Further experience with the syndrome of "normal" pressure hydrocephalus

Idiopathic normal pressure hydrocephalus: historical context and a contemporary guide

Idiopathic normal pressure hydrocephalus (NPH) was described in 1965 as a syndrome in which hydrocephalus develops but with a normal cerebrospinal fluid (CSF) pressure, causing shunt-responsive gait apraxia, cognitive impairment and urinary incontinence. Not all patients respond to shunting despite having the clinical syndrome with appropriate radiological features. This has led to considerable debate over subsequent decades regarding idiopathic NPH. It is now understood that asymptomatic communicating hydrocephalus can develop in many healthy older people, and that over time this can develop into a symptomatic state that sometimes responds to CSF shunting, but to a variable extent. This review looks at the historical background of NPH, the use of predictive tests, the current state of clinical evidence for the diagnosis and treatment of idiopathic NPH and the possible underlying causes, to provide a contemporary practical guide for assessing patients with the radiological features of idiopathic NPH.

Clinical utility of paced finger tapping assessment in idiopathic normal pressure hydrocephalus

Background

The Finger Tapping (F-T) test is useful for assessing motor function of the upper limbs in patients with idiopathic normal pressure hydrocephalus (iNPH). However, quantitative evaluation of F-T for iNPH has not yet been established. The purpose of this study was to investigate the usefulness of the quantitative F-T test and optimal measurement conditions as a motor evaluation and screening test for iNPH.

Methods

Sixteen age-matched healthy controls (mean age 73 ± 5 years; 7/16 male) and fifteen participants with a diagnosis of definitive iNPH (mean age 76 ± 5 years; 8/15 male) completed the study (mean ± standard deviation). F-T performance of the index finger and thumb was quantified using a magnetic sensing device. The performance of repetitive F-T by participants was recorded in both not timing-regulated and timing-regulated conditions. The mean value of the maximum amplitude of F-T was defined as M-Amplitude, and the mean value of the maximum velocity of closure of F-T was defined as cl-Velocity.

Results

Finger Tapping in the iNPH group, with or without timing control, showed a decrease in M-Amplitude and cl-Velocity compared to the control group. We found the only paced F-T with 2.0 Hz auditory stimuli was found to improve both M-Amplitude and cl-Velocity after shunt surgery.

Conclusion

The quantitative assessment of F-T with auditory stimuli at the rate of 2.0 Hz may be a useful and potentially supplemental screening method for motor assessment in patients with iNPH.

Clinical Feature and Outcomes of Secondary Hydrocephalus Caused by Head Trauma

Objective

Post-traumatic hydrocephalus (PTH) is a frequent and serious complication following brain injury. The incidence of PTH varies greatly among studies. The purpose of this study was to investigate the incidence and treatment of PTH in patients with head trauma.

Methods

We examined 956 patients with head trauma who visited our center from January 2012 to December 2015. The hydrocephalus diagnosis was based on radiologic findings and clinical features, and patients were classified into the mild (Group 1, Glasgow Coma Scale score [GCS] 13–15), moderate (Group 2, GCS 9–12), or severe (Group 3, GCS 3–8) brain injury group according to their GCS at admission. To compare these groups, we used age, gender, radiologic findings, PTH developmental period, and postoperative results (Glasgow Outcome Scale).

Results

Of the 956 patients, 24 (2.5%) developed PTH. PTH occurred in 11 (1.4%), 3 (5.6%), and 10 (7.0%) patients in Groups 1, 2, and 3, respectively. Of the 24 patients with PTH, 22 (91.7%) developed PTH within 12 weeks post-trauma; the higher the GCS, the later the onset, and the lower the GCS, the earlier the onset (p=0.019). Twenty-one patients underwent ventriculoperitoneal shunting, and 13 had improved symptoms.

Conclusion

The incidence of PTH cannot be ignored. The possibility of PTH needs to be considered in patients with head trauma and appropriate follow-up should be undertaken. PTH is a treatable complication and patients' quality of life and neurological status can be improved if the appropriate treatment is selected and applied.

