The innervation of extensor hallucis longus muscle:  an anatomical study for selective neurotomy.
OBJECTIVE
This study is aimed to describe the observable anatomical variants of the innervation of extensor hallucis longus muscle (EHLM) in order to have the surgical coordinates to perform neurotomy on the targeted branches of its innervation and to give a valuable alternative to the commonly used technique of fascicular subepineurial neurotomy in patients affected by toe hyperextension dystonia.


METHODS
In 15 fresh cadavers of adults, 29 lower limbs (14 right and 15 left) were studied. Anatomical dissections to isolate the innervating branches of EHLM were performed. Each branch from EHLM was analyzed by microscopical opening of the epineurium to observe the number of nerve fascicles. Various measurements were made to obtain anatomical coordinates for surgery.


RESULTS
The distance between the most prominent point of the head of the fibula and the origin of the nervous branches innervating the EHLM is not proportional to the length of the leg. In 72.4% of the studied legs, the distance between the origin of the first branch innervating the EHLM and the origin of the deep peroneal nerve is 7 +/- 2 cm. In 80% of legs, the distance between the origin of the second branch and the origin of the deep peroneal nerve is 10 +/- 1.1 cm. In only one limb with double innervation, two fascicles were found, while in six limbs (25%) only one fascicle was found.


CONCLUSIONS
This anatomical study traced some valuable surgical coordinates useful for the execution of a selective peripheral neurotomy on the nerve branch innervating the EHLM.
Vittoria
Nazzi
N
Department of Neurosurgery, Fondazione IRCCS-Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy.
Giuseppe
Messina
M
Ivano
Dones
D
Giovanni
Broggi
B
D000368:Aged; D000369:Aged, 80 and over; D004210:Dissection / Q000379:methods; D005260:Female; D006801:Humans; D007866:Leg / Q000294:innervation*; D008297:Male; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation*; D016067:Nerve Transfer / Q000379:methods*; D010525:Peripheral Nerves / Q000601:surgery; D010543:Peroneal Nerve / Q000033:anatomy & histology* / Q000601:surgery*; D014034:Toes / Q000294:innervation*