Multimodal MRI Longitudinal Assessment of White and Gray Matter in Different SPG Types of Hereditary Spastic Paraparesis

Hereditary spastic paraplegias (HSP) are a group of genetically and clinically heterogeneous neurologic disorders. Hereby we describe a relatively large group of patients (pts) affected by HSP studied at baseline (31 pts) and at follow-up (mean period 28.9 ± 8.4 months; 23 pts) with multimodal advanced MRI: high-resolution T1 images for voxel-based morphometry (VBM) analysis, magnetic resonance spectroscopy (MRS), and diffusion tensor imaging (DTI). An age-matched healthy control (HC) group underwent the same neuroimaging protocol in a time schedule matched with the HSP patients. At baseline, VBM showed gray matter (GM) reduction in HSP in the right pre-frontal cortex and bilaterally in the thalami. MRS at baseline depicted in HSP patients compared to the HC group reduction of NAA/Cr ratio in the right pre-frontal region, increase of Cho/Cr ratio in the right pre-central regions, and increase of mI/Cr ratio on the left pre-central area. At cross-sectional follow-up analysis and longitudinal evaluation, no VBM and MRS statistically significant results were obtained. Tract-based spatial statistics (TBSS) analysis showed widespread DTI brain white matter (WM) alterations in patients compared to HC at baseline, which are characterized by reduction of fractional anisotropy (FA) and increase of mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity, as confirmed on cross-analysis of the follow-up dataset. A longitudinal analysis with TBSS in HSP patients did not show significant variations, while upon applying region-based analysis we found increased FA and decreased MD and AD in specific brain WM fiber complex during follow-up. The changes were not correlated with the clinical presentation (pure vs complicated HSP), motor function, and motility indexes or history of specific treatments (botulinum toxin). In conclusion, the cross-sectional analysis of the multiparametric MRI data in our HSP patients confirmed the non-prominent involvement of the cortex in the primary motor regions but rather of other more associative areas. On the contrary, DTI demonstrated a widespread involvement of the brain WM, including the primary motor regions, which was confirmed at follow-up. The longitudinal analysis revealed an apparent inversion of tendency when considering the expected evolution of a neurodegenerative process: we detected an increase of FA and a decrease of MD and AD. These time-related modifications may suggest a repair attempt by the residual central WM fibers, which requires confirmation with a larger group of patients and with a longer time interval.

Sudden Sensorineural Hearing Loss: MR Imaging

Hearing loss greater than 30 dB over three contiguous pure-tone frequencies occurring within a three day period is defined as sudden hearing loss. It is usually sensorineural (SSNHL), unilateral and appears as an otologic emergency. SSNHL has many possibile etiologies such as: labyrinthine viral infection, ischemic or hemorrhagic illness, trauma, immuno-mediated inner ear disease, tumor, inner ear malformation, and an imbalance between perilymphatic and endolymphatic fluid pressure. Nevertheless in almost 80% of cases SSNHL belongs to the idiopathic category because the etiology is unknown. The aim of this study was to test the diagnostic impact of two MR devices. Fifteen cases of SSNHL studied with a 1.5 T unit in our hospital between January 2006 and December 2008 within two weeks of the onset were retrospectively evaluated. Since January 2009 three more patients affected by SSNHL have been scanned with a 3T MR unit. We discuss the diagnostic sensitivity, clinical usefulness and the cost-benefit ratio of the MR systems.

Clinical Recovery despite Cortical Cerebral and Cerebellar Damage in Heat Stroke

The prognosis of heat stroke has considerably improved with a mortality rate drop to 10% when therapeutic measurements including external cooling and aggressive rehydration are adopted. The role of imaging in predicting prognosis is uncertain. Some noted that development of cortical cerebellar atrophy is associated with development of a pancerebellar syndrome, while others suggested that evidence of cerebral cortical damage due to hypoxic-ischemic injury implies a poor prognosis. We observed a 17-year-old female who presented with lost of consciousness and seizure while jogging on a hot summer day followed by multi-organ failure. Brain MRI revealed a symmetric area of T2 hyperintensity and decreased diffusion in the cortical gyri of the frontal lobes. The patient made a complete recovery. MRI two years later showed disappearance of signal changes in the frontal cortex, but progressive atrophy of the cerebellum which was clinically silent. Our observation challenges the view of a close correlation between the imaging findings and prognosis in heat stroke.