus in combination with grasp reflexes. In both cases the grasp reflexes disappeared following high volume cerebrospinal fluid removal. In one of the cases the grasp reflexes returned over a period of weeks but again resolved following definitive cerebrospinal fluid shunting surgery, and remained absent until final follow up at 9 months. We hypothesise that resolving grasp reflexes following high volume CSF removal has both diagnostic and prognostic value in normal pressure hydrocephalus, encouraging larger studies on the relevance of primitive reflexes in NPH.

NEUROPSYCHOLOGICAL EFFECTS OF SHUNT TREATMENT IN IDIOPATHIC NORMAL PRESSURE HYDROCEPHALUS

OBJECTIVE

To prospectively evaluate the effects of shunting on the neuropsychological performance of patients with idiopathic normal pressure hydrocephalus (INPH), to compare their performance with that of healthy individuals, and to estimate the predictive utility of putatively important factors.

METHODS

A consecutive series of 47 patients with INPH underwent neurological, radiological, and neuropsychological examinations before and 3 months after shunt surgery. The same neuropsychological tests, measuring simple and target reaction times, dexterity, memory and learning, working memory, and aspects of executive functioning, were also administered to 159 healthy individuals.

RESULTS

Performance on all neuropsychological tests, except Simple Reaction Time and Digit Span, significantly improved after surgery, with more severe functional deficits showing greatest improvement. Age, education, duration, vascular comorbidity, sex, and onset symptom all failed to predict the neuropsychological effects of treatment. Despite improvement 3 months after shunt surgery, INPH patients were still outperformed by healthy individuals.

CONCLUSION

Most of the wide range of neuropsychological functions that are affected by INPH are markedly improved by shunt treatment, but not completely restored.

Features of gait most responsive to tap test in normal pressure hydrocephalus

OBJECTIVE

To identify components of gait associated with a positive tap test (TT) in patients with idiopathic normal pressure hydrocephalus (iNPH).

PATIENTS AND METHODS

Thirty-three patients with iNPH underwent clinical evaluation pre- and post-TT and were classified as responders (Rs) or non-responders (NRs). Elements of gait were assessed with a formal standardized Gait Scale and compared between groups.

RESULTS

Analysis of pre/post-TT group differences revealed an interaction for Total Gait Score and Walking Score, with improvements in responders only. Total Gait Scores improved by 29% in the Rs and 4.85% in the NRs. Rs showed significant post-TT improvements on a timed 10m walk, turning, and balance. Tandem walking, turning, truck balance and start stop hesitation showed trends toward improvement.

CONCLUSIONS

The classic features of gait often used in determining diagnosis of NPH (wide based stride, reduced foot-floor clearance, and small steps) were not helpful in identifying responders to the TT. Walking speed, steps for turning, and tendency towards falling were most likely to improve post-TT. These straightforward measures can readily be adapted into clinical practice to assist in determination of shunt candidacy.

Measurement of peak CSF flow velocity at cerebral aqueduct, before and after lumbar CSF drainage, by use of phase-contrast MRI: utility in the management of idiopathic normal pressure hydrocephalus

OBJECTIVE

Since it was first described, normal pressure hydrocephalus (NPH) and its treatment by means of cerebrospinal fluid (CSF) shunting have been the focus of much investigation. Whatever be the cause of NPH, it has been hypothesized that in this disease there occurs decreased arterial expansion and an increased brain expansion leading to increased transmantle pressure. We cannot measure the latter, but fortunately the effect of these changes (increased peak flow velocity through the aqueduct) can be quantified with cine phase-contrast magnetic resonance imaging (MRI). This investigation was thus undertaken to characterize and measure CSF peak flow velocity at the level of the aqueduct, before and after lumbar CSF drainage, by means of a phase-contrast cine MRI and determine its role in selecting cases for shunt surgery.

PATIENTS AND METHODS

37 patients with clinically suspected NPH were included in the study. Changes in the hyperdynamic peak CSF flow velocity with 50 ml lumbar CSF drainage (mimicking shunt) were evaluated in them for considering shunt surgery.

RESULTS

14 out of 15 patients who were recommended for shunt surgery, based on changes peak flow velocity after lumbar CSF drainage, improved after shunt surgery. None of the cases which were not recommended for shunt surgery, based on changes in CSF peak flow velocity after lumbar CSF drainage, improved after shunt surgery (2 out of 22 cases).

