ABSTRACT
KANDID is an advanced EMG decision support system dedicated to the support of the clinical neurophysiologist during EMG examinations. It has facilities for test planning, automatized and structured data interpretation, EMG diagnosis, explanation, and reporting. In a prospective European multicenter field trial, the agreement levels between clinical neurophysiologists and KANDID's diagnostic statements were measured under ordinary clinical EMG practice. KANDID was assessed in 159 individual patient EMG examinations by nine clinical neurophysiologists at seven different EMG laboratories. The reasoning of KANDID was considered understandable for the examiners in 80-90% of cases. The agreement level for the electrophysiological states of muscles and nerves between KANDID and the individual examiners was, on average, 81%. The corresponding diagnostic agreement with KANDID was, on average, 61%. A pronounced interexaminer variation in the agreement level related to the different EMG centers was observed. All Danish and Belgian examiners agreed with KANDID in more than 50% of their cases with regard to the EMG diagnosis, while the English examiners were in agreement with KANDID in 50% or less of their cases. These differences were possibly due to differences in epidemiology, examination techniques, control material, and examination planning strategies. It is concluded that it is possible to transfer systems like KANDID out of their development sites and apply them successfully if they can be locally customized by the clinical end users via editors.
Subject(s)
Decision Making, Computer-Assisted , Diagnosis, Computer-Assisted , Electromyography , Neuromuscular Diseases/physiopathology , Humans , Observer Variation , Prospective StudiesABSTRACT
A technique of quantitative EMG suitable for use in babies and young children is described. No specific level of force is required and portions of EMG as short as 100 ms are suitable for analysis. A specially modified Medelec APA6 action potential analyser converted the EMG into two pulse trains representing amplitude pulses and turns pulses with a display on the CRT screen. The ratio of the mean amplitude/turns per second was determined for between 15 and 20 different portions of EMG to produce a Mean Ratio of mean amplitude/turns per second. Ninety-seven children were investigated for neuromuscular disease. Twenty-two had a primary muscle disease, 21 a neurogenic process and 25 no neuromuscular disease. This last group was called the Apparent control group. The problem of obtaining control values is discussed. A 5-year follow-up study found no change in the clinical diagnosis of the patients in the 3 groups. Numerical limits for the Mean Ratio of mean amplitude/turns per second for the Apparent control group are defined.
Subject(s)
Child Development , Electromyography/methods , Neuromuscular Diseases/diagnosis , Adolescent , Child , Child, Preschool , Diagnosis, Differential , Follow-Up Studies , Humans , Infant , Muscle Contraction , Neural ConductionABSTRACT
Weak electrical stimuli were applied to sensory fibers of the median nerve at the wrist, and the ascending action potentials were recorded at the elbow. This was done with or without a preceding conditioning stimulus to test for supernormal excitability to the second stimulus. In the resting nerve, supernormal excitability was present from 3 to 20 msec after a conditioning shock. After a period of ischemia, excitability was both exaggerated and prolonged. This observations confirms the presence in sensory fibers of a phenomenon previously described in motor fibers.
Subject(s)
Ischemia/physiopathology , Median Nerve/physiopathology , Neural Conduction , Neurons, Afferent/physiology , Action Potentials , Evoked Potentials , Humans , Time Factors , Ulnar Nerve/physiopathologyABSTRACT
Spike and wave activity is detected by analogue circuitry which separately filters the spike and the slow wave components from the EEG. The filter outputs are converted to DC voltages, which are then compared with individually adjusted threshold voltages. A detector output pulse is produced when both the spike and the wave threshold levels are exceeded. A graph of the incidence of spike and wave activity per 15 min intervals over 24 h is plotted by a microcomputer and modified impact printer. The analysis is carried out at 60 times real time on EEG recordings obtained from unrestrained patients using a portable cassette-tape recorder.
Subject(s)
Electroencephalography/instrumentation , Monitoring, Physiologic/instrumentation , Epilepsy/diagnosis , Humans , MicrocomputersABSTRACT
Mechanisms involved in maintaining bulk and strength in partially denervated muscles of patients with neurogenic lesions are discussed. Estimation of muscle fiber hypertrophy by electrophysiological examination is possible, but it depends on the construction of sampling electrodes with precise geometry. The arrangement of muscle fibers of motor units within the muscle is discussed by analogy with the four-color map problem. An experiment to measure the twitch tensions of individual motor units in man is devised; it requires the use of microprocessor control of the stimulus and recurrent measurements of the twitch forces.
Subject(s)
Muscles/pathology , Neuromuscular Diseases/pathology , Animals , Humans , Hypertrophy , Muscle Contraction , Neuromuscular Diseases/physiopathology , Rabbits , RatsABSTRACT
In 14 patients with wasting of the hand due to a cervical rib and band, motor and sensory conduction studies on the peripheral parts of the median and ulnar nerves were helpful in establishing the correct diagnosis. The median nerve findings excluded carpal tunnel syndrome even when the clinical pattern of wasting in the hand suggested this diagnosis. Preservation of conduction velocity in the ulnar nerve excluded ulnar entrapment at the elbow; the reduced amplitude of the ulnar sensory action potentials (SAPs) indicated that the lesion was distal to the dorsal root ganglia. In 3 patients with ulnar SAP amplitudes that were low but not clearly abnormal, the level of the lesion was confirmed by a reduced response to intradermal injection of histamine on the inner side of the forearm.
Subject(s)
Cervical Rib Syndrome/physiopathology , Neural Conduction , Thoracic Outlet Syndrome/physiopathology , Action Potentials , Adolescent , Adult , Electromyography , Electrophysiology , Female , Hand , Humans , Male , Median Nerve/physiopathology , Middle Aged , Muscular Atrophy/etiology , Muscular Atrophy/physiopathology , Ulnar Nerve/physiopathologyABSTRACT
The technique of automatic analysis of the electromyogram has been applied to patients with chronic partial denervation due to a wide variety of causes. Elevation of the mean amplitude more than 2 SD above the control group mean without significant change in the mean turns count was a consistent index of chronic partial denervation. The degree of elevation was linked to the severity of the weakness in motor neurone disease. Elevation of mean amplitude of comparable degree was found in patients with motor neuropathies of long duration. The elevation of mean amplitude is considered to be due to increase in the density of muscle fibres in the motor units due to reinnervation.
