Abnormal parameters of magnetically evoked motor-evoked potentials in patients with cervical spondylotic myelopathy
ABSTRACT Magnetic stimulation (MS), which is used to evaluate motor pathways, is helpful in evaluating cervical spinal cord compression (cervical myelopathy [CM]). Previous studies have shown that the central motor conduction time (CMCT), which is the time taken for the nerve impulses to reach the cervical spinal roots after the stimulation of the motor cortex, is prolonged in CM. However, the duration of motor-evoked potentials (MEPs) in CM has not been studied in detail.
To compare the duration, CMCT and amplitude of MEPs by MS between patients with clinical and magnetic resonance imaging (MRI) features of CM and a control group.
A cross-sectional study done at Teaching Hospital, Peradeniya, Sri Lanka.
Consecutive patients with clinical features of cervical spondylotic myelopathy, without coexisting neurological abnormality.
Transcranial and cervical spinal magnetic stimulation were performed on 21 patients with clinical and MRI features of spondylotic CM (mean age, 43.5years; range, 36-63 years; 9 men) and 17 healthy volunteers (mean age, 39.05 years; range, 23-54yrs; 6 males) using a circular coil with a Magstim 200 stimulator. MEPs were recorded over abductor digiti minimi muscle on both hands.
Seventeen patients had upper motor neuron (UMN) features in all four limbs; in the others, both lower limbs and one upper limb were affected. The upper limbs with UMN features had shorter duration MEPs compared with the control group. The CMCT and the total motor conduction time were also delayed in the CM group. All three differences were very highly significant (t=5.75, -3.76, 5.27; p<.001). The amplitudes showed no significant difference between the two groups (t=1.27, p=.208).
This study shows that in addition to the CMCT, the duration of MEPs is also useful in evaluating patients with CM using MS.
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ABSTRACT: Study Design. Prospective cohort studyObjective. To assess the correlation between central motor conduction time (CMCT) and various subjective and objective clinical assessment measures in patients with cervical spondylotic myelopathy (CSM) undergoing decompressive surgerySummary of Background Data. CSM can cause a spectrum of neurological deficits across individuals. Subjective clinical assessments of disease severity may lack the sensitivity of objective tests. Transcranial magnetic stimulation (TMS) provides objective electrophysiologic data on the integrity of the corticospinal tracts, which may be useful for monitoring disease progression or neurological improvement after surgery.Methods. Patients undergoing surgical decompression for CSM performed subjective and objective testing before surgery and at 1, 3, 6 and 12 months after surgery. Subjective measures included modified Japanese Orthopaedic Assessment (mJOA), Neck Disability Index (NDI), Nurick grade, and visual analog scale (VAS) score. Objective measures included CMCT as measured using TMS, the 10-meter walk test (10MWT), the 9-hole peg task (9HPT), and grip and release test (GRT). Primary outcome was the correlation between CMCT and subjective or objective measures at preoperative and postoperative time points. Secondary outcome was the correlation between preoperative CMCT and performance in subjective or objective testing after surgical intervention.Results. Improvement in both subjective and objective measures was observed after surgery. CMCT correlated with other objective measures (10MWT, 9HPT, and GRT) both at baseline and after decompressive surgery in these 17 patients with CSM. Patients with high baseline CMCTs were associated with poor performance on the 10MWT, 9HPT, and GRT. mJOA correlated with CMCT at baseline but not after surgical intervention. CMCT was not associated with other subjective measures, such as NDI, Nurick grade, and VAS, at preoperative or postoperative time points.Conclusion. CMCT as measured by TMS is a responsive objective assessment of CSM. It can be used to monitor disease severity and neurological function before and after surgical intervention. Prolonged baseline CMCT may be associated with worse surgical outcomes.Spine 04/2014; 39(14). DOI:10.1097/BRS.0000000000000358 · 2.45 Impact Factor
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ABSTRACT: Magnetic stimulation is a non-invasive and painless technique for studying the motor pathways in medical neurology. A time-varying magnetic field induces an electrical field in conducting objects, such as nervous tissue. The technique can be applied to nerve roots and peripheral nerves or to the motor cortex of the brain in human and veterinary medicine. In this review, the basic principles, applications and risk factors of peripheral nerve and motor cortex stimulation in human and veterinary medicine are discussed.The Veterinary Journal 02/2011; 187(2):174-81. DOI:10.1016/j.tvjl.2009.12.008 · 2.17 Impact Factor
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ABSTRACT: Based on reports published so far, organophosphorus (OP) compounds do remarkable harm to human health. In 1995 there was an outbreak of organophosphorus-ester induced delayed neuropathy (OPIDN) due to tri-ortho-cresyl phosphate (TOCP) poisoning in northern suburbs of Xi'an in China. The 74 affected patients were treated and followed up after definite diagnosis. 13 years later, all the epidemiological data obtained from 61 survivors were evaluated, and 15 patients underwent clinical, laboratory, neuroimaging and electrophysiological examinations. In addition, a review of the literature about the possible mechanism of OPIDN was made. According to our investigation, of 61 survivors, 35 patients almost regained normal function of limbs and work outside; 23 patients walked with bilateral support and could perform housework; and 3 patients could not self-care. The patients undergoing examinations presented spasticity and minor lower leg muscle atrophy without sensory impairment. Laboratory investigations and brain and spinal cord magnetic resonance imaging examinations were normal. Neurophysiological investigations also showed normal electroencephalogram and visual, brainstem auditory and somatosensory evoked potentials. Motor evoked potential (MEP) obtained from the upper limbs had normal central motor conduction time (CMCT). However, the CMCT of MEP response recorded from the bilateral lower limbs was delayed, or showed even no MEP responses. Motor and sensory nerve conduction velocity and electromyography studies were normal except for two severely affected patients. TOCP showed long-term effects on the nervous system and influenced the quality of life. OP compounds should be strictly regulated to prevent similar occurrences.NeuroToxicology 08/2009; 30(6):1084-7. DOI:10.1016/j.neuro.2009.06.006 · 3.05 Impact Factor