CONCLUSION

The study concluded that the phase-contrast MR imaging, done before and after CSF drainage, is a sensitive method to support the clinical diagnosis of normal pressure hydrocephalus, selecting patients of NPH who are likely to benefit from shunt surgery, and to select patients of NPH who are not likely to benefit from shunt surgery.

A mathematical model of survival in a newly inserted ventricular shunt

OBJECT

The object of this study was to mathematically model the prognosis of a newly inserted shunt in pediatric or adult patients with hydrocephalus.

METHODS

A structured search was performed of the English-language literature for case series reporting shunt failure, patient mortality, and shunt removal rates after shunt insertion. A metaanalytic model was constructed to pool data from multiple studies and to predict the outcome of a shunt after insertion. Separate models were used to predict shunt survival rates for children (patients < 17 years old) and adults.

RESULTS

Shunt survival rates in children and adults were calculated for 1 year (64.2 and 80.1%, respectively), 5 years (49.4 and 60.2%, respectively), and the median (4.9 and 7.3 years, respectively). The longer-term rates predicted by the model agree closely with those reported in the literature.

CONCLUSIONS

This model gives a comprehensive view of the fate of a shunt for hydrocephalus after insertion. The advantages of this model compared with Kaplan-Meier survival curves are discussed. The model used in this study may provide useful prognostic information and aid in the early evaluation of new shunt designs and techniques.

Have we made progress in preventing shunt failure? A critical analysis

OBJECT

The goal of this study was to determine whether failure rates of hydrocephalus shunts have fallen over the years as a result of experience or technical improvements.

METHODS

A structured search was performed of the English language literature for case series reporting failure rates after shunt insertion. A metaanalytic model was constructed to pool data from multiple studies and to analyze failure rates statistically for temporal trends. Separate models were used for children (< 17 years old) and adults.

RESULTS

In children, the shunt failure rate was 31.3% for the 1st year and 4.5% per year thereafter. There were no significant changes in either rate over time. Although 1st-year failure rates in adults have fallen slightly over time, late failure rates have risen.

CONCLUSIONS

Progress in preventing shunt failures has not been made over the last several decades. Any improvements made in shunt materials or insertion techniques have been overshadowed by biological and other factors.

Normal-pressure hydrocephalus: White matter lesions correlate negatively with gait improvement after lumbar puncture

OBJECTIVES

To test relations between white matter lesions (WML) load in Normal Pressure Hydrocephalus (NPH) patients and gait characteristics at baseline, duration of symptoms, gait improvement after lumbar puncture (LP), vascular risk factors.

PATIENTS

Fifteen idiopathic NPH patients.

METHODS

Patients underwent a timed walking test, before and after LP. Five gait variables were assessed and improvement percentages were calculated. WML load was rated regionally and globally in T2 weighted MRI images, using a simple visual scale. Spearman or Pearson correlation coefficients were used to test relations between variables.

RESULTS

Significant negative correlations were found between WML scores and gait improvement after CSF removal but not with duration of symptoms or gait variables before LP.

CONCLUSIONS

WML seem to contribute to the irreversibility of symptoms in NPH but not to the pathophysiological mechanisms that lead to them.

Continuous intraventricular pressure monitoring for diagnosis of normal-pressure hydrocephalus

OBJECTIVES

Normal-pressure hydrocephalus (NPH) syndrome is treatable by implantation of a cerebrospinal fluid (CSF) shunt. However, diagnosis of NPH by clinical and radiological findings alone is unreliable, and co-existing structural dementia can contribute to low success rates after shunt implantation. The aim of our study was to investigate whether long-term results after shunt implantation in NPH improve when surgical candidates are selected by continuous intraventricular pressure monitoring (CIPM).

PATIENTS AND METHODS

Ninety-two consecutive patients who were admitted with suspected NPH received CIPM for 48 h including an intraventricular steady-state infusion test to determine the resistance outflow. With positive CIPM, shunt implantation was performed and the patients were prospectively followed up for 1 to 10 years (median 6.5 years).

