Amyloid Positive Hydrocephalus: A Hydrocephalic Variant of Alzheimer’s Disease?

Background: Alzheimer’s disease (AD) and normal pressure hydrocephalus (NPH) commonly coexist. Objective: We aimed to characterize an overlapping syndrome of AD and NPH that presents with gait disturbance, ventriculomegaly on magnetic resonance imaging, and significant amyloid deposition on positron emission tomography (PET). Methods: Of 114 patients who underwent cerebrospinal fluid (CSF) drainage for a possible diagnosis of NPH between 2015 and 2020 in Samsung Medical Center, we identified 24 patients (21.1%) with the NPH patients with amyloid deposition on PET, which we referred to as hydrocephalic AD in this study. We compared their clinical and imaging findings with those of 123 typical AD without hydrocephalic signs/symptoms. We also investigated the frequency and potential predictors of the tap test response in hydrocephalic AD. Results: Evans’ index was 0.36±0.03, and a disproportionately enlarged subarachnoid space was present in 54.2% of the hydrocephalic AD patients. The mean age (75.2±7.3 years) and the APOE4 frequency (68.2%) did not differ from those of AD controls. However, the hydrocephalic AD patients showed better memory and language performance, and a thinner cingulate cortex. About 42% of the hydrocephalic AD patients responded to the tap test, of whom seven underwent shunt surgery. Cognition did not improve, whereas gait improved after shunt surgery in all. Conclusion: Hydrocephalic AD has different neuropsychological and imaging characteristics from typical AD. Future studies are warranted to further investigate the effect of CSF removal on their clinical course and to elucidate the pathophysiological interaction between amyloid and NPH.

White Matter Characteristics of Cognitive Impairment in Tap-Test Positive Idiopathic Normal Pressure Hydrocephalus: A Diffusion Tensor Tract-Based Spatial Study

The present study was designed to systemically evaluate changes in the diffusion tensor imaging (DTI)-derived parameters of iNPH (idiopathic normal pressure hydrocephalus) patients with different responses to the tap test (TT), and to correlate cognitive impairment with white matter (WM) degeneration. This study included 22 iNPH patients and 14 healthy controls with structural magnetic resonance imaging (MRI) and DTI scanning. DTI was used to explore the differences in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) for all participants. DTI parameters were evaluated using an ROI (region of interest)-based and tract-based spatial statistics (TBSS) approach. Neuropsychological assessments and the idiopathic normal pressure hydrocephalus grading scoring scale (iNPHGS) were performed. Compared to the TT non-responders, the TT responders group had significantly lower FA values in the corpus callosum, cingulum cingulate gyrus, superior longitudinal fasciculus, and lower AD values in the right cingulum cingulate gyrus and the left posterior thalamic radiation. Besides, the MD values were significantly increased in the corpus callosum, left anterior corona radiata, and the RD values in the corpus callosum and cingulum cingulate gyrus. In addition, the cognitive improvement was negatively correlated with FA of the corpus callosum, cingulum cingulate gyrus, and MD values of the genu of corpus callosum. While, the cognitive improvement was positively related to the AD of the cingulum cingulate gyrus, superior longitudinal, and RD values of the corpus callosum, cingulum cingulate gyrus and uncinate fasciculus. The ROI specific WM lesions in iNPH patients are the underlying basis for cognitive impairment.

Normal pressure hydrocephalus. Results of shunting correlated with diagnostic tests in 55 patients

Object: The purpose of this study was to evaluate the efficacy of ventricular shunting in normal pressure hydrocephalus (NPH). Methods: The authors retrospectively studied outcomes in NPH patients in whom shunts were implanted. At follow-up examinations up to one year, clinical symptoms were recorded according to a new NPH outcome rating scale, the modified Rankin score and the Mini-Mental State Examination. Comorbidities and complications during this period were also analyzed. Results: A total of 55 patients with NPH were included, with a male predominance (69% of men), an average age of 70 years. Comorbidities are multiple, hypertension is the most common factor in 55% of cases. 76% of patients are classified as having idiopathic NPH. The CSF tap test allows the evacuation of at least 40 ml of CSF and RCSF measurements in 55 patients. All these patients received a shunt withe programmable valve. An improvement in gait was observed in 88% of patients, 91% in balance and 84% in continence. The improvement in the field of neuropsychology is 34% after one year of shunt. 87% of patients were improved according to mRS. 27% of patients had complications and were treated conservatively or surgically. Conclusions: Ventricular shunt implantation is a safe procedure and can improve symptoms in 98% of patients with NPH in the medium term. Keywords: Cerebrospinal fluid (CSF) tap test; Normal pressure hydrocephalus (NPH); NPH assessment scores; Programmable valve; Symptomatic triade of Hakim

P12.09 Clinical features and management of normal pressure hydrocephalus associated with non-obstructive vestibular schwannoma

BACKGROUND Some (elderly) patients present a communicating (normal pressure) hydrocephalus (NPH) in association with or secondary to vestibular schwannoma (VS). We aim to investigate the usefulness ventriculo-peritoneal shunt (VPS) without tumor removal. MATERIALS AND METHODS 8 patients aged from 50 to 78 years received both diagnosis of VS (mean maximum diameter 21 mm, range 13–28 mm) and NPH. None presented the classical Hakim’s triad. They presented isolated ataxia with gait impairment and loss of equilibrium. It was hard to distinguish if these symptoms were due to NPH or to VIII cranial nerve compression. They underwent TAP test, through a lumbar puncture with a very slow whithdrawal of at least 30 ml of cerebrospinal fluid (CSF). RESULTS None of the 8 patients presented improvement after lumbar puncture. Despite this, we decided to proceed with VPS in 4 patients because of a high risk of falls.... All these 4 patients showed clinical improvement after VPS.. The VS were treated as follows: 4 surgery, 2 radiosurgery, 2 observation. CONCLUSIONS Although some authors indicate VS removal as the best option to improve also NPH symptoms, some patients present high risk of falls in the presence of a small VS. These clinical features are more likely to be relayed related to NPH instead of VS.. VPS carries lower postoperative risks compared to VS removal. For this reason, VPS has to be considered, even without a positive response to a TAP test, as a good alternative to improve quality of life in patient affected by NPH associated with VS.

Research on the Distribution Rule of Percussion Response Pulse Width in Coin-Tap Test

The coin-tap method performs nondestructive testing by measuring the width of the tapping response pulse on the surface of the material. Existing studies have shown that defects in the material will cause the width of the tapping response pulse to increase. However, experiments have confirmed that different detection positions in the defective area will show different values of the width of the tapping response pulse, and the physical laws behind it have not been studied yet. To discuss its physical meaning, a mathematical model of the defective area is established, a method for calculating the width of the tapping response pulse is proposed, and a composite honeycomb structure with preset defects is used for data testing. Both the test results and the calculation results show that the pulse width of the tapping response will decrease with the increase of the defect depth and the deviation of the tapping position from the defect center. The consistency between the calculated results and the experimental results shows that the established defect model and pulse width calculation method can better explain the distribution law of the pulse width of the tapping response in the defective area.