Is the walk ratio a window to the cerebellum in multiple sclerosis? A structural magnetic resonance imaging study.

BACKGROUND AND PURPOSE: Existing research studies have demonstrated a relationship between magnetic resonance imaging (MRI) neuroimaging measures and walking speed in people with multiple sclerosis (PwMS). However, to date there are no data as to the brain structures involved in gait coordination and control in PwMS. Therefore, the aim of our study was to investigate the association between walk ratio, an indicator of gait coordination, and related brain structures in PwMS. METHODS: A brain MRI was performed by a 3.0-T MR scanner in conjunction with a volumetric analysis based on three-dimensional T1-weighted images. Regions of interest were volumes of the hippocampus, amygdala, putamen, caudate, pallidum, thalamus, cerebellum and the corpus callosum regions. Walking speed and walk ratio, defined as step length divided by step rate, was measured whilst walking on an electronic walkway. RESULTS: In all, 343 PwMS (41.1 ± 13.4 years, 69.1% female, median Expanded Disability Status Scale 2.5) were included in the study. A significant association was found between the left cerebellum volume and walk ratio after controlling for age, gender, total cranial volume and disability; R2  = 0.379, P = 0.002. A similar association was found between the right cerebellum volume and walk ratio, R2  = 0.364, P = 0.002. No correlations were observed between walk ratio and the thalamus, basal ganglia, hippocampus, amygdala and the corpus callosum volumes. No association was found between walking speed and all brain measures. CONCLUSIONS: The walk ratio should be considered when evaluating and assessing PwMS presenting with ataxia. Furthermore, it is also hypothesized that a low walk ratio indicates a lower cerebellum volume in the MS population.

Characterizing neutral modes of fractional states in the second Landau level.

Fractionally charged quasiparticles, which obey non-abelian statistics, were predicted to exist in the ν=8/3, ν=5/2, and ν=7/3 fractional quantum Hall states (in the second Landau level). Here we present measurements of charge and neutral modes in these states. For both ν=7/3 and ν=8/3 states, we found a quasiparticle charge e=1/3 and an upstream neutral mode only in ν=8/3-excluding the possibility of non-abelian Read-Rezayi states and supporting Laughlin-like states. The absence of an upstream neutral mode in the ν=7/3 state also proves that edge reconstruction was not present in the ν=7/3 state, suggesting its absence also in ν=5/2 state, and thus may provide further support for the non-abelian anti-pfaffian nature of the ν=5/2 state.

Observation of a quarter of an electron charge at the nu = 5/2 quantum Hall state.

The fractional quantum Hall effect, where plateaus in the Hall resistance at values of h/nue2 coexist with zeros in the longitudinal resistance, results from electron correlations in two dimensions under a strong magnetic field. (Here h is Planck's constant, nu the filling factor and e the electron charge.) Current flows along the sample edges and is carried by charged excitations (quasiparticles) whose charge is a fraction of the electron charge. Although earlier research concentrated on odd denominator fractional values of nu, the observation of the even denominator nu = 5/2 state sparked much interest. This state is conjectured to be characterized by quasiparticles of charge e/4, whose statistics are 'non-abelian'-in other words, interchanging two quasiparticles may modify the state of the system into a different one, rather than just adding a phase as is the case for fermions or bosons. As such, these quasiparticles may be useful for the construction of a topological quantum computer. Here we report data on shot noise generated by partitioning edge currents in the nu = 5/2 state, consistent with the charge of the quasiparticle being e/4, and inconsistent with other possible values, such as e/2 and e. Although this finding does not prove the non-abelian nature of the nu = 5/2 state, it is the first step towards a full understanding of these new fractional charges.

Understanding autoimmune mechanisms in multiple sclerosis using gene expression microarrays: treatment effect and cytokine-related pathways.

