Evaluation of motor neuron excitability by CMAP scanning with modulated current

It is important to have better evaluation and understanding of the motor neuron physiology, with the goal to early and objectively diagnose and treat patients with neurodegenerative pathologies. The Compound Muscle Action Potential (CMAP) scan is a non-invasive diagnosis technique for neurodegenerative pathologies, such as ALS, and enables a quick analysis of the muscle action potentials in response to motor nerve stimulation. This work aims to study the influence of different pulse modulated waveforms in peripheral nerve excitability by CMAP scan technique on healthy subjects. A total of 13 healthy subjects were submitted to the same test. The stimuli were applied in the medium nerve on the right wrist and electromyography signal collected on the Abductor Pollicis Brevis (APB) muscle surface on the right thumb. Stimulation was performed with an increasing intensities range from 4 to 30 mA, with varying steps, 3 stimuli per step. The procedure was repeated 4 times per subject, each repetition using a different single pulse stimulation waveform: monophasic square, monophasic triangular, monophasic quadratic and biphasic square. Results were retrieved from the averaging of the stimuli on each current intensity step. The square pulse needs less current intensity to generate the same response amplitude regarding the other waves and presents a more steep curve slope and this effect is gradually decreasing for the triangular and quadratic pulse,respectively, being the difference even more evident regarding the biphasic pulse. The control of the waveform stimulation pulse allows varying the stimulusresponse curve slope.

Risk factors for physical disability at diagnosis of 19,283 new cases of leprosy

INTRODUCTION: The purpose of this study was to evaluate risk factors for physical disability at the moment of leprosy diagnosis. METHODS: This is a retrospective, descriptive and exploratory investigation of 19,283 patients with leprosy, registered in the State of Minas Gerais, Brazil, between 2000 and 2005. RESULTS: The risk of Grade 2 disability was 16.5-fold higher in patients with lepromatous leprosy, and 12.8-fold higher in patients presenting the borderline form, compared to patients presenting indeterminate leprosy. The occurrence of more than one thickened nerve increased the odds of a patient developing Grade 2 disability, 8.4-fold. Age <15 years, multibacillary leprosy and no formal education presented 7.0, 5.7 and 5.6 odds of developing physical disability, respectively. CONCLUSIONS: These factors should be considered as strong prognostic indicators in the development of physical disability at diagnosis.