Revisiting secondary normal pressure hydrocephalus: does it exist? A review

OBJECTIVE There are several etiologies that can lead to the development of secondary normal pressure hydrocephalus (sNPH). The aim of this study was to evaluate the etiology, diagnosis, treatment, and outcome in patients with sNPH and to highlight important differences between the separate etiologies. METHODS A comprehensive review of the literature was performed to identify studies conducted between 1965 and 2015 that included data regarding the etiology, treatment, diagnosis, and outcome in patients with sNPH. Sixty-four studies with a total of 1309 patients were included. The inclusion criteria of this study were articles that were written in English, included more than 2 patients with the diagnosis of sNPH, and contained data regarding the etiology, diagnosis, treatment, or outcome of NPH. The most common assessment of clinical improvement was based on the Stein and Langfitt grading scale or equivalent improvement on other alternative ordinal grading scales. RESULTS The main etiologies of sNPH were subarachnoid hemorrhage (SAH) in 46.5%, head trauma in 29%, intracranial malignancies in 6.2%, meningoencephalitis in 5%, and cerebrovascular disease in 4.5% of patients. In 71.9% of patients the sNPH was treated with ventriculoperitoneal shunt placement, and 24.4% had placement of a ventriculoatrial shunt. Clinical improvement after shunt placement was reported in 74.4% and excellent clinical improvement in 58% of patients with sNPH. The mean follow-up period after shunt placement was 13 months. Improvement was seen in 84.2% of patients with SAH, 83% of patients with head trauma, 86.4% of patients with brain tumors, 75% of patients with meningoencephalitis, and 64.7% of patients with NPH secondary to stroke. CONCLUSIONS Secondary NPH encompasses a diverse group of clinical manifestations associated with a subset of patients with acquired hydrocephalus. The most common etiologies of sNPH include SAH and traumatic brain injury. Secondary NPH does indeed exist, and should be differentiated from idiopathic NPH based on outcome and on clinical, pathophysiological, and epidemiological characteristics, but should not be considered as a separate entity.

Inhibition of transforming growth factor-β attenuates brain injury and neurological deficits in a rat model of germinal matrix hemorrhage

BACKGROUND AND PURPOSE

Transforming growth factor-β (TGF-β) overproduction and activation of the TGF-β pathway are associated with the development of brain injury following germinal matrix hemorrhage (GMH) in premature infants. We examined the effects of GMH on the level of TGF-β1 in a novel rat collagenase-induced GMH model and determined the effect of inhibition of the TGF receptor I.

METHODS

In total, 92 seven-day old (P7) rats were used. Time-dependent effects of GMH on the level of TGF-β1 and TGF receptor I were evaluated by Western blot. A TGF receptor I inhibitor (SD208) was administered daily for 3 days, starting either 1 hour or 3 days after GMH induction. The effects of GMH and SD208 on the TGF-β pathway were evaluated by Western blot at day 3. The effects of GMH and SD208 on cognitive and motor function were also assessed. The effects of TGF receptor I inhibition by SD208 on GMH-induced brain injury and underlying molecular pathways were investigated by Western blot, immunofluorescence, and morphology studies 24 days after GMH.

RESULTS

GMH induced significant delay in development, caused impairment in both cognitive and motor functions, and resulted in brain atrophy in rat subjects. GMH also caused deposition of both vitronectin (an extracellular matrix protein) and glial fibrillary acidic protein in perilesion areas, associated with development of hydrocephalus. SD208 ameliorated GMH-induced developmental delay, improved cognitive and motor functions, and attenuated body weight loss. SD208 also decreased vitronectin and glial fibrillary acidic protein deposition and decreased GMH-induced brain injury.

CONCLUSIONS

Increased level of TGF-β1 and activation of the TGF-β pathway associate with the development of brain injury after GMH. SD208 inhibits GMH-induced activation of the TGF-β pathway and leads to an improved developmental profile, partial recovery of cognitive and motor functions, and attenuation of GMH-induced brain atrophy and hydrocephalus.

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.

Priorities for hydrocephalus research: report from a National Institutes of Health-sponsored workshop

OBJECT

Treatment for hydrocephalus has not advanced appreciably since the advent of cerebrospinal fluid (CSF) shunts more than 50 years ago. Many questions remain that clinical and basic research could address, which in turn could improve therapeutic options. To clarify the main issues facing hydrocephalus research and to identify critical advances necessary to improve outcomes for patients with hydrocephalus, the National Institutes of Health (NIH) sponsored a workshop titled "Hydrocephalus: Myths, New Facts, and Clear Directions." The purpose of this paper is to report on the recommendations that resulted from that workshop.

METHODS

The workshop convened from September 29 to October 1, 2005, in Bethesda, Maryland. Among the 150 attendees was an international group of participants, including experts in pediatric and adult hydrocephalus as well as scientists working in related fields, neurosurgeons, laboratory-based neuroscientists, neurologists, patient advocates, individuals with hydrocephalus, parents, and NIH program and intramural staff. Plenary and breakout sessions covered injury and recovery mechanisms, modeling, biomechanics, diagnosis, current treatment and outcomes, complications, quality of life, future treatments, medical devices, development of research networks and information sharing, and education and career development.