RESULTS

CIPM was negative in 37 patients. Fifty-five patients had a positive CIPM and received CSF shunt. 96.1% of them improved from gait disturbance, 77.1% from cognitive impairment and 75.7% from urinary dysfunction. Clinical improvement remained during long-term follow-up in all but 3 patients who showed a decline at 4, 5 and 7 years, respectively. CIPM-related complications (ventriculitis) occurred in only one patient.

CONCLUSION

CIPM is a safe and valuable tool to establish a reliable diagnosis of NPH and to identify promising surgical candidates.

Gait disturbance in normal pressure hydrocephalus: A clinical study

The origin of gait disturbance in normal pressure hydrocephalus (NPH) is poorly understood. We assessed the frequency of frontal and sub-cortical hypokinetic gait clinical features and changes in gait variables after lumbar puncture (LP), in 15 patients with idiopathic NPH. Hypokinesia and disequilibrium were the main features, suggesting dysfunction of the basal ganglia (BG) and the frontal lobe (FL), respectively. Disequilibrium responded worse to LP and frontal signs were more frequent in patients that did not improve after LP. This could be related to earlier disturbance of frontal gait control.

LONG-TERM OUTCOME IN PATIENTS WITH SUSPECTED NORMAL PRESSURE HYDROCEPHALUS

OBJECTIVE

To evaluate the outcome of patients with suspected normal pressure hydrocephalus at 6 months and 5 years after shunt surgery.

METHODS

Seventy-five patients (mean age, 72.5 6 9 yr), with normal pressure hydrocephalus symptoms were included. Fifty-four patients with positive lumbar infusion and/or cerebrospinal fluid tap tests received a cerebrospinal fluid shunt, whereas 21 patients with negative test results did not undergo operation. Walk, reaction time, memory, and identical forms tests were used as baseline (before surgery) tests and were repeated at short- (6.1 6 4.6 mo) and long-term (5.5 6 1.4 yr) follow-up evaluations. Activities of daily life functions were assessed using the Barthel index.

RESULTS

At the 6-month follow-up examination, 83% of the operated patients improved in gait, 65% improved in reaction time, 46% improved in memory, and 31% improved in identical forms tests; 96% found themselves subjectively improved. Because of unrelated mortality (37%) and declining general health from comorbidity, only 27 patients were available for the 5-year follow-up evaluation. Twenty-three of these patients had been treated with a shunt and had a remaining improvement in close to 40% in gait and reaction time, whereas fewer than 10% had an improvement in cognitive tests. Fifty-six percent reported subjective improvement compared with preoperative findings. More patients (64%) improved if younger than 75 years; for patients older than 75 years, only 11% of the patients improved. The Barthel index was higher (P &lt; 0.05) in improved patients.

CONCLUSION

Patients with normal pressure hydrocephalus benefit from shunt surgery for at least 5 years. High mortality rate, comorbidity, and old age hamper good long-term outcome and emphasize the importance of patient selection.

Predicting the outcome of shunt surgery in normal pressure hydrocephalus

We studied retrospectively the effectiveness of the repeated lumbar CSF tap test (RTT), lumbar external CSF drainage (LED) and radioisotope cisternography (RIC) in predicting the outcome of shunt surgery, as well as the diagnostic and prognostic value of periventricular hyperintensity (PVH) and of the classic clinical triad in normal pressure hydrocephalus. Two hundred and seventy patients were referred to the Departments of Neurosurgery, in Nancy, France and in Istanbul, Turkey. The decision to perform surgery was based on the clinical presentation (all patients had at least two symptoms of the classic clinical triad), neuroimaging examinations and the results of the RTT (taps were performed on three consecutive days and at each tap a minimum of 30 to 40 cc of CSF was removed), the LED (drainage was performed for 3 days and the volume of CSF drained daily was a minimum of 150 to 250 cc) or the RIC. After all shunt procedures, postoperative assessments verified improvements in 88% of the RTT group, 91% of the LED group and 66% of the RIC group. Gait disturbance had improved in 90% at the end of the second and twelfth month follow-up. Cognitive dysfunction had improved in 79% at the second and in 77% at the twelfth month follow-up. Urinary incontinence had improved in 66% at the second and in 62% at the twelfth month follow-up. From the surgical point of view, the greatest difficulty is not to make the diagnosis, but rather to identify the appropriate patients to operate on. The decision to perform shunt surgery should be based on strict clinical findings associated with CT and MRI criteria and especially with positive RTT or LED test results.

