ADC evaluation of the corticospinal tract in multiple sclerosis

Ultrasound elastography in the evaluation of peripheral neuropathies: a systematic review of the literature

Peripheral neuropathy is associated with an increase in intraneural pressure, and hence ultrasound elastography seems to be an ideal method to detect early stages of this condition based on changes in the affected nerve stiffness. The aim of this systematic review was to analyse the applicability of strain elastography (SE) and shear wave elastography (SWE) in the evaluation of peripheral nerves in patients with neuropathy of various aetiologies. Published evidence shows clearly that ultrasound elastography can accurately diagnose many types of peripheral neuropathies (carpal tunnel syndrome and other entrapment neuropathies, diabetic peripheral neuropathy and peripheral neuropathy associated with other systemic diseases), sometimes at the stages at which the condition is still asymptomatic. However, it is still unclear whether elastographic changes within the nerves precede functional anomalies detectable on nerve conduction studies. Also, relatively little is known about the relationship between the stiffness of peripheral nerves and the severity of peripheral neuropathy and its underlying condition. Based on the reproducibility data, SWE seems to be superior to SE. Nevertheless, the sources of heterogeneity in the peripheral nerve stiffness in healthy persons need to be identified, and the sets of reference values for specific peripheral nerves need to be determined. Finally, the potential confounding effect of hardening artefacts, such as bones, on the stiffness of peripheral nerves needs to be verified. After addressing all these issues, elastographic evaluation of peripheral nerve stiffness might become a reliable, easily accessible, and convenient diagnostic test performed routinely in patients with various peripheral neuropathies.

Restriction spectrum imaging of white matter and its relation to neurological disability in multiple sclerosis

BACKGROUND

Restriction spectrum imaging (RSI) is a recently introduced magnetic resonance imaging diffusion technique. The utility of RSI in multiple sclerosis (MS) is unknown.

OBJECTIVE

To investigate the association between RSI-derived parameters and neurological disability in MS.

METHODS

Seventy-seven relapsing-remitting MS patients were scanned with RSI on a 3-T scanner. RSI-derived parameters: fast and slow apparent diffusion coefficient (sADC), fractional anisotropy, restricted fractional anisotropy, neurite density (ND), cellularity, extracellular water fraction, and free water fraction, were obtained in white matter lesions (WML) and normal appearing white matter (NAWM). Patients were divided into three groups according to their expanded disability status scale (EDSS): with minimal, low, and substantial disability (<2.5, 2.5-3, and >3, respectively). Group comparisons and correlation analyses were performed.

RESULTS

All tested RSI-derived parameters differed between WML and NAWM ( p < 0.001 for all pairwise comparisons). The sADC in WML showed largest difference across disability subgroups (analysis of variance (ANOVA): F = 5.1, η² = 0.12, p = 0.008). ND in NAWM showed strongest correlation with disability (ϱ = -0.39, p < 0.001).

CONCLUSION

The strongest correlation with EDSS of ND obtained in NAWM indicates that processes outside lesions are important for disability in MS. Our study suggests that RSI-derived parameters may help understand the "clinico-radiological paradox" and improve disease monitoring in MS.

Diffusion-weighted imaging of normal appearing corticospinal tracts in patients with multiple sclerosis

Aim To determine if there are differences in ADC values between normal appearing corticospinal tracks in patients with MS compared to ADC values in controls. Material and methods The study population comprised 62 consecutive MS patients (36 women and 26 men; mean age 36.45±8.63 years). 50 control subjects with no neurological disabilities or intracranial were included the study (32 women and 18 men; mean age 40.18±12.25 years). All ADC maps were independently evaluated by two experienced radiologists. ROI of approximately 15-18 mm² in capsula interna and 10-12 mm² in mesencephalon were placed bilaterally for measurement of ADC values. Three circular ROIs were placed-one each side for internal capsule-and 6 total ROIs from right and left internal capsule were averaged for each patient. Mesencephelon ADC measurements were performed similarly. Result The mean ADC values of the left internal capsule in MS patients were significiantly lower than the control group (p:0.002). No statistically significant difference was found between the MS patients and control group mean ADC values of the right internal capsule (p>0.05). The mean ADC values of the right and left mesencephalon in MS patients were significiantly lower than the control group (respectively; p:0.031, p<0.001). The mean ADC values of the left internal capsule were significiantly lower than the right internal capsule in MS patients (p<0.001). The mean ADC values of the left mesencephalon were significiantly lower than the right mesencephalon in MS patients (p<0.001). Conclusion The mean ADC values of the normal-appearing corticospinal tract in MS patients were significantly lower than the control group except for the right internal capsule.

Hemolytic Uremic Syndrome-associated Encephalopathy Successfully Treated with Corticosteroids

The encephalopathy that occurs in association with hemolytic uremic syndrome (HUS), which is caused by enterohemorrhagic Escherichia coli (E. coli), has a high mortality rate and patients sometimes present sequelae. We herein describe the case of a 20-year-old woman who developed encephalopathy during the convalescent stage of HUS caused by E.coli O26. Hyperintense lesions were detected in the pons, basal ganglia, and cortex on diffusion-weighted brain MRI. From the onset of HUS encephalopathy, we treated the patient with methylprednisolone (mPSL) pulse therapy alone. Her condition improved, and she did not present sequelae. Our study shows that corticosteroids appear to be effective for the treatment of some patients with HUS encephalopathy.

The relationship between cognitive function and high-resolution diffusion tensor MRI of the cingulum bundle in multiple sclerosis

BACKGROUND

Imaging can provide noninvasive neural markers of disease progression in multiple sclerosis (MS) that are related to behavioral and cognitive symptoms. Past work suggests that diffusion tensor imaging (DTI) provides a measure of white matter pathology, including demyelination and axonal counts.

OBJECTIVES

In the current study, the authors investigate the relationship of DTI measures in the cingulum bundle to common deficits in MS, including episodic memory, working memory, and information processing speed.

METHODS

Fifty-seven patients with MS and 17 age- and education-matched controls underwent high-spatial resolution diffusion scans and cognitive testing. Probabilistic tracking was used to generate tracks from the posterior cingulate cortex to the entorhinal cortex.

RESULTS

Radial and axial diffusivity values were significantly different between patients and controls (p < 0.031), and in patients bilateral diffusion measures were significantly related to measures of episodic memory and speed of processing (p < 0.033).

CONCLUSIONS

The tractography-based measures of posterior cingulum integrity reported here support further development of DTI as a viable measure of axonal integrity and cognitive function in patients with MS.