RESULTS

The conclusions were as follows: 1) current methods of diagnosis, treatment, and outcomes monitoring need improvement; 2) frequent complications, poor rate of shunt survival, and poor quality of life for patients lead to unsatisfactory outcomes; 3) investigators and caregivers need additional methods to monitor neurocognitive function and control of CSF variables such as pressure, flow, or pulsatility; 4) research warrants novel interdisciplinary approaches; 5) understanding of the pathophysiological and recovery mechanisms of neuronal function in hydrocephalus is poor, warranting further investigation; and 6) both basic and clinical aspects warrant expanded and innovative training programs.

CONCLUSIONS

The research priorities of this workshop provide critical guidance for future research in hydrocephalus, which should result in advances in knowledge, and ultimately in the treatment for this important disorder and improved outcomes in patients of all ages.

Prevalence of probable idiopathic normal pressure hydrocephalus in a Norwegian population

OBJECTIVE

The clinical condition normal pressure hydrocephalus (NPH) is one of the few conditions with dementia that can be successfully treated. Even though NPH was described more than 40 years ago, information on prevalence and incidence of this disease is scarce. The objective of this study was to obtain information about prevalence of iNPH in a Norwegian population.

METHODS

In a stable population of 220,000 inhabitants, structured and intensive efforts were directed towards the public via local newspapers, radio and television channels, and directed towards the healthcare professionals via personal letters and lectures, to recruit patients with idiopathic NPH (iNPH) investigation during a 12-month period. This population is served by only one neurological department and one neurosurgical department, thus avoiding any leakage of patients during the investigation period. We determined those patients fulfilling the diagnostic criteria of probable iNPH.

RESULTS

Eighty-six patients were referred, of whom 48 patients fulfilled the diagnostic criteria of probable iNPH. This equals a minimum prevalence of iNPH in our population of 21.9/100,000. Most importantly, the prevalence was increasing with age. When excluding patients who had symptoms for more than 1 year, we found an incidence of 5.5/100,000/year.

CONCLUSIONS

In this Norwegian population of 220,000 inhabitants, we found a prevalence of probable iNPH of 21.9/100,000 and an incidence of 5.5/100,000. The numbers should be regarded as minimum estimates.

Shunts in normal-pressure hydrocephalus: do we place too many or too few?

OBJECT

The average 65-year-old patient with moderate dementia can look forward to only 1.4 quality-adjusted life years (QALYs), that is, longevity times quality of life. Some of these patients suffer from normal-pressure hydrocephalus (NPH) and respond dramatically to shunt insertion. Currently, however, NPH cannot be diagnosed with certainty. The authors constructed a Markov decision analysis model to predict the outcome in patients with NPH treated with and without shunts.

METHODS

Transition probabilities and health utilities were obtained from a review of the literature. A sensitivity analysis and Monte Carlo simulation were applied to test outcomes over a wide range of parameters. Using shunt response and complication rates from the literature, the average patient receiving a shunt would gain an additional 1.7 QALYs as a result of automatic shunt insertion. Even if 50% of patients receiving a shunt have complications, the shunt response rate would need to be less than 5% for empirical shunt insertion to do more harm than good. Authors of most studies have reported far better statistics.

CONCLUSIONS

In summary, many more patients with suspected NPH should be considered for shunt insertion.

Diagnosing idiopathic normal-pressure hydrocephalus

OBJECTIVE

The precise incidence and prevalence of idiopathic normal-pressure hydrocephalus (INPH) is not known, and evidence-based clinical diagnostic criteria have not been developed previously. This report contains evidence-based guidelines for clinical diagnosis of INPH that are intended to facilitate future epidemiological studies of INPH, promote earlier and more accurate diagnosis, and ultimately improve treatment outcome.

METHODS

The criteria for the diagnosis of INPH are based on evidence from the medical literature, supplemented as necessary by expert opinion. From 1966 to 2003, 653 publications on "normal-pressure hydrocephalus" were cited in MEDLINE, including 29 articles that met the more stringent criteria of including "idiopathic normal-pressure hydrocephalus" in their title. Additional studies were considered that explicitly identified INPH cases and/or specified the criteria for a diagnosis of INPH. Studies were graded according to the class of evidence and results summarized in evidentiary tables. For issues of clinical relevance that lacked substantive evidence from the medical literature, the opinions of consulting experts were considered and contributed to "Options."

RESULTS

Evidence-based guidelines for the clinical diagnosis of INPH have been developed. A detailed understanding of the range of clinical manifestations of this disorder and adherence to practice guidelines should improve the timely and accurate recognition of this disorder.