IS AQUEDUCTAL STROKE VOLUME, MEASURED WITH CINE PHASE-CONTRAST MAGNETIC RESONANCE IMAGING SCANS USEFUL IN PREDICTING OUTCOME OF SHUNT SURGERY IN SUSPECTED NORMAL PRESSURE HYDROCEPHALUS?

OBJECTIVE

To evaluate clinical usefulness of cerebrospinal fluid stroke volume (SV) assessed in the cerebral aqueduct, via cine phase-contrast magnetic resonance imaging, for predicting outcome after shunt surgery in suspected normal pressure hydrocephalus.

METHODS

Thirty-eight patients with suspected normal pressure hydrocephalus were included. SV was assessed using cine phase-contrast magnetic resonance imaging, and the results were kept blinded until postoperative follow-up after 7 ± 5.8 months (mean ± standard deviation). Selection to surgery was based on a positive lumbar infusion test or cerebrospinal fluid tap test, and outcome was evaluated with objective tests.

RESULTS

Six patients were excluded from SV measurements because of technical difficulties. Eight patients were not operated (negative lumbar infusion test and cerebrospinal fluid tap test). SV in the not operated patients (mean, 66 ± 53 μl) did not differ from the operated patients (95 ± 78 μl; P= 0.335). Operated patients showed statistically significant improvements in walk (P= 0.020), reaction time (P= 0.006), and memory (P= 0.001) tests. Patients were divided into three groups according to SV range: low (0–50 μl), middle (51–100 μl), and high (&gt;100 μl). No statistically significant (P&gt; 0.05) improvements in any of the objective tests were found in any of the SV ranges. The numbers of individually improved patients were similar in the different SV ranges: six out of seven in the low, nine out of nine in the middle, and five out of eight in the high range. Weak correlations were found between SV and the initial pulse amplitude (Rs= 0.043; P= 0.014) as well as the plateau pulse amplitude (Rs= 0.043; P= 0.014) as measured with the lumbar infusion test.

CONCLUSION

The data from this study show no evidence that cine phase-contrast magnetic resonance imaging measurements of SV in the cerebral aqueduct are useful for selecting patients with normal pressure hydrocephalus symptoms to shunt surgery.

Screening tests for normal-pressure hydrocephalus: sensitivity, specificity, and cost

Object

Many tests have been proposed to help choose candidates for shunt insertion in cases of suspected normal-pressure hydrocephalus (NPH). It is unclear what sensitivity and specificity a prospective test must have to improve outcomes, compared with the results of automatic shunt insertion.

Methods

The authors adapted the decision analysis model used in a companion article to allow for application of a screening test. Using the reported sensitivities and specificities of several such tests, they evaluated the effects such tests would have on the expected outcome of an average 65-year-old patient with moderate dementia. They also evaluated the cost-effectiveness of a theoretical screening test with superior sensitivity and specificity.

Conclusions

Although external lumbar drainage comes quite close, none of the screening tests reported to date have sufficient sensitivity and specificity to improve expected outcome in an average candidate, compared with the results of automatic shunt placement in cases of suspected NPH. In addition, even a theoretically improved test would need to be considerably less expensive than prolonged lumbar drainage to be cost-effective in clinical practice.

Atraumatic Joint and Limb Pain in the Elderly

Patients who visit the emergency department often have complaints of joint and limb pain. The differential diagnosis, clinical presentation, and treatment choices can be vastly different in the young- or middle-aged population compared with the elderly population, and the concerns of each group must be addressed. The emergency physician is in a unique position in that they are frequently the first to see these individuals and have the opportunity to intervene before permanent disability ensues. Some of the more common etiologies of atraumatic joint and limb pain, including crystal deposition diseases such as gout and pseudogout, osteoarthritis, septic arthritis, and inflammatory arthritides such as rheumatoid arthritis will be addressed in this article. In addition,several arthritides specific to the elderly population such as poly-myalgia rheumatica and associated giant cell arteritis will be covered. Finally a discussion of cervical and lumbar disc disease, as well as gait disorders, and their impact on the elderly, will be presented.

