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Idiopathic normal pressure hydrocephalus (iNPH) is a debated entity with controversial pathogenesis, diagnostic criteria, and predictors of response after ventriculoperitoneal shunt (VPS). Parkinsonian signs are frequently reported in the clinical picture, sometimes due to the coexistence of an underlying neurodegenerative parkinsonism and sometimes in the absence thereof. To distinguish these two scenarios is crucial, since they may carry different long-term response to CSF drainage. 123I-FP-CIT-SPECT was believed to be helpful in this regard, however its role in predicting surgical outcome has been disputed. We illustrate a patient presented with gait disturbance, urinary incontinence, and asymmetrical parkinsonian signs, who underwent a 3T brain MRI and a 123I-FP-CIT-SPECT. VPS was performed. The patient repeated a 123I-FP-CIT-SPECT, 18 months after the operation, and was clinically followed up for 24 months. Our patient displayed clinical and radiological criteria for iNPH and an abnormal asymmetrical uptake in 123I-FP-CIT-SPECT, consistent with her asymmetrical parkinsonism. However, the organization of the substantia nigra studied with iron-sensitive sequences in 3T brain MRI scan appeared intact. The patient revealed an improvement both clinically and in 123I-FP-CIT-SPECT at postsurgical follow-up. Our report suggests that abnormal 123I-FP-CIT-SPECT may not necessarily reveal an overlap with neurodegenerative parkinsonism; its partial reversibility may suggest that the mechanical effect exerted on the striatum by ventriculomegaly ultimately leads to downregulation of dopaminergic transporters which may improve after VPS.

A 50-year-old patient developed ataxia, nystagmus, and palatal tremor. Conventional magnetic resonance imaging (MRI) revealed inferior olivary nuclei enlargement and hyperintensity in T2-weighted images, indicating hypertrophic olivary degeneration (HOD). The patient's past medical history reported proton therapy for an VIII cranial nerve Schwannoma. Here, we aimed to investigate the potential alterations involving tracts and nuclei composing the dentato-rubro-olivary pathway (Guillain-Mollaret triangle) using an advanced ultra-high field (7 T) MRI protocol. The patient underwent a 7 T-MRI brain exam, including a multi-echo gradient-echo sequence for quantitative susceptibility mapping and diffusion tensor imaging (DTI). The DTI dataset was elaborated for tractography and computation of tensor metrics. 7 T-MRI allowed the depiction of the brainstem tracts and nuclei composing the Guillain-Mollaret triangle. Both qualitative and quantitative analyses of these structures demonstrated damage to the right red nucleus and the dentato-rubral tracts bilaterally. These findings are consistent with the pathophysiology of HOD and were confirmed in a follow-up MRI. This study highlights the capability of 7 T-MRI to depict and investigate brainstem substructures such as tracts and nuclei. To the best of our knowledge, this is the first study to depict all tracts composing the Guillain-Mollaret triangle and directly document their alterations in HOD.

The role of Nigrosome 1 (N1) in neurodegeneration and motor disorders, particularly in Parkinson’s disease (PD), is increasingly recognized. The study of this region using quantitative measures, such as iron quantification through Quantitative Susceptibility Mapping (QSM), can provide enlightening insights into some pathological features of these diseases representing important biomarkers. However, the small size and the vanishing contrast with respect to the surrounding substantia nigra in PD patients make the segmentation of N1 challenging. For this reason, we provide a probabilistic atlas of the N1 portion corresponding to the swallow-tail hyperintensity, hereafter referred to as the Dorsolateral Nigral Hyperintensity (DNH), created on a high-resolution multi-parametric template from T1-weighted, T2*-weighted, and QSM images acquired in vivo at 7 T. The atlas also includes quantitative T2* and R2* templates and is provided in the MNI standard space. It aims to facilitate the study of N1, avoiding operator-dependent biases in segmentations, and allowing the standardisation of the quantitative assessment.

