Vitamin B12 status does not influence central motor conduction time in asymptomatic elderly people: a transcranial magnetic stimulation study.

INTRODUCTION: Vitamin B12 deficiency causes neurologic and psychiatric disease, especially in older adults. Subacute combined degeneration is characterized by damage to the posterior and lateral spinal cord affecting the corticospinal tract. OBJECTIVE: To test corticospinal tract projections using motor evoked potentials (MEPs) by transcranial magnetic stimulation (TMS) in asymptomatic older adults with low vitamin B12 (B12) levels. METHODS: Cross-sectional study of 53 healthy older adults (>70 years). MEPs were recorded in the abductor pollicis brevis and tibialis anterior muscles, at rest and during slight tonic contraction. Central motor conduction time (CMCT) was derived from the latency of MEPs and peripheral motor conduction time (PMCT). Neurophysiological variables were analyzed statistically according to B12 status. RESULTS: Median age was 74.3 ± 3.6 years (58.5% women). Twenty-six out of the 53 subjects had low vitamin B12 levels (B12 < 221 pmol/l). MEPs were recorded for all subjects in upper and lower extremities. There were no significant differences in either latency or amplitude of MEPs and CMCT between low and normal B12 groups. There was a significant PMCT delay in the lower extremities in the low B12 group (p = 0.014). CONCLUSIONS: No subclinical abnormality of the corticospinal tract is detected in asymptomatic B12-deficient older adults. The peripheral nervous system appears to be more vulnerable to damage attributable to this vitamin deficit. The neurophysiological evaluation of asymptomatic older adults with lower B12 levels should be focused mainly in peripheral nervous system evaluation.

Motor evoked potentials by transcranial magnetic stimulation in healthy elderly people.

INTRODUCTION: Transcranial magnetic stimulation (TMS) is a non-invasive, safe, and painless method for evaluating the corticospinal pathway. The population of older adults is growing, along with the prevalence of neurological diseases common to this group. Latency and amplitude of motor evoked potentials (MEPs) vary among healthy subjects and no reference normal values for MEPs in healthy older adults are available. OBJECTIVE: To create a reference value for MEPs by TMS for healthy older adults. METHODS: Descriptive study in 36 healthy 70-year-old and older subjects. A 90-mm circular coil Magstim® magnetic stimulator was applied over Cz and Fz. Recording was done in the abductor pollicis brevis and tibialis anterior muscles, at rest and during sustained tonic contraction. Central motor conduction time (CMCT) was derived from MEP latency and peripheral motor conduction time (PMCT). Values were related to age, gender, standing height, and knee height. RESULTS: Mean age was 73.3 ± 2.4 years (58% female). In the upper extremity, average MEP latency was 23.3 ± 1.9 ms at rest and 19.9 ± 1.9 ms during tonic contraction. In the lower extremity, average MEP latency was 30.6 ± 2.5 ms at rest and 27.2 ± 2.3 ms during tonic contraction. There was a significant correlation between MEP latency and standing height, greater in the lower extremities. Female gender appeared as an independent factor determining lower MEP latency, but not CMCT, in upper and lower extremities. CONCLUSION: We have provided clinically useful reference values for MEPs by TMS in healthy adults older than 70 years of age. As in the younger population, standing height is important in defining normal MEPs. The difference between genders might be due to the lower height of women.

Thymectomy for non-thymomatous myasthenia gravis.

BACKGROUND: Treatments currently used for patients with myasthenia gravis (MG) include steroids, non-steroid immune suppressive agents, plasma exchange, intravenous immunoglobulin and thymectomy. Data from randomized controlled trials (RCTs) support the use of some of these therapeutic modalities and the evidence for non-surgical therapies are the subject of other Cochrane reviews. Significant uncertainty and variation persist in clinical practice regarding the potential role of thymectomy in the treatment of people with MG. OBJECTIVES: To assess the efficacy and safety of thymectomy in the management of people with non-thymomatous MG. SEARCH METHODS: On 31 March 2013, we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL (2013, Issue 3), MEDLINE (January 1966 to March 2013), EMBASE (January 1980 to March 2013) and LILACS (January 1992 to March 2013) for RCTs. Two authors (RS and GC) read all retrieved abstracts and reviewed the full texts of potentially relevant articles. These two authors checked references of all manuscripts identified in the review to identify additional articles that were of relevance and contacted experts in the field to identify additional published and unpublished data. Where necessary, authors were contacted for further information. SELECTION CRITERIA: Randomized or quasi-randomized controlled trials of thymectomy against no treatment or any medical treatment, and thymectomy plus medical treatment against medical treatment alone, in people with non-thymomatous MG.We did not use measured outcomes as criteria for study selection. DATA COLLECTION AND ANALYSIS: We planned that two authors would independently extract data onto a specially designed data extraction form and assess risk of bias; however, there were no included studies in the review. We would have identified any adverse effects of thymectomy from the included trials. MAIN RESULTS: We did not identify any RCTs testing the efficacy of thymectomy in the treatment of MG. In the absence of data from RCTs, we were unable to do any further analysis. AUTHORS' CONCLUSIONS: There is no randomized controlled trial literature that allows meaningful conclusions about the efficacy of thymectomy on MG. Data from several class III observational studies suggest that thymectomy could be beneficial in MG. An RCT is needed to elucidate if thymectomy is useful, and to what extent, in MG.