CONCLUSION

It is recommended that INPH be classified into probable, possible, and unlikely categories. We hope that these criteria will be widely applied in clinical practice and will promote greater consistency in patient selection in future clinical investigations involving INPH.

Predictors of outcome in patients with normal-pressure hydrocephalus

Despite knowledge emerging over the last 40 years, the postoperative results after shunt implantation in patients diagnosed with normal-pressure hydrocephalus (NPH) have not improved significantly over the last decade. For that reason predictors have to be identified in order to preoperatively predict outcome. From 1982 to 2000 we prospectively studied 200 patients diagnosed with NPH. From the patients, who were surgically treated by a shunt implantation we reexamined 155 (78%) postoperatively a mean time interval of 7 months. The NPH was graded according to the results of the intrathecal infusion test in an early stage NPH (without brain atrophy) and late stage NPH (with brain atrophy). In our study, we focussed attention on the possible predictors: patients age, length of disease, clinical signs (gait ataxia, dementia and bladder incontinence), aetiology idiopathic/secondary as well as implanted valve type and the value of resistance to cerebrospinal fluid outflow. To measure the outcome we used the NPH recovery rate and as the statistical test the chi(2) according to Pearson. In 80 patients with an early stage NPH (without cerebral atrophy), a short course of disease (<1 year), a slight degree of dementia and an implanted Miethke-Dual-Switch valve were significant predictors for a positive postoperative outcome. The outflow resistance measured in the intrathecal infusion test showed only a minimal relevance to outcome. Those 75 patients with a late state NPH (with cerebral atrophy) had a better outcome when dementia was not present, the outflow resistance was above 20mm Hg/min/ml, the CSF tap-test was positive and a Miethke-Dual-Switch valve was implanted.

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.

Disturbed spatial learning of rats after intraventricular administration of transforming growth factor-beta 1

Patients with subarachnoid hemorrhage (SAH) who later suffer hydrocephalus show persistently high levels of transforming growth factor-beta 1 (TGF-beta 1) in the cerebrospinal fluid after the onset of SAH. Recombinant TGF-beta 1 induces hydrocephalus in mice. This study examined the spatial learning ability of rats after intraventricular administration of TGF-beta 1. Thirteen-week-old Wistar rats were treated with 0.8 or 8.0 micrograms of human recombinant TGF-beta 1 by direct injection or via osmotic pump. Three months later, their spatial learning ability was evaluated with a Morris water maze. Ventricular size, ultrastructural features, and sodium-potassium-adenosine triphosphatase (Na+, K(+)-ATPase) activity of the subarachnoid space were examined. All three TGF-beta 1-treated groups clearly exhibited impaired spatial learning ability, but they did not exhibit ventricular dilation. Histological examination revealed subarachnoid fibrosis and deactivation of Na+, K(+)-ATPase in the arachnoid cells. These findings are similar to those of our previous experiments involving injection of TGF-beta 1 in mice. The present and previous studies suggest that subarachnoid fibrosis is an important factor in the disturbance of the spatial learning ability of rats, whereas ventricular size is less important.

Normal pressure hydrocephalus: developments in determining surgical prognosis

Research into normal pressure hydrocephalus has often focused on the clinical dilemma of selecting patients who will benefit from cerebrospinal fluid diversion. Recent developments in imaging and lumbar infusion tests are throwing light on the underlying pathophysiology, providing researchers with new avenues for the development of reliable investigative tools.

Movement disorders in adult hydrocephalus

In a prospective series of symptomatic adult hydrocephalus characterized by gait disturbance, cognitive impairment, and/or urinary incontinence, 88 of 118 patients (75%) had additional akinetic, tremulous, hypertonic, or hyperkinetic movement disorders. Their prevalence was highest in patients with idiopathic normal pressure hydrocephalus (NPH) of the elderly (56/65 patients, 86%), and they were less frequent in patients with secondary NPH (10/15, 66%), with nonhydrodynamic atrophic/other hydrocephalus (20/33, 61%), and with obstructive hydrocephalus/aqueductal stenosis (2/5, 40%). Akinetic symptoms were found in 73 of 118 patients (62%), and the most frequent movement disorder was upper extremity bradykinesia (55%). Akinetic, tremulous, hypertonic, and hyperkinetic movement disorders were exclusively secondary to causes not related to hydrocephalus in 24 of 118 patients (20%). The proportion of patients with movement disorders not attributable to only such causes was highest in the idiopathic NPH group (44/65, 68%). Thirteen of 118 patients (11%) presented with a parkinsonian syndrome. There was evidence for coexistent Parkinson's disease in four of these patients. Parkinsonism was found to be secondary to NPH in five patients and was found improved after shunting. Akinetic symptoms in patients with NPH generally responded favorably to CSF diversion, which was evident in 80% of a subset of this group. Various other movement disorders did not show definite improvement. The high prevalence of bradykinesia and other akinetic symptoms in NPH and the beneficial effect of shunting on such symptoms suggest that NPH may cause a more generalized disorder of motor function.

