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Background: Disproportionately enlarged subarachnoid space hydrocephalus (DESH) findings on MRI were described as a prognostic factor for responsiveness to the treatment of idiopathic normal pressure hydrocephalus (iNPH). Our premise is that DESH could be associated with compression of the cerebral white matter. Microstructural changes can be identified using diffusion tensor imaging (DTI), specifically fractional anisotropy (FA). The aim of this study is to compare FA in iNPH patients with and without DESH and healthy controls., Methods: We analysed 1.5-T MRI scans of patients fulfilling the criteria of probable or possible iNPH and positive supplementary tests before and after surgery (ventriculo-peritoneal shunt). FA was measured in the anterior and posterior limb of the internal capsule (PLIC) and in the corpus callosum. Patients were divided into the DESH and non-DESH group. These data were also compared to FA values in the control group., Results: Twenty-seven patients and 24 healthy controls were enrolled. DESH was present in 15 patients and lacking in 12. Twenty-three iNPH patients were shunt responders (85.2 %), and 4 were non-responders (14.8 %). All patients in the DESH group were shunt responders. In the non-DESH group, eight patients were responders (66.7 %). A significant difference between the DESH and non-DESH group was found in the FA of the PLIC. The mean value of FA in the PLIC was 0.72 in the DESH group and 0.66 in the non-DESH group. After the surgery FA decreased in both groups. In the DESH iNPH group FA PLIC decreased to 0.65 and in the non-DESH iNPH group to 0.60. In the healthy controls, the mean FA in the PLIC was 0.58., Conclusion: DESH on MRI scans is related to a higher FA in the PLIC with a decrease after the surgery. It reflects a more severe compression of the white matter than in non-DESH patients or healthy volunteers. DESH patients had better outcome than non-DESH patients. This study confirmed the importance of DESH as a supportive sign for iNPH.

Normal pressure hydrocephalus (NPH) is a clinical syndrome characterized by gait disturbances, urinary incontinence and dementia. Clinical presentation overlaps with Alzheimer disease (AD). Early recognition thus early intervention (shunting) is important for successful treatment, but lack of a diagnostic test with sufficient sensitivity and specificity complicates the diagnosis. We performed literature search and composed a structured review of imaging biomarkers of NPH. Morphometric studies are not sufficient to diagnose NPH. Hydrocephalus is a common finding in elderly people due to the symmetric brain atrophy and is even more pronounced in patients with AD. The key MRI biomarker seems to be diffusion tensor imaging (DTI). According to recent studies, the DTI analysis of the splenium corporis callosi, posterior limb of internal capsule, hippocampus and fornix combined with measurement of Evans index is a promising MRI biomarker of NPH and could be used for NPH diagnostics and in the differential diagnosis from AD and other dementias.

Background: The anatomy and somatotopy of the pyramidal tract during its course in the internal capsule has recently been discussed by many publications. However, the reports on the anatomy of the clinically more important supraventricular portion of the tract are scarce. The objective of this study is to investigate the anatomy and somatotopy of the supraventricular portion of the pyramidal tract., Methods: In 13 patients undergoing surgery with subcortical electric stimulation for tumors located in the supraventricular white matter close to the pyramidal tract (as depicted by diffusion tensor tracking [DTT]), the relationship between the position of the stimulation point and the motor response in the arm or leg was analyzed. Additionally, the somatotopic organization of the tract was studied using separate tracking of arm and leg fibers in 20 healthy hemispheres. Finally, the course of the tract was studied by dissecting 15 previously frozen human hemispheres., Results: In most cases, subcortical stimulation during the resection of tumors located behind and in front of the pyramidal tract elicited leg and arm movement, respectively. This association of stimulation point position with motor response type was significant. A DTT study of the somatotopy demonstrated a varying degree of rotation of the leg and arm fibers from mediolateral to posteroanterior configuration. Anatomic dissections demonstrated a folding-fan like structure of the pyramidal tract with a similar rotation pattern., Conclusion: The pyramidal tract undergoes a large part of its rotation from mediolateral to posteroanterior configuration during its course in the supraventricular white matter, although interindividual differences exist.

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Copyright of Česká a Slovenská Neurologie a Neurochirurgie is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)