Two patients with CSF shunting systems exhibited symptoms of altered intracranial pressure. Initial neuroimaging led to misinterpretation, but integrating clinical history and follow-up imaging revealed the true diagnosis. In the first case, reduced ventricular size was mistaken for CSF overdrainage, while the actual problem was increased intracranial pressure, as seen in slit ventricle syndrome. In the second case, symptoms attributed to intracranial hypertension were due to CSF overdrainage causing tonsillar displacement and hydrocephalus. Adjusting the spinoperitoneal shunt pressure resolved symptoms and imaging abnormalities. These cases highlight the necessity of correlating clinical presentation with a deep understanding of CSF dynamics in shunt assessments.

Quantitative Susceptibility Mapping (QSM) can measure iron concentration increase in the primary motor cortex (M1) of patients with Amyotrophic Lateral Sclerosis (ALS). However, such alteration is confined to only specific regions interested by upper motor neuron pathology; therefore, mean QSM values in the entire M1 have limited diagnostic accuracy in discriminating between ALS patients and control subjects. This study investigates the diagnostic accuracy of a broader set of M1 QSM distribution indices in classifying ALS patients and controls. Mean, standard deviation, skewness and kurtosis of M1 QSM values were used either individually or as combined predictors in support vector machines. The classification performance was compared to that obtained by the radiological assessment of T2* signal hypo-intensity of M1 in susceptibility-weighted MRI. The least informative index for the classification of ALS patients and controls was the subject’s mean QSM value in M1. The highest diagnostic performance was obtained when all the distribution indices of positive QSM values in M1 were considered, which yielded a diagnostic accuracy of 0.90, with sensitivity = 0.89 and specificity = 1. The radiological assessment of M1 yielded a diagnostic accuracy of 0.79, with sensitivity = 0.76 and specificity = 0.90. The joint evaluation of QSM distribution indices could support the clinical examination in ALS diagnosis and patient monitoring.

Objectives Hereditary spastic paraplegia (HSP) is a group of genetic neurodegenerative diseases characterised by upper motor neuron (UMN) impairment of the lower limbs. The differential diagnosis with primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) can be challenging. As microglial iron accumulation was reported in the primary motor cortex (PMC) of ALS cases, here we assessed the radiological appearance of the PMC in a cohort of HSP patients using iron-sensitive MR imaging and compared the PMC findings among HSP, PLS, and ALS patients. Methods We included 3-T MRI scans of 23 HSP patients, 7 PLS patients with lower limb onset, 8 ALS patients with lower limb and prevalent UMN onset (UMN-ALS), and 84 ALS patients with any other clinical picture. The PMC was visually rated on 3D T2*-weighted images as having normal signal intensity, mild hypointensity, or marked hypointensity, and differences in the frequency distribution of signal intensity among the diseases were investigated. Results The marked hypointensity in the PMC was visible in 3/22 HSP patients (14%), 7/7 PLS patients (100%), 6/8 UMN-ALS patients (75%), and 35/84 ALS patients (42%). The frequency distribution of normal signal intensity, mild hypointensity, and marked hypointensity in HSP patients was different than that in PLS, UMN-ALS, and ALS patients ( p < 0.01 in all cases). Conclusions Iron-sensitive imaging of the PMC could provide useful information in the diagnostic work - up of adult patients with a lower limb onset UMN syndrome, as the cortical hypointensity often seen in PLS and ALS cases is apparently rare in HSP patients. Key Points • The T2* signal intensity of the primary motor cortex was investigated in patients with HSP, PLS with lower limb onset, and ALS with lower limb and prevalent UMN onset (UMN-ALS) using a clinical 3-T MRI sequence . • Most HSP patients had normal signal intensity in the primary motor cortex (86%); on the contrary, all the PLS and the majority of UMN-ALS patients (75%) had marked cortical hypointensity . • The T2*-weighted imaging of the primary motor cortex could provide useful information in the differential diagnosis of sporadic adult-onset UMN syndromes .