Voxel-based assessment of spinal tap test-induced regional cerebral blood flow changes in normal pressure hydrocephalus

OBJECTIVE

Normal pressure hydrocephalus (NPH) is a cause of dementia that may be amended by medical intervention. Its diagnosis is therefore of major importance and the establishment of response criteria to cerebrospinal fluid (CSF) shunting is essential. One of these criteria is the clinical response to spinal tap. The accuracy of the spinal tap test could potentially be improved by adding neuroimaging of regional cerebral blood flow (rCBF) changes to the response criteria. Statistical parametric mapping (SPM) is a voxel-based method of image analysis that may be used to statistically assess the significance of rCBF changes. The objective of this study was to evaluate, by SPM, spinal tap test-induced rCBF changes in patients with NPH syndrome.

METHODS

Forty patients with NPH syndrome underwent hexamethylpropylene amine oxime (HMPAO) brain single photon emission computed tomography (SPECT) before and after a spinal tap test (1-day split-dose protocol). The differences in rCBF between these pairs of scans were analysed by SPM in the whole group and between subgroups divided according to gait improvement at the spinal tap test.

RESULTS

In the whole group of patients, there was no statistical difference between pre- and post-spinal tap SPECT images. SPM analysis of patients grouped as a function of their clinical response to the spinal tap test revealed a significant post-spinal tap rCBF increase in the bilateral dorsolateral frontal and left mesiotemporal cortex in clinically responding compared with non-responding patients.

CONCLUSION

According to SPM analysis, gait improvement at the spinal tap test in patients with NPH syndrome is associated with an rCBF increase localized in the bilateral dorsolateral frontal and left mesiotemporal cortex.

Lumbar infusion test in normal pressure hydrocephalus

OBJECTIVE

To compare potential clinical value of plateau pressure (P(pl)), resistance to outflow (R(out)), pulse-pressure amplitude (P(plA)) and rate of pressure increase (v(P)), taken from the constant rate lumbar infusion test (LIT), as predictors for the outcome of shunt surgery.

METHODS

Recordings from preoperative LIT in 55 patients were scrutinized for the values of P(pl), P(plA), v(P) and R(out). Gait, memory, spatial capacity and reaction ability were tested before and 6 months after shunt surgery.

RESULTS

Forty-three (78%) of the patients improved. There were no statistically significant differences in P(pl), R(out), P(plA) or v(P) between improved and not improved patients. Five patients with P(pl) below 22 mmHg (the cut off level) improved after shunting, while 16 and eight patients with R(out) below the cut off levels of 18 and 14 mmHg/ml/min improved. P(plA) correlated with P(pl) and R(out) (r = 0.74 and 0.63, respectively). In the group of patients with high P(plA) (>/=20 mmHg) as many as 93% improved but a high P(plA) did not recruit more improved patients than P(pl) or R(out) alone.

CONCLUSION

v(P) or P(plA) does not add useful information to P(pl) for selecting patients with suspected NPH for surgery. R(out) calculations from LIT does not provide advantage over using the steady-state plateau pressure for selecting patients for surgery and may increase the risk of missing patients who should benefit from surgery.

Cognitive Recovery in Idiopathic Normal Pressure Hydrocephalus After Shunt

OBJECTIVE

Evaluate long-term changes in cognition after ventriculoperitoneal shunt insertion in patients with idiopathic normal pressure hydrocephalus.

BACKGROUND

Although studies have indicated that treatment of normal pressure hydrocephalus with ventriculoperitoneal shunt improves gait, effects of treatment on cognition have been inconsistent. Several studies have reported no significant improvement on neuropsychological tests in patients with idiopathic normal pressure hydrocephalus. Selection of candidates for shunt surgery using a trial of controlled spinal fluid drainage via lumbar catheter may result in more consistent improvement in cognition.

DESIGN/METHODS

This was a prospective, longitudinal study of performance on neuropsychological tests before and 6 to 12 months after insertion of a ventriculoperitoneal shunt in 10 patients with idiopathic normal pressure hydrocephalus who showed improvement in at least 1 clinical symptom with temporary lumbar drainage. Nonparametric tests were used to evaluate change.

