Selective feedback control of spastic musculature in a canine model.
Muscular spasm, the etiology of which remains elusive, has been difficult to control. The authors, therefore, proposed selective restraint of forced contractions by a closed-loop circuit. In four dogs, the strap (n = 6) and thyroarytenoid (n = 4) muscles were submitted to tetanic contractions via bipolar supramaximal stimulation (30 Hz, 6 mA, 0.5 msec) of ansa hypoglossi and recurrent laryngeal nerves, respectively. Subsequent reduction of distance between two sonomicrometer crystals embedded into muscle was used in lieu of "spastic information" for a stimulator to deliver blocking signals through tripolar electrodes passed downstream. By modifying frequency (30-110 Hz) and current (60-95%) distribution between the central cathode and the peripheral anodes, significant relaxation (up to 100%) was recorded within "blocking windows," varying with each nerve (3-18 mA sweeps). The selective restraint of unwanted contractions, leaving "normal" subthreshold tone undisturbed, may offer a more mature approach to spastic disorders than destructive procedures, such as nerve section and its chemical counterpart, botulinum toxin injection.
Broniatowski
M
M
Department of Otolaryngology, Cleveland Clinic Foundation, Ohio.
Azar
K
K
Davies
C R
CR
Jacobs
G B
GB
Tucker
H M
HM
D000200:Action Potentials; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004558:Electric Stimulation; D005246:Feedback; D007821:Laryngeal Muscles / Q000294:innervation / Q000503:physiopathology; D009119:Muscle Contraction / Q000502:physiology; D009128:Muscle Spasticity / Q000503:physiopathology / Q000628:therapy*; D009469:Neuromuscular Junction / Q000503:physiopathology