[Magnetomyography with the SQUID]

The results of investigations of the neuromuscular system in man using a SQUID magnetometer with a second-order gradiometer detector are presented. After electrical stimulation of the tibial nerve in the hollow of the knee and the triggering of a monosynaptic proprioceptic reflex (Hoffmann-(H-)reflex), the biomagnetic field was recorded from the dorsal surface of the lower leg (soleus muscle of the m. triceps surae). The results obtained indicate that, over and beyond the data provided by electromyography, diagnostic information is provided on the state of the neuronal reflex pathways including muscle effector function. The biomagnetic field was evaluated in terms of latency, intensity, composition, characteristic behaviour and site of generation of the signal. In the geometry used, this noninvasive measuring technique can be employed for office observation of the spread of excitation through the muscle, as demonstrated by the response obtained following supramaximal stimulation of the supply nerve.