METHOD OF SECURING CEREBROSPINAL FLUID 39 



omitted, two or three coats of the iodin . being sufficient. After the 

 fluid has been secured, the iodin may be removed with alcohol and 

 gauze. The operator's hands should be cleansed carefully and washed 

 in alcohol and bichlorid solution or weak formalin, or he may put on 

 sterilized rubber gloves before handling the needle and performing the 

 operation itself. 



Anesthesia. In the majority of instances an anesthetic is not 

 necessary. In tabes dorsalis and general paralysis (two conditions 

 most frequently requiring spinal puncture) the operation is peculiarly 

 painless. Sick children are apparently not greatly disturbed, but in 

 adults it may be necessary to infiltrate the skin about the site of punc- 

 ture with 1 per cent, eucain (sterile) or cocain solution. Ethyl chlorid is 

 much less satisfactory, except for the mental effect it has upon the 

 patient. Children may receive a few drops of ether. With nervous 

 patients it is good practice to obviate nervous shock by adopting a few 

 simple precautions against causing unnecessary pain. 



Technic of Lumbar Puncture. The patient may either sit in a 

 chair and bend forward, or lie on the left side on the edge of a bed or 

 table. In the case of sick persons, particularly children, the latter 

 position is necessary; it is also advisable with nervous patients, as they 

 are likely to bend backward suddenly or jump up when the needle is 

 inserted, and I have known the needle to be broken off at such a time. 

 (See p. 752.) The back should be arched backward, the patient bend- 

 ing forward, and the knees being drawn up over the abdomen. 



The needle should be made of flexible, not rigid, material; for adults, 

 a needle 10 cm. long, having a bore of 1 to 1.5 mm. and furnished with a 

 stilet, will be found satisfactory. For children, a shorter needle may be 

 used, but the bore should be about the same as that used for adults. 

 The needle should be sterilized carefully by boiling in water for several 

 minutes. 



The operator now selects a "soft spot" for puncture. By running 

 the finger along the spines of the vertebrae, this will be found to be be- 

 tween the third and fourth lumbar spinous processes, about on a level 

 with the posterior superior spines of the ilia. The needle is grasped 

 firmly and inserted with a sudden thrust, exactly in the median line, 

 and straight forward. The thrust should be sufficient to push the 

 needle through the skin and muscles into the spinous ligaments; it 

 may then be inserted more slowly, a sudden "give way" indicating 

 that the canal has been entered (Fig. 18). This route is better than the 

 lateral route, as there is less danger of striking vertebral processes or 



