PARALYSIS OF THE OBTURATOR NERVE 173 



been frequently seen, and has been attributed to various causes, such, tor 

 instance, as the pressure of a tumour which had formed on the course 

 ot the nerve, &c. 



For the first rational connection of the effect with its cause in this 

 country we are indebted to the observations of W. Willis, who in 1903 

 described two cases of paralysis of this nerve due to the pressure of a 

 callus formed as the result of fracture of the pubic bone in front of the 

 obturator foramen. The cases were first diagnosed as fractured pelvis. 

 A careful examination through the vagina revealed the presence of a soft 

 swelling at the seat of the fracture in front of the foramen, which later on 

 became very much harder. Regarding the alteration in the conformation 

 of the muscles supplied by the nerve, much less assistance to diagnosis in 

 this respect is rendered in the case of obturator paralysis than in paralysis 

 of most other nerves, since the muscles, even when well developed, do 

 not form very well-marked elevations, and present a more or less flattened 

 appearance. When they become atrophied, therefore, there is not such 

 a pronounced difference in the contour of the part as we find, for instance, 

 in the parts supplied by the anterior crural and musculo-spiral nerves 

 when these nerves are paralysed. During the earlier stages the animal 

 can both abduct and adduct the limb, but the latter power becomes 

 gradually lost, the period elapsing coinciding with that required for the 

 formation of the callus. In the later stages there may be observed a falling 

 away in bulk of the muscles on the inner aspect of the thigh, the skin 

 covering the gracilis particularly appearing very much relaxed ; a fold of 

 skin may easily be grasped with the hand. As during the healing of the 

 fracture the callus becomes condensed and diminishes in size, the want 

 of power of adduction becomes less marked, and is gradually regained, 

 and after a period of about three months the muscles appear to be able 

 to carry out their functions again. 



Regarding the treatment, therefore, we find that complete rest for a 

 prolonged period is indicated, and nerve tonics, such as strychnine, should 

 be administered periodically. 