Posttraumatic ventriculomegaly: hydrocephalus or atrophy? A new approach for diagnosis using CSF dynamics

Cerebrospinal fluid (CSF) dynamics were correlated to the changes in ventricular size during the first 3 months posttrauma in patients with severe head injury (Glasgow Coma Scale score < or = 8, 75 patients) to distinguish between atrophy and hydrocephalus as the two possible causes of posttraumatic ventriculomegaly. Using the bolus injection technique, the baseline intracranial pressure (ICP), pressure volume index, and resistance for CSF absorption (R0) provided a three-dimensional profile of CSF dynamics that was correlated with ventricular size and Glasgow Outcome Scale (GOS) score at 3, 6, and 12 months posttrauma. Patients were separated into five different groups based on changes in ventricular size, presence of atrophy, and CSF dynamics. Group 1 (normal group, 41.3%) demonstrated normal ventricular size and normal ICP. Group 2 (benign intracranial hypertension group, 14.7%) showed normal ventricular size and elevated ICP. Group 3 (atrophy group, 24%) displayed ventriculomegaly, normal ICP, and normal R0. Group 4 (normal-pressure hydrocephalus group, 9.3%) had ventriculomegaly, normal ICP, and high R0. Group 5 (high-pressure hydrocephalus group, 10.7%) showed ventriculomegaly and elevated ICP with or without high R0. The GOS score in the nonhydrocephalic groups (Groups 1, 2, and 3) was better than in the hydrocephalic groups (Groups 4 and 5). It is concluded from these results that 44% of head injury survivors may develop posttraumatic ventriculomegaly. Posttraumatic hydrocephalus, as identified by abnormal CSF dynamics, was diagnosed in 20% of survivors and their outcome was significantly worse. This study demonstrates the importance of using CSF dynamics as an aid in diagnosis of posttraumatic hydrocephalus and identifying those patients who may benefit from shunt placement.

Three decades of normal pressure hydrocephalus: are we wiser now?

Images

Clinical parameters in 74 consecutive patients shunt operated for normal pressure hydrocephalus

Seventy four consecutive patients diagnosed as normal pressure hydrocephalus (NPH) and operated with a ventriculo-peritoneal shunt were followed prospectively for an average of 2.1 years. The mean age was 64 years. The effect of the operation was estimated by calculating 6 indices expression social functioning, neurological signs, gait ability, continence, psychometric performance and psychiatric condition. Ninety-six % had mental symptoms, 95% gait disturbances and 75% incontinence. Improvement was observed in 78% after shunt surgery, while 22% deteriorated. Psychiatric improvement was seen in 80% and 76% improved in gait ability. Improvement was highest in the group caused by subarachnoid hemorrhage (98%) while 73% with idiopathic NPH improved. Old age was not correlated to poorer response, while long-standing pre-operative symptoms yielded worse results. No single symptom or sign could predict a positive outcome of the operation. Eleven % of the patients could leave long-term care institutions and there was a 36% reduction of aid in daily living. Complications to shunt surgery were observed in 50% of the patients and shunt related mortality was 1%. Shunt malfunction was the most frequent complication (31%) followed by infection (19%). Epilepsy developed in 9% after surgery. All shunt complication except one appeared within the first year after surgery.

Reappraisal of the intracranial pressure and cerebrospinal fluid dynamics in patients with the so-called "normal pressure hydrocephalus" syndrome

