Interest of peripheral anesthetic blocks as a diagnosis and prognosis tool in patients with spastic equinus foot: a clinical and electrophysiological study of the effects of block of nerve branches to the triceps surae muscle.
OBJECTIVE
To evaluate clinically and electrophysiologically the effects of selective anesthetic blocks of motor nerve branches to the triceps surae muscle on lower limb stretch reflex in patients with spastic equinus foot.


METHODS
Eleven patients were assessed before and after selective anesthetic block of the superior soleus nerve or the gastrocnemius nerves, performed by lidocaine injection. The stretch reflex (SR) of the ankle with the knee flexed or extended and the Achilles tendon reflex (TR) were scored clinically. Additionally, the direct M response and the H reflex to tibial nerve stimulation were recorded on the three heads of the triceps surae muscle. The ratio of H reflex to M response of maximal amplitudes (H(max)/M(max)) was calculated.


RESULTS
The SR and TR mean scores were significantly reduced after soleus nerve block but not after gastrocnemius nerve block. Electrophysiologically, H(max) and H(max)/M(max) ratios were significantly reduced for the soleus muscle after soleus nerve block and for the lateral (but not medial) gastrocnemius muscle after gastrocnemius nerve block.


CONCLUSIONS
Soleus nerve block appeared more appropriate than gastrocnemius nerve block to relieve spasticity clinically. In addition, the decrease in H(max)/M(max) ratio suggested that lidocaine preferentially blocked proprioceptive Ia fibers rather than A-alpha motor fibers.


CONCLUSIONS
Selective anesthetic blocks of nerve branches to the triceps surae muscle are useful in the assessment of lower limb spasticity and can benefit from H reflex investigation. H reflex recordings showed a preferential susceptibility of muscle spindle afferents to local anesthetics and supported the hypothesis of a prominent role of the soleus muscle in spastic ankle. The clinical and electrophysiological effects induced by anesthetic blocks may help to guide therapeutic interventions, such as neurotomy, neurolysis or botulinum toxin injection.
Buffenoir
Kevin
K
Service de Neurochirurgie, Hôpital Henri Mondor, Assistance Publique-Hôpitaux de Paris, Créteil, France.
Decq
Philippe
P
Lefaucheur
Jean-Pascal
JP
D000293:Adolescent; D000328:Adult; D000368:Aged; D000779:Anesthetics, Local / Q000494:pharmacology; D002648:Child; D004558:Electric Stimulation; D004576:Electromyography; D004863:Equinus Deformity / Q000150:complications*; D005260:Female; D006181:H-Reflex / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology; D009128:Muscle Spasticity / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D009470:Muscle Spindles / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D009407:Nerve Block / Q000379:methods; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D011237:Predictive Value of Tests; D012026:Reflex, Stretch / Q000187:drug effects / Q000502:physiology; D013979:Tibial Nerve / Q000187:drug effects* / Q000503:physiopathology
D000779:Anesthetics, Local; D008012:Lidocaine