RESULTS

Significant group improvements at follow-up were demonstrated on tests of verbal memory as well as in 1 test of psychomotor speed. Eight of 10 patients showed improvement by more than 1 standard deviation on at least 1 memory test. Six of 10 patients improved significantly on more than 50% of the tests administered.

CONCLUSIONS

Patients with idiopathic normal pressure hydrocephalus who show clinical improvement (in any symptom) after lumbar drainage are likely to show significant long-term improvement in memory after ventriculoperitoneal shunt.

Comparison between the lumbar infusion and CSF tap tests to predict outcome after shunt surgery in suspected normal pressure hydrocephalus

OBJECTIVE

To compare the lumbar infusion test and the cerebrospinal fluid (CSF) tap test for predicting the outcome of shunt surgery in patients with suspected normal pressure hydrocephalus.

METHODS

68 patients with suspected normal pressure hydrocephalus were studied. The absence of preceding history indicated idiopathic disease in 75% of these. All patients were assessed twice with walking and psychometric tests before lumbar infusion test and tap test assessments. The lumbar infusion test was done using a constant infusion rate (0.80 ml/min) and regarded as positive if the steady state CSF plateau pressure reached levels of > 22 mm Hg (resistance to outflow > 14 mm Hg/ml/min). The tap test was regarded as positive if two or more of four different test items improved after CSF removal. As the variability in baseline test results was large, the better of two evaluations was used in comparisons with the results after CSF removal, as well as to evaluate the outcome after shunt surgery. Only patients with a positive lumbar infusion test or a positive tap test had surgery.

RESULTS

The results of the CSF tap test and the lumbar infusion test agreed in only 45% of the patients. Of the total cohort, 47 (69%) had positive test results and were operated on; 45 (96%) of these reported subjective improvement, and postoperative assessments verified the improvements in 38 (81%). Improvements were highly significant in walking, memory, and reaction time tests (p < 0.001). Most of the patients improved by surgery (84%) were selected by a positive lumbar infusion test, and only 42% by a positive tap test. Positive predictive values were 80% for lumbar infusion test and 94% for tap test. The false negative predictions in the operated group were much higher (58%) with the tap test than with the lumbar infusion test (16%).

CONCLUSIONS

Both the lumbar infusion test and the tap test can predict a positive outcome of shunt operations in unselected patients with suspected normal pressure hydrocephalus. The two tests are complementary and should be used together for optimal patient selection.

Clinical features of third ventriculostomy failures classified by fenestration patency

BACKGROUND

To evaluate strategies for treating endoscopic third ventriculostomy (ETV) failure, we assessed patients, clinical features at failure, and the outcome of VP shunt placement at re-operation, classifying patients by fenestration patency.

METHODS

Thirty-six patients with failed ETV were evaluated retrospectively. All but 4 had cine phase-contrast magnetic resonance (MR) images at re-operation to determine whether the fenestration was patent, and were grouped into "patent" and "no flow" groups. Symptoms at re-operation, the interval to failure, and outcome of re-operation were compared between these groups.

RESULTS

Progression of elevated intracranial pressure (ICP) signs was significantly more frequent in the "no flow" group than the "patent" group (p = 0.0025). The median interval to failure was 2.5 months, with no statistical difference between the "patent" group (median 4.0 months) and the "no flow" group (median 1.1 months). Re-operations consisted of 29 shunt placements, 4 redo ETVs, and 3 combinations of both. Kaplan-Meier estimation indicates that 41% of shunts would be expected to fail by 5.2 years. The success rate of shunt placement was somewhat worse in the "no flow" group, although the difference was not statistically significant (p = 0.066). Four patients in the "patent" group treated with shunt placements eventually became shunt-independent with continuously patent fenestration; these were considered delayed successes.

CONCLUSION

Patients with signs of elevated ICP and "no flow" findings on MR should be given emergency treatment because they have a high risk of symptom progression. The clinical differences between "patent" and "no flow" fenestration at re-operation after ETV failure are considered to be worthy of further study.