Fifty-four shunt-responsive patients were selected from a prospective protocol directed to study patients with suspected normal pressure hydrocephalus (NPH). Patients with gait disturbances, dementia, non-responsive L-Dopa Parkinsonism, urinary or faecal incontinence and an Evans ratio greater or equal to 0.30 on the CT scan were included in the study. As a part of their work-up all patients underwent intracranial pressure monitoring and hydrodynamic studies using Marmarou's bolus test. According to mean intracranial pressure (ICP) and the percentage of high amplitude B-waves, patients were subdivided in the following categories: 1) Active hydrocephalus (mean ICP above 15 mmHg), which is in fact no tone normal pressure hydrocephalus; 2) Compensated unstable hydrocephalus, when mean ICP was below 15 mmHg and B-waves were present in more than 25% of the total recording time and 3) Compensated stable hydrocephalus when ICP was lower or equal to 15 mmHg and beta waves were present in less than 25% of the total recording time. The majority of the patients in this study (70%) presented continuous high or intermittently raised ICP (active or unstable compensated hydrocephalus group). Mean resistance to outflow of CSF (Rout) was 38.8 mm Hg/ml/min in active hydrocephalus and 23.5 mm Hg/ml/min in the compensated group (Students t-test, p less than 0.05). Higher resistance to outflow was found in patients with obliterated cortical sulci and obliterated Sylvian cisterns in the CT scan. No statistically significant correlation was found when plotting the percentage of beta waves against pressure volume index (PVI), compliance or Rout. An exponential correlation was found when plotting beta waves against the sum of conductance to outflow and compliance calculated by PVI method (r = 0.79). Patients with the so-called normal pressure hydrocephalus syndrome have different ICP and CSF dynamic profiles. Additional studies taking into consideration these differences are necessary before defining the sensitivity, specificity and predictive value of ICP monitoring and CSF studies in selecting appropriate candidates for shunting.

Shoplifting associated with normal-pressure hydrocephalus: report of a case

A 52-year-old woman who had been apprehended for shoplifting was found to have normal-pressure hydrocephalus due to aqueduct stenosis. We ascribe the shoplifting to impairment of social judgment, which was one of the observed features of a dementia. Cerebrospinal fluid diversion by means of a ventriculo-peritoneal shunt resulted in resolution of her symptoms.

Normal pressure hydrocephalus associated with cauda equina neurinoma

A 65-year-old woman with normal pressure hydrocephalus experienced improved gait and hydrocephalus following surgical resection of a cauda equina neurinoma. Fibrinogen, detected in the cerebrospinal fluid, may be involved in the pathophysiological process of normal pressure hydrocephalus.

Age-dependent changes of cerebral ventricular size. Part I: Review of intracranial fluid collections

The age distributions of communicating hydrocephalus (CH), pseudotumour cerebri (PC) slit-ventricle syndrome (SVS), and chronic subdural haematomas (CSH) were reviewed in the medical literature. An age-related incidence was found: CH and CSH predominated in neonates less than 2 years and adults older than 55 years, while PC and SVS occurred mainly in older children and young adults. The latter two patient groups seem to show a greater resistance to ventricular dilatation in the presence of decreased CSF absorption. This may be related to larger volume and state of maturity of the cerebrum. On the other hand, neonates and the elderly more readily develop enlarged ventricles, in association with impairment of CSF absorption, or subdural fluid collections. Factors including status of cranial sutures, cerebral atrophy, cerebral water content, degree of cerebral myelination, and glial cell composition, may contribute to the age-related incidence of the four disorders investigated. Similarly, the development of ventriculomegaly may depend upon cerebral elastic properties besides the pri mary disturbance of CSF dynamics. The authors postulate that the size of cerebral ventricles in disorders of the cerebrospinal fluid (CSF) absorption is related to the elastic properties and volume of the brain. Furthermore, cerebral volume and elastic properties may also contribute to the age distribution of chronic subdural haematomas (CSH).

Normal pressure hydrocephalus presenting as Parkinson's syndrome

Although extrapyramidal features in normal pressure hydrocephalus (NPH) are not uncommon, presentations with Parkinson's syndrome as the predominant feature are rare and may give rise to diagnostic difficulties. Failure of patients with parkinsonism to respond to therapy, should alert one to the possibility of NPH.

Non-tumoural aqueduct stenosis and normal pressure hydrocephalus in the elderly

From 1981 to 1985 a prospective study on normal pressure hydrocephalus was performed. One of the aims of this study was to determine the site of CSF obstruction. Among 17 consecutive patients with a tentative diagnosis of normal pressure hydrocephalus, nine appeared to have non-communicating hydrocephalus most probably due to primary non-tumoural aqueduct stenosis. This unexpected finding provides evidence that non-tumoural aqueduct stenosis is a frequent cause of normal pressure hydrocephalus in older patients. Some clinical, aetiological and therapeutic aspects in this particular subgroup are discussed.

Posttraumatic hydrocephalus--a retrospective review

The authors retrospectively reviewed all cases of acquired hydrocephalus admitted to the Institute of Neurological Sciences, Glasgow, Scotland, within a 5-year period and encountered 17 cases of posttraumatic hydrocephalus. These represented 0.7% of 2374 cases of severe head injury. Hydrocephalus became symptomatic within 1 year from the time of injury in 16 of 17 cases. Meningitis, traumatic subarachnoid hemorrhage, posterior fossa mass, supratentorial clot with contralateral ventricular dilatation, and craniotomy contributed to the development of posttraumatic hydrocephalus. After shunting, eight patients (50%) improved markedly and four (25%) slightly.

