In vivo proton MR spectroscopy ( 1 H-MRS) is used extensively to study brain diseases and to add metabolic information to diagnostic MR examinations undertaken in routine clinical practice. The main central nervous system (CNS) metabolites detectable by 1 H-MRS are N-acetyl aspartate (NAA), creatine plus phosphocreatine (Cr), choline-containing compounds (Cho), and myoinositol (mI). Quantitative evaluation of these metabolites would be useful for the study of major spinal cord diseases, such as multiple sclerosis (MS), spinocerebellar ataxias, and intraaxial tumors, mainly because NAA may serve a neuronal marker function (1-4) in establishing axonal integrity (5-8), and mI signal change may be a marker of astrocytosis (9 -13).However, spinal cord proton spectroscopy is challenging because of technical difficulties that limit the quality of the spectroscopic data. The main drawbacks are the strong magnetic field inhomogeneities present in the spinal cord region, respiratory and cardiac movements, and the small size of the spinal cord. On a 3T system the increased signal-to-noise ratio (SNR) can help to find a good compromise between the size of the acquisition volume and the number of repetitions required to obtain a total acquisition time that is feasible in a clinical environment.Because of these technical challenges, few studies of spinal cord 1 H-MRS have been published to date. One study (14) quantified the main metabolites in six healthy volunteers using a 1.5T system (14). Another study involving MS patients and 12 healthy subjects was conducted (15), but the quantification data were not reported. A detailed study of the cervical spine proton spectroscopy protocol on a 2T system equipped with a purpose-built quadrature surface coil compared the concentrations of NAA, Cr, and mI on cervical spine and some brain areas in six healthy volunteers (16 -17). Two recent abstracts described studies on a 3T system: one involved a preliminary qualitative single-voxel comparison of the cervical and dorsal spine of a healthy volunteer and cervical spine tumor spectra (18), and one was a preliminary MR spectroscopic imaging (MRSI) quantification study (19).Our purpose was to devise an acquisition and postprocessing protocol to quantify the main CNS metabolites on the cervical spinal cord on a 3T system with standard equipment to include the spectroscopy study in routine clinical spinal cord imaging and define the normal metabolite concentrations in this location to use as a reference. This study presents a protocol for quantitative cervical spinal cord single-voxel MRS with the first mean relative concentrations for NAA, Cr, Cho, and mI in a group of 10 healthy volunteers using a clinical 3T system. These concentrations were also compared with brainstem metabolite contents in healthy subjects that were previously acquired with the same system. Statistical analysis confirmed a significant difference in metabolite concentrations between the spinal cord and the brainstem. MATERIALS AND METHODSSpinal cord 1 H-MRS examinatio...

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Background: Gait disturbances are typical of persons with idiopathic normal pressure hydrocephalus (iNPH) without signs distinctive from other neurodegenerative and vascular conditions. Cerebrospinal fluid tap-test (CSF-TT) is expected to improve the motor performance of iNPH patients and is a prognostic indicator in their surgical management. This observational prospective study aims to determine which spatio-temporal gait parameter(s), measured during instrumented motor tests, and clinical scale(s) may provide a relevant contribution in the evaluation of motor performance pre vs. post CSF-TT on iNPH patients with and without important vascular encephalopathy. Methods: Seventy-six patients (20 with an associated vascular encephalopathy) were assessed before, and 24 and 72 h after the CSF-TT by a timed up and go test (TUG) and an 18 m walking test (18 mW) instrumented using inertial sensors. Tinetti Gait, Tinetti Balance, Gait Status Scale, and Grading Scale were fulfilled before and 72 h after the CSF-TT. Stride length, cadence and total time were selected as the outcome measures. Statistical models with mixed effects were implemented to determine the relevant contribution to response variables of each quantitative gait parameter and clinical scales. Results and conclusion: From baseline to 72 h post CSF-TT patients improved significantly by increasing cadence in 18 mW and TUG (on average of 1.7 and 2.4 strides/min respectively) and stride length in 18 mW (on average of 3.1 cm). A significant reduction of gait apraxia was reflected by modifications in double support duration and in coordination index. Tinetti Gait, Tinetti Balance and Gait Status Scale were able to explain part of the variability of response variables not covered by instrumental data, especially in TUG. Grading Scale revealed the highest affinity with TUG total time and cadence when considering clinical scales alone. Patients with iNPH and an associated vascular encephalopathy showed worst performances compared to pure iNPH but without statistical significance. Gait improvement following CSF-TT was comparable in the two groups. Overall these results suggest that, in order to augment CSF-TT accuracy, is key to assess the gait pattern by analyzing the main spatiotemporal parameters and set post evaluation at 72 h. Trial registration: Approved by ethics committee: CE 14131 23/02/2015.

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Background Idiopathic normal pressure hydrocephalus (iNPH) is a neurological condition with gait apraxia signs from its early manifestation. Ventriculoperitoneal shunt (VPS) is a surgical procedure available for treatment. The Cerebrospinal fluid Tap Test (CSF-TT) is a quick test used as selection criterion for VPS treatment. Its predictive capacity for VPS outcomes is still sub judice. This study is aimed to test the hypothesis that wearable motion sensors provide valid measures to manage iNPH patients with gait apraxia. Methods Forty-two participants of the Bologna PRO-Hydro observational cohort study were included in the analyses. The participants performed the Timed Up and Go (TUG) and the 18 m walking test (18mW) with inertial sensors at baseline, three days after the CSF-TT, and six months after VPS. 21 instrumental variables described gait and postural transitions from TUG and 18mW recordings. Furthermore, participants were clinically assessed with scales (clinical variables). We tested the hypothesis by analysing the concurrent validity of instrumental and clinical variables, their individual- and group-level responsiveness to VPS, and their predictive validity for VPS outcomes after CSF-TT. Results The instrumental variables showed moderate to high correlation with the clinical variables. After VPS, most clinical and instrumental variables showed statistically significant improvements that reflect a reduction of apraxic features of gait. Most instrumental variables, but only one clinical variable (i.e., Tinetti POMA), had predictive value for VPS outcomes (significant adjusted R2 in the range 0.12–0.70). Conclusions These results confirm that wearable inertial sensors may represent a valid tool to complement clinical evaluation for iNPH assessment and prognosis.

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