Review of techniques useful for the assessment of sensory small fiber neuropathies: Report from an IFCN expert group.

Nerve conduction studies (NCS) are an essential aspect of the assessment of patients with peripheral neuropathies. However, conventional NCS do not reflect activation of small afferent fibers, including Aδ and C fibers. A definitive gold standard for laboratory evaluation of these fibers is still needed and therefore, clinical evaluation remains fundamental in patients with small fiber neuropathies (SFN). Several clinical and research techniques have been developed for the assessment of small fiber function, such as (i) microneurography, (ii) laser evoked potentials, (iii) contact heat evoked potentials, (iv) pain-related electrically evoked potentials, (v) quantitative thermal sensory testing, (vi) skin biopsy-intraepidermal nerve fiber density and (vii) corneal confocal microscopy. The first five are physiological techniques, while the last two are morphological. They all have advantages and limitations, but the combined use of an appropriate selection of each of them would lead to gathering invaluable information for the diagnosis of SFN. In this review, we present an update on techniques available for the study of small afferent fibers and their clinical applicability. A summary of the anatomy and important physiological aspects of these pathways, and the clinical manifestations of their dysfunction is also included, in order to have a minimal common background.

Neuropathic pain syndrome displayed by malingerers.

Among 237 patients communicating chronic pain, associated with sensory-motor and "autonomic" displays, qualifying taxonomically for neuropathic pain, there were 16 shown through surveillance to be malingerers. When analyzed through neurological methods, their profile was characteristically atypical. There were no objective equivalents of peripheral or central processes impairing nerve impulse transmission. In absence of medical explanation, all 16 had been adjudicated, by default, the label complex regional pain syndrome (CRPS). The authors emphasize that CRPS patients may not only harbor unrecognized pathology ("lesion") of the nervous system (CRPS II), hypothetical central neuronal "dysfunction" (CRPS I), or conversion disorder, but may display a recognizable simulated illness without neuropsychiatric pathology.

Surgical versus non-surgical treatment for carpal tunnel syndrome.

BACKGROUND: Carpal tunnel syndrome results from entrapment of the median nerve in the wrist. Common symptoms are tingling, numbness, and pain in the hand that may radiate to the forearm or shoulder. Most symptomatic cases are treated non-surgically. OBJECTIVES: The objective is to compare the efficacy of surgical treatment of carpal tunnel syndrome with non-surgical treatment. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group Trials Register (January 2008), MEDLINE (January 1966 to January 2008), EMBASE (January 1980 to January 2008) and LILACS (January 1982 to January 2008). We checked bibliographies in papers and contacted authors for information about other published or unpublished studies. SELECTION CRITERIA: We included all randomised and quasi-randomised controlled trials comparing any surgical and any non-surgical therapies. DATA COLLECTION AND ANALYSIS: Two authors independently assessed the eligibility of the trials. MAIN RESULTS: In this update we found four randomised controlled trials involving 317 participants in total. Three of them including 295 participants, 148 allocated to surgery and 147 to non-surgical treatment reported information on our primary outcome (improvement at three months of follow-up). The pooled estimate favoured surgery (RR 1.23, 95% CI 1.04 to 1.46). Two trials including 245 participants described outcome at six month follow-up, also favouring surgery (RR 1.19, 95% CI 1.02 to 1.39).Two trials reported clinical improvement at one year follow-up. They included 198 patients favouring surgery (RR 1.27, 95% CI 1.05 to 1.53). The only trial describing changes in neurophysiological parameters in both groups also favoured surgery (RR 1.44, 95% CI 1.05 to 1.97). Two trials described need for surgery during follow-up, including 198 patients. The pooled estimate for this outcome indicates that a significant proportion of people treated medically will require surgery while the risk of re-operation in surgically treated people is low (RR 0.04 favouring surgery, 95% CI 0.01 to 0.17). Complications of surgery and medical treatment were described by two trials with 226 participants. Although the incidence of complications was high in both groups, they were significantly more common in the surgical arm (RR 1.38, 95% CI 1.08 to 1.76). AUTHORS' CONCLUSIONS: Surgical treatment of carpal tunnel syndrome relieves symptoms significantly better than splinting. Further research is needed to discover whether this conclusion applies to people with mild symptoms and whether surgical treatment is better than steroid injection.

Pandemic influenza A (H1N1) 2009 with neurological manifestations, a case series.

OBJECTIVES: Describe a series of atypical presentations of pandemic influenza A (H1N1) 2009. METHODS: Description of case series using hospital records. RESULTS: Six patients aged 1 to 65 years with confirmed pandemic influenza A (H1N1) 2009 infection presented with neurological complications within 2 to 5 days after the first signs of influenza-like illness. All six were admitted with seizures or altered mental status. No abnormalities were found in brain scans or cerebral spinal fluid studies of any of the six. All were discharged without sequelae within days of admission. CONCLUSIONS: This is only the second report of pandemic influenza presenting with neurological manifestations. Clinicians caring for patients when pandemic influenza is prevalent in their communities should maintain a high level of awareness of the potential atypical presentations with which this disease can appear.