Is normal pressure hydrocephalus a valid concept in 2002? A reappraisal in five questions and proposal for a new designation of the syndrome as "chronic hydrocephalus"

The authors question the current validity of the traditional concept of normal pressure hydrocephalus (NPH) as it was described by Adams and Hakim in 1965. The classic features of the disease are addressed. It is concluded that most of the historical statements made three decades ago need to be revised. Especially, the term "normal pressure" hydrocephalus probably does not match the actual manometric profile of patients with NPH. Similarly, the terms"curable"and "reversible" dementia are inadequate to designate the mental alterations of NPH. That NPH is non-specific to the adult population is also stressed, since it may be not uncommonly encountered in paediatrics, especially in an implanted shunt malfunction. The term "chronic hydrocephalus" without reference to cerebrospinal fluid pressure and to the age of the patient is proposed instead of NPH, which seems out of step with current knowledge of the pressure profile and with the diagnosis and decision making context in patients with so called NPH.

The value of temporary external lumbar CSF drainage in predicting the outcome of shunting on normal pressure hydrocephalus

OBJECTIVE

It has been reported that temporary external lumbar CSF drainage (ELD) is a very accurate test for predicting the outcome after ventricular shunting in patients with normal pressure hydrocephalus (NPH). However, only a limited number of patients have been studied for assessing the predictive accuracy of ELD. Therefore, the value of ELD in predicting the outcome after a ventriculoperitoneal shunt in patients with presumed NPH was assessed.

METHODS

All patients with presumed NPH were invited to participate in this study. Clinical assessment, MRI, and neuropsychological evaluation were followed by a lumbar CSF tap test consisting of removing 40 ml CSF. When this test resulted in marked clinical improvement of gait impairment, mental disturbances, or both, the patient was shunted without further tests. In patients with either questionable or no improvement after the CSF tap test, ELD was carried out. The value of ELD for predicting the outcome after shunting was calculated by correlating the results of ELD with that of ventriculoperitoneal shunting.

RESULTS

Between January 1994 and December 2000, 49 presumed NPH patients from three institutes were included. Forty three had idiopathic, and the remaining six had secondary NPH. Forty eight patients were shunted; 39 had an ELD of whom 38 completed the test. After 2 months 35 of the 48 (73%) shunted patients had improved. The predictive value of a positive ELD was 87% (95% confidence interval (95% CI) 62-98) and that of a negative ELD 36% (95% CI 17-59). In two patients serious test related complications (meningitis) occurred without residual deficit.

CONCLUSION

The study suggests that although the predictive value of a positive ELD is high, that of a negative ELD is deceptively low because of the high rate of false negative results. The costs and invasiveness of the test and the possibility of serious test related complications further limits its usefulness in managing patients with presumed NPH.

Idiopathic normal pressure hydrocephalus: a systematic review of diagnosis and outcome

OBJECTIVE

Patient selection for cerebrospinal fluid diversion is difficult, because idiopathic normal pressure hydrocephalus (INPH) mimics other neurodegenerative disorders and no findings reliably predict outcome. The literature was reviewed to identify diagnostic criteria that predict shunt response and to formulate prognostic expectations.

METHODS

MEDLINE was searched, and 44 articles meeting predetermined criteria were included.

RESULTS

Clinical series were frequently retrospective with small patient numbers and unstandardized outcome evaluation. Clinical findings suggestive of shunt responsiveness were the complete triad (gait disturbance, urinary incontinence, and dementia) with early gait disturbance. Degree of hydrocephalus was not correlated with clinical improvement. Reduction of the subcortical low-blood flow area was correlated with improvement in three small studies. Clinical response to prolonged cerebrospinal fluid drainage predicted shunt outcome in all cases in two small series. Overall, 59% (range, 24-100%) of patients improved after shunting, and 29% (range, 10-100%) of patients experienced prolonged improvement. Complications occurred in 38% (range, 5-100%) of patients, additional surgery was required in 22% (range, 0-47%) of patients, and there was a 6% (range, 0-35%) combined rate of permanent neurological deficit and death.

CONCLUSION

Shunting INPH is associated with an approximately 29% rate of significant improvement and a 6% significant complication rate. Enlargement of the subcortical low-flow area and clinical improvement secondary to prolonged lumbar drainage may provide additive predictive value above clinical and computed tomographic criteria. A multicenter clinical trial that focuses on the value of ancillary tests, defines the clinical course of a patient with a ventriculoperitoneal shunt, and evaluates the cost effectiveness of shunting INPH is needed to better describe outcome from shunting in INPH.