Multiple sclerosis (MS) is a central nervous system disease in which activated autoreactive T-cells invade the blood brain barrier and initiate an inflammatory response that leads to myelin destruction and axonal loss. The etiology of MS, as well as the mechanisms associated with its unexpected onset, the unpredictable clinical course spanning decades, and the different rates of progression leading to disability over time, remains an enigma. We have applied gene expression microarrays technology in peripheral blood mononuclear cells (PBMC) to better understand MS pathogenesis and better target treatment approaches. A signature of 535 genes were found to distinguish immunomodulatory treatment effects between 13 treated and 13 untreated MS patients. In addition, the expression pattern of 1109 gene transcripts that were previously reported to significantly differentiate between MS patients and healthy subjects were further analyzed to study the effect of cytokine-related pathways on disease pathogenesis. When relative gene expression for 26 MS patients was compared to 18 healthy controls, 30 genes related to various cytokine-associated pathways were identified. These genes belong to a variety of families such as interleukins, small inducible cytokine subfamily and tumor necrosis factor ligand and receptor. Further analysis disclosed seven cytokine-associated genes within the immunomodulatory treatment signature, and two cytokine-associated genes SCYA4 (small inducible cytokine A4) and FCAR (Fc fragment of IgA, CD89) that were common to both the MS gene expression signature and the immunomodulatory treatment gene expression signature. Our results indicate that cytokine-associated genes are involved in various pathogenic pathways in MS and also related to immunomodulatory treatment effects.

Long-term morbidity and mortality after spinal cord injury: 50 years of follow-up.

OBJECTIVE: To determine the long-term mortality rate and the types of morbidity among all people with spinal cord injuries (SCI) that occurred during the 1948 Israel War of Independence. METHOD: Chart review and telephone interviews for collecting demographic data, injury characteristics, marital status, physical activities, employment, morbidity and mortality. RESULTS: Twenty individuals with SCI (19 males, one female). There was no regular follow-up during the first 20 years post injury. The most frequent morbidities were genito-urinary, cardiovascular and decubiti. Ten (50%) had died during this overall follow-up interval. The average age at death was 60 years. The cause of death was cardiovascular in six, neoplastic disease in two, pneumonia in one, and one died from an unknown cause. CONCLUSIONS: The data analysis showed that those who died participated less in physical activity and fewer were employed as compared to the survivors.

Postsurgical prevertebral abscess of the cervical spine.

OBJECTIVES: Prevertebral abscess formation is an uncommon occurrence following cervical spine fusion surgery. Abscesses may present early or in a delayed fashion and require surgical drainage and long-term antibiotic treatment. The issues of osteomyelitis and the need for plate removal remain unresolved. STUDY DESIGN: A case series of six tetraplegic patients admitted for rehabilitation to the Chaim Sheba Medical Center (Tel Hashomer, Israel) is presented. METHODS: Five patients were trauma patients; one patient underwent repeated procedures and irradiation for tumor of the cervical spine. All patients developed prevertebral abscesses after a mean period of 30 days from their fusion surgery. Computed tomography scan was used in all patients to establish the diagnosis and define the extent of the infective process. All patients underwent one or more drainage procedures. The plate was removed in two patients at 1 and 4 months. RESULTS: Infection completely resolved in four patient and was refractory in one patient with malignant tumor, and a chronic small fistula remained in one case. Staphylococcus aureus was the main infective organism, but mixed infections were the rule. Even for a protracted course of infection, no significant osteomyelitis was encountered. CONCLUSIONS: Abscess formation after instrumentation of the neck may be more common than formerly recognized. Despite the prolonged course of disease and treatment, osteomyelitis is not a major concern. There is no automatic indication for plate removal to control infection, although plating may be safely removed after 10 to 12 weeks if the neck is explored and the cervical spine is stable. A high index of suspicion is warranted, and early recognition and diagnosis, prompt surgical drainage under general anesthesia, and long-term antibiotic treatment are key for eradication of the infective process. Prophylactic antibiotics may be of value. Meticulous antisepsis and surgical technique should be maintained to reduce the incidence of these severe complications.