The syndrome of normal-pressure hydrocephalus

A series of 40 patients with the syndrome of normal-pressure hydrocephalus is presented. Diagnosis was based on clinical and computerized tomography (CT) scan criteria and was followed by the insertion of a ventriculoperitoneal shunt in every instance. All patients responded favorably to treatment (four of them had a fair outcome), and this response was maintained. There was one postoperative death, but no other serious complications. This study demonstrates that it is possible to diagnose the syndrome of normal-pressure hydrocephalus on the basis of clinical and CT scan criteria without any other invasive investigations. Such patients should respond favorably to an adequately functioning shunting system.

[Normal-pressure hydrocephalus and cerebellar hematoma. Report of a case with necropsy]

The authors report the case of a 64-year-old man who presented normal pressure hydrocephalus in the course of hypertensive and arteriosclerotic vasculopathy confirmed by postmortem examination. A blood clot was found on the central area of the left cerebellar hemisphere. The clinical features and the pathogenesis of normal pressure hydrocephalus and cerebellar hemorrhage are reviewed and discussed.

Surgically reversible hypothalamic hypopituitarism due to aqueductal stenosis. Case report

A 13-year-old girl was referred for evaluation of the deceleration in her rate of linear growth, an arrest in the progression of her pubertal maturation, and bifrontal headaches. Detailed endocrinological and radiological studies revealed the following abnormalities: partial growth hormone deficiency, prepubertal luteinizing hormone and follicle-stimulating hormone responses to exogenous gonadotropin-releasing hormone, aqueductal stenosis with obstructive hydrocephalus, and marked focal dilation of her third ventricle. Ventriculoperitoneal shunting resulted in increased linear growth, resumption of pubertal development, and correction of her documented neuroendocrine abnormalities.

Cerebrospinal fluid proteins and cells in normal-pressure hydrocephalus

A total of 21 patients with normal-pressure hydrocephalus were examined. Cerebrospinal fluid (CSF) was collected before and after operation with a ventriculoperitoneal shunt. A slight plasma-like protein pattern indicating a blood-brain barrier (BBB) dysfunction was seen in 38% of the patients before operation. No characteristic changes could be found in the "CSF-specific" protein fraction. After the shunt operation 65% of the patients had a BBB dysfunction to macromolecules and 70% had two additional acidic protein bands in the CSF-specific fraction. Ventricular CSF protein content was 73% of lumbar CSF content when shunts were patent. Isotope encephalography showed a radionuclide accumulation at the intracranial part of the shunt system, indicating that the BBB damage might be located round the shunt catheter.

Neurophysiological study of normal pressure hydrocephalus

A neuropsychological Mental Deterioration Battery (MDB) was used to identify deterioration profiles of 43 patients afflicted with normal pressure hydrocephalus (NPH) (n = 18) or other forms of dementia (n = 25). The NPH patients submitted to a shunt-intervention (n = 10) were also evaluated after surgery. A comparison of profiles, obtained from the experimental and control groups, shows that NPH patients seem to be more impaired in tests designed to detect frontal lobe involvement. Some implications of the relatively greater impairment of frontal functions in NPH dementia are discussed.

Chronic adult hydrocephalus due to uncommon causes

The authors report on four unusual cases of chronic adult hydrocephalus extracted from a large personal series of patients with hydrocephalic dementia. A syndrome resembling that of normal pressure hydrocephalus was due to the following aetiologies in these patients: Paget's disease of the skull, unruptured cerebral arteriovenous malformation, colloid cyst of the third ventricle, and cerebromeningeal cysticercosis. All these patients exhibited disturbances in cerebrospinal fluid dynamics at the time of study, and were considerably improved by CSF shunting. The value of the continuous CSF pressure monitoring and the constant infusion test in selecting patients with chronic hydrocephalus for shunt therapy is emphasized.

Normal pressure hydrocephalus--high pressure normocephalus

The case history to be presented spans most of the lifetime of a young lady who is now twenty-two years old, and it reflects the stages of development of our knowledge of several important neurosurgical concepts.

Acquired hydrocephalus VI. The influence of some competitive diseases in the treatment of acquired hydrocephalus

Based on the results of quantitative isotope ventriculography (QIV) a group of 25 patients was divided into 17 hydrocephalic and 8 non- or doubtfully hydrocephalic patients. An atrio-ventricular shunt (A-V shunt) was inserted in all 25 patients. Eight of the hydrocephalic patients improved or became well, while nine hydrocephalic patients were unchanged, worse or dead at the time of follow-up. These nine patients suffered either from severe brain damage, chronic alcoholism over several years, arterial hypertension, severe diabetes, or acute meningo-encephalitis caused by a virus infection. None of the eight non- or doubtfully hydrocephalic patients improved after the operation. From this it was concluded that QIV is of considerable diagnostic value in acquired hydrocephalus.

The limitation of pulsatile flow through the aqueduct of Sylvius as a cause of hydrocephalus

The concept is advanced that hydrocephalus results from limitation in the pulsatile flow of CSF downwards through the aqueduct of Sylvius during systole which is necessary to accommodate for the pulsatile pressure and volume increase that accompanies the propagation of the arterial pulse through the brain. Evidence is given to show that flow through the fixed human aqueduct is disturbed and not laminar. Further, with the pressures availalbe, the aqueduct is only just large enough to pass the quantity of fluid which must be vented extracranially during systole. Should the capacity of this systolic venting mechanism be exceeded, physical strain will cause cellular damage in the periventricular and periaqueductal regions which, if prolonged, will lead to tissue destruction and hydrocephalus. There appear to be two main causes for hydrocephalus resulting from this mechanism. Firstly, structural lesions, restricting the lumina of the CSF-venting pathways, especially the aqueduct, will reduce the volume of CSF that can flow through these pathways during systole. The hydrocephalic process will then be continuous and only limited when tissue destruction reduces the systolic volume expansion of the brain such that it can be accomodated by the restricted CSF venting pathways. Secondly, conditions which may increase the amount of the systolic volume expansion of the brain beyond the capacity of the CSF venting pathways. Raised mean intracranial pressure is the most important of these conditions. In such cases the hydrocephalus will be limited by the duration of the causal process and possibly also by the enlargement of the venting pathways, as a result of tissue destruction. This hypothesis also accounts for hydrocephalus resulting from obliteration of the cortical subarachnoid space, obstruction to the cranial venous drainage, deformities in the region of the foramen magnum and arterial encroachment upon the ventricular system.

Ventricular differences between hydrostatic hydrocephalus and hydrocephalus ex vacuo by computed tomography

Transaxial CT scans of 100 patients with hydrostatic hydrocephalus and 50 patients with hydrocephalus ex vacuo have been reviewed with respect to measurements of: frontal horn ratio, width of the temporal horns, width of the third ventricle, width of cerebral fissures and sulci. The diagnosis of hydrostatic hydrocephalus is probable when (a) both temporal tips are visualized and measure 2 mm or greater in width and the sylvian and interhemispheric fissures and cerebral sulci are not visible, or (b) there is visualization of temporal horn tips measuring 2 mm or greater in width and the lateral ventricles are symmetrically enlarged with the frontal horn ratio 0.50 or more.

Adult idiopathic communicating hydrocephalus with and without shunting

The outcome in 37 adult patients with idiopathic communicating hydrocephalus treated by ventriculoatrial shunting is presented. Only 33% showed definite improvement, and no diagnostic procedures accurately predicted the outcome of surgery. These were compared with a "control" group of 12 patients who were not shunted; 50% of these were stable for up to 36 months. These findings, and the high frequency of serious complications (35%), suggest caution in recommending a shunt procedure.

Quantitative cisternography

By quantitative cisternography using a stationary detector system with correction for tissue background, an exponential elimination of 131I-HSA from the basal cisterns was demonstrated, allowing calculation of a biologic half time (BHT) of the clearance curve of a satisfactory level of reproducibility. 'Normal' range of BHT was calculated. Demented patients had significantly longer BHT. In 4 patients with normal pressure hydrocephalus prolonged BHT turned normal after shunting, paralleled by marked clinical improvement, in contrast to previous findings in 4 patients with presenile dementia. The method is now being modified employing 111In-DTPA and a computer assisted gamma camera for regional dynamic analysis.

Parkinsonism and dementia with acoustic neurinomas. Report of three cases

Three cases of acoustic neurinoma with parkinsonism and dementia are reported. The characteristics of parkinsonism seen in these cases consisted of the rapid development of symptoms and symmetrical rigidity. In all cases there was a marked enlargement of the ventricular system and transient improvement in their mental states was observed following ventriculoperitoneal shunt or removal of the tumor. In an autopsy case there were no pathological findings in the cerebral cortex, basal ganglia, substantia nigra or pontine nuclei. It was concluded that parkinsonism and dementia in these patients were caused by chronic hydrocephalus due to the